CDK Inhibitors Show Impressive Activity in Advanced Breast Cancer

ANNE FASSL HTTPS://ORCID.ORG/0000-0003-2777-0585YAN GENGAND PIOTR SICINSKI HTTPS://ORCID.ORG/0000-0002-8859-5234 Authors Info & Affiliations

Are Cyclin D and cdk Inhibitors A Good Target for Chemotherapy?

Posted in Biological Networks, Cancer and Current Therapeutics, CANCER BIOLOGY & Innovations in Cancer Therapy, Cell Biology, Clinical & Translational, Disease Biology, Disease Biology, Small Molecules in Development of Therapeutic Drugs, Drug Toxicity, FDA, FDA Regulatory Affairs, Pharmaceutical Discovery, Pharmaceutical Drug Discovery, tagged anti-cancer therapy, Biology, breast cancer, Cancer - General, CDER, CDK4, CDK6, cell cycle, cell cycle protein, Center for Drug Evaluation and Research, chemotherapeutic toxicity, Clinical trial, cyclin D, DNA, FDA approval, Food and Drug Administration, health, letrazole, Pfizer, research, science, serious adverse event on October 14, 2015| Leave a Comment »

Are Cyclin D and cdk Inhibitors A Good Target for Chemotherapy?

Curator: Stephen J. Williams, Ph.D.

UPDATED 7/12/2022

see below for great review

CDK4 and CDK6 kinases: From basic science to cancer therapy

SCIENCE

14 Jan 2022

Vol 375, Issue 6577

DOI: 10.1126/science.abc1495

Targeting cyclin-dependent kinases

Cyclin-dependent kinases (CDKs), in complex with their cyclin partners, modulate the transition through phases of the cell division cycle. Cyclin D–CDK complexes are important in cancer progression, especially for certain types of breast cancer. Fassl et al. discuss advances in understanding the biology of cyclin D–CDK complexes that have led to new concepts about how drugs that target these complexes induce cancer cell cytostasis and suggest possible combinations to widen the types of cancer that can be treated. They also discuss progress in overcoming resistance to cyclin D–CDK inhibitors and their possible application to diseases beyond cancer. —GKA

Structured Abstract

BACKGROUND

Cyclins and cyclin-dependent kinases (CDKs) drive cell division. Of particular importance to the cancer field are D-cyclins, which activate CDK4 and CDK6. In normal cells, the activity of cyclin D–CDK4/6 is controlled by the extracellular pro-proliferative or inhibitory signals. By contrast, in many cancers, cyclin D–CDK4/6 kinases are hyperactivated and become independent of mitogenic stimulation, thereby driving uncontrolled tumor cell proliferation. Mouse genetic experiments established that cyclin D–CDK4/6 kinases are essential for growth of many tumor types, and they represent potential therapeutic targets. Genetic and cell culture studies documented the dependence of breast cancer cells on CDK4/6. Chemical CDK4/6 inhibitors were synthesized and tested in preclinical studies. Introduction of these compounds to the clinic represented a breakthrough in breast cancer treatment and will likely have a major impact on the treatment of many other tumor types.

ADVANCES

Small-molecule CDK4/6 inhibitors (palbociclib, ribociclib, abemaciclib) showed impressive results in clinical trials for patients with hormone receptor–positive breast cancers. Addition of CDK4/6 inhibitors to standard endocrine therapy substantially extended median progression-free survival and prolonged median overall survival. Consequently, all three CDK4/6 inhibitors have been approved for treatment of women with advanced or metastatic hormone receptor–positive breast cancers. In the past few years, the renewed interest in CDK4/6 biology has yielded several surprising discoveries. The emerging concept is that CDK4/6 kinases regulate a much wider set of cellular functions than anticipated. Consequently, CDK4/6 inhibitors, beyond inhibiting tumor cell proliferation, affect tumor cells and the tumor environment through mechanisms that are only beginning to be elucidated. For example, inhibition of CDK4/6 affects antitumor immunity acting both on tumor cells and on the host immune system. CDK4/6 inhibitors were shown to enhance the efficacy of immune checkpoint blockade in preclinical mouse cancer models. These new concepts are now being tested in clinical trials.

OUTLOOK

Palbociclib, ribociclib, and abemaciclib are being tested in more than 300 clinical trials for more than 50 tumor types. These trials evaluate CDK4/6 inhibitors in combination with a wide range of therapeutic compounds that target other cancer-relevant pathways. Several other combination treatments were shown to be efficacious in preclinical studies and will enter clinical trials soon. Another CDK4/6 inhibitor, trilaciclib, is being tested for its ability to shield normal cells of the host from cytotoxic effects of chemotherapy. New CDK4/6 inhibitors have been developed and are being assessed in preclinical and clinical trials. The major impediment in the therapeutic use of CDK4/6 inhibitors is that patients who initially respond to treatment often develop resistance and eventually succumb to the disease. Moreover, a substantial fraction of tumors show preexisting, intrinsic resistance to CDK4/6 inhibitors. One of the main challenges will be to elucidate the full range of resistance mechanisms. Even with the current, limited knowledge, one can envisage the principles of new, improved approaches to overcome known resistance mechanisms. Another largely unexplored area for future study is the possible involvement of CDK4/6 in other pathologic states beyond cancer. This will be the subject of intense studies, and it may extend the utility of CDK4/6 inhibitors to the treatment of other diseases.

Targeting cyclin D–CDK4/6 for cancer treatment.

D-cyclins (CycD) activate CDK4 and CDK6 in G₁ phase of the cell cycle and promote cell cycle progression by phosphorylating the retinoblastoma protein RB1. RB1 inhibits E2F transcription factors; phosphorylation of RB1 activates E2F-driven transcription. In many cancers, CycD-CDK4/6 is constitutively activated and drives uncontrolled cell proliferation. The development of small-molecule CDK4/6 inhibitors provided a therapeutic tool to repress constitutive CycD-CDK4/6 activity and to inhibit cancer cell proliferation. As with several targeted therapies, tumors eventually develop resistance and resume cell proliferation despite CDK4/6 inhibition. New combination treatments, involving CDK4/6 inhibitors plus inhibition of other pathways, are being tested in the clinic to delay or overcome the resistance.

Abstract

Cyclin-dependent kinases 4 and 6 (CDK4 and CDK6) and their activating partners, D-type cyclins, link the extracellular environment with the core cell cycle machinery. Constitutive activation of cyclin D–CDK4/6 represents the driving force of tumorigenesis in several cancer types. Small-molecule inhibitors of CDK4/6 have been used with great success in the treatment of hormone receptor–positive breast cancers and are in clinical trials for many other tumor types. Unexpectedly, recent work indicates that inhibition of CDK4/6 affects a wide range of cellular functions such as tumor cell metabolism and antitumor immunity. We discuss how recent advances in understanding CDK4/6 biology are opening new avenues for the future use of cyclin D–CDK4/6 inhibitors in cancer treatment.

Cyclin D1, the activator of CDK4 and CDK6, was discovered in the early 1990s (1, 2). The role of cyclin D1 in oncogenesis was already evident at the time of its cloning, as it was also identified as the protein product of the PRAD1 oncogene, which is rearranged and overexpressed in parathyroid adenomas (3), and of the BCL1 oncogene, which is rearranged in B-lymphocytic malignancies (4). Subsequently, the remaining two D-type cyclins, D2 and D3, were discovered on the basis of their homology to cyclin D1 (1).

Cyclins serve as regulatory subunits of cyclin-dependent kinases (CDKs) (5). Shortly after the discovery of D-cyclins, CDK4 and CDK6 were identified as their kinase partners (6). Mouse gene knockout studies revealed that CDK4 and CDK6 play redundant roles in development, and combined ablation of CDK4 and CDK6 was found to result in embryonic lethality (7). The essentially identical phenotype was seen in cyclin D–knockout mice, thereby confirming the role of D-cyclins as CDK4/6 activators in vivo (8). Surprisingly, these analyses revealed that many normal nontransformed mammalian cell types can proliferate without any cyclin D–CDK4/6 activity (7, 8).

CDK4 and CDK6 are expressed at constant levels throughout the cell cycle. By contrast, D-cyclins are labile proteins that are transcriptionally induced upon stimulation of cells with growth factors. For this reason, D-cyclins are regarded as links between the cellular environment and the cell cycle machinery (6).

Cell cycle inhibitors play an important role in regulating the activity of cyclin D–CDK4/6 (Fig. 1). The INK inhibitors (p16^INK4A, p15^INK4B, p18^INK4C, p19^INK4D) bind to CDK4 or CDK6 and prevent their interaction with D-type cyclins, thereby inhibiting cyclin D–CDK4/6 kinase activity. By contrast, KIP/CIP inhibitors (p27^KIP1, p57^KIP2, p21^CIP1), which inhibit the activity of CDK2-containing complexes, serve as assembly factors for cyclin D–CDK4/6 (6, 9). This was demonstrated by the observation that mouse fibroblasts devoid of p27^KIP1 and p21^CIP1 fail to assemble cyclin D–CDK4/6 complexes (10).

Fig. 1. Molecular events governing progression through the G₁ phase of the cell cycle.

The mammalian cell cycle can be divided into G₁, S (DNA synthesis), G₂, and M (mitosis) phases. During G₁ phase, cyclin D (CycD)–CDK4/6 kinases together with cyclin E (CycE)–CDK2 phosphorylate the retinoblastoma protein RB1. This activates the E2F transcriptional program and allows entry of cells into S phase. Members of the INK family of inhibitors (p16^INK4A, p15^INK4B, p18^INK4C, and p19^INK4D) inhibit cyclin D–CDK4/6; KIP/CIP proteins (p21^CIP1, p27^KIP1, and p57^KIP2) inhibit cyclin E–CDK2. Cyclin D–CDK4/6 complexes use p27^KIP1 and p21^CIP1 as “assembly factors” and sequester them away from cyclin E–CDK2, thereby activating CDK2. Proteins that are frequently lost or down-regulated in cancers are marked with green arrows, overexpressed proteins with red arrows.

p27^KIP1 can bind cyclin D–CDK4/6 in an inhibitory or noninhibitory mode, depending on p27^KIP1 phosphorylation status. Cyclin D–p27^KIP1-CDK4/6 complexes are catalytically inactive unless p27^KIP1 is phosphorylated on Tyr⁸⁸ and Tyr⁸⁹ (11). Two molecular mechanisms may explain this switch. First, Tyr⁸⁸/Tyr⁸⁹ phosphorylation may dislodge the helix of p27^KIP1 from the CDK active site and allow adenosine triphosphate (ATP) binding (12). Second, the presence of tyrosine-unphosphorylated p27^KIP1 within the cyclin D–CDK4 complex prevents the activating phosphorylation of CDK4’s T-loop by the CDK-activating kinase (CAK) (12). Brk has been identified as a physiological kinase of p27^KIP1 (13); Abl and Lyn can phosphorylate p27^KIP1 in vitro, but their in vivo importance remains unclear (11, 14).

The activity of cyclin D–CDK4/6 is also regulated by proteolysis. Cyclin D1 is an unstable protein with a half-life of less than 30 min. At the end of G₁ phase, cyclin D1 is phosphorylated at Thr²⁸⁶ by GSK3β (15). This facilitates association of cyclin D1 with the nuclear exportin CRM1 and promotes export of cyclin D1 from the nucleus to the cytoplasm (16). Subsequently, phosphorylated cyclin D1 becomes polyubiquitinated by E3 ubiquitin ligases, thereby targeting it for proteasomal degradation. Several substrate receptors of E3 ubiquitin ligases have been implicated in recognizing phosphorylated cyclin D1, including F-box proteins FBXO4 (along with αB crystallin), FBXO31, FBXW8, β-TrCP1/2, and SKP2 (17). The anaphase-promoting complex/cyclosome (APC/C) was also proposed to target cyclin D1 while F-box proteins FBXL2 and FBXL8 target cyclins D2 and D3 (17, 18). Surprisingly, the level and stability of cyclin D1 was unaffected by depletion of several of these proteins, indicating that some other E3 plays a rate-limiting role in cyclin D1 degradation (19). Indeed, recent studies reported that D-cyclins are ubiquitinated and targeted for proteasomal degradation by the E3 ubiquitin ligase CRL4, which uses AMBRA1 protein as its substrate receptor (20–22).

Cyclin D–CDK4/6 in cancer

Genomic aberrations of the cyclin D1 gene (CCND1) represent frequent events in different tumor types. The t(11;14)(q13;q32) translocation juxtaposing CCND1 with the immunoglobulin heavy-chain (IGH) locus represents the characteristic feature of mantle-cell lymphoma and is frequently observed in multiple myeloma or plasma cell leukemia (23, 24). Amplification of CCND1 is seen in many other malignancies—for example, in 13 to 20% of breast cancers (23, 24), more than 40% of head and neck squamous cell carcinomas, and more than 30% of esophageal squamous cell carcinomas (23). A higher proportion of cancers (e.g., up to 50% of mammary carcinomas) overexpress cyclin D1 protein (24). Also, cyclins D2 and D3, CDK4, and CDK6 are overexpressed in various tumor types (5, 9). Cyclin D–CDK4/6 can also be hyperactivated through other mechanisms such as deletion or inactivation of INK inhibitors, most frequently p16^INK4A (5, 9, 23). Altogether, a very large number of human tumors contain lesions that hyperactivate cyclin D–CDK4/6 (5).

An oncogenic role for cyclin D–CDK4/6 has been supported by mouse cancer models. For example, targeted overexpression of cyclin D1 in mammary glands of transgenic mice led to the development of mammary carcinomas (25). Also, overexpression of cyclin D2, D3, or CDK4, or loss of p16^INK4a resulted in tumor formation (9).

Conversely, genetic ablation of D-cyclins, CDK4, or CDK6 decreased tumor sensitivity (9). For instance, Ccnd1– or Cdk4-null mice, or knock-in mice expressing kinase-inactive cyclin D1–CDK4/6, were resistant to develop human epidermal growth factor receptor 2 (HER2)–driven mammary carcinomas (26–29). An acute, global shutdown of cyclin D1 in mice bearing HER2-driven tumors arrested tumor growth and triggered tumor-specific senescence while having no obvious impact on normal tissues (30). Likewise, an acute ablation of CDK4 arrested tumor cell proliferation and triggered tumor cell senescence in a KRAS-driven non–small-cell lung cancer (NSCLC) mouse model (31). These observations indicated that CDK4 and CDK6 might represent excellent therapeutic targets in cancer treatment.

CDK4/6 functions in cell proliferation and oncogenesis

The best-documented function of cyclin D–CDK4/6 in driving cell proliferation is phosphorylation of the retinoblastoma protein, RB1, and RB-like proteins, RBL1 and RBL2 (5, 6) (Fig. 1). Unphosphorylated RB1 binds and inactivates or represses E2F transcription factors. According to the prevailing model, phosphorylation of RB1 by cyclin D–CDK4/6 partially inactivates RB1, leading to release of E2Fs and up-regulation of E2F-transcriptional targets, including cyclin E. Cyclin E forms a complex with its kinase partner, CDK2, and completes full RB1 phosphorylation, leading to activation of the E2F transcriptional program and facilitating S-phase entry (5, 6). In normal, nontransformed cells, the activity of cyclin D–CDK4/6 is tightly regulated by the extracellular mitogenic milieu. This links inactivation of RB1 with mitogenic signals. In cancer cells carrying activating lesions in cyclin D–CDK4/6, the kinase is constitutively active, thereby decoupling cell division from proliferative and inhibitory signals (5).

This model has been questioned by the demonstration that RB1 exists in a monophosphorylated state throughout G₁ phase and becomes inactivated in late G₁ by cyclin E–CDK2, which “hyperphosphorylates” RB1 on multiple residues (32). However, recent single-cell analyses revealed that cyclin D–CDK4/6 activity is required for the hyperphosphorylation of RB1 throughout G₁, whereas cyclin E/A–CDK maintains RB1 hyperphosphorylation in S phase (33). Moreover, phosphorylation of RB1 by cyclin D–CDK4/6 was shown to be required for normal cell cycle progression (34).

In addition to this kinase-dependent mechanism, up-regulation of D-cyclin expression and formation of cyclin D–CDK4/6 complexes lead to redistribution of KIP/CIP inhibitors from cyclin E–CDK2 complexes (which are inhibited by these proteins) to cyclin D–CDK4/6 (which use them as assembly factors), thereby activating the kinase activity of cyclin E–CDK2 (6). Cyclin E–CDK2 in turn phosphorylates RB1 and other cellular proteins and promotes cell cycle progression.

Cyclin D1–CDK4/6 directly phosphorylates, stabilizes, and activates the transcription factor FOXM1. This promotes cell cycle progression and protects cancer cells from entering senescence (35). Cyclin D–CDK4 also phosphorylates and inactivates SMAD3, which mediates transforming growth factor–β (TGF-β) antiproliferative response. CDK4/6-dependent phosphorylation of SMAD3 inhibits its transcriptional activity and disables the ability of TGF-β to induce cell cycle arrest (36). FZR1/CDH1, an adaptor protein of the APC complex, is another phosphorylation substrate of CDK4. Depletion of CDH1 in human cancer cells partially rescued the proliferative block upon CDK4/6 inhibition, and it cooperated with RB1 depletion in restoring full proliferation (37).

Cyclin D–CDK4/6 also phosphorylates and inactivates TSC2, a negative regulator of mTORC1, thereby resulting in mTORC1 activation. Conversely, inhibition of CDK4/6 led to decreased mTORC1 activity and reduced protein synthesis in cells representing different human tumor types. It was proposed that through TSC2 phosphorylation, activation of cyclin D–CDK4/6 couples cell growth with cell division (38). Consistent with this, the antiproliferative effect of CDK4/6 inhibition was reduced in cells lacking TSC2 (38).

MEP50, a co-regulatory factor of protein arginine-methyltransferase 5 (PRMT5), is phosphorylated by cyclin D1–CDK4. Through this mechanism, cyclin D1–CDK4/6 increases the catalytic activity of PRMT5/MEP50 (39). It was proposed that deregulation of cyclin D1–CDK4 kinase in tumor cells, by increasing PRMT5/MEP50 activity, reduces the expression of CUL4, a component of the E3 ubiquitin-ligase complex, and stabilizes CUL4 targets such as CDT1 (39). In addition, by stimulating PRMT5/MEP50-dependent arginine methylation of p53, cyclin D–CDK4/6 suppresses the expression of key antiproliferative and pro-apoptotic p53 target genes (40). Another study proposed that PRMT5 regulates splicing of the transcript encoding MDM4, a negative regulator of p53. CDK4/6 inhibition reduced PRMT5 activity and altered the pre-mRNA splicing of MDM4, leading to decreased levels of MDM4 protein and resulting in p53 activation. This, in turn, up-regulated the expression of a p53 target, p21^CIP1, that blocks cell cycle progression (41).

During oncogenic transformation of hematopoietic cells, chromatin-bound CDK6 phosphorylates the transcription factors NFY and SP1 and induces the expression of p53 antagonists such as PRMT5, PPM1D, and MDM4 (42). Also, in acute myeloid leukemia cells expressing constitutively activated FLT3, CDK6 binds the promoter region of the FLT3 gene as well as the promoter of PIM1 pro-oncogenic kinase and stimulates their expression. Treatment of FLT3-mutant leukemic cells with a CDK4/6 inhibitor decreased FLT3 and PIM1 expression and triggered cell cycle arrest and apoptosis (43). The relevance of these various mechanisms in the context of human tumors is unclear and requires further study.

Mechanism of action of CDK4/6 inhibitors

Three small-molecule CDK4/6 inhibitors have been extensively characterized in preclinical studies: palbociclib and ribociclib, which are highly specific CDK4/6 inhibitors, and abemaciclib, which inhibits CDK4/6 and other kinases (Table 1). It has been assumed that these compounds act in vivo by directly inhibiting cyclin D–CDK4/6 (9). This simple model has been recently questioned by observations that palbociclib inhibits only cyclin D–CDK4/6 dimers, but not trimeric cyclin D–CDK4/6-p27^KIP1 (44). However, it is unlikely that substantial amounts of cyclin D–CDK4 dimers ever exist in cells, because nearly all cyclin D–CDK4 in vivo is thought to be complexed with KIP/CIP proteins (11, 14, 44). Palbociclib also binds monomeric CDK4 (44). Surprisingly, treatment of cancer cells with palbociclib for 48 hours failed to inhibit CDK4 kinase, despite cell cycle arrest, but it inhibited CDK2 (44). Hence, palbociclib might prevent the formation of active CDK4-containing complexes (through binding to CDK4) and indirectly inhibit CDK2 by liberating KIP/CIP inhibitors. This model needs to be reconciled with several observations. First, treatment of cells with CDK4/6 inhibitors results in a rapid decrease of RB1 phosphorylation on cyclin D–CDK4/6-dependent sites, indicating an acute inhibition of CDK4/6 (45–47). Moreover, CDK4/6 immunoprecipitated from cells can be inhibited by palbociclib (48) and p21^CIP-associated cyclin CDK4/6 kinase is also inhibited by treatment of cells with palbociclib (49). Lastly, CDK2 is dispensable for proliferation of several cancer cell lines (50, 51), hence the indirect inhibition of CDK2 alone is unlikely to be responsible for cell cycle arrest.

Name of compound	IC₅₀	Other known targets	Stage of clinical development
Palbociclib (PD-0332991)	D1-CDK4, 11 nM; D2-CDK6, 15 nM; D3-CDK4, 9 nM		FDA-approved for HR⁺/HER2^– advanced breast cancer in combination with endocrine therapy; phase 2/3 trials for several other tumor types
Ribociclib (LEE011)	D1-CDK4, 10 nM; D3-CDK6, 39 nM		FDA-approved for HR⁺/HER2^– advanced breast cancer in combination with endocrine therapy; phase 2/3 trials for several other tumor types
Abemaciclib (LY2835219)	D1-CDK4, 0.6 to 2 nM; D3-CDK6, 8 nM	Cyclin T1–CDK9, PIM1, HIPK2, CDKL5, CAMK2A, CAMK2D, CAMK2G, GSK3α/β, and (at higher doses) cyclin E/A–CDK2 and cyclin B–CDK1	FDA-approved for early (adjuvant) and advanced HR⁺/HER2^– breast cancer in combination with endocrine therapy; FDA-approved as monotherapy in advanced HR⁺/HER2^– breast cancer; phase 2/3 trials for several other tumor types
Trilaciclib (G1T28)	D1-CDK4, 1 nM; D3-CDK6, 4 nM		FDA-approved for small-cell lung cancer to reduce chemotherapy-induced bone marrow suppression; phase 2/3 trials for other solid tumors
Lerociclib (G1T38)	D1-CDK4, 1 nM; D3-CDK6, 2 nM		Phase 1/2 trials for HR⁺/HER2^– advanced breast cancer and EGFR-mutant non–small-cell lung cancer
SHR6390	CDK4, 12 nM; CDK6, 10 nM		Phase 1/2/3 trials for HR⁺/HER2^– advanced breast cancer and other solid tumors
PF-06873600	CDK4, 0.13 nM (K_i), CDK6, 0.16 nM (K_i)	CDK2, 0.09 nM (K_i)	Phase 2 trials for HR⁺/HER2^– advanced breast cancer and other solid tumors
FCN-437	D1-CDK4, 3.3 nM; D3-CDK6, 13.7 nM		Phase 1/2 trials for HR⁺/HER2^– advanced breast cancer and other solid tumors
Birociclib (XZP-3287)	Not reported		Phase 1/2 trials for HR⁺/HER2^– advanced breast cancer and other solid tumors
HS-10342	Not reported		Phase 1/2 trials for HR⁺/HER2^– advanced breast cancer and other solid tumors
CS3002	Not reported		Phase 1 trial for solid tumors

Table 1. Currently available CDK4/6 inhibitors.

This table lists major inhibitors of CDK4 and CDK6, half-maximal inhibitory concentration (IC₅₀) for different cyclin D–CDK4/6 complexes (if known), other known targets, and the stage of clinical development. K_i, inhibitory constant.

Palbociclib, ribociclib, and abemaciclib were shown to block binding of CDK4 and CDK6 to CDC37, the kinase-targeting subunit of HSP90, thereby preventing access of CDK4/6 to the HSP90-chaperone system (52). Because the HSP90-CDC37 complex stabilizes several kinases (53), these observations suggest that CDK4/6 inhibitors, by disrupting the interaction between CDC37 and CDK4 or CDK6, might promote degradation of CDK4 and CDK6. However, depletion of CDK4/6 is typically not observed upon treatment with CDK4/6 inhibitors (54). More studies are needed to resolve these conflicting reports and to establish how CDK4/6 inhibitors affect the cell cycle machinery in cancer cells.

Validation of CDK4/6 inhibitors as anticancer agents

Consistent with the notion that RB1 represents the major rate-limiting substrate of cyclin D–CDK4/6 in cell cycle progression (55–57), palbociclib, ribociclib, and abemaciclib were shown to block proliferation of several RB1-positive cancer cell lines, but not cell lines that have lost RB1 expression (46, 58, 59). Breast cancer cell lines representing the luminal, estrogen receptor–positive (ER⁺) subtype were shown to be most susceptible to cell proliferation arrest upon palbociclib treatment (45). Palbociclib, ribociclib, abemaciclib, and another CDK4/6 inhibitor, lerociclib, were demonstrated to display potent antitumor activity in xenografts of several tumor types, including breast cancers (46, 60–62). Palbociclib and abemaciclib cross the blood-brain barrier and inhibit growth of intracranial glioblastoma (GBM) xenografts, with abemaciclib being more efficient in reaching the brain (63, 64). Recently, additional CDK4/6 inhibitors were shown to exert therapeutic effects in mouse xenograft models of various cancer types, including SHR6390 (65), FCN-437 (66), and compound 11 (67); the latter two were reported to cross the blood-brain barrier. In most in vivo studies, the therapeutic effect was dependent on expression of intact RB1 protein in tumor cells (46, 63). However, antitumor effects of palbociclib were also reported in bladder cancer xenografts independently of RB1 status; this was attributed to decreased phosphorylation of FOXM1 (68).

Tumor cell senescence upon CDK4/6 inhibition

In addition to blocking cell proliferation, inhibition of CDK4/6 can also trigger tumor cell senescence (63), which depends on RB1 and FOXM1 (35, 54). The role of RB1 in enforcing cellular senescence is well established (69). In addition, cyclin D–CDK4/6 phosphorylates and activates FOXM1, which has anti-senescence activity (35, 70). Senescence represents a preferred therapeutic outcome to cell cycle arrest, as it may lead to a durable inhibition of tumor growth.

It is not clear what determines the extent of senescence upon treatment of cancer cells with CDK4/6 inhibitors. A recent study showed that inhibition of CDK4/6 leads to an RB1-dependent increase in reactive oxygen species (ROS) levels, resulting in activation of autophagy, which mitigates the senescence of breast cancer cells in vitro and in vivo (71). Co-treatment with palbociclib plus autophagy inhibitors strongly augmented the ability of CDK4/6 inhibitors to induce tumor cell senescence and led to sustained inhibition of cancer cell proliferation in vitro and of xenograft growth in vivo (71). Decreased mTOR signaling after long-term CDK4/6 inhibition was shown to be essential for the induction of senescence in melanoma cells, and activation of mTORC1 overrode palbociclib-induced senescence (72). Others postulated that expression of the chromatin-remodeling enzyme ATRX and degradation of MDM2 determines the choice between quiescence and senescence upon CDK4/6 inhibition (73). Inhibition of CDK4 causes dissociation of the deubiquitinase HAUSP/USP7 from MDM2, thereby driving autoubiquitination and proteolytic degradation of MDM2, which in turn promotes senescence. This mechanism requires ATRX, which suggests that expression of ATRX can be used to predict the senescence response (73). Two additional proteins that play a role in this process are PDLIM7 and type II cadherin CDH18. Expression of CDH18 correlated with a sustained response to palbociclib in a phase 2 trial for patients with liposarcoma (74).

Markers predicting response to CDK4/6 inhibition

Only tumors with intact RB1 respond to CDK4/6 inhibitor treatment by undergoing cell cycle arrest or senescence (9, 58). In addition, “D-cyclin activating features” (CCND1 translocation, CCND2 or CCND3 amplification, loss of the CCND1-3 3′-untranslated region, and deletion of FBXO31 encoding an F-box protein implicated in cyclin D1 degradation) were shown to confer a strong response to abemaciclib in cancer cell lines (58). Moreover, co-deletion of CDKN2A and CDKN2C (encoding p16^INK4A/p19^ARF and p18^INK4C, respectively) confers palbociclib sensitivity in glioblastoma (75). Thr¹⁷² phosphorylation of CDK4 and Tyr⁸⁸ phosphorylation of p27^KIP1 (both associated with active cyclin D–CDK4) correlate with sensitivity of breast cancer cell lines or tumor explants to palbociclib (76, 77). Surprisingly, in PALOMA-1, PALOMA-2, and PALOMA-3 trials (78–80), and in another independent large-scale study (81), CCND1 gene amplification or elevated levels of cyclin D1 mRNA or protein were not predictive of palbociclib efficacy. Conversely, overexpression of CDK4, CDK6, or cyclin E1 is associated with resistance of tumors to CDK4/6 inhibitors (see below).

Synergy of CDK4/6 inhibitors with other compounds

Several preclinical studies have documented the additive or synergistic effects of combining CDK4/6 inhibitors with inhibitors of the receptor tyrosine kinases as well as phosphoinositide 3-kinase (PI3K), RAF, or MEK (Table 2). This synergism might be because these pathways impinge on the cell cycle machinery through cyclin D–CDK4/6 (82–86). In some cases, the effect was seen in the presence of specific genetic lesions, such as EGFR, BRAF^V600E, KRAS, and PIK3CA mutations (59, 87–89) (Table 2). When comparing different dosing regimens, continuous treatment with a MEK inhibitor with intermittent palbociclib resulted in more complete tumor responses than other combination schedules (90). Treatment with CDK4/6 inhibitors sensitized cancer cells to ionizing radiation (63) or cisplatin (68). The synergism with platinum-based chemotherapy was attributed to the observation that upon this treatment, CDK6 phosphorylates and stabilizes the FOXO3 transcription factor, thereby promoting tumor cell survival. Consequently, inhibition of CDK6 increases platinum sensitivity by enhancing tumor cell death (91).

CDK4/6 inhibitor	Synergistic target	Inhibitor	Disease
Palbociclib	PI3K	Taselisib, pictilisib	PIK3CA mutant TNBC
	AR	Enzalutamide	Androgen receptor–positive TNBC
	EGFR	Erlotinib	TNBC, esophageal squamous cell carcinoma
	RAF	PLX4720	BRAF-V600E mutant melanoma
	MEK	Trametinib	KRAS mutant colorectal cancer
	MEK	PD0325901 (mirdametinib)	KRAS or BRAFV600E mutant colorectal cancer
	MEK	MEK162 (binimetinib)	KRAS mutant colorectal cancer
	MEK	AZD6244 (selumetinib)	Pancreatic ductal adenocarcinoma
	PI3K/mTOR	BEZ235 (dactolisib), AZD0855, GDC0980 (apitolisib)	Pancreatic ductal adenocarcinoma
	IGF1R/InsR	BMS-754807	Pancreatic ductal adenocarcinoma
	mTOR	Temsirolimus	Pancreatic ductal adenocarcinoma
	mTOR	AZD2014 (vistusertib)	ER⁺ breast cancer
	mTOR	MLN0128 (sapanisertib)	Intrahepatic cholangiocarcinoma
	mTOR	Everolimus	Melanoma, glioblastoma
Ribociclib	PI3K	GDC-0941 (pictilisib), BYL719 (alpelisib)	PIK3CA mutant breast cancer
	PDK1	GSK2334470	ER⁺ breast cancer
	EGFR	Nazartinib	EGFR-mutant lung cancer
	RAF	Encorafenib	BRAF-V600E mutant melanoma
	mTOR	Everolimus	T-ALL
	Inflammation	Glucocorticoid dexamethasone	T-ALL
	γ-Secretase	Compound E	T-ALL
Abemaciclib	HER2	Trastuzumab	HER2⁺ breast cancer
	EGFR and HER2	Lapatinib	HER2⁺ breast cancer
	RAF	LY3009120, vemurafenib	KRAS mutant lung or colorectal cancer, NRAS or BRAF-V600E mutant melanoma
		Temozolomide (alkylating agent)	Glioblastoma

Table 2. Combination treatments that demonstrated synergy with CDK4/6 inhibitors in preclinical studies.

TNBC, triple-negative breast cancer; AR, androgen receptor; ER⁺, estrogen receptor–positive; T-ALL, T cell acute lymphoblastic leukemia; HER2⁺, human epidermal growth factor receptor 2–positive; PI3K, phosphoinositide 3-kinase; EGFR, epidermal growth factor receptor; IGF1R, insulin-like growth factor 1 receptor, InsR, insulin receptor.

In several instances, co-treatment with CDK4/6 inhibitors prevented the development of resistance to other compounds or inhibited the proliferation of resistant tumor cells. Co-treatment of melanoma patient-derived xenografts (PDXs) with ribociclib plus the RAF inhibitor encorafenib delayed or prevented development of encorafenib resistance (92). PDXs that acquired encorafenib resistance remained sensitive to the combination of encorafenib plus ribociclib (59). Treatment of BRAF^V600E-mutant melanoma xenografts with palbociclib plus the BRAF^V600E inhibitor PLX4720 prevented development of resistance (89). BRAF^V600E-mutant melanoma cell lines that acquired resistance to the BRAF^V600E inhibitor vemurafenib remained sensitive to palbociclib or abemaciclib, and xenografts underwent senescence and tumor regression upon CDK4/6 inhibition (72, 93). Treatment of ALK-mutant, ALK kinase inhibitor–resistant neuroblastoma xenografts with palbociclib restored the sensitivity to these compounds (94). A combination of PI3K and CDK4/6 inhibitors overcame the intrinsic and acquired resistance of breast cancers to PI3K inhibitors and resulted in regression of PIK3CA-mutant xenografts (88).

Up-regulation of cyclin D1 expression was shown to mediate acquired resistance of HER2⁺ tumors to anti-HER2 therapies in a mouse breast cancer model (95). Treatment of mice bearing trastuzumab-resistant tumors or PDXs of resistant HER2⁺ mammary carcinomas with abemaciclib restored the sensitivity of tumors to HER2 inhibitors and inhibited tumor cell proliferation. Moreover, in the case of treatment-naïve tumors, co-administration of abemaciclib significantly delayed the development of resistance to anti-HER2 therapies (95).

Several anticancer treatments, such as chemotherapy, target dividing cells. Because CDK4/6 inhibitors block tumor cell proliferation, they might impede the effects of chemotherapy. Indeed, several reports have documented that co-administration of CDK4/6 inhibitors antagonized the antitumor effects of compounds that act during S phase (doxorubicin, gemcitabine, methotrexate, mercaptopurine) or mitosis (taxanes) (96, 97). However, some authors reported synergistic effects (98, 99), although the molecular underpinnings are unclear.

A recent report documented that administration of CDK4/6 inhibitors prior to taxanes inhibited tumor cell proliferation and impeded the effect of taxanes (100). By contrast, administration of taxanes first (or other chemotherapeutic compounds that act on mitotic cells or cells undergoing DNA synthesis), followed by CDK4/6 inhibitors, had a strong synergistic effect. The authors showed that by repressing the E2F-dependent transcriptional program, CDK4/6 inhibitors impaired the expression of genes required for DNA-damage repair via homologous recombination. Because treatment of cancer cells with chemotherapy triggers DNA damage, the impairment of DNA-damage repair induced cytotoxicity, thereby explaining the synergistic effect (100).

Cells with impaired homologous recombination rely on poly-(ADP-ribose) polymerase (PARP) for double-stranded DNA-damage repair, which renders them sensitive to PARP inhibition. Indeed, a strong synergistic effect has been demonstrated between CDK4/6 inhibitors and PARP inhibitors in PDX-derived cell lines (100). Such synergy was also reported for ovarian cancer cells (101). Another study found that inhibition of CDK4/6 resulted in down-regulation of PARP levels (102).

Protection against chemotherapy-induced toxicity

Administration of palbociclib to mice induced reversible quiescence in hematopoietic stem/progenitor cells (HSPCs). This effect protected mice from myelosuppression after total-body irradiation. Moreover, treatment of tumor-bearing mice with CDK4/6 inhibitors together with irradiation mitigated radiation-induced toxicity without compromising the therapeutic effect (103). Co-administration of a CDK4/6 inhibitor, trilaciclib, with cytotoxic chemotherapy (5-FU, etoposide) protected animals from chemotherapy-induced exhaustion of HSPCs, myelosuppression, and apoptosis of bone marrow (60, 104). These observations led to phase 2 clinical trial, which evaluated the effects of trilaciclib administered prior to etoposide and carboplatin for treatment of small-cell lung cancer. Trilaciclib improved myelopreservation while having no adverse effect on antitumor efficacy (105). A similar phase 2 clinical trial investigating trilaciclib in combination with gemcitabine and carboplatin chemotherapy in patients with metastatic triple-negative breast cancer (TNBC) did not observe a significant difference in myelosuppression. However, this study demonstrated an overall survival benefit of the combination therapy (106, 107).

Metabolic function of CDK4/6 in cancer cells

The role of CDK4/6 in tumor metabolism is only starting to be appreciated (Fig. 2A). Treatment of pancreatic cancer cells with CDK4/6 inhibitors was shown to induce tumor cell metabolic reprogramming (108). CDK4/6 inhibition increased the numbers of mitochondria and lysosomes, activated mTOR, and increased the rate of oxidative phosphorylation, likely through an RB1-dependent mechanism (108). Combined inhibition of CDK4/6 and mTOR strongly suppressed tumor cell proliferation (108). Moreover, CDK4/6 can phosphorylate and inactivate TFEB, the master regulator of lysosomogenesis, and through this mechanism reduce lysosomal numbers. Conversely, CDK4/6 inhibition activated TFEB and increased the number of lysosomes (109). Another mechanism linking CDK4/6 and lysosomes was provided by the observation that treatment of TNBC cells with CDK4/6 inhibitors decreased mTORC1 activity and impaired the recruitment of mTORC1 to lysosomes (110). Consistent with the idea that mTORC1 inhibits lysosomal biogenesis, CDK4/6 inhibition increased the number of lysosomes in tumor cells. Because an increased lysosomal biomass underlies some cases of CDK4/6 inhibitor resistance (see below) (111), stimulation of lysosomogenesis by CDK4/6 inhibitors might limit their clinical efficacy by inducing resistance.

Fig. 2. CDK4 and CDK6: More than cell cycle kinases.

Although the role of CDK4 and CDK6 in cell cycle progression has been well documented, both kinases regulate several other functions that are only now starting to be unraveled. (A) Inhibition of CDK4/6 (CDK4/6i) affects lysosome and mitochondrial numbers as well as oxidative phosphorylation. Cyclin D3–CDK6 phosphorylates glycolytic enzymes 6-phosphofructokinase (PFKP) and pyruvate kinase M2 (PKM2), thereby controlling ROS levels via the pentose phosphate (PPP) and serine synthesis pathways. (B) Inhibition of CDK4/6 affects antitumor immunity, acting both within cancer cells and on the immune system of the host. In tumor cells, inhibition of CDK4/6 impedes expression of an E2F target, DNA methyltransferase (DNMT). DNMT inhibition reduces methylation of endogenous retroviral genes (ERV) and increases intracellular levels of double-stranded RNA (dsRNA) (*114*). In effector T cells, inhibition of CDK4/6 stimulates NFAT transcriptional activity and enhances secretion of IFN-γ and interleukin 2 (IL-2) (*115*).

Lastly, CDK4/6 inhibition impaired lysosomal function and the autophagic flux in cancer cells. It was argued that this lysosomal dysfunction was responsible for the senescent phenotype in CDK4/6 inhibitor–treated cells (110). Because lysosomes are essential for autophagy, the authors co-treated TNBC xenografts with abemaciclib plus an AMPK activator, A769662 (which induces autophagy), and found that this led to cancer cell death and subsequent regression of tumors (110).

Cyclin D3–CDK6 phosphorylates and inhibits two rate-limiting glycolytic enzymes, 6-phosphofructokinase and pyruvate kinase M2. This redirects glycolytic intermediates into the pentose phosphate pathway (PPP) and serine synthesis pathway. Through this mechanism, cyclin D3–CDK6 promotes the production of reduced nicotinamide adenine dinucleotide phosphate (NADPH) and reduced glutathione (GSH) and helps to neutralize ROS (112). Treatment of tumors expressing high levels of cyclin D3–CDK6 (such as leukemias) with CDK4/6 inhibitors reduced the PPP- and serine-synthesis pathway flow, thereby depleting the antioxidants NADPH and GSH. This increased ROS levels and triggered tumor cell apoptosis (112).

Another link between cyclin D–CDK4/6 in metabolism and cancer was provided by the observation that livers of obese/diabetic mice up-regulate cyclin D1 expression (113). Treatment of these mice with an antidiabetic compound, metformin, reduced liver cyclin D1 levels and largely protected mice against development of hepatocellular carcinoma. Also, genetic ablation of cyclin D1 protected obese/diabetic mice from liver cancer, and administration of palbociclib inhibited liver cancer progression. These treatments had no effect on tumors in nonobese animals (113). These observations raise the possibility of using antidiabetic compounds with CDK4/6 inhibitors for treatment of liver cancers in obese patients.

CDK4/6 inhibitors and antitumor immune responses

Several recent reports have started to unravel how inhibition of CDK4/6 influences antitumor immune responses, acting both on tumor cells as well as on the tumor immune environment (Fig. 2B). Treatment of breast cancer–bearing mice or breast cancer cells with abemaciclib activated expression of endogenous retroviral elements in tumor cells, thereby increasing the levels of double-stranded RNA. This, in turn, stimulated production of type III interferons and increased presentation of tumor antigens. Hence, CDK4/6 inhibitors, by inducing viral gene expression, trigger antiviral immune responses that help to eliminate the tumor (114).

Inhibition of CDK4/6 also affects the immune system by impeding the proliferation of CD4⁺FOXP3⁺ regulatory T cells (T_regs), which normally inhibit the antitumor response. Because cytotoxic CD8⁺ T cells are less affected by CDK4/6 inhibition, abemaciclib treatment decreases the T_reg/CD8⁺ ratio of intratumoral T cells and facilitates tumor cell killing by cytotoxic CD8⁺ T cells (114).

Inhibition of CDK4/6 also resulted in activation of T cells through derepression of NFAT signaling. NFAT4 (and possibly other NFATs) are phosphorylated by cyclin D3–CDK6 (115). Inhibition of CDK4/6 decreased phosphorylation of NFATs, resulting in their nuclear translocation and enhanced transcriptional activity. This caused up-regulation of NFAT targets, resulting in T cell activation, which enhanced the antitumor immune response. In addition, CDK4/6 inhibitors increased the infiltration of effector T cells into tumors, likely because of elevated levels of chemokines CXCL9 and CXCL10 after CDK4/6 inhibitor treatment (115). Abemaciclib treatment also induced inflammatory and activated T cell phenotypes in tumors and up-regulated the expression of immune checkpoint proteins CD137, PD-L1, and TIM-3 on CD4⁺ and CD8⁺ cells (116).

CDK4/6 inhibition also caused up-regulation of PD-L1 protein expression in tumor cells (117, 118). This effect was shown to be independent of RB1 status in the tumor. Mechanistically, CDK4/6 phosphorylates and stabilizes SPOP, which promotes PD-L1 polyubiquitination and degradation (118). Cyclin D–CDK4 also represses expression of PD-L1 through RB1. Specifically, cyclin D–CDK4/6-mediated phosphorylation of RB1 on S249/T252 promotes binding of RB1 to NF-κB protein p65, and this represses the expression of a subset NF-κB–regulated genes, including PD-L1 (119).

These observations prompted tests of the efficacy of combining CDK4/6 inhibitors with antibodies that elicit immune checkpoint blockade. Indeed, treatment of mice bearing autochthonous breast cancers, or cancer allografts, with CDK4/6 inhibitors together with anti-PD-1/PD-L1 antibodies enhanced the efficacy of immune checkpoint blockade and led to complete tumor regression in a high proportion of animals (114, 115, 118). Conversely, activation of the cyclin D–CDK4 pathway by genomic lesions in human melanomas correlated with resistance to anti–PD-1 therapy (117).

Some authors did not observe synergy when abemaciclib was administered concurrently with immune checkpoint inhibitors in allograft tumor models (116, 120). However, a strong synergistic antitumor effect was detected when abemaciclib was administered first (and continued) and anti–PD-L1 antibody was administered later. The combined treatment induced immunological memory, as mice that underwent tumor regression were resistant to rechallenge with the same tumor (116). Abemaciclib plus anti–PD-L1 treatment increased infiltration of CD4⁺ and CD8⁺ T cells into tumors, and increased the expression of major histocompatibility complex class I (MHC-I) and MHC-II on tumor cells and on macrophages and MHC-I on dendritic cells (116). In the case of anti–CTLA-4 plus anti–PD-1 treatment in melanoma allograft model, the synergistic effect was observed when immune checkpoint inhibitor treatment was started first, followed by abemaciclib (120).

The synergistic antitumor effect of PI3K and CDK4/6 inhibitors in TNBC is mediated, in part, by enhancement of tumor immunogenicity (121). Combined treatment of TNBC cells with ribociclib plus the PI3K inhibitor apelisib synergistically up-regulated the expression of immune-related pathways in tumor cells, including proteins involved in antigen presentation. Co-treatment of tumor-bearing mice also decreased proliferation of CD4⁺FOXP3⁺ T_reg cells, increased activation of intratumoral CD4⁺ and CD8⁺ T cells, increased the frequency of tumor-infiltrating NKT cells, and decreased the numbers of intratumoral immunosuppressive myeloid-derived suppressor cells. Moreover, combined treatment strongly augmented the response to immune checkpoint therapy with PD-1 and CTLA-4 antibodies (121).

Single-cell RNA sequencing of human melanomas identified an immune resistance program expressed by tumor cells that correlates with T cell exclusion from the tumor mass and immune evasion by tumor cells. The program can predict the response of tumors to immune checkpoint inhibitors. Treatment of human melanoma cells with abemaciclib repressed this program in an RB1-dependent fashion (120).

Together, these findings indicate that CDK4/6 inhibitors may convert immunologically “cold” tumors into “hot” ones. The most pressing issue is to validate these findings in a clinical setting. The utility of combining CDK4/6 inhibitors with PD-1 or PD-L1 antibodies is currently being evaluated in several clinical trials. Note that the effects of CDK4/6 inhibition on the immune system of the host are independent of tumor cell RB1 status, raising the possibility of using CDK4/6 inhibitors to also boost the immune response against RB1-negative tumors.

CDK4/6 inhibitors in clinical trials

Table 3 summarizes major clinical trials with CDK4/6 inhibitors. Given early preclinical data indicating that breast cancers—in particular, the hormone receptor–positive ones—are very sensitive to CDK4/6 inhibition (as discussed above), many clinical trials have focused on this cancer type. Most studies have evaluated CDK4/6 inhibitors administered together with anti-estrogens (the aromatase inhibitors letrozole or anastrozole, or the estrogen receptor antagonist fulvestrant) for treatment of advanced/metastatic HR⁺/HER2^– breast cancers in postmenopausal women. Addition of CDK4/6 inhibitors significantly extended median progression-free survival (78, 122–130) and prolonged median overall survival (131–134). Moreover, abemaciclib has shown clinical activity when administered as a single agent (135). Consequently, palbociclib, ribociclib, and abemaciclib have been approved by the US Food and Drug Administration (FDA) for treatment of patients with advanced/metastatic HR⁺/HER2^– breast cancer (Box 1). A recent phase 3 clinical trial, MonarchE, evaluated abemaciclib plus standard endocrine therapy in treatment of patients with early-stage, high-risk, lymph node–positive HR⁺/HER2^– breast cancer. Addition of abemaciclib reduced the risk of breast cancer recurrence (136). This is in contrast to the similar PALLAS study reported this year, which found no benefit of adding palbociclib to endocrine therapy for women with early-stage breast cancer (137). Analysis of patient populations in these two trials may help to explain the different outcomes. It is also possible that the favorable outcome of the MonarchE study reflects a broader spectrum of kinases inhibited by abemaciclib. The utility of CDK4/6 inhibitors in early-stage breast cancer remains unclear and is being addressed in ongoing clinical trials (PALLAS, PENELOPE-B, EarLEE-1, MonarchE) (138).

CDK4/6 inhibitor	Trial name	Trial details	Treatment	Patients	Outcome	Ref.	Other outcomes
Palbociclib	PALOMA-1	Randomized phase 2	Aromatase inhibitor letrozole alone (standard of care) versus letrozole plus palbociclib	Postmenopausal women with advanced ER⁺/HER2^– breast cancer who had not received any systemic treatment for their advanced disease	Addition of palbociclib markedly increased median PFS from 10.2 months in the letrozole group to 20.2 months in the palbociclib plus letrozole group	(78)	On the basis of this result, palbociclib received a “Breakthrough Therapy” designation status from FDA and was granted accelerated approval, in combination with letrozole, for the treatment of ER⁺/HER2^– metastatic breast cancer
Palbociclib	PALOMA-2	Double-blind phase 3	Palbociclib plus letrozole as first- line therapy	Postmenopausal women with ER⁺/HER2^– breast cancer	Addition of palbociclib strongly increased median PFS: 14.5 months in the placebo- letrozole group versus 24.8 months in the palbociclib-letrozole group	(123)	Palbociclib was equally efficacious in patients with luminal A and B breast cancers, and there was no single biomarker associated with the lack of clinical benefit, except for RB1 loss; CDK4 amplification was associated with endocrine resistance, but this was mitigated by addition of palbociclib; tumors with high levels of FGFR2 and ERBB3 mRNA displayed greater PFS gain after addition of palbociclib (79)
Palbociclib	PALOMA-3	Randomized phase 3	Estrogen receptor antagonist fulvestrant plus placebo versus fulvestrant plus palbociclib	Women with HR⁺/HER2^– metastatic breast cancer that had progressed on previous endocrine therapy	The study demonstrated a substantial prolongation of median PFS in the palbociclib- treated group: 4.6 months in the placebo plus fulvestrant group versus 9.5 months in the palbociclib plus fulvestrant group; addition of palbociclib also extended median overall survival from 28.0 months (placebo-fulvestrant) to 34.9 months (palbociclib- fulvestrant); estimated rate of survival at 3 years was 41% versus 50%, respectively	(124, 125, 135)
Palbociclib	NeoPalAna	Palbociclib in an neoadjuvant setting (i.e., prior to surgery)	Compared the effects of an aromatase inhibitor anastrozole versus palbociclib plus anastrozole on tumor cell proliferation	Women with newly diagnosed clinical stage II/III ER⁺/HER2^– breast cancer	Addition of palbociclib enhanced the antiproliferative effect of anastrozole	(161)
Palbociclib	PALLAS	Randomized phase 3	Palbociclib plus standard endocrine therapy versus endocrine therapy alone	Patients with early (stage 2 or 3), HR⁺/HER2^– breast cancer	Preliminary results indicate that the trial is unlikely to show a statistically significant improvement of invasive disease-free survival	(138)
Palbociclib	PENELOPE-B		Palbociclib in patients with early breast cancer at high risk of recurrence		Ongoing
Ribociclib	MONA LEESA-2	Randomized phase 3	Ribociclib plus letrozole versus placebo plus letrozole	First-line treatment for postmenopausal women with HR⁺/HER2^– recurrent or metastatic breast cancer who had not received previous systemic therapy for advanced disease	At 18 months, PFS was 42.2% in the placebo-letrozole group and 63.0% in the ribociclib- letrozole group	(126)
Ribociclib	MONA LEESA-3	Phase 3	Ribociclib plus fulvestrant	Patients with advanced (metastatic or recurrent) HR⁺/HER2^– breast cancer who have either received no treatment for the advanced disease or previously received a single line of endocrine therapy for the advanced disease	Addition of ribociclib significantly extended median PFS, from 12.8 months (placebo-fulvestrant) to 20.5 months (ribociclib- fulvestrant); overall survival at 42 months was also extended from 45.9% (placebo-fulvestrant) to 57.8% (ribociclib-fulvestrant)	(127, 133)
Ribociclib	MONA LEESA-7	Phase 3 randomized, double-blind	Ribociclib versus placebo together with an anti- estrogen tamoxifen or an aromatase inhibitor (letrozole or anastrozole)	Premenopausal and perimenopausal women with HR⁺/HER2^– advanced breast cancer who had not received previous treatment with CDK4/6 inhibitors	Ribociclib significantly increased median PFS from 13.0 months in the placebo-endocrine therapy group to 23.8 months in the ribociclib-endocrine therapy group; overall survival was also strongly prolonged in the ribociclib group (estimated overall survival at 42 months was 46.0% for the placebo group and 70.2% in the ribociclib group)	(128, 132)
Ribociclib	EarLEE-1	Phase 3 trial	Ribociclib in the treatment of early- stage, high-risk HR⁺/HER2^– breast cancers		Ongoing
Abemaciclib	MONARCH 1	Phase 2 trial	Abemaciclib as a single agent	Women with HR⁺/HER2^– metastatic breast cancer who had progressed on or after prior endocrine therapy and had 1 or 2 chemotherapy regimens in the metastatic setting	Abemaciclib exhibited promising activity in these heavily pretreated patients with poor prognosis; median PFS was 6.0 months and overall survival 17.7 months	(136)	The most common adverse events were diarrhea, fatigue, and nausea (136)
Abemaciclib	MONARCH 2	Double-blind phase 3	Abemaciclib in combination with fulvestrant	Women with HR⁺/HER2^– breast cancer who had progressed while receiving endocrine therapy, or while receiving first-line endocrine therapy for metastatic disease	Addition of abemaciclib significantly increased PFS from 9.3 months in the placebo-fulvestrant to 16.4 in the abemaciclib-fulvestrant group; median overall survival was also extended from 37.3 months to 46.7 months	(129, 134)
Abemaciclib	MONARCH 3	Randomized phase 3 double-blind	Abemaciclib plus an aromatase inhibitor (anastrozole or letrozole)	Postmenopausal women with advanced HR⁺/HER2^– breast cancer who had no prior systemic therapy in the advanced setting	Addition of abemaciclib prolonged PFS from 14.8 months (in the placebo-aromatase inhibitor group) to 28.2 months (abemaciclib-aromatase inhibitor group)	(130, 131)
Abemaciclib	MonarchE	Phase 3 study	Endocrine with or without abemaciclib	Patients with HR⁺/HER2^– lymph node–positive, high-risk early breast cancer	Preliminary analysis indicates that addition of abemaciclib resulted in a significant improvement of invasive disease-free survival and of distant relapse- free survival	(137)
Trilaciclib		Randomized phase 2 study	Chemotherapy alone (gemcitabine and carboplatin), versus concurrent administration of trilaciclib plus chemotherapy, versus administration of trilaciclib prior to chemotherapy (to mitigate the cytotoxic effect of chemotherapy on bone marrow)	Patients with recurrent or metastatic triple-negative breast cancer who had no more than two previous lines of chemotherapy	Addition of trilaciclib did not offer detectable myeloprotection, but resulted in increased overall survival (from 12.8 months in the chemotherapy-only group to 20.1 months in the concurrent trilaciclib and chemotherapy group and 17.8 months in trilaciclib before chemotherapy group)	(162)	The most common adverse events were neutropenia, thrombocytopenia, and anemia (162)

Table 3. Major past clinical trials with CDK4/6 inhibitors.

ER⁺, estrogen receptor–positive; HER2^–, human epidermal growth factor receptor 2–negative; HR⁺, hormone receptor–positive; PFS, progression-free survival. FGFR2, fibroblast growth factor receptor 2; ERBB3, receptor tyrosine-protein kinase erbB-3.

Palbociclib

Approved by FDA in 2016, in combination with fulvestrant for the treatment of hormone receptor–positive, HER2-negative (HR⁺/HER2^–) advanced or metastatic breast cancer in women with disease progression following endocrine therapy. Approved in 2017 for the treatment of HR⁺/HER2^– advanced or metastatic breast cancer in combination with an aromatase inhibitor as initial endocrine-based therapy in postmenopausal women.

Palbociclib is administered at a dose of 125 mg (given orally) daily for 3 weeks followed by 1 week off, or 200 mg daily for 2 weeks followed by 1 week off. The rate-limiting toxicities are neutropenia, thrombocytopenia, and anemia.

Ribociclib

Approved by FDA in 2017, in combination with an aromatase inhibitor as initial endocrine-based therapy for the treatment of postmenopausal women with HR⁺/HER2^– advanced or metastatic breast cancer. In 2018, the FDA expanded the indication for ribociclib in combination with an aromatase inhibitor for pre/perimenopausal women with HR⁺/HER2^– advanced or metastatic breast cancer, as initial endocrine-based therapy. FDA also approved ribociclib in combination with fulvestrant for postmenopausal women with HR⁺/HER2^– advanced or metastatic breast cancer, as initial endocrine-based therapy or following disease progression on endocrine therapy.

Ribociclib is administered at a dose of 600 mg (given orally) daily for 3 weeks followed by 1 week off. The main toxicities are neutropenia and thrombocytopenia.

Abemaciclib

Approved by FDA in 2017, in combination with fulvestrant for women with HR⁺/HER2^– advanced or metastatic breast cancer with disease progression following endocrine therapy. In addition, abemaciclib was approved as monotherapy for women and men with HR⁺/HER2^– advanced or metastatic breast cancer with disease progression following endocrine therapy and prior chemotherapy in the metastatic setting. Approved by FDA in 2018 in combination with an aromatase inhibitor as initial endocrine-based therapy for postmenopausal women with HR⁺/HER2^– advanced or metastatic breast cancer. Approved by FDA in 2021 for adjuvant treatment of early-stage HR⁺/HER2^– breast cancer in combination with endocrine therapy.

Abemaciclib is administered at a dose of 200 mg (given orally) every 12 hours. The dose-limiting toxicity is fatigue. Neutropenia is also observed but is not rate-limiting. Other severe side effects include diarrhea and nausea.

Currently, palbociclib is being used in 164 active or recruiting clinical trials, ribociclib in 69 trials, and abemaciclib in 98 trials for more than 50 tumor types (139). These trials evaluate combinations of CDK4/6 inhibitors with a wide range of compounds (Table 4). Trials with trilaciclib test the benefit of this compound in preserving bone marrow and the immune system.

Additional target	Inhibitor	Immune checkpoint inhibitor	Tumor type	Trial identifier
*Palbociclib*
Aromatase	Letrozole, anastrozole, exemestane		HR⁺ breast cancer, HR⁺ ovarian cancer, metastatic breast cancer, metastatic endometrial cancer	NCT04130152, NCT03054363, NCT03936270, NCT04047758, NCT02692755, NCT02806050, NCT03870919, NCT02040857, NCT04176354, NCT02028507, NCT03220178, NCT02592083, NCT02603679, NCT04256941, NCT03425838, NCT02894398, NCT02297438, NCT02730429, NCT02142868, NCT02942355
LHRH	LHRH agonists: goserelin, leuprolide		HR⁺ breast cancer	NCT03969121, NCT03423199, NCT01723774, NCT02917005, NCT02592746, NCT03628066
ER	ER antagonists: fulvestrant, tamoxifen		HR⁺ breast cancer, metastatic breast cancer	NCT02668666, NCT02738866, NCT03184090, NCT04526028, NCT02513394, NCT03560856, NCT02760030, NCT03079011, NCT03227328, NCT03809988, NCT02764541, NCT03007979, NCT03633331
ER	Selective estrogen receptor degraders (SERDs): G1T48, ZN-c5, SAR439859, AZD9833, GDC-9545		HR⁺ breast cancer	NCT03455270, NCT04546009, NCT04436744, NCT04478266, NCT03560531, NCT03616587, NCT03284957, NCT03332797
ER	Selective estrogen receptor modulator (SERM): bazedoxifene		HR⁺ breast cancer	NCT03820830, NCT02448771
Aromatase + PD-1	Letrozole, anastrozole	Pembrolizumab, nivolumab	Stage IV ER⁺ breast cancer	NCT02778685, NCT04075604
PD-1		Nivolumab, pembrolizumab, MGA012	Liposarcoma	NCT04438824
PD-L1		Avelumab	AR⁺ breast cancer, TNBC, ER⁺/HER2^– metastatic breast cancer	NCT04360941, NCT03147287
EGFR + PD-L1	Cetuximab	Avelumab	Squamous cell carcinoma of the head and neck	NCT03498378
HER2	Tucatinib, trastuzumab, pertuzumab, T-DM1, ZW25		HER2⁺ breast cancer	NCT03530696, NCT03054363, NCT02448420, NCT03709082, NCT03304080, NCT02947685
EGFR/HER2	Neratinib		Advanced solid tumors with EGFR mutation/amplification, HER2 mutation/amplification, HER3/4 mutation, or KRAS mutation	NCT03065387
EGFR	Cetuximab		Metastatic colorectal cancer, squamous cell carcinoma of the head and neck	NCT03446157, NCT02499120
FGFR	Erdafitinib		ER⁺/HER2^–/FGFR-amplified metastatic breast cancer	NCT03238196
FGFR1-3	Rogaratinib		FGFR1-3⁺/HR⁺ breast cancer	NCT04483505
IGF-1R	Ganitumab		Ewing sarcoma	NCT04129151
VEGF1-3 receptors + PD-L1	Axitinib	Avelumab	NSCLC	NCT03386929
RAF	Sorafenib		Leukemia	NCT03132454
MEK	PD-0325901, binimetinib		KRAS mutant NSCLC, TNBC, KRAS and NRAS mutant metastatic or unresectable colorectal cancer	NCT02022982, NCT03170206, NCT04494958, NCT03981614
ERK	Ulixertinib		Advanced pancreatic cancer and other solid tumors	NCT03454035
PI3K	Copanlisib		HR⁺ breast cancer	NCT03128619
PI3K	Taselisib, pictilisib, GDC-0077		PIK3CA mutant advanced solid tumors, PIK3CA mutant and HR⁺ breast cancer	NCT02389842, NCT04191499, NCT03006172
PI3K/mTOR	Gedatolisib		Metastatic breast cancer, advanced squamous cell lung, pancreatic, head and neck cancer and other solid tumors	NCT02684032, NCT03065062, NCT02626507
mTOR	Everolimus, vistusertib		HR⁺ breast cancer	NCT02871791
AKT	Ipatasertib		HR⁺ breast cancer, metastatic breast cancer, metastatic gastrointestinal tumors, NSCLC	NCT03959891, NCT04060862, NCT04591431
BTK	Ibrutinib		Mantle cell lymphoma	NCT03478514
BCL-2	Venetoclax		ER⁺/BCL-2⁺ advanced or metastatic breast cancer	NCT03900884
AR	AR antagonists: bicalutamide		AR⁺ metastatic breast cancer	NCT02605486
Lysosome + aromatase	Hydroxychloroquine + letrozole		ER⁺ breast cancer	NCT03774472
Proliferating cells	Standard chemotherapy		Stage IV ER⁺ breast cancer	NCT03355157
Proliferating cells	Radiation		Stage IV ER⁺ breast cancer	NCT03870919, NCT03691493, NCT04605562
BCR-ABL	Bosutinib		HR⁺ breast cancer	NCT03854903
*Ribociclib*
Aromatase	Letrozole, anastrozole, exemestane		HR⁺ breast cancer, metastatic breast cancer, ovarian cancer	NCT04256941, NCT03425838, NCT03822468, NCT02712723, NCT03673124, NCT02941926, NCT03248427, NCT03671330, NCT02333370, NCT01958021, NCT03425838
LHRH	LHRH agonists: goserelin, leuprolide		HR⁺ breast cancer	NCT03944434
ER	ER antagonists: fulvestrant		HR⁺ breast cancer, advanced breast cancer	NCT03227328, NCT02632045, NCT02632045, NCT03555877
PD-1		Spartalizumab	Breast cancer and ovarian cancer, recurrent and/or metastatic head and neck squamous cell carcinoma, melanoma	NCT03294694, NCT04213404, NCT03484923
HER2	Trastuzumab, pertuzumab, T-DM1		HER2⁺ breast cancer	NCT03913234, NCT02657343
EGFR	Nazartinib (EGF816)		EGFR mutant NSCLC	NCT03333343
RAF	Encorafenib, LXH254		NSCLC, BRAF mutant melanoma	NCT02974725, NCT03333343, NCT04417621, NCT02159066
MEK	Binimetinib		BRAF V600-dependent advanced solid tumors, melanoma	NCT01543698, NCT02159066
PI3K	Alpelisib		Breast cancer with PIK3CA mutation	NCT03439046
mTOR	Everolimus		Advanced dedifferentiated liposarcoma, leiomyosarcoma, glioma, astrocytoma, glioblastoma, endometrial carcinoma, pancreatic cancer, neuroendocrine tumors	NCT03114527, NCT03355794, NCT03834740, NCT03008408, NCT02985125, NCT03070301
mTOR + inflammation	Everolimus + dexamethasone		ALL	NCT03740334
SHP2	TNO155		Advanced solid tumors	NCT04000529
AR	AR antagonists: bicalutamide, enzalutamide		TNBC, metastatic prostate carcinoma	NCT03090165, NCT02555189
HDAC	Belinostat		TNBC, ovarian cancer	NCT04315233
proliferating cells	Standard chemotherapy		Ovarian cancer, metastatic solid tumors, soft tissue sarcoma, hepatocellular carcinoma	NCT03056833, NCT03237390, NCT03009201, NCT02524119
*Abemaciclib*
Aromatase	Letrozole, anastrozole, exemestane		HR⁺ breast cancer, metastatic breast cancer, endometrial cancer	NCT04256941, NCT03425838, NCT04227327, NCT04393285, NCT04305236, NCT03643510, NCT03675893, NCT04352777, NCT04293393, NCT02057133
ER	ER antagonists: fulvestrant		Advanced breast cancer, low-grade serous ovarian cancer	NCT03227328, NCT03531645, NCT04158362, NCT01394016
PD-1		Nivolumab, pembrolizumab	Head and neck cancer, g astroesophageal cancer, NSCLC, HR⁺ breast cancer	NCT04169074, NCT03655444, NCT03997448, NCT02779751
ER + PD-L1	ER antagonists: fulvestrant	Atezolizumab	HR⁺ breast cancer, metastatic breast cancer	NCT03280563
AKT + ER + PD-L1	Ipatasertib + ER antagonists: fulvestrant	Atezolizumab	HR⁺ breast cancer	NCT03280563
PD-L1		LY3300054	Advanced solid tumors	NCT02791334
HER2	Trastuzumab		HER2⁺ metastatic breast cancer	NCT04351230
Receptor tyrosine kinases	Sunitinib		Metastatic renal cell carcinoma	NCT03905889
IGF-1/IGF-2	Xentuzumab		HR⁺ breast cancer	NCT03099174
VEGF-A	Bevacizumab		Glioblastoma	NCT04074785
PI3K	Copanlisib		HR⁺ breast cancer, metastatic breast cancer	NCT03939897
PI3K/mTOR	LY3023414		Metastatic cancer	NCT01655225
ERK1/2	LY3214996		tumors with ERK1/2 mutations, glioblastoma, metastatic cancer	NCT04534283, NCT04391595, NCT02857270
*Trilaciclib*
Proliferating cells	Chemotherapy		SCLC: This trial evaluates the potential clinical benefit of trilaciclib in preventing chemotherapy-induced myelosuppression in patients receiving chemotherapy	NCT04504513
Proliferating cells + PD-L1	Carboplatin + etoposide	Atezolizumab	SCLC: This trial investigates the potential clinical benefit of trilaciclib in preserving the bone marrow and the immune system, and enhancing antitumor efficacy when administered with chemotherapy	NCT03041311
Proliferating cells	Topotecan		SCLC: This trial investigates the potential clinical benefit of trilaciclib in preserving the bone marrow and the immune system, and enhancing the antitumor efficacy of chemotherapy when administered prior to chemotherapy	NCT02514447
Proliferating cells	Carboplatin + gemcitabine		Metastatic TNBC: This study investigates the potential clinical benefit of trilaciclib in preserving the bone marrow and the immune system, and enhancing the antitumor efficacy of chemotherapy when administered prior to chemotherapy	NCT02978716
*Lerociclib*
ER	ER antagonist: fulvestrant		HR⁺/HER2^– metastatic breast cancer	NCT02983071
EGFR	Osimertinib		EGFR mutant NSCLC	NCT03455829
*SHR6390*
ER	ER antagonist: fulvestrant		HR⁺/HER2^– recurrent/ metastatic breast cancer	NCT03481998
Aromatase	Letrozole, anastrozole		HR⁺/HER2^– recurrent/ metastatic breast cancer	NCT03966898, NCT03772353
EGFR/HER2	Pyrotinib		HER2⁺ gastric cancer, HER2⁺ metastatic breast cancer	NCT04095390, NCT03993964
AR	AR antagonists: SHR3680		metastatic TNBC	NCT03805399
*PF-06873600*
Endocrine therapy	Single agent and then in combination with endocrine therapy		HR⁺/HER2^– metastatic breast cancer, ovarian and fallopian tube cancer, TNBC and other tumors	NCT03519178
*FCN-473c*
Aromatase	Letrozole		ER⁺/HER2^– advanced breast cancer	NCT04488107

Table 4. Ongoing clinical trials testing new combinations with CDK4/6 inhibitors.

HR⁺, hormone receptor–positive; LHRH, luteinizing hormone–releasing hormone; ER⁺, estrogen receptor–positive; PD-1, programmed cell death protein 1; PD-L1, programmed cell death 1 ligand 1; AR⁺, androgen receptor–positive; TNBC, triple-negative breast cancer; EGFR, epidermal growth factor receptor; HER2⁺, human epidermal growth factor receptor 2–positive; FGFR, fibroblast growth factor receptor; IGFR, insulin-like growth factor receptor; VEGF, vascular endothelial growth factor receptor; PI3K, phosphoinositide 3-kinase; NSCLC, non–small-cell lung cancer; ALL, acute lymphoblastic leukemia; SCLC, small-cell lung cancer.

http://newdrugapprovals.org/2015/02/05/fda-approves-ibrance-for-postmenopausal-women-with-advanced-breast-cancer/

Resistance to CDK4/6 inhibitors

Although CDK4/6 inhibitors represent very effective agents in cancer treatment, nearly all patients eventually develop resistance and succumb to the disease. Moreover, a substantial fraction of tumors show intrinsic resistance to treatment with CDK4/6 inhibitors (Fig. 3).

Fig. 3. Mechanisms of cancer cell resistance to CDK4/6 inhibition.

Known mechanisms include loss of RB1, activation of pathways impinging on CycD-CDK4/6, amplification of the *CDK4/6* genes and overexpression of CDK6 protein, activation of CycE-CDK2, and lysosomal sequestration of CDK4/6 inhibitors. Blank pieces of the puzzle denote additional mechanisms that remain to be discovered.

The best-documented mechanism of preexisting and acquired resistance is the loss of RB1 (71, 81, 140). Acquired RB1 loss has been detected in PDXs (141), in circulating tumor DNA (ctDNA) (142, 143), and in tumors from patients treated with CDK4/6 inhibitors (144, 145). However, RB1 mutations are likely subclonal and are seen in only 5 to 10% of patients (143, 145).

Increased expression of CDK6 was shown to underlie acquired resistance to CDK4/6 inhibitors. Amplification of the CDK6 gene and the resulting overexpression of CDK6 protein were found in abemaciclib-resistant ER⁺ breast cancer cells (146) and in ctDNA of patients with ER⁺ breast cancers that progressed during treatment with palbociclib plus endocrine therapy (147). Also, CDK4 gene amplification conferred insensitivity to CDK4/6 inhibition in GBM and sarcomas (148–150), whereas overexpression of CDK4 protein was associated with resistance to endocrine therapy in HR⁺ breast cancers (79).

Resistant breast cancer cells can also up-regulate the expression of CDK6 through suppression of the TGF-β/SMAD4 pathway by the microRNA miR-432-5p. In this mechanism, exosomal expression of miR-432-5p mediates the transfer of the resistance phenotype between neighboring cell populations (151). Another mechanism of CDK6 up-regulation in ER⁺ breast cancers is the loss of FAT1, which represses CDK6 expression via the Hippo pathway. Loss of FAT1 triggers up-regulation of CDK6 expression by the Hippo pathway effectors TAZ and YAP. Moreover, genomic alterations in other components of the Hippo pathway, although rare, are also associated with reduced sensitivity to CDK4/6 inhibitors (81).

Genetic lesions that activate pathways converging on D-type cyclins can cause resistance to CDK4/6 inhibitors. These include (i) FGFR1/2 gene amplification or mutational activation, detected in ctDNA from patients with ER⁺ breast cancers that progressed upon treatment with palbociclib plus endocrine therapy (147); (ii) hyperactivation of the MAPK pathway in resistant prostate adenocarcinoma cells, possibly due to increased production of EGF by cancer cells (152); and (iii) increased secretion of FGF in palbociclib-resistant KRAS-mutant NSCLC cells, which stimulates FGFR1 signaling in an autocrine or paracrine fashion, resulting in activation of ERK1/2 and mTOR as well as up-regulation of D-cyclin, CDK6, and cyclin E expression (153). Analyses of longitudinal tumor biopsies from a melanoma patient revealed an activating mutation in the PIK3CA gene that conferred resistance to ribociclib plus MEK inhibitor treatment (154). It is possible that these lesions elevate the cellular levels of active cyclin D–CDK4/6 complexes, thereby increasing the threshold for CDK4/6 inhibition.

Formation of a noncanonical cyclin D1–CDK2 complex was shown to represent another mechanism of acquired CDK4/6 inhibitor resistance. Such a complex was observed in palbociclib-treated ER⁺ breast cancer cells and was implicated in overcoming palbociclib-induced cell cycle arrest (141). Also, depletion of AMBRA1 promoted the interaction of D-cyclins with CDK2, resulting in resistance to CDK4/6 inhibitors (20, 22); it remains to be seen whether this represents an intrinsic or acquired resistance mechanism in human tumors.

Genetic analyses revealed that activation of cyclin E can bypass the requirement for cyclin D–CDK4/6 in development and tumorigenesis (155, 156). Hence, it comes as no surprise that increased activity of cyclin E–CDK2 is responsible for a large proportion of intrinsic and acquired resistance to CDK4/6 inhibitors. Several different mechanisms can activate cyclin E–CDK2 kinase in resistant tumor cells: (i) Down-regulation of KIP/CIP inhibitors results in increased activity of cyclin E–CDK (54, 157). (ii) Loss of PTEN expression, which activates AKT signaling, leads to nuclear exclusion of p27^KIP1. This in turn prevents access of p27^KIP1 to CDK2, resulting in increased CDK2 kinase activity (144). (iii) Activation of the PI3K/AKT pathway causes decreased levels of p21^CIP1. Co-treatment of melanoma PDXs with MDM2 inhibitors (which up-regulate p21^CIP1 via p53) sensitized intrinsically resistant tumor cells to CDK4/6 inhibitors (158). (iv) Up-regulation of cyclin D1 levels triggers sequestration of KIP/CIP inhibitors from cyclin E–CDK2 to cyclin D–CDK4/6, thereby activating the former (158). (v) Amplification of the CCNE1 gene and increased levels of cyclin E1 protein result in elevated activity of E-CDK2 kinase (141). (vi) mTOR signaling has been shown to up-regulate cyclin E1 (and D1) in KRAS-mutated pancreatic cancer cells; CDK2 activity was essential for CDK4/6 inhibitor resistance in this setting (159). (vii) Up-regulation of PDK1 results in activation of the AKT pathway, which increases the expression of cyclins E and A and activates CDK2 (160). (viii) In CDK4/6 inhibitor–resistant melanoma cells, high levels of RNA-binding protein FXR1 increase translation of the amino acid transporter SLC36A1. Up-regulation of SLC36A1 expression activates mTORC1, which in turn increases CDK2 expression (161). All these lesions are expected to allow cell proliferation, despite CDK4/6 inhibition, as a consequence of the activation of the downstream cell cycle kinase CDK2.

The role for cyclin E–CDK2 in CDK4/6 inhibitor resistance has been confirmed in clinical trials. In patients with advanced ER⁺ breast cancer treated with palbociclib and letrozole or fulvestrant, the presence of proteolytically cleaved cytoplasmic cyclin E in tumor tissue conferred strongly shortened progression-free survival (71). Moreover, analyses of PALOMA-3 trial for patients with ER⁺ breast cancers revealed lower efficacy of palbociclib plus fulvestrant in patients displaying high cyclin E mRNA levels in metastatic biopsies (80). Amplification of the CCNE1 gene was detected in ctDNA of patients with ER⁺ breast cancers that progressed on palbociclib plus endocrine therapy (147). Also, amplification of the CCNE2 gene (encoding cyclin E2) was seen in a fraction of CDK4/6 inhibitor–resistant HR⁺ mammary carcinomas (145, 162).

Collectively, these analyses indicate that resistant cells may become dependent on CDK2 for cell cycle progression. Indeed, depletion of CDK2 or inhibition of CDK2 kinase activity in combination with CDK4/6 inhibitors blocked proliferation of CDK4/6 inhibitor–resistant cancer cells (111, 141, 158–161). Recently, two CDK2-specific inhibitors, PF-07104091 (163) and BLU0298 (164), have been reported. PF-07104091 is now being tested in a phase 2 clinical trial in combination with palbociclib plus antiestrogens. Another recent study identified a novel compound, PF-3600, that inhibits CDK4/6 and CDK2 (165). PF3600 had potent antitumor effects against xenograft models of intrinsic and acquired resistance to CDK4/6 inhibition (165). A phase 2 clinical trial is currently evaluating this compound as a single agent and in combination with endocrine therapy in patients with HR⁺/HER2^– breast cancer and other cancer types.

Whole-exome sequencing of 59 HR⁺/HER2^– metastatic breast tumors from patients treated with CDK4/6 inhibitors and anti-estrogens revealed eight alterations that likely conferred resistance: RB1 loss; amplification of CCNE2 or AURKA; activating mutations or amplification of AKT1, FGFR2, or ERBB2; activating mutations in RAS genes; and loss of ER expression. The frequent activation of AURKA (in 27% of resistant tumors) raises the possibility of combining CDK4/6 inhibitors with inhibitors of Aurora A kinase to overcome resistance (145).

In contrast to ER⁺ mammary carcinomas, TNBCs are overall resistant to CDK4/6 inhibition (45). A subset of TNBCs display high numbers of lysosomes, which causes sequestration of CDK4/6 inhibitors into the expanded lysosomal compartment, thereby preventing their action on nuclear CDK4/6. Preclinical studies revealed that lysosomotropic agents that reverse the lysosomal sequestration (such as chloroquine, azithromycin, or siramesine) render TNBC cells fully sensitive to CDK4/6 inhibition (71, 111). These observations now need to be tested in clinical trials for TNBC patients.

Outlook

Although D-cyclins and CDK4/6 were discovered 30 years ago, several aspects of cyclin D–CDK4/6 biology, such as their role in antitumor immunity, are only now starting to be appreciated. The full range of cyclin D–CDK4/6 functions in tumor cells remains unknown. It is likely that these kinases play a much broader role in cancer cells than is currently appreciated. Hence, the impact of CDK4/6 inhibition on various aspects of tumorigenesis requires further study. Also, treatment of patients with CDK4/6 inhibitors likely affects several aspects of host physiology, which may be relevant to cancer progression.

In the next years, we will undoubtedly witness the development and testing of new CDK4/6 inhibitors. Because activation of CDK2 represents a frequent CDK4/6 inhibitor resistance mechanism, compounds that inhibit CDK4/6 and CDK2 may prevent or delay the development of resistance. Conversely, selective compounds that inhibit CDK4 but not CDK6 may allow more aggressive dosing, as they are expected not to result in bone marrow toxicity caused by CDK6 inhibition. New, less basic CDK4/6 inhibitor compounds (111) may escape lysosomal sequestration and may be efficacious against resistant cancer types such as TNBC. Degrader compounds, which induce proteolysis of cyclin D rather than inhibit cyclin D–CDK4/6 kinase, may have superior properties, as they would extinguish both CDK4/6-dependent and -independent functions of D-cyclins in tumorigenesis. Moreover, dissolution of cyclin D–CDK4/6 complexes is expected to liberate KIP/CIP inhibitors, which would then inhibit CDK2. D-cyclins likely play CDK-independent functions in tumorigenesis—for example, by regulating gene expression (166). However, their role in tumor biology and the utility of targeting these functions for cancer treatment remain largely unexplored.

An important challenge will be to test and identify combinatorial treatments involving CDK4/6 inhibitors for the treatment of different tumor types. CDK4/6 inhibitors trigger cell cycle arrest of tumor cells and, in some cases, senescence. It will be essential to identify combination treatments that convert CDK4/6 inhibitors from cytostatic compounds to cytotoxic ones, which would unleash the killing of tumor cells. Genome-wide high-throughput screens along with analyses of mouse cancer models and PDXs will help to address this point. Another largely unexplored area of cyclin D–CDK4/6 biology is the possible involvement of these proteins in other pathologies, such as metabolic disorders. Research in this area may extend the use of CDK4/6 inhibitors to treatment of other diseases. All these unresolved questions ensure that CDK4/6 biology will remain an active area of basic, translational, and clinical research for several years to come.

CDK inhibitors and Breast Cancer

The U.S. Food and Drug Administration today granted accelerated approval to Ibrance (palbociclib) to treat advanced (metastatic) breast cancer inr postmenopausal women with estrogen receptor (ER)-positive, human epidermal growth factor receptor 2 (HER2)-negative metastatic breast cancer who have not yet received an endocrine-based therapy. It is to be used in combination with letrozole, another FDA-approved product used to treat certain kinds of breast cancer in postmenopausal women.

See Dr. Melvin Crasto’s blog posts on the announcement of approval of Ibrance (palbociclib) at

and about the structure and mechanism of action of palbociclib

http://newdrugapprovals.org/2014/01/05/palbociclib/

From the CancerNetwork at http://www.cancernetwork.com/aacr-2014/cdk-inhibitors-show-impressive-activity-advanced-breast-cancer

CDK Inhibitors Show Impressive Activity in Advanced Breast Cancer

News | April 08, 2014 | AACR 2014, Breast Cancer

By Anna Azvolinsky, PhD

Chemical structure of palbociclib

Palbociclib and LY2835219 are both cyclin-dependent kinase (CDK) 4/6 inhibitors. CDK4 and CDK6 are kinases that, together with cyclin D1, facilitate the transition of dividing cells from the G1 to the S (synthesis) phase of the cell cycle. Preclinical studies have shown that breast cancer cells rely on CDK4 and CDK6 for division and growth, and that selective CDK4/6 inhibitors can arrest the cells at this G1/S phase checkpoint.

The results of the phase II trial of palbociclib and phase I trial of LY2835219 both indicated that hormone receptor (HR)-positive disease appears to be the best marker to predict patient response.

LY2835219 Phase I Trial Demonstrates Early Activity

The CDK4/6 inhibitor LY2835219 has demonstrated early activity in heavily pretreated women with metastatic breast cancer. Nineteen percent of these women (9 out of 47) had a partial response and 51% (24 out of 47) had stable disease following monotherapy with the oral CDK4/6 inhibitor. Patients had received a median of seven prior therapies, and 75% had metastatic disease in the lung, liver, or brain. The median age of patients was 55 years.

All of the partial responses were in patients with HR-positive disease. The overall response rate for this patient subset was 25% (9 of 36 patients). Twenty of the patients with stable disease had HR-positive disease, with 13 patients having stable disease lasting 24 weeks or more.

Despite treatment, disease progression occurred in 23% of the patients.

These results were presented at a press briefing by Amita Patnaik, MD, associate director of clinical research at South Texas Accelerated Research Therapeutics in San Antonio, Texas, at the 2014 American Association for Cancer Research (AACR) Annual Meeting, held April 5–9, in San Diego.

The phase I trial of LY2835219 enrolled 132 patients with five different tumor types, including metastatic breast cancer. Patients received 150-mg to 200-mg doses of the oral drug every 12 hours.

The overall disease control rate was 70% for all patients and 81% among the 36 HR-positive patients.

The median progression-free survival (PFS) was 5.8 months for all patients and 9.1 months for HR-positive patients. Patnaik noted that the median PFS is still a moving target, as 18 patients, all with HR-positive disease, remain on therapy.

“The data are rather encouraging for a very heavily pretreated patient population,” said Patnaik during the press briefing.

Even though the trial was not designed to compare efficacy based on breast cancer subpopulations, the results in HR-positive tumors are particularly encouraging, according to Patnaik.

Common adverse events thought to be treatment-related were diarrhea, nausea, fatigue, vomiting, and neutropenia. These adverse events occurred in 5% or less of patients at grade 3 or 4 toxicity, except neutropenia, which occurred as a grade 3 or 4 toxicity in 11% of patients. Patnaik noted during the press briefing that the neutropenia was uncomplicated and did not result in discontinuation of therapy by any of the patients.

Palbociclib Phase II Data “Impressive”

The addition of the oral CDK4/6 inhibitor palbociclib resulted in an almost doubling of PFS in first-line treatment of postmenopausal metastatic breast cancer patients with HR-positive disease compared with a control population. The patients in this trial were not previously treated for their metastatic breast cancer, unlike the patient population in the phase I LY2835219 trial.

Patients receiving the combination of palbociclib at 125 mg once daily plus letrozole at 2.5 mg once daily had a median PFS of 20.2 months compared with a median of 10.2 months for patients treated with letrozole alone (hazard ratio = 0.488; P = .0004).

Richard S. Finn, MD, assistant professor of medicine at the University of California, Los Angeles, presented the data from the phase II PALOMA-1 trial at a press briefing at the AACR Annual Meeting.

A total of 165 patients were randomized 1:1 to either the experimental arm or control arm.

Forty-three percent of patients in the combination arm had an objective response compared with 33% of patients in the control arm.

Overall survival (OS), a secondary endpoint in this trial, was encouraging but the results are still preliminary, said Finn during the press briefing. The median OS was 37.5 months in the palbociclib arm compared with 33.3 months in the letrozole alone arm (P = .21). Finn noted that long-term follow-up is necessary to establish the median OS. “This first look of the survival data is encouraging. This is a front-line study, and it is encouraging that there is early [separation] of the curves,” he said.

No new toxicities were reported since the interim trial results. Common adverse events included leukopenia, neutropenia, and fatigue. The neutropenia could be quickly resolved and was uncomplicated and not accompanied by fever, said Finn.

Palbociclib is currently being tested in two phase III clinical trials: The PALOMA-3 trial is testing the combination of palbociclib with letrozole and fulvestrant in late-stage metastatic breast cancer patients who have failed endocrine therapy. The PENELOPE-B trial is testing palbociclib in combination with standard endocrine therapy in HR-positive breast cancer patients with residual disease after neoadjuvant chemotherapy and surgery.

References

Patnaik A, Rosen LS, Tolaney SM, et al. Clinical activity of LY2835219, a novel cell cycle inhibitor selective for CDK4 and CDK6, in patients with metastatic breast cancer. American Association for Cancer Research Annual Meeting 2014; April 5–9, 2014; San Diego. Abstr CT232.
Finn RS, Crown JP, Lang I, et al. Final results of a randomized phase II study of PD 0332991, a cyclin-dependent kinase (CDK)-4/6 inhibitor, in combination with letrozole vs letrozole alone for first-line treatment of ER+/HER2-advanced breast cancer (PALOMA-1; TRIO-18). American Association for Cancer Research Annual Meeting 2014; April 5–9, 2014; San Diego. Abstr CT101.

– See more at: http://www.cancernetwork.com/aacr-2014/cdk-inhibitors-show-impressive-activity-advanced-breast-cancer#sthash.f29smjxi.dpuf

The Cell Cycle and Anti-Cancer Targets

From Cell Cycle in Cancer: Cyclacel Pharmaceuticals™ (note dotted arrows show inhibition of steps e.g. p21, p53)

For a nice video slideshow explaining a bit more on cyclins and the cell cycle please see video below:

Cell Cycle. 2012 Nov 1; 11(21): 3913.

doi: 10.4161/cc.22390

PMCID: PMC3507481

Cyclin-dependent kinase 4/6 inhibition in cancer therapy

Neil Johnson and Geoffrey I. Shapiro^*

See the article “Therapeutic response to CDK4/6 inhibition in breast cancer defined by ex vivo analyses of human tumors” in volume 11 on page 2756.

See the article “CDK4/6 inhibition antagonizes the cytotoxic response to anthracycline therapy” in volume 11 on page 2747.

This article has been cited by other articles in PMC.

Cyclin-dependent kinases (CDKs) drive cell cycle progression and control transcriptional processes. The dysregulation of multiple CDK family members occurs commonly in human cancer; in particular, the cyclin D-CDK4/6-retinoblastoma protein (RB)-INK4 axis is universally disrupted, facilitating cancer cell proliferation and prompting long-standing interest in targeting CDK4/6 as an anticancer strategy. Most agents that have been tested inhibit multiple cell cycle and transcriptional CDKs and have carried toxicity. However, several selective and potent inhibitors of CDK4/6 have recently entered clinical trial. PD0332991, the first to be developed, resulted from the introduction of a 2-aminopyridyl substituent at the C2-position of a pyrido(2,3-d)pyrimidin-7-one backbone, affording exquisite selectivity toward CDK4/6.¹ PD0332991 arrests cells in G₁ phase by blocking RB phosphorylation at CDK4/6-specfic sites and does not inhibit the growth of RB-deficient cells.² Phase I studies conducted in patients with advanced RB-expressing cancers demonstrated mild side effects and dose-limiting toxicities of neutropenia and thrombocytopenia, with prolonged stable disease in 25% of patients.³^,4 In cyclin D1-translocated mantle cell lymphoma, PD0332991 extinguished CDK4/6 activity in patients’ tumors, resulting in markedly reduced proliferation, and translating to more than 1 year of stability or response in 5 of 17 cases.⁵

Two recent papers from the Knudsen laboratory make several important observations that will help guide the continued clinical development of CDK4/6 inhibitors. In the study by Dean et al., surgically resected patient breast tumors were grown on a tissue culture matrix in the presence or absence of PD0332991. Crucially, these cultures retained associated stromal components known to play important roles in cancer pathogenesis and therapeutic sensitivities, as well as key histological and molecular features of the primary tumor, including expression of ER, HER2 and K_i-67. Similar to results in breast cancer cell lines,⁶ the authors demonstrate that only RB-positive tumors have growth inhibition in response to PD0332991, irrespective of ER or HER2 status, while tumors lacking RB were completely resistant. This result underscores RB as the predominant target of CDK4/6 in breast cancer cells and the primary marker of drug response in primary patient-derived tumors. As expected, RB-negative tumors routinely demonstrated robust expression of p16^INK4A; however, p16^INK4A expression was not always a surrogate marker for RB loss, supporting the importance of direct screening of tumors for RB expression to select patients appropriate for CDK4/6 inhibitor clinical trials.

In the second study, McClendon et al. investigated the efficacy of PD0332991 in combination with doxorubicin in triple-negative breast cancer cell lines. Again, RB functionality was paramount in determining response to either PD0332991 monotherapy or combination treatment. In RB-deficient cancer cells, CDK4/6 inhibition had no effect in either instance. However, in RB-expressing cancer cells, CDK4/6 inhibition and doxorubicin provided a cooperative cytostatic effect, although doxorubicin-induced cytotoxicity was substantially reduced, assessed by markers for mitotic catastrophe and apoptosis. Additionally, despite cytostatic cooperativity, CDK4/6 inhibition maintained the viability of RB-proficient cells in the presence of doxorubicin, which repopulated the culture after removal of drug. These results reflect previous data demonstrating that ectopic expression of p16^INK4A can protect cells from the lethal effects of DNA damaging and anti-mitotic chemotherapies.⁷ Similar results have been reported in MMTV-c-neu mice bearing RB-proficient HER2-driven tumors, where PD0332991 compromised carboplatin-induced regressions,⁸ suggesting that DNA-damaging treatments should not be combined concomitantly with CDK4/6 inhibition in RB-proficient tumors.

To combine CDK4/6 inhibition with cytotoxics, sequential treatment may be considered, in which CDK4/6 inhibition is followed by DNA damaging chemotherapy; cells relieved of G₁ arrest may synchronously enter S phase, where they may be most susceptible to agents disrupting DNA synthesis. Release of myeloma cells from a prolonged PD0332991-mediated G₁ block leads to S phase synchronization; interestingly, all scheduled gene expression is not completely restored (including factors critical to myeloma survival such as IRF4), further favoring apoptotic responses to cytotoxic agents.⁹ Furthermore, in RB-deficient tumors, CDK4/6 inhibitors may be used to maximize the therapeutic window between transformed and non-transformed cells treated with chemotherapy. In contrast to RB-deficient cancer cells, RB-proficient non-transformed cells arrested in G₁ in response to PD0332991 are afforded protection from DNA damaging agents, thereby reducing associated toxicities, including bone marrow suppression.⁸

In summary, the current work provides evidence for RB expression as a determinant of response to CDK4/6 inhibition in primary tumors and highlights the complexity of combining agents targeting the cell cycle machinery with DNA damaging treatments.

Dean JL, McClendon AK, Hickey TE, Butler LM, Tilley WD, Witkiewicz AK, Knudsen ES. Therapeutic response to CDK4/6 inhibition in breast cancer defined by ex vivo analyses of human tumors Cell Cycle 2012 11 2756 61 doi: 10.4161/cc.21195.

Notes

McClendon AK, Dean JL, Rivadeneira DB, Yu JE, Reed CA, Gao E, Farber JL, Force T, Koch WJ, Knudsen ES. CDK4/6 inhibition antagonizes the cytotoxic response to anthracycline therapy Cell Cycle 2012 11 2747 55 doi: 10.4161/cc.21127.

Footnotes

Previously published online: www.landesbioscience.com/journals/cc/article/22390

Author information ► Copyright and License information ►

References

Toogood PL, et al. J Med Chem. 2005;48:2388–406. doi: 10.1021/jm049354h. [PubMed] [Cross Ref]
Fry DW, et al. Mol Cancer Ther. 2004;3:1427–38. [PubMed]
Flaherty KT, et al. Clin Cancer Res. 2012;18:568–76. doi: 10.1158/1078-0432.CCR-11-0509. [PubMed] [Cross Ref]
Schwartz GK, et al. Br J Cancer. 2011;104:1862–8. doi: 10.1038/bjc.2011.177. [PMC free article] [PubMed] [Cross Ref]
Leonard JP, et al. Blood. 2012;119:4597–607. doi: 10.1182/blood-2011-10-388298. [PubMed] [Cross Ref]
Dean JL, et al. Oncogene. 2010;29:4018–32. doi: 10.1038/onc.2010.154. [PubMed] [Cross Ref]
Stone S, et al. Cancer Res. 1996;56:3199–202. [PubMed]
Roberts PJ, et al. J Natl Cancer Inst. 2012;104:476–87. doi: 10.1093/jnci/djs002. [PMC free article] [PubMed] [Cross Ref]
Huang X, et al. Blood. 2012;120:1095–106. doi: 10.1182/blood-2012-03-415984. [PMC free article] [PubMed] [Cross Ref]

Cell Cycle. 2012 Jul 15; 11(14): 2756–2761.

doi: 10.4161/cc.21195

PMCID: PMC3409015

Therapeutic response to CDK4/6 inhibition in breast cancer defined by ex vivo analyses of human tumors

Jeffry L. Dean,^{1 , 2}A. Kathleen McClendon,^{1 , 2}Theresa E. Hickey,³Lisa M. Butler,³Wayne D. Tilley,³Agnieszka K. Witkiewicz,^{4 , 2 ,*} and Erik S. Knudsen^{1 , 2 ,*}

See commentary “Cyclin-dependent kinase 4/6 inhibition in cancer therapy” in volume 11 on page 3913.

This article has been cited by other articles in PMC.

Abstract

To model the heterogeneity of breast cancer as observed in the clinic, we employed an ex vivo model of breast tumor tissue. This methodology maintained the histological integrity of the tumor tissue in unselected breast cancers, and importantly, the explants retained key molecular markers that are currently used to guide breast cancer treatment (e.g., ER and Her2 status). The primary tumors displayed the expected wide range of positivity for the proliferation marker Ki67, and a strong positive correlation between the Ki67 indices of the primary and corresponding explanted tumor tissues was observed. Collectively, these findings indicate that multiple facets of tumor pathophysiology are recapitulated in this ex vivo model. To interrogate the potential of this preclinical model to inform determinants of therapeutic response, we investigated the cytostatic response to the CDK4/6 inhibitor, PD-0332991. This inhibitor was highly effective at suppressing proliferation in approximately 85% of cases, irrespective of ER or HER2 status. However, 15% of cases were completely resistant to PD-0332991. Marker analyses in both the primary tumor tissue and the corresponding explant revealed that cases resistant to CDK4/6 inhibition lacked the RB-tumor suppressor. These studies provide important insights into the spectrum of breast tumors that could be treated with CDK4/6 inhibitors, and defines functional determinants of response analogous to those identified through neoadjuvant studies.

Keywords: ER, PD0332991, breast cancer, cell cycle, ex vivo

Author information ► Copyright and License information ►

Introduction

Breast cancer is a highly heterogeneous disease.¹^–⁴ Such heterogeneity is known to influence patient response to both standard of care and experimental therapeutics. In regards to biomarker-driven treatment of breast cancers, it was initially recognized that the presence of the estrogen receptor α (ER) in a fraction of breast cancer cells was associated with the response to tamoxifen and similar anti-estrogenic therapies.⁵^,⁶ Since this discovery, subsequent marker analyses and gene expression profiling studies have further divided breast cancer into a series of distinct subtypes that harbor differing and often divergent therapeutic sensitivities.¹^–³ While clearly important in considering the use of several current standard of care therapies, these markers, or molecular sub-types, do not necessarily predict the response to new therapeutic approaches that are currently undergoing clinical development. Thus, there is the continued need for functional analyses of drug response and the definition of new markers that can be used to direct treatment strategies.

Currently, all preclinical cancer models are associated with specific limitations. It is well known that cell culture models lack the tumor microenvironment known to have a significant impact on tumor biology and therapeutic response.⁷^–⁹ Xenograft models are dependent on the host response for the engraftment of tumor cells in non-native tissues, which do not necessarily recapitulate the nuances of complex tumor milieu.¹⁰ In addition, genetically engineered mouse models, while enabling the tumor to develop in the context of the host, can develop tumors that do not mirror aspects of human disease.¹⁰ Furthermore, it remains unclear whether any preclinical model truly represents the panoply of breast cancer subtypes that are observed in the clinic. Herein, we utilized a primary human tumor explant culture approach to interrogate drug response, as well as specific determinants of therapeutic response, in an unselected series of breast cancer cases.

Cell Cycle. 2012 Jul 15; 11(14): 2747–2755.

doi: 10.4161/cc.21127

PMCID: PMC3409014

CDK4/6 inhibition antagonizes the cytotoxic response to anthracycline therapy

Kathleen McClendon,^{1 , †}Jeffry L. Dean,^{1 , †}Dayana B. Rivadeneira,¹Justine E. Yu,¹Christopher A. Reed,¹Erhe Gao,²John L. Farber,³Thomas Force,²Walter J. Koch,²and Erik S. Knudsen^{1 ,*}

See commentary “Cyclin-dependent kinase 4/6 inhibition in cancer therapy” in volume 11 on page 3913.

This article has been cited by other articles in PMC.

http://www.onclive.com/publications/contemporary-oncology/2014/november-2014/targeting-cell-cycle-progression-cdk46-inhibition-in-breast-cancer/1

Abstract

Triple-negative breast cancer (TNBC) is an aggressive disease that lacks established markers to direct therapeutic intervention. Thus, these tumors are routinely treated with cytotoxic chemotherapies (e.g., anthracyclines), which can cause severe side effects that impact quality of life. Recent studies indicate that the retinoblastoma tumor suppressor (RB) pathway is an important determinant in TNBC disease progression and therapeutic outcome. Furthermore, new therapeutic agents have been developed that specifically target the RB pathway, potentially positioning RB as a novel molecular marker for directing treatment. The current study evaluates the efficacy of pharmacological CDK4/6 inhibition in combination with the widely used genotoxic agent doxorubicin in the treatment of TNBC. Results demonstrate that in RB-proficient TNBC models, pharmacological CDK4/6 inhibition yields a cooperative cytostatic effect with doxorubicin but ultimately protects RB-proficient cells from doxorubicin-mediated cytotoxicity. In contrast, CDK4/6 inhibition does not alter the therapeutic response of RB-deficient TNBC cells to doxorubicin-mediated cytotoxicity, indicating that the effects of doxorubicin are indeed dependent on RB-mediated cell cycle control. Finally, the ability of CDK4/6 inhibition to protect TNBC cells from doxorubicin-mediated cytotoxicity resulted in recurrent populations of cells specifically in RB-proficient cell models, indicating that CDK4/6 inhibition can preserve cell viability in the presence of genotoxic agents. Combined, these studies suggest that while targeting the RB pathway represents a novel means of treatment in aggressive diseases such as TNBC, there should be a certain degree of caution when considering combination regimens of CDK4/6 inhibitors with genotoxic compounds that rely heavily on cell proliferation for their cytotoxic effects.

Click on Video Link for Dr. Tolaney slidepresentation of recent data with CDK4/6 inhibitor trial results https://youtu.be/NzJ_fvSxwGk

Audio and slides for this presentation are available on YouTube: http://youtu.be/NzJ_fvSxwGk

Sara Tolaney, MD, MPH, a breast oncologist with the Susan F. Smith Center for Women’s Cancers at Dana-Farber Cancer Institute, gives an overview of phase I clinical trials and some of the new drugs being tested to treat breast cancer. This talk was originally given at the Metastatic Breast Cancer Forum at Dana-Farber on Oct. 5, 2013.

A great article on current clinical trials and explanation of cdk inhibitors by Sneha Phadke, DO; Alexandra Thomas, MD at the site OncoLive

cdk4/6 inhibitor Ibrance Has Favorable Toxicity and Adverse Event Profile

As discussed in earlier posts and the Introduction to this chapter on Cytotoxic Chemotherapeutics, most anti-cancer drugs developed either to target DNA, DNA replication, or the cell cycle usually have similar toxicity profile which can limit their therapeutic use. These toxicities and adverse events usually involve cell types which normally exhibit turnover in the body, such as myeloid and lymphoid and granulocytic series of blood cells, epithelial cells lining the mucosa of the GI tract, as well as follicular cells found at hair follicles. This understandably manifests itself as common toxicities seen with these types of agents such as the various cytopenias in the blood, nausea vomiting diarrhea (although there are effects on the chemoreceptor trigger zone), and alopecia.

It was felt that the cdk4/6 inhibitors would show serious side effects similar to other cytotoxic agents and this definitely may be the case as outlined below:

(Side effects of palbociclib) From navigatingcancer.com

Palbociclib may cause side effects. Tell your doctor if any of these symptoms are severe or do not go away:

nausea
diarrhea
vomiting
decreased appetite
tiredness
numbness or tingling in your arms, hands, legs, and feet
sore mouth or throat
unusual hair thinning or hair loss

Some side effects can be serious. If you experience any of these symptoms, call your doctor immediately or get emergency medical treatment:

fever, chills, or signs of infection
shortness of breath
sudden, sharp chest pain that may become worse with deep breathing
fast, irregular, or pounding heartbeat
rapid breathing
weakness
unusual bleeding or bruising
nosebleeds

The following is from FDA Drug Trials Snapshot of Ibrance™:

See PDF on original submission and CDER review

original FDA Ibrance submission

original FDA Ibrance submission

CDER Review Ibrance

4.3 Preclinical Pharmacology/Toxicology

For full details, please see Pharmacology/Toxicology review by Dr. Wei Chen The nonclinical studies adequately support the safety of oral administration of palbociclib for the proposed indication and the recommendation from the team is for approval. Non-clinical studies of palbociclib included safety pharmacology studies, genotoxicity

studies, reproductive toxicity studies, pharmacokinetic studies, toxicokinetic studies and repeat-dose general toxicity studies which were conducted in rats and dogs. The pivotal toxicology studies were conducted in compliance with Good Laboratory Practice regulation.

Pharmacology:

As described above, palbociclib is an inhibitor of CDK4 and CDK6. Palbociclib modulates downstream targets of CDK4 and CDK6 in vitro and induces G1 phase cell cycle arrest and therefore acts to inhibit DNA synthesis and cell proliferation. Combination of palbociclib with anti-estrogen agents demonstrated synergistic inhibition

of cell proliferation in ER+ breast cancer cells. Palbociclib showed anti-tumor efficacy in animal tumor model studies. Safety pharmacology studies with palbociclib demonstrated adverse effects on both the respiratory and cardiovascular function of dogs at a dose of 125mg/day (four times and 50-times the human clinical exposure

respectively) based on mean unbound Cmax.

General toxicology:

Palbociclib was studied in single dose toxicity studies and repeated dose studies in rats and dogs. Adverse effects in the bone marrow, lymphoid tissues, and male reproductive organs were observed at clinically relevant exposures. Partial to complete reversibility of toxicities to the hematolymphopoietic and male reproductive systems was demonstrated following a recovery period (4-12 weeks), with the exception of the male reproductive organ findings in dogs. Gastrointestinal, liver, kidney, endocrine/metabolic (altered glucose metabolism), respiratory, ocular, and adrenal effects were also seen.

Genetic toxicology:

Palbociclib was evaluated for potential genetic toxicity in in vitro and in vivo studies. The Ames bacterial mutagenicity assay in the presence or absence of metabolic activation demonstrated non-mutagenicity. In addition, palbociclib did not induce chromosomal aberrations in cultured human peripheral blood lymphocytes in the presence or absence of metabolic activation. Palbociclib was identified as aneugenic based on kinetochore analysis of micronuclei formation in an In vitro assay in CHO-WBL cells. In addition, palbociclib was shown to induce micronucleus formation in male rats at doses 100

mg/kg/day (10x human exposure at the therapeutic dose) in an in vivo rat micronucleus assay.

Reproductive toxicology: No effects on estrous cycle and no reproductive toxicities were noticed in standard assays.

Pharmacovigilance (note please see PDF for more information)

Deaths Associated With Trials: Although a few deaths occurred during some trials no deaths were attributed to the drug.

Non-Serious Adverse Events:

(note a reviewers comment below concerning incidence of pulmonary embolism is a combination trial with letrazole)

Tumor Suppressor Pathway, Hippo pathway, is responsible for Sensing Abnormal Chromosome Numbers in Cells and Triggering Cell Cycle Arrest, thus preventing Progression into Cancer

Nonhematologic Cancer Stem Cells [11.2.3]

New methods for Study of Cellular Replication, Growth, and Regulation

Multiple Lung Cancer Genomic Projects Suggest New Targets, Research Directions for Non-Small Cell Lung Cancer

Proteomics, Metabolomics, Signaling Pathways, and Cell Regulation: a Compilation of Articles in the Journal http://pharmaceuticalintelligence.com

In Focus: Targeting of Cancer Stem Cells

http://s.hswstatic.com/gif/nanotechnology-6.gif

Confluence of Chemistry, Physics, and Biology

Posted in Alzheimer's Disease, Bacterial Resistance, BioInks, Biological Networks, Biomarkers & Medical Diagnostics, BioTechnology - Venture Creation, Cancer and Current Therapeutics, CANCER BIOLOGY & Innovations in Cancer Therapy, Chemical Biology and its relations to Metabolic Disease, Clinical & Translational, MicroEngineering Cell-Tissue & Systems, tagged anti-cancer therapy, gold nanoparticles, nano particles, nanotechnology, nanotherapeutic, T2DM on September 24, 2015| Leave a Comment »

Confluence of Chemistry, Physics, and Biology

Curator: Larry H. Bernstein, MD, FCAP

How Nanotechnology Works by Kevin Bonsor and Jonathan Strickland

Image Source:
http://s.hswstatic.com/gif/nanotechnology-4.gif

There’s an unprecedented multidisciplinary convergence of scientists dedicated to the study of a world so small, we can’t see it — even with a light microscope. That world is the field of nanotechnology, the realm ofatoms and nanostructures.Nanotechnology is so new, no one is really sure what will come of it. Even so, predictions range from the ability to reproduce things like diamonds and food to the world being devoured by self-replicating nanorobots.In order to understand the unusual world of nanotechnology, we need to get an idea of the units of measure involved. A centimeter is one-hundredth of a meter, a millimeter is one-thousandth of a meter, and a micrometer is one-millionth of a meter, but all of these are still huge compared to the nanoscale. A nanometer (nm) is one-billionth of a meter, smaller than the wavelength of visible light and a hundred-thousandth the width of a human hair

[source 2=”Lab</a>” language=”href=”][/source]

As small as a nanometer is, it’s still large compared to the atomic scale. An atom has a diameter of about 0.1 nm. An atom’s nucleus is much smaller — about 0.00001 nm. Atoms are the building blocks for all matter in our universe. You and everything around you are made of atoms. Nature has perfected the science of manufacturing matter molecularly. For instance, our bodies are assembled in a specific manner from millions of living cells. Cells are nature’s nanomachines. At the atomic scale, elements are at their most basic level. On the nanoscale, we can potentially put these atoms together to make almost anything.

In a lecture called “Small Wonders:The World of Nanoscience,” Nobel Prize winner Dr. Horst Störmer said that the nanoscale is more interesting than the atomic scale because the nanoscale is the first point where we can assemble something — it’s not until we start putting atoms together that we can make anything useful.

In this article, we’ll learn about what nanotechnology means today and what the future of nanotechnology may hold. We’ll also look at the potential risks that come with working at the nanoscale.

In the next section, we’ll learn more about our world on the nanoscale.

The World of Nanotechnology

Experts sometimes disagree about what constitutes the nanoscale, but in general, you can think ofnanotechnology dealing with anything measuring between 1 and 100 nm. Larger than that is the microscale, and smaller than that is the atomic scale.

Nanotechnology is rapidly becoming an interdisciplinary field. Biologists, chemists, physicists and engineers are all involved in the study of substances at the nanoscale. Dr. Störmer hopes that the different disciplines develop a common language and communicate with one another

[source 1=”” 2=”2="2="2="2="2="2="2="href="http://video.google.com/videoplay?docid">Störmer"""""""” language=”:”][/source]

Only then, he says, can we effectively teach nanoscience since you can't understand the world of nanotechnology without a solid background in multiple sciences.

One of the exciting and challenging aspects of the nanoscale is the role that quantum mechanics plays in it. The rules of quantum mechanics are very different from classical physics, which means that the behavior of substances at the nanoscale can sometimes contradict common sense by behaving erratically. You can’t walk up to a wall and immediately teleport to the other side of it, but at the nanoscale an electron can — it’s called electron tunneling. Substances that are insulators, meaning they can’t carry an electric charge, in bulk form might become semiconductors when reduced to the nanoscale. Melting points can change due to an increase in surface area. Much of nanoscience requires that you forget what you know and start learning all over again.

So what does this all mean? Right now, it means that scientists are experimenting with substances at the nanoscale to learn about their properties and how we might be able to take advantage of them in various applications. Engineers are trying to use nano-size wires to create smaller, more powerful microprocessors. Doctors are searching for ways to use nanoparticles in medical applications. Still, we’ve got a long way to go before nanotechnology dominates the technology and medical markets.

In the next section, we’ll look at two important nanotechnology structures: nanowires and carbon nanotubes.

IT’S A SMALL WORLD AFTER ALL

At the nanoscale, objects are so small that we can’t see them — even with a light microscope. Nanoscientists have to use tools like scanning tunneling microscopes or atomic force microscopes to observe anything at the nanoscale. Scanning tunneling microscopes use a weak electric current to probe the scanned material. Atomic force microscopes scan surfaces with an incredibly fine tip. Both microscopes send data to a computer, which can assemble the information and project it graphically onto a monitor

[source 1=”” 2=”2="2="2="2="2="2="2="href="http://search.eb.com/eb/article-9384821">Encyclopædia"""""""” 3=”Britannica” language=”:”][/source]

Nanowires and Carbon Nanotubes

Currently, scientists find two nano-size structures of particular interest: nanowires and carbon nanotubes. Nanowires are wires with a very small diameter, sometimes as small as 1 nanometer. Scientists hope to use them to build tiny transistors for computer chips and other electronic devices. In the last couple of years, carbon nanotubes have overshadowed nanowires. We’re still learning about these structures, but what we’ve learned so far is very exciting.

A carbon nanotube is a nano-size cylinder of carbon atoms. Imagine a sheet of carbon atoms, which would look like a sheet of hexagons. If you roll that sheet into a tube, you’d have a carbon nanotube. Carbon nanotube properties depend on how you roll the sheet. In other words, even though all carbon nanotubes are made of carbon, they can be very different from one another based on how you align the individual atoms.

With the right arrangement of atoms, you can create a carbon nanotube that’s hundreds of times stronger than steel, but six times lighter

[source 1=”” 2=”2="2="2="2="2="2="2="href="http://science.howstuffworks.com/nanotechnology6.htm">The"""""""” 3=”Ecologist” language=”:”][/source]

Engineers plan to make building material out of carbon nanotubes, particularly for things like cars and airplanes. Lighter vehicles would mean better fuel efficiency, and the added strength translates to increased passenger safety.

Carbon nanotubes can also be effective semiconductors with the right arrangement of atoms. Scientists are still working on finding ways to make carbon nanotubes a realistic option for transistors in microprocessors and other electronics.

In the next section, we’ll look at products that are taking advantage of nanotechnology.

GRAPHITE VS. DIAMONDS

What’s the difference between graphite and diamonds? Both materials are made of carbon, but both have vastly different properties. Graphite is soft; diamonds are hard. Graphite conducts electricity, but diamonds are insulators and can’t conduct electricity. Graphite is opaque; diamonds are usually transparent. Graphite and diamonds have these properties because of the way the carbon atoms bond together at the nanoscale.

Products with Nanotechnology

You might be surprised to find out how many products on the market are already benefiting from nanotechnology.

Bridgestone engineers developed this Quick Response Liquid Powder Display, a flexible digital screen, using nanotechnology.

Yoshikazu Tsuno/AFP/Getty Images

Sunscreen – Many sunscreens contain nanoparticles of zinc oxide or titanium oxide. Older sunscreen formulas use larger particles, which is what gives most sunscreens their whitish color. Smaller particles are less visible, meaning that when you rub the sunscreen into your skin, it doesn’t give you a whitish tinge.
Self-cleaning glass – A company called Pilkington offers a product they call Activ Glass, which uses nanoparticles to make the glassphotocatalytic and hydrophilic. The photocatalytic effect means that when UV radiation from light hits the glass, nanoparticles become energized and begin to break down and loosen organic molecules on the glass (in other words, dirt). Hydrophilic means that when water makes contact with the glass, it spreads across the glass evenly, which helps wash the glass clean.
Clothing – Scientists are using nanoparticles to enhance your clothing. By coating fabrics with a thin layer of zinc oxide nanoparticles, manufacturers can create clothes that give better protection from UV radiation. Some clothes have nanoparticles in the form of little hairs or whiskers that help repel water and other materials, making the clothing stain-resistant.
Scratch-resistant coatings – Engineers discovered that adding aluminum silicate nanoparticles to scratch-resistant polymer coatings made the coatings more effective, increasing resistance to chipping and scratching. Scratch-resistant coatings are common on everything from cars to eyeglass lenses.
Antimicrobial bandages – Scientist Robert Burrell created a process to manufacture antibacterial bandages using nanoparticles of silver. Silver ions block microbes’ cellular respiration
[source 1=”” 2=”2="2="2="2="2="2="2="href="http://www.burnsurgery.org/Modules/silver/section2.htm">Burnsurgery.org</a>"""""""” language=”:”][/source]

. In other words, silver smothers harmful cells, killing them.

New products incorporating nanotechnology are coming out every day. Wrinkle-resistant fabrics, deep-penetrating cosmetics, liquid crystal displays (LCD) and other conveniences using nanotechnology are on the market. Before long, we’ll see dozens of other products that take advantage of nanotechnology ranging from Intel microprocessors to bio-nanobatteries, capacitors only a few nanometers thick. While this is exciting, it’s only the tip of the iceberg as far as how nanotechnology may impact us in the future.

In the next section, we’ll look at some of the incredible things that nanotechnology may hold for us.

TENNIS, ANYONE?

Nanotechnology is making a big impact on the tennis world. In 2002, the tennis racket company Babolat introduced the VS Nanotube Power racket. They made the racket out of carbon nanotube-infused graphite, meaning the racket was very light, yet many times stronger than steel. Meanwhile, tennis ball manufacturer Wilson introduced the Double Core tennis ball. These balls have a coating of clay nanoparticles on the inner core. The clay acts as a sealant, making it very difficult for air to escape the ball.

Accelerate Your Time to Print Using ANSYS™ SpaceClaim 2015

Switching between multiple tools to prepare 3D models for printing is not only time consuming, but also inefficient and costly to maintain. In the 2015 release, ANSYS SpaceClaim has honed its 3D printing capabilities while adding a multitude of new features to streamline model preparation, providing you with the best 3D printing model prep solution.

ANSYS™ SpaceClaim 2015 provides new features to the STL Prep module, including:

A one-click tool for adding a desired thickness to a part for printing
Automatic facet smoothing for building precision into 3D parts
A minimum thickness detection feature to check for areas falling below a tolerance limit
An unsupported material warning with an overhangs button to add support material where it is needed

http://www.spaceclaim.com/en/Mkting/ppc_SpaceClaim2015_FacetedModels_Video_ThankYou.aspx

The Future of Nanotechnology

In the world of “Star Trek,” machines called replicators can produce practically any physical object, from weapons to a steaming cup of Earl Grey tea. Long considered to be exclusively the product of science fiction, today some people believe replicators are a very real possibility. They call it molecular manufacturing, and if it ever does become a reality, it could drastically change the world.

http://s.hswstatic.com/gif/nanotechnology-7.gif

Atoms and molecules stick together because they have complementary shapes that lock together, or charges that attract. Just like with magnets, a positively charged atom will stick to a negatively charged atom. As millions of these atoms are pieced together by nanomachines, a specific product will begin to take shape. The goal of molecular manufacturing is to manipulate atoms individually and place them in a pattern to produce a desired structure.

The first step would be to develop nanoscopic machines, called assemblers, that scientists can program to manipulate atoms and molecules at will. Rice University Professor Richard Smalley points out that it would take a single nanoscopic machine millions of years to assemble a meaningful amount of material. In order for molecular manufacturing to be practical, you would need trillions of assemblers working together simultaneously. Eric Drexler believes that assemblers could first replicate themselves, building other assemblers. Each generation would build another, resulting in exponential growth until there are enough assemblers to produce objects

[source 1=”” 2=”2="2="2="2="2="2="2="href="http://www.kurzweilai.net/articles/art0604.html">Ray"""""""” 3=”Kurzweil” language=”:”][/source]

Assemblers might have moving parts like the nanogears in this concept drawing.

Trillions of assemblers and replicators could fill an area smaller than a cubic millimeter, and could still be too small for us to see with the naked eye. Assemblers and replicators could work together to automatically construct products, and could eventually replace all traditional labor methods. This could vastly decrease manufacturing costs, thereby making consumer goods plentiful, cheaper and stronger. Eventually, we could be able to replicate anything, including diamonds, water and food. Famine could be eradicated by machines that fabricate foods to feed the hungry.

Nanotechnology may have its biggest impact on the medical industry. Patients will drink fluids containing nanorobots programmed to attack and reconstruct the molecular structure of cancer cells and viruses. There’s even speculation that nanorobots could slow or reverse the aging process, and life expectancy could increase significantly. Nanorobots could also be programmed to perform delicate surgeries — suchnanosurgeons could work at a level a thousand times more precise than the sharpest scalpel

[source 1=”” 2=”2="2="2="2="2="2="2="href="http://www.nanomedicine.com/Papers/IntlJSurgDec05.pdf">International"""""""” 3=”Journal” 4=”of” 5=”Surgery” language=”:”][/source]

By working on such a small scale, a nanorobot could operate without leaving the scars that conventional surgery does. Additionally, nanorobots could change your physical appearance. They could be programmed to perform cosmetic surgery, rearranging your atoms to change your ears, nose, eye color or any other physical feature you wish to alter.

Nanotechnology has the potential to have a positive effect on the environment. For instance, scientists could program airborne nanorobots to rebuild the thinning ozone layer. Nanorobots could remove contaminants from water sources and clean up oil spills. Manufacturing materials using the bottom-upmethod of nanotechnology also creates less pollution than conventional manufacturing processes. Our dependence on non-renewable resources would diminish with nanotechnology. Cutting down trees, mining coal or drilling for oil may no longer be necessary — nanomachines could produce those resources.

Many nanotechnology experts feel that these applications are well outside the realm of possibility, at least for the foreseeable future. They caution that the more exotic applications are only theoretical. Some worry that nanotechnology will end up like virtual reality — in other words, the hype surrounding nanotechnology will continue to build until the limitations of the field become public knowledge, and then interest (and funding) will quickly dissipate.

In the next section, we’ll look at some of the challenges and risks of nanotechnology.

HOW NEW IS NANOTECHNOLOGY?

In 1959, physicist and future Nobel prize winner Richard Feynman gave a lecture to the American Physical Society called “There’s Plenty of Room at the Bottom.” The focus of his speech was about the field of miniaturization and how he believed man would create increasingly smaller, powerful devices.

In 1986, K. Eric Drexler wrote “Engines of Creation” and introduced the term nanotechnology. Scientific research really expanded over the last decade. Inventors and corporations aren’t far behind — today, more than 13,000 patents registered with the U.S. Patent Office have the word “nano” in them

[source 1=”” 2=”2="2="2="2="2="2="2="href="http://www.uspto.gov/patft/index.html">U.S."""""""” 3=”Patent” 4=”and” 5=”Trademark” 6=”Office” language=”:”][/source]

Nanotechnology Challenges, Risks and Ethics

http://s.hswstatic.com/gif/nanotechnology-5.gif

The most immediate challenge in nanotechnology is that we need to learn more about materials and their properties at the nanoscale. Universities and corporations across the world are rigorously studying how atoms fit together to form larger structures. We’re still learning about how quantum mechanics impact substances at the nanoscale.

Because elements at the nanoscale behave differently than they do in their bulk form, there’s a concern that some nanoparticles could be toxic. Some doctors worry that the nanoparticles are so small, that they could easily cross the blood-brain barrier, a membrane that protects the brain from harmful chemicals in the bloodstream. If we plan on using nanoparticles to coat everything from our clothing to our highways, we need to be sure that they won’t poison us.

Closely related to the knowledge barrier is the technical barrier. In order for the incredible predictions regarding nanotechnology to come true, we have to find ways to mass produce nano-size products like transistors and nanowires. While we can use nanoparticles to build things like tennis rackets and make wrinkle-free fabrics, we can’t make really complex microprocessor chips with nanowires yet.

There are some hefty social concerns about nanotechnology too. Nanotechnology may also allow us to create more powerful weapons, both lethal and non-lethal. Some organizations are concerned that we’ll only get around to examining the ethical implications of nanotechnology in weaponry after these devices are built. They urge scientists and politicians to examine carefully all the possibilities of nanotechnology before designing increasingly powerful weapons.

If nanotechnology in medicine makes it possible for us to enhance ourselves physically, is that ethical? In theory, medical nanotechnology could make us smarter, stronger and give us other abilities ranging from rapid healing to night vision. Should we pursue such goals? Could we continue to call ourselves human, or would we become transhuman — the next step on man’s evolutionary path? Since almost every technology starts off as very expensive, would this mean we’d create two races of people — a wealthy race of modified humans and a poorer population of unaltered people? We don’t have answers to these questions, but several organizations are urging nanoscientists to consider these implications now, before it becomes too late.

Not all questions involve altering the human body — some deal with the world of finance and economics. If molecular manufacturing becomes a reality, how will that impact the world’s economy? Assuming we can build anything we need with the click of a button, what happens to all the manufacturing jobs? If you can create anything using a replicator, what happens to currency? Would we move to a completely electronic economy? Would we even need money?

Whether we’ll actually need to answer all of these questions is a matter of debate. Many experts think that concerns like grey goo and transhumans are at best premature, and probably unnecessary. Even so, nanotechnology will definitely continue to impact us as we learn more about the enormous potential of the nanoscale.

APOCALYPTIC GOO

Eric Drexler, the man who introduced the word nanotechnology, presented a frightening apocalyptic vision — self-replicating nanorobots malfunctioning, duplicating themselves a trillion times over, rapidly consuming the entire world as they pull carbon from the environment to build more of themselves. It’s called the “grey goo” scenario, where a synthetic nano-size device replaces all organic material. Another scenario involves nanodevices made of organic material wiping out the Earth — the “green goo” scenario.

The Technion’s Russell Berrie Nanotechnology Institute is a world-leader in nanotechnology research having made seminal discoveries in the field.

Breakthroughs in Nanotechnology

Prof. Ester Segal and a team of Israeli and American researchers find that silicon nanomaterials used for the localized delivery of chemotherapy drugs behave differently in cancerous tumors than they do in healthy tissues. The findings could help scientists better design such materials to facilitate the controlled and targeted release of the chemotherapy drugs to tumors.
Associate Professor Alex Leshansky of the Faculty of Chemical Engineering is part of an international team that has created a tiny screw-shaped propeller that can move in a gel-like fluid, mimicking the environment in a living organism. The breakthrough brings closer the day robots that are only nanometers – billionths of a meter – in length, can maneuver and perform medicine inside the human body and possibly inside human cells.
Prof. Amit Miller and a team of researchers at the Technion and Boston University have discovered a simple way to control the passage of DNA molecules through nanopore sensors. The breakthrough could lead to low-cost, ultra-fast DNA sequencing that would revolutionize healthcare and biomedical research, and spark major advances in drug development, preventative medicine and personalized medicine.

– Israeli Prime Minister Benjamin Netanyahu presents U.S. President Barack Obama with nano-sized inscribed replicas of the Declarations of Independence of the United States and the State of Israel. The replicas were created by scientists at the Technion’s Russell Berrie Nanotechnology Institute (RBNI). (03/13)

– Prof. Nir Tessler has found a way to generate an electrical field inside solar cells that use inorganic nanocrystals or “quantum dots,” making them more suitable for building an energy-efficient nanocrystal solar cell. (11/11)

– Researchers led by Prof. Wayne Kaplan discover the nature of nanometer-thick layers between different materials and find that they have both solid and liquid properties. The results could enable scientists to improve the resilience of the bond between ceramic materials and metals, two types of materials that “do not like” to come into contact. Applications include cutting tools for metal-working; composites for brake pads; the joins between metal conducting wires and chips in computers; and the application of protective ceramic coatings on jet engine blades. (05/11)

– Israeli President Shimon Peres presents Pope Benedict XVI with a “Nano-Bible” smaller than a pinhead. Created by researchers at the Technion-Israel Institute of Technology, the complete punctuated and vowelized version of the Old Testament takes up just 0.5 square millimeters. The idea to write the Bible on such a tiny surface was conceived by Professor Uri Sivan, the first head of the university’s Russell Berrie Nanotechnology Institute (RBNI). (05/09)

Nanotechnology and medicine

Expert Opinion on Biological Therapy 2003; Volume 3, Issue 4, 655-663
Dwaine F Emerich & Christopher G Thanos http://dx.doi.org:/10.1517/14712598.3.4.655

Nanotechnology, or systems/device manufacture at the molecular level, is a multidisciplinary scientific field undergoing explosive development. The genesis of nanotechnology can be traced to the promise of revolutionary advances across medicine, communications, genomics and robotics. On the surface, miniaturisation provides cost effective and more rapidly functioning mechanical, chemical and biological components. Less obvious though is the fact that nanometre sized objects also possess remarkable self-ordering and assembly behaviours under the control of forces quite different from macro objects. These unique behaviours are what make nanotechnology possible, and by increasing our understanding of these processes, new approaches to enhancing the quality of human life will surely be developed. A complete list of the potential applications of nanotechnology is too vast and diverse to discuss in detail, but without doubt one of the greatest values of nanotechnology will be in the development of new and effective medical treatments (i.e., nanomedicine). This review focuses on the potential of nanotechnology in medicine, including the development of nanoparticles for diagnostic and screening purposes, artificial receptors, DNA sequencing using nanopores, manufacture of unique drug delivery systems, gene therapy applications and the enablement of tissue engineering.

Nanotechnology in Medicine – Nanomedicine

The use of nanotechnology in medicine offers some exciting possibilities. Some techniques are only imagined, while others are at various stages of testing, or actually being used today.

Nanotechnology in medicine involves applications of nanoparticles currently under development, as well as longer range research that involves the use of manufactured nano-robots to make repairs at the cellular level (sometimes referred to as nanomedicine).

Whatever you call it, the use of nanotechnology in the field of medicine could revolutionize the way we detect and treat damage to the human body and disease in the future, and many techniques only imagined a few years ago are making remarkable progress towards becoming realities.

Nanotechnology in Medicine Application: Drug Delivery

One application of nanotechnology in medicine currently being developed involves employing nanoparticles to deliver drugs, heat, light or other substances to specific types of cells (such as cancer cells). Particles are engineered so that they are attracted to diseased cells, which allows direct treatment of those cells. This technique reduces damage to healthy cells in the body and allows for earlier detection of disease.

For example, nanoparticles that deliver chemotherapy drugs directly to cancer cells are under development. Tests are in progress for targeted delivery of chemotherapy drugs and their final approval for their use with cancer patients is pending. One company, CytImmune has published the results of a Phase 1 Clinical Trial of their first targeted chemotherapy drug and another company, BIND Biosciences, has published preliminary results of a Phase 1 Clinical Trial for their first targeted chemotherapy drug and is proceeding with a Phase 2 Clinical Trial.

Researchers at the University of Illinois have demonstated that gelatin nanoparticles can be used to deliver drugs to damaged brain tissue.

Researchers at MIT using nanoparticles to deliver vaccine. The nanoparticles protect the vaccine, allowing the vaccine time to trigger a stronger immune response.

Reserchers are developing a method to release insulin that uses a sponge-like matrix that contains insulin as well as nanocapsules containing an enzyme. When the glucose level rises the nanocapsules release hydrogen ions, which bind to the fibers making up the matrix. The hydrogen ions make the fibers positively charged, repelling each other and creating openings in the matrix through which insulin is released.

Researchers are developing a nanoparticle that can be taken orally and pass through the lining of the intestines into the bloodsteam. This should allow drugs that must now be delivered with a shot to be taken in pill form.

Researchers are also developing a nanoparticle to defeat viruses. The nanoparticle does not actually destroy viruses molecules, but delivers an enzyme that prevents the reproduction of viruses molecules in the patients bloodstream.

Read more about nanomedicine in drug delivery

Nanotechnology in Medicine Application: Therapy Techniques

Researchers have developed “nanosponges” that absorb toxins and remove them from the bloodstream. The nanosponges are polymer nanoparticles coated with a red blood cell membrane. The red blood cell membrane allows the nanosponges to travel freely in the bloodstream and attract the toxins.

Researchers have demonstrated a method to generate sound waves that are powerful, but also tightly focused, that may eventually be used for noninvasive surgery. They use a lens coated with carbon nanotubes to convert light from a laser to focused sound waves. The intent is to develop a method that could blast tumors or other diseased areas without damaging healthy tissue.

Researchers are investigating the use of bismuth nanoparticles to concentrate radiation used in radiation therapy to treat cancer tumors. Initial results indicate that the bismuth nanoparticles would increase the radiation dose to the tumor by 90 percent.

Nanoparticles composed of polyethylene glycol-hydrophilic carbon clusters (PEG-HCC) have been shown to absorb free radicals at a much higher rate than the proteins out body uses for this function. This ability to absorb free radicals may reduce the harm that is caused by the release of free radicals after a brain injury.

Targeted heat therapy is being developed to destroy breast cancer tumors. In this method antibodies that are strongly attracted to proteins produced in one type of breast cancer cell are attached to nanotubes, causing the nanotubes to accumulate at the tumor. Infrared light from a laser is absorbed by the nanotubes and produces heat that incinerates the tumor.

Read more about nanomedicine therapy techniques

Nanotechnology in Medicine Application: Diagnostic Techniques

Reseachers at MIT have developed a sensor using carbon nanotubes embedded in a gel; that can be injected under the skin to monitor the level of nitric oxide in the bloodstream. The level of nitric oxide is important because it indicates inflamation, allowing easy monitoring of imflammatory diseases. In tests with laboratory mice the sensor remained functional for over a year.

Researchers at the University of Michigan are developing a sensor that can detect a very low level of cancer cells, as low as 3 to 5 cancer cells in a one milliliter in a blood sample. They grow sheets of graphene oxide, on which they attach molecules containing an antibody that attaches to the cancer cells. They then tag the cancer cells with fluorescent molecules to make the cancer cells stand out in a microscope.

Researchers have demonstrated a way to use nanoparticles for early diagnosis of infectious disease. The nanoparticles attach to molecules in the blood stream indicating the start of an infection. When the sample is scanned for Raman scattering the nanoparticles enhance the Raman signal, allowing detection of the molecules indicating an infectious disease at a very early stage.

A test for early detection of kidney damage is being developed. The method uses gold nanorodsfunctionalized to attach to the type of protein generated by damaged kidneys. When protein accumulates on the nanorod the color of the nanorod shifts. The test is designed to be done quickly and inexpensively for early detection of a problem.

Nanotechnology in Medicine Application: Anti-Microbial Techniques

One of the earliest nanomedicine applications was the use of nanocrystalline silver which is as an antimicrobial agent for the treatment of wounds, as discussed on the Nucryst Pharmaceuticals Corporation website.

A nanoparticle cream has been shown to fight staph infections. The nanoparticles contain nitric oxide gas, which is known to kill bacteria. Studies on mice have shown that using the nanoparticle cream to release nitric oxide gas at the site of staph abscesses significantly reduced the infection.

Burn dressing that is coated with nanocapsules containing antibotics. If a infection starts the harmful bacteria in the wound causes the nanocapsules to break open, releasing the antibotics. This allows much quicker treatment of an infection and reduces the number of times a dressing has to be changed.

A welcome idea in the early study stages is the elimination of bacterial infections in a patient within minutes, instead of delivering treatment with antibiotics over a period of weeks. You can read about design analysis for the antimicrobial nanorobot used in such treatments in the following article: Microbivores: Artifical Mechanical Phagocytes using Digest and Discharge Protocol.

Nanotechnology in Medicine Application: Cell Repair

Nanorobots could actually be programmed to repair specific diseased cells, functioning in a similar way to antibodies in our natural healing processes. Read about design analysis for one such cell repair nanorobot in this article: The Ideal Gene Delivery Vector: Chromallocytes, Cell Repair Nanorobots for Chromosome Repair Therapy

Nanotechnology in Medicine: Company Directory

Company	Product
CytImmune	Gold nanoparticles for targeted delivery of drugs to tumors
NanoBio	Nanoemulsions for nasal delivery to fight viruses (such as the flu and colds) or through the skin to fight bacteria

More nanomedicine companies

Nanotechnology in Medicine: Resources

National Cancer Institute Alliance for Nanotechnology in Cancer; This alliance includes aNanotechnology Characterization Lab as well as eight Centers of Cancer Nanotechnology Excellence.

Alliance for NanoHealth; This alliance includes eight research institutions performing collaborative research.

European Nanomedicine platform

The National Institute of Health (NIH) is funding research at eight Nanomedicine Development Centers.

Page 2: Nanomedicine based upon nano-robots

Compiled by Earl Boysen of Hawk’s Perch Technical Writing, LLC and UnderstandingNano.com.

Future impact of nanotechnology on medicine and dentistry

Mallanagouda Patil,¹ Dhoom Singh Mehta,² and Sowjanya Guvva³

J Indian Soc Periodontol. 2008 May-Aug; 12(2): 34–40.

doi: 10.4103/0972-124X.44088 PMCID: PMC2813556

The human characteristics of curiosity, wonder, and ingenuity are as old as mankind. People around the world have been harnessing their curiosity into inquiry and the process of scientific methodology. Recent years have witnessed an unprecedented growth in research in the area of nanoscience. There is increasing optimism that nanotechnology applied to medicine and dentistry will bring significant advances in the diagnosis, treatment, and prevention of disease. Growing interest in the future medical applications of nanotechnology is leading to the emergence of a new field called nanomedicine. Nanomedicine needs to overcome the challenges for its application, to improve the understanding of pathophysiologic basis of disease, bring more sophisticated diagnostic opportunities, and yield more effective therapies and preventive properties. When doctors gain access to medical robots, they will be able to quickly cure most known diseases that hobble and kill people today, to rapidly repair most physical injuries our bodies can suffer, and to vastly extend the human health span. Molecular technology is destined to become the core technology underlying all of 21^st century medicine and dentistry. In this article, we have made an attempt to have an early glimpse on future impact of nanotechnology in medicine and dentistry.

Keywords: Nanodentistry, nanomedicine, nanoscience, nanotechnology

INTRODUCTION

The world began without man, and it will complete itself without him. …Cloude Levi Strauss. Winfred Phillips, DSc, said, “You have to be able to fabricate things, you have to be able to analyze things, you have to be able to handle things smaller than ever imagined in ways not done before”.[1] Many researchers believed that in future, scientific devices that are dwarfed by dust mites may one day be capable of grand biomedical miracles.

The vision of nanotechnology introduced in 1959 by late Nobel Physicist Richard P Faynman in dinner talk said, “There is plenty of room at the bottom,”[2] proposed employing machine tools to make smaller machine tools, these are to be used in turn to make still smaller machine tools, and so on all the way down to the atomic level, noting that this is “a development which I think cannot be avoided”. He suggested nanomachines, nanorobots, and nanodevices ultimately could be used to develop a wide range of automically precise microscopic instrumentation and manufacturing tools, could be applied to produce a vast quantities of ultrasmall computers and various nanoscale microscale robots.

Feynman’s idea remained largely undiscussed until the mid-1980s, when the MIT educated engineer K Eric Drexler published “Engines of Creation”, a book to popularize the potential of molecular nanotechnology.[3]

Nano comes from the Greek word for dwarf, usually nanotechnology is defined as the research and development of materials, devices, and systems exhibiting physical, chemical, and biological properties that are different from those found on a larger scale (matter smaller than scale of things like molecules and viruses).[4]

Old rules don’t apply, small things behave differently. Researchers in nanoland are also making really, really small things with astonishing properties like the carbon nanotube. Chris Papadopoulos, a nanotechnology researcher says, “The carbon nanotube is the poster boy for nanotechnology”. It’s is a very thin sheet of graphite that’s formed into a tube, its strength can be harnessed by embedding them in constructive materials, among other applications, nanotubes may be part of future improvements for high-performance air craft.

In nanoland, tiny differences in size can add up to huge differences in function. Ted Sergent, author of The dance of Molecules, says matter is tunable at nanoscale. For example, change the length of a guitar string and you change the sound it makes; change the size of semiconductors called quantum dots, and you change their rainbow of colors from a single material. Sergent made a three-nanometric dot that ‘glows’ blue, and four nanometer dot that glows red and a five nanometer dot that emits infrared rays or heat.

Nanotechnology will affect everything, says William Atkinson, author of Nanoscom. Nanotechnology and the big changes coming from the inconceivably small. It’ll be like a blizzard; snowflakes whose weight you can’t detect can bring a city to a standstill. Nanotechnology is going to be like that.

The unique quantum phenomena that happen at the nanoscale, draw researchers from many different disciplines to the field, including medicine, chemistry, physics, engineering, and others (dentistry).

The scientists in the field of regenerative medicine and tissue engineering are continually looking for new ways to apply the principles of cell transplantation, material science, and bioengineering to construct biological substitutes that will restore and maintain normal function in diseased and injured tissue. Development of more refined means of delivering medications at therapeutic levels to specific sites is an important clinical issue, for applications of such technology in medicine, and dentistry.[5]

Nanomedicine

The field of “Nanomedicine” is the science and technology of diagnosing, treating, and preventing disease and traumatic injury, of relieving pain, and of preserving and improving human health, using nanoscale structured materials, biotechnology, and genetic engineering, and eventually complex machine systems and nonorobots.[5] It was perceived as embracing five main subdisciplines that in many ways are overlapping by common technical issues [Figure 1].

Figure 1

Dimensions in Nanomedicine

Nanodiagnostics

It is the use of nanodevices for the early disease identification or predisposition at cellular and molecular level. In in-vitro diagnostics, nanomedicine could increase the efficiency and reliability of the diagnostics using human fluids or tissues samples by using selective nanodevices, to make multiple analyses at subcellular scale, etc. In in vivo diagnostics, nanomedicine could develop devices able to work inside the human body in order to identify the early presence of a disease, to identify and quantify toxic molecules, tumor cells.

Regenerative medicine

It is an emerging multidisciplinary field to look for the reparation, improvement, and maintenance of cells, tissues, and organs by applying cell therapy and tissue engineering methods. With the help of nanotechnology it is possible to interact with cell components, to manipulate the cell proliferation and differentiation, and the production and organization of extracellular matrices.

Present day nanomedicine exploits carefully structured nanoparticles such as dendrimers, carbon fullerenes (buckyballs), and nanoshells to target specific tissues and organs. These nanoparticles may serve as diagnostic and therapeutic antiviral, antitumor, or anticancer agents. Years ahead, complex nanodevices and even nanorobots will be fabricated, first of biological materials but later using more durable materials such as diamond to achieve the most powerful results.[6]

The human body is comprised of molecules, hence the availablity of molecular nanotechnology will permit dramatic progress to address medical problems and will use molecular knowledge to maintain and improve human health at the molecular scale.

Applications in medicine

Within 10–20 years it should become possible to construct machines on the micrometer scale made up of parts on the nanometer scale. Subassemblies of such devices may include such as useful robotic components as 100 nm manipulater arms, 10 nm sorting rotors for molecule by molecule reagent purification, and smooth super hard surfaces made of automically flawless diamond.

Nanocomputers would assume the important task of activating, controlling, and deactivating such nanomechanical devices. Nanocomputers would store and execute mission plans, receive and process external signals and stimuli, communicate with other nanocomputers or external control and monitoring devices, and possess contextual knowledge to ensure safe functioning of the nanomechanical devices. Such technology has enormous medical and dental implications.

Programmable nanorobotic devices would allow physicians to perform precise interventions at the cellular and molecular level. Medical nanorobots have been proposed for genotological[7] applicatons in pharmaceuticals research,[8] clinical diagnosis, and in dentistry,[9] and also mechanically reversing atherosclerosis, improving respiratory capacity, enabling near-instantaneous homeostasis, supplementing immune system, rewriting or replacing DNA sequences in cells, repairing brain damage, and resolving gross cellular insults whether caused by irreversible process or by cryogenic storage of biological tissues.

Feynman offered the first known proposal for a nanorobotic surgical procedure to cure heart disease,[2] “A friend of mine (Albert R. Hibbs) suggests a very interesting possibility for relatively small machines. He says that, although it is a very wild idea, it would be interesting in surgery if you could swallow the surgeon. You put the mechanical surgeon inside the blood vessel and it goes into the heart and looks around. It finds out which valve is the faulty and takes a little knife and slices it out, that we can manufacture an object that maneuvers at that level, other small machines might be permanently incorporated in the body to assist some inadequately functioning organs”.[2]

Many disease causing culprits such as bacteria and viruses are nanosize. So, it only makes sense that nanotechnology would offer us ways of fighting back. The ancient greeks used silver to promote healing and prevent infection, but the treatment took backseat when antibiotics came on the scene. Nycryst pharmaceuticals (Canada) revived and improved an old cure by coating a burn and wound bandage with nanosize silver particles that are more reactive than the bulk form of metal. They penetrate into skin and work steadily. As a result, burn victims can have their dressings changed just once a week.

Genomics and protomics research is already rapidly elucidating the molecular basis of many diseases. This has brought new opportunities to develop powerful diagnostic tools able to identify genetic predisposition to diseases. In the future, point of care diagnosis will be routinely used to identify those patients requiring preventive medication to select the most appropriate medication for individual patients, and to monitor response to treatment. Nanotechnology has a vital role to play in realizing cost-effective diagnostic tools.

Chris Backous developing Lab–on-Chip to give doctor immediate results from medical tests for cancer and viruses, it gets its information by analyzing the genetic material in individual cells. Advances in gene sequencing mean this can now be done quickly and sequencing with tiny samples of body fluids or tissues such as blood, bone marrow, or tumors. The device can also detect the BK virus, a sign of trouble in patients who have had kidney transplants. Ultimately (Pilarski thinks,) chip technology will be able to detect what kind of flu a person has, or, even if they have SARS or HIV.

Nanotechnology has the potential to offer invaluable advances such as use of nanocoatings to slow the release of asthma medication in the lungs, allowing people with asthma to experience longer periods of relief from symptoms after using inhalants. Thus, what nanotechnology tries to do is essentially make drug particles in such a way, that they don’t dissolve that fast, done this with.

Nanosensors developed for military use in recognizing airborne rogue agents and chemical weapons to detect drugs and other substances in exhaled breath.[1] Basically, you can detect many drugs in breath, but the amount you detect in breath is going to be related to the amount that you take and also to whether it partitions well between the blood and the breath. Drug abuse like marijuna (and things like), concentration of alcohol, testing of athletes for banned substances, and individual’s drug treatment programs are two areas long overdue for breath detection technologies. We see this in future totally replacing urine testing.

Currently, most legal and illegal drug overdoses have no specific way to be effectively neutralized, using nanoparticles as absorbents of toxic drugs, is another area of medical nanoscience that is rapidly gaining momentum. Goal is design nanostructures that effectively bind molecular entities, which currently don’t have effective treatments. We are putting nanosponges into the blood stream and they are soaking up toxic drug molecules to reduce the free amount in the blood, in turn, causes a resolution of the toxicity that was there before you put the nanosponges into the blood.

French and Italian researchers have come up with a completely new approach to render anticancer and antiviral nucleoside analoges significantly more potent. By linking the nucleoside analoges to sequalene, a biochemical precursor to the whole family of steroids, the researchers observed the self-organization of amphiphilic molecules in water. These nanoassemblies exhibited superior anticancer activity in vitro in human cancer cells.

Laurie B Gower, PhD, has been researching bone formation and structure at the nanoscale level. She is examining biomimetic methods of constructing a synthetic bone graft substitute with a nanostructured architecture that matches natural bone so that it would be accepted by the body and guide the cells toward the mending of damaged bones. Biomineralization refers to minerals that are formed biologically, which have very different properties than geological minerals or lab-formed crystals. The crystal properties found in bone are manipulated at nanoscale and are imbedded within collagen fibers to create an interpenetrating organic–inorganic composite with unique mechanical properties. She foresees numerous implications of the material in the future of osteology.

Hichan Fenniri, a chemistry professor, tried to make artificial joints act more like natural ones. Fenniri has made a nanotube coating for titanium hip or knee, is very good mimic of collagen, as a result of coating attracts and attaches more bone cells, osteoblasts, which help in bone growth quickly than uncoated hip or knee.

There is ongoing attempts to build ‘medical microrobots’ for in vivo medical use.[10] In 2002, Ishiyama et al,[11] at Tohku University developed tiny magnetically driven spinning screws intended to swim along veins and carry drugs to infected tissues or even to burrow into tumors and kill them with heat. In 2005, Brad Nelson’s[12] team reported the fabrication of a microscopic robot, small enough (approximately 200 µm) to be injected into the body through a syringe. They hope that this device or its descendants might someday be used to deliver drugs or perform minimally invasive eye surgery. Gorden’s[9,13] group at the University of Manitoba has also proposed magnetically controlled ‘cytobots’ and ‘karyobots’ for performing wireless intracellular and intranuclear surgery.

‘Respirocytes’, the first theoreotical design study of a complete medical nanorobot ever published in peer-reviewed journal described a hypothetical artificial mechanical red blood cell or ‘respirocyte’ made of 18 billion precisely arranged structural atoms.[10,14] The respirocyte is a bloodborne spherical 1 µm diamondedoid 1000 atmosphere pressure vessel with reversible molecule selective surface pumps powered by endogenous serum glucose. This nanorobot would deliver 236 times more oxygen to body tissues per unit volume than natural red cells and would manage carbonic acidity, controlled by gas concentration sensors and an onboard nanocomputer.

Nanorobotic microbivores

Artificial phagocytes called microbivores could patrol the bloodstream, seeking out and digesting unwanted pathogens including bacteria, viruses, or fungi.[10,15] Microbivores would achieve complete clearance of even the most severe septicemic infections in hours or less. The nanorobots do not increase the risk of sepsis or septic shock because the pathogens are completely digested into harmless sugars, amino acids, and the like, which are the only effluents from the nanorobot.

Surgical nanorobotics

A surgical nanorobot, programmed or guided by a human surgeon, could act as a semiautonomous on site surgeon inside the human body, when introduced into the body through vascular system or cavities. Such a device could perform various functions such as searching for pathology and then diagnosing and correcting lesions by nanomanipulation, coordinated by an onboard computer while maintaining contact with the supervising surgeon via coded ultrasound signals.[10]

The earliest forms of cellular nanosurgery are already being explored today. For example, rapidly vibrating (100 Hz) micropipette with a <1 µm tip diameter has been used to completely cut dentrites from single neurons without damaging cell viability.[16] Axotomy of roundworm neurons was performed by femtosecond laser surgery, after which the axons functionally regenerated.[17] Femtolaser acts like a pair of nanoscissors by vaporizing tissue locally while leaving adjacent tissue unharmed. Femtolaser surgery has performed the individual chromosomes.[18]

Nanogenerators’

They could make new class of self-powered implantable medical devices, sensors, and portable electronics, by converting mechanical energy from body movement, muscle stretching, or water flow into electricity.

Nanogenerators produce electric current by bending and then releasing zinc oxide nanowires, which are both piezoelectric and semiconducting. Nanowires can be grown on polymer-based films, use of flexible polymer substrates could one day allow portable devices to be powered by movement of their users.

“Our bodies are good at converting chemical energy from glucose into the mechanical energy of our muscles,” Wang (faculty at Peking University and National Center for Nanoscience and Technology of China) explained “these nanogenerators can take mechanical energy and convert it to electrical energy for powering devices inside the body. This could open up tremendous possibilities for self-powered implantable medical devices.”

Nanodentistry

Nanodentistry will make possible the maintenance of comprehensive oral health by employing nanomaterials, biotechnology, including tissue engineering, and ultimately, dental nanorobotics. New potential treatment opportunities in dentistry may include, local anesthesia, dentition renaturalization, permanent hypersensitivity cure, complete orthodontic realignments during a single office visit, covalently bonded diamondised enamel, and continuous oral health maintenance using mechanical dentifrobots.

When the first micro-size dental nanorobots can be constructed, dental nanorobots might use specific motility mechanisms to crawl or swim through human tissue with navigational precision, acquire energy, sense, and manipulate their surroundings, achieve safe cytopenetration and use any of the multitude techniques to monitor, interrupt, or alter nerve impulse traffic in individual nerve cells in real time.

These nanorobot functions may be controlled by an onboard nanocomputer that executes preprogrammed instructions in response to local sensor stimuli. Alternatively, the dentist may issue strategic instructions by transmitting orders directly to in vivo nanorobots via acoustic signals or other means.

Inducing anesthesia

One of the most common procedure in dental practice, to make oral anesthesia, dental professionals will instill a colloidal suspension containing millions of active analgesic micron-sized dental nanorobot ‘particles’ on the patient’s gingivae. After contacting the surface of the crown or mucosa, the ambulating nanorobots reach the dentin by migrating into the gingival sulcus and passing painlessly through the lamina propria or the 1–3-micron thick layer of loose tissue at the cementodentinal junction. On reaching dentin, the nanorobots enter dentinal tubules holes that are 1–4 microns in diameter and proceed toward the pulp, guided by a combination of chemical gradients, temperature differentials, and even positional navigation, all under the control of the onboard nanocomputer as directed by the dentist.[9]

There are many pathways to choose from, near to CEJ, midway between junction and pulp, and near to pulp. Tubules diameter increases as it nears the pulp, which may facilitate nanorobot movement, although circumpulpal tubule openings vary in numbers and size (tubules number density 22,000 mm DEJ, 37,000 mm square midway, ans 48000 mm square near to pulp). Tubules branching patterns, between primary and irregular secondary dentin, regular secondary dentin in young and old teeth (sclerosing) may present a significant challenge to navigation.

The presence of natural cells that are constantly in motion around and inside the teeth including human gingival and pulpal fibroblasts, cementoblasts of the CDJ, bacteria inside dentinal tubules, odontoblasts near the pulp dentin border, and lymphocytes within the pulp or lamina propria suggested that such journey should be feasible by cell-sized nanorobots of similar mobility.

Once installed in the pulp and having established control over nerve impulse traffic, the analgesic dental nanorobots may be commanded by the dentist to shut down all sensitivity in any particular tooth that requires treatment. When on the hand-held controller display, the selected tooth immediately becomes numb. After the oral procedures completed, the dentist orders the nanorobots to restore all sensation, to relinguish control of nerve traffic and to engress, followed by aspiration. Nanorobotic analgesics offer greater patient comfort and reduced anxiety, no needles, greater selectivity, and controllability of the analgesic effect, fast and completely reversible switchable action and avoidance of most side effects and complications.

Tooth repair

Nanorobotic manufacture and installation of a biologically autologous whole replacement tooth that includes both mineral and cellular components, that is, ‘complete dentition replacement therapy’ should become feasible within the time and economic constraints of a typical office visit through the use of an affordable desktop manufacturing facility, which would fabricate the new tooth in the dentist’s office.

Chen et al[19] took advantage of these latest developments in the area of nanotechnology to simulate the natural biomineralization process to create the hardest tissue in the human body, dental enamel, by using highly organized microarchitectural units of nanorod-like calcium hydroxyapatite crystals arranged roughly parallel to each other.

Dentin hypersensitivity

Natural hypersensitive teeth have eight times higher surface density of dentinal tubules and diameter with twice as large than nonsensitive teeth. Reconstructive dental nanorobots, using native biological materials, could selectively and precisely occlude specific tubules within minutes, offering patients a quick and permanent cure.[9]

Tooth repositioning

Orthodontic nanorobots could directly manipulate the periodontal tissues, allowing rapid and painless tooth straightening, rotating and vertical repositioning within minutes to hours.

Tooth renaturalization

This procedure may become popular, providing perfect treatment methods for esthetic dentistry. This trend may begin with patients who desire to have their (1) old dental amalgams excavated and their teeth remanufactured with native biological materials, and (2) full coronal renaturalization procedures in which all fillings, crowns, and other 20^th century modifications to the visible dentition are removed with the affected teeth remanufactured to become indistinguishable from original teeth.

Dental durability and cosmetics

Durability and appearance of tooth may be improved by replacing upper enamel layers with covalently bonded artificial materials such as sapphire or diamond,[20] which have 20–100 times the hardness and failure strength of natural enamel or contemporary ceramic veneers and good biocompatibility. Pure sapphire and diamond are brittle and prone to fracture, can be made more fracture resistant as part of a nanostructured composite material that possibly includes embedded carbon nanotubes.

Nanorobotic dentifrice (dentifrobots) delivered by mouthwash or toothpaste could patrol all supragingival and subgingival surfaces at least once a day metabolizing trapped organic mater into harmless and odorless vapors and performing continous calculus debridement.

Properly configured dentifrobots could identify and destroy pathogenic bacteria residing in the plaque and elsewhere, while allowing the 500 species of harmless oral microflora to flourish in a healthy ecosystem. Dentifrobots also would provide a continous barriers to halitosis, since bacterial putrification is the central metabolic process involved in oral malodor. With this kind of daily dental care available from an early age, conventional tooth decay and gingival deseases will disappear into the annals of medical history.

Potential benefits of nanotechnology are its ability to exploit the atomic or molecular properties of materials and the development of newer materials with better properties. Nanoproducts can be made by: building-up particles by combining atomic elements and using equipments to create mechanical nanoscale objects.

Nanotechnology has improved the properties of various kinds of fibers.[21] Polymer nanofibers with diameters in the nanometer range, possess a larger surface area per unit mass and permit an easier addition of surface functionalities compared to polymer microfibers.[21,22] Polymer nanofiber materials have been studied as drug delivery systems, scaffolds for tissue engineering and filters. Carbon fibers with nanometer diamensions showed a selective increase in osteoblast adhesion necessary for successful orthopedic/dental implant applications due to a high degree of nanometer surface roughness.[23]

Nonagglomerated discrete nanoparticles are homogenously manufactured in resins or coatings to produce nanocomposites. The nanofiller used include an aluminosilicate powder having a mean particles size of about 80 nm and 1:4 M ratio of alumina to silica. Advantages – superior hardness, flexible strength, modulus of elasticity, translucency and esthetic appeal, excellent color density, high polish, and polish retention, and excellent handling properties.[24] (Filtek O supreme Univrasl Restorative Pure Nano O).

Heliometer, microfilled composite resin, a close examination of this composite suggests that a form of nanotechnology was in use years ago, yet never recognized.

Nanosolutions produce unique and dispersible nanoparticles that can be added to various solvents, paints, and polymers in which they are dispersed homogenously. Nanotechnology in bonding agents ensures homogeneity and so the operator can now be totally confident that the adhesive is perfectly mixed every time.

Nanofillers are integrated in the vinylsiloxanes, producing a unique addition siloxane impression material. Better flow, improved hydrophilic properties, hence fewer voids at margin and better model pouring, enhanced detail precision.[25]

DISCUSSION

Nanotechnology is part of a predicted future in which dentistry and periodontal practice may become more high-tech and more effective looking to manage individual dental health on a microscopic level by enabling us to battle decay where it begins with bacteria. Construction of a comprehensive research facility is crucial to meet the rigorous requirements for the development of nanotechnologies.

Researchers are looking at ways to use microscopic entities to perform tasks that are now done by hand or with equipment. This concept is known as nanotechnology. Tiny machines, known as nanoassemblers, could be controlled by computer to perform specialized jobs. The nanoassemblers could be smaller than a cell nucleus so that they could fit into places that are hard to reach by hand or with other technology. Used to destroy bacteria in the mouth that cause dental caries or even repair spots on the teeth where decay has set in, by use of computer to direct these tiny workers in their tasks.

Nanotechnology has tremendous potential, but social issues of public acceptance, ethics, regulation, and human safety must be addressed before molecular nanotechnology can be seen as the possibility of providing high quality dental care to the 80% of the world’s population that currently receives no significant dental care.

Role of periodontitis will continue to evolve along the lines of currently visible trends. For example, simple self-care neglect will become fewer, while cases involving cosmetic procedures, acute trauma, or rare disease conditions will become relatively more commonplace.

Trends in oral health and disease also may change the focus on specific diagnostic and treatment modalities. Increasingly preventive approaches will reduce the need for cure prevention a viable approach for the most of them.

Diagnosis and treatment will be customized to match the preferences and genetics of each patient. Treatment options will become more numerous and exciting. All this will demand, even more so than today, the best technical abilities, professional skills that are the hallmark of the contemporary dentist and periodontist. Developments are expected to accelerate significantly.

Nanometers and nanotubes, technologies could be used to administer drugs more precisely. Technology should be able to target specific cells in a patient suffering from cancer or other life-threatening conditions. Toxic drugs used to fight these illnessess would become much more direct and consequently less harmful to the body.

CONCLUSION

The visions described in this article may sound unlikely, implausible, or even heretic. Yet, the theoretical and applied research to turn them into reality is progressing rapidly. Nanotechnology will change dentistry, healthcare, and human life more profoundly than many developments of the past. As with all technologies, nanotechnology carries a significant potential for misuse and abuse on a scale and scope never seen before. However, they also have potential to bring about significant benefits, such as improved health, better use of natural resources, and reduced environmental pollution. These truly are the days of miracle and wonder.

Current work is focused on the recent developments, particularly of nanoparticles and nanotubes for periodontal management, the materials developed from such as the hollow nanospheres, core shell structures, nanocomposites, nanoporous materials, and nanomembranes will play a growing role in materials development for the dental industry.

Once nanomechanics are available, the ultimate dream of every healer, medicine man and physician throughout recorded history will, at last become a reality. Programmable and controllable microscale robots comprised of nanoscale parts fabricated to nanometer precision will allow medical doctors to execute curative and reconstructive procedures in the human body at the cellular and molecular levels. Nanomedical physicians of the 21^st century will still make good use of the body’s natural healing powers and homeostatic mechanisms, because all else equal, those interventions are best that intervene least.

Footnotes

Source of Support: Nil

Conflict of Interest: None declared.

REFERENCES

Rocco Castoro. U F expects big things from the science of small, nanotechnology. Think Small. The POST 02-2005.
Feynman RP. There’s plenty of room at the bottom. Eng Sci. 1960;23:22–36.
Drexler KE. New era of nanotechnology. New York: Anchor Press; 1986. Engines of creation: The coming era of nanotechnology; pp. 99–129.
Freitas RA., Jr . Basic capabilities. Vol 1. Texas: Landes Bioscience; 1999. Nanomedicine. Available from: http//www.nanomedicine.com[last accessed on 2000 Sep 26] Georgetown.
European Science Foundation. Nanomedicine. Forward look on Nanomedicine. 2005
Frietas RA., Jr Current status of nanomedicine and medical nanorobotics. J Comut Ther Nanosci.2005;2:1–25.
Fahy GM. Short-term and long term possibilities for interventive gerontology. Mt Sinai J Med.1991;58:328–40. [PubMed]
Fahy GM. Molecular nanotechnology and its possible pharmaceutical implications. In: Bezold C, Halperin JA, Eng JL, editors. 2020 visions: Health care information standards and technologies. Rockville, MD: U.S Pharmacopenial Convention; 1993. pp. 152–9.
Freitas RA., Jr Nanodentistry. J Am Dent Assoc. 2000;131:1559–66. [PubMed]
Freitas R., Jr Nanotechnology, nanomedicine and nanosurgery. Int J Surg. 2005;3:243–6. [PubMed]
Ishiyama K, Sendoh M, Arai KI. Magnetic micromachines for medical applications. J Magn Mater.2002;242:1163–5.
Nelson B, Rajamani R. Biomedical micro-robotic system. In: Eighth international conference on medical image computing and computer assised intervention. MICCAI; 2005; Available from:http://www.miccai2005.orgPalm Springs CA: 26-29 Otober 2005.
Chrusch DD, Podaima BW, Gordon R. Cytobots: Intracellular robotic micromanipulators. In: Kinsner W, Sebak A, editors. Conference proceedings, 2002 IEEE Canadian conference on electrical and computer engineering; 2002 May 12-15; Winnipeg, Canada. Winnipeg: IEEE; 2002.
Freitas RA., Jr Exploratory design in medical nanotechnology: A mechanical artificial red cell. Artif Cells Blood Substit Immobil Biotechnol. 1998;26:411–30. [PubMed]
Freitas RA., Jr Microbivores: Artificial mechanical phagocytes using digest and discharge protocol. J Evol Technol. 2005;14:1–52.
Kirson ED, Yaari Y. A novel technique for micro-dissection of neuronal processes. J Neurosci Methods.2000;98:119–22. [PubMed]
Yanik MF, Cinar H, Cinar HN, Chisholm AD, Jin Y, Ben-Yakar A. Neurosurgery: functional regeneration after laser axotomy. Nature. 2004;432:822. [PubMed]
Konig K, Riemann I, Fischer P, Halbhuber KJ. Intracellular nanosurgery with near infrared femtosecond laser pulses. Cell Mol Biol. 1999;45:195–201. [PubMed]
Chen HF, Clarkson BH, Sunk, Mansfield JF. Self assembly of synthetic hydroxyaptite nanorods into enamel prism like structure. J Colloid Interf Sci. 2005;188:97–103. [PubMed]
Yunshin S, Park HN, Kim KH. Biologic evaluation of Chitosan Nanofiber Membrane for guided bone regeneration. J Periodontol. 2005;76:1778–84. [PubMed]
Reifman EM. Diamond teeth. In: Crandall BC, editor. Nanotechnology: Molecular speculations on global abundance. Cambridge, Mass: MIT Press; 1996. pp. 81–6.
Jayraman K, Kotaki M, Zhang Y, Mox, Ramakrishna S. Recent advances in Polymer nanofibers. J Nanosci Nanotechnol. 2004;4:52–65. [PubMed]
Katti DS, Robinson KW, Ko FK, Laurenci CT. Bioresorbable nanofiber based systems for wound healing and drug delivery: Optimisation of fabrication parameters. J Biomed Mater Res. 2004;70:282–96.[PubMed]
Price RL, Ellison K, Haberstroh KM, Webster TJ. Nano-meter surface roughness increases select osteoblasts adhesion on carbon nanofiber compacts. J Biomed Mater Res. 2004;70:129–38. [PubMed]
Nano A. The A to Z of nanotechnology And nanomaterials. The Institute of nanotechnology, Azom Co Ltd; 2003.

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2813556/?report=reader

The MIT-Harvard Center for Cancer Nanotechnology Excellence is a collaborative effort among MIT, Harvard University, Harvard Medical School, Massachusetts General Hospital, and Brigham and Women’s Hospital. It is one of eight Centers of Cancer Nanotechnology Excellence awarded by The National Cancer Institute (NCI), part of the National Institutes of Health (NIH). It focuses on developing a diversified portfolio of nanoscale devices for targeted delivery of cancer therapies, diagnostics, non-invasive imaging, and molecular sensing. In addition to general oncology applications, the Consortium focuses on prostate, brain, lung, ovarian, and colon cancer.

Examples of projects that the Consortium is undertaking include the development of:

Targeted nanoparticles for treating prostate cancer
Polymer nanoparticles and quantum dots for siRNA delivery
Next-generation magnetic nanoparticles for multimodal, non-invasive tumor imaging
Implantable, biodegradable microelectromechanical systems (MEMS), also known as lab-on-a-chip devices, for in vivo molecular sensing of tumor-associated biomolecules
Low-toxicity nanocrystal quantum dots for biomedical sensing

In addition to drawing on the scientific and technological expertise of its investigators, the Consortium uses available facilities for toxicology testing and the extensive mouse models of cancer collection at the collaborating institutions.

Nanotechnology and CancerNanotechnology is one of the most popular areas of scientific research, especially with regard to medical applications. We’ve already discussed some of the new detection methods that should bring about cheaper, faster and less invasive cancer diagnoses. But once the diagnosis occurs, there’s still the prospect of surgery, chemotherapy or radiation treatment to destroy the cancer. Unfortunately, these treatments can carry serious side effects. Chemotherapy can cause a variety of ailments, including hair loss, digestive problems, nausea, lack of energy and mouth ulcers.But nanotechnologists think they have an answer for treatment as well, and it comes in the form o ftargeted drug therapies. If scientists can load their cancer-detecting gold nanoparticles with anticancer drugs, they could attack the cancer exactly where it lives. Such a treatment means fewer side effects and less medication used. Nanoparticles also carry the potential for targeted and time-release drugs. A potent dose of drugs could be delivered to a specific area but engineered to release over a planned period to ensure maximum effectiveness and the patient’s safety.These treatments aim to take advantage of the power of nanotechnology and the voracious tendencies of cancer cells, which feast on everything in sight, including drug-laden nanoparticles. One experiment of this type used modified bacteria cells that were 20 percent the size of normal cells. These cells were equipped with antibodies that latched onto cancer cells before releasing the anticancer drugs they contained.Another used nanoparticles as a companion to other treatments. These particles were sucked up by cancer cells and the cells were then heated with a magnetic field to weaken them. The weakened cancer cells were then much more susceptible to chemotherapy.It may sound odd, but the dye in your blue jeans or your ballpoint pen has also been paired with gold nanoparticles to fight cancer. This dye, known as phthalocyanine, reacts with light. The nanoparticles take the dye directly to cancer cells while normal cells reject the dye. Once the particles are inside, scientists “activate” them with light to destroy the cancer. Similar therapies have existed to treat skin cancers with light-activated dye, but scientists are now working to use nanoparticles and dye to treat tumors deep in the body.From manufacturing to medicine to many types of scientific research, nanoparticles are now rather common, but some scientists have voiced concerns about their negative health effects. Nanoparticles’ small size allows them to infiltrate almost anywhere. That’s great for cancer treatment but potentially harmful to healthy cells and DNA. There are also questions about how to dispose of nanoparticles used in manufacturing or other processes. Special disposal techniques are needed to prevent harmful particles from ending up in the water supply or in the general environment, where they’d be impossible to track.Gold nanoparticles are a popular choice for medical research, diagnostic testing and cancer treatment, but there are numerous types of nanoparticles in use and in development. Bill Hammack, a professor of chemical engineering at the University of Illinois, warned that nanoparticles are “technologically sweet” [Source: Marketplace]. In other words, scientists are so wrapped up in what they can do, they’re not asking if they should do it. The Food and Drug Administration has a task force on nanotechnology, but as of yet, the government has exerted little oversight or regulation.
The U.S. Food and Drug Administration (FDA)regulates a wide range of products, including foods, cosmetics, drugs, devices, veterinary products, and tobacco products some of which may utilize nanotechnology or contain nanomaterials. Nanotechnology allows scientists to create, explore, and manipulate materials measured in nanometers (billionths of a meter). Such materials can have chemical, physical, and biological properties that differ from those of their larger counterparts.Guidance documents issued
- On June 24, 2014, FDA issued three final guidance documentsrelated to the use of nanotechnology in regulated products,incuding cosmetics and food substances.
- On August 5, 2015, FDA issued one final guidance documentrelated to the use of nanotechnology in food for animals.
  - FDA Guidance on Nanotechnology
    1. Nanotechnology Fact Sheet
    2. FDA issues three final guidances related to nanotechnology applications in regulated products, including cosmetics and food substances (June 2014)
    3. FDA issues final guidance on the use of nanotechnology in food for animals (August 2015)
    4. Nanotechnology in TherapeuticsA Focus on Nanoparticles as a Drug Delivery SystemSuwussa Bamrungsap; Zilong Zhao; Tao Chen; Lin Wang; Chunmei Li; Ting Fu; Weihong TanDisclosuresNanomedicine. 2012;7(8):1253-1271.AbstractContinuing improvement in the pharmacological and therapeutic properties of drugs is driving the revolution in novel drug delivery systems. In fact, a wide spectrum of therapeutic nanocarriers has been extensively investigated to address this emerging need. Accordingly, this article will review recent developments in the use of nanoparticles as drug delivery systems to treat a wide variety of diseases. Finally, we will introduce challenges and future nanotechnology strategies to overcome limitations in this field.IntroductionNanotechnology involves the engineering of functional systems at the molecular scale. Such systems are characterized by unique physical, optical and electronic features that are attractive for disciplines ranging from materials science to biomedicine. One of the most active research areas of nanotechnology is nanomedicine, which applies nanotechnology to highly specific medical interventions for the prevention, diagnosis and treatment of diseases.^[1,2,401] The surge in nanomedicine research during the past few decades is now translating into considerable commercialization efforts around the globe, with many products on the market and a growing number in the pipeline. Currently, nanomedicine is dominated by drug delivery systems, accounting for more than 75% of total sales.^[3]
      Nanomaterials fall into a size range similar to proteins and other macromolecular structures found inside living cells. As such, nanomaterials are poised to take advantage of existing cellular machinery to facilitate the delivery of drugs. Nanoparticles (NPs) containing encapsulated, dispersed, absorbed or conjugated drugs have unique characteristics that can lead to enhanced performance in a variety of dosage forms. When formulated correctly, drug particles are resistant to settling and can have higher saturation solubility, rapid dissolution and enhanced adhesion to biological surfaces, thereby providing rapid onset of therapeutic action and improved bioavailability. In addition, the vast majority of molecules in a nanostructure reside at the particle surface,^[4] which maximizes the loading and delivery of cargos, such as therapeutic drugs, proteins and polynucleotides, to targeted cells and tissues. Highly efficient drug delivery, based on nanomaterials, could potentially reduce the drug dose needed to achieve therapeutic benefit, which, in turn, would lower the cost and/or reduce the side effects associated with particular drugs. Furthermore, NP size and surface characteristics can be easily manipulated to achieve both passive and active drug targeting. Site-specific targeting can be achieved by attaching targeting ligands, such as antibodies or aptamers, to the surface of particles, or by using guidance in the form of magnetic NPs. NPs can also control and sustain release of a drug during transport to, or at, the site of localization, altering drug distribution and subsequent clearance of the drug in order to improve therapeutic efficacy and reduce side effects.
      
      Nanotechnology could be strategically implemented in new developing drug delivery systems that can expand drug markets. Such a plan would be applied to drugs selected for full-scale development based on their safety and efficacy data, but which fail to reach clinical development because of poor biopharmacological properties, for example, poor solubility or poor permeability across the intestinal epithelium, situations that translate into poor bioavailability and undesirable pharmacokinetic properties.^[5] The new drug delivery methods are expected to enable pharmaceutical companies to reformulate existing drugs on the market, thereby extending the lifetime of products and enhancing the performance of drugs by increasing effectiveness, safety and patient adherence, and ultimately reducing healthcare costs.^[6–8]
      
      Commercialization of nanotechnology in pharmaceutical and medical science has made great progress. Taking the USA alone as an example, at least 15 new pharmaceuticals approved since 1990 have utilized nanotechnology in their design and drug delivery systems. In each case, both product development and safety data reviews were conducted on a case-by-case basis, using the best available methods and procedures, with an understanding that postmarketing vigilance for safety issues would be ongoing. Some representative examples of therapeutic nanocarriers on the market are briefly described in Table 1.
      
      In this review, we focus mainly on the application of nanotechnology to drug delivery and highlight several areas of opportunity where current and emerging nanotechnologies could enable novel classes of therapeutics. We look at challenges and general trends in pharmaceutical nanotechnology, and we also explore nanotechnology strategies to overcome limitations in drug delivery. However, this article can only serve to provide a glimpse into this rapidly evolving field, both now and what may be expected in the future.
      
      Nanocarriers & Their Applications
      
      Various nanoforms have been attempted as drug delivery systems, varying from biological substances, such as albumin, gelatin and phospholipids for liposomes, to chemical substances, such as various polymers and solid metal-containing NPs (Figure 1). Polymer–drug conjugates, which have high size variation, are normally not considered as NPs. However, since their size can still be controlled within 100 nm, they are also included in these nanodelivery systems. These nanodelivery systems can be designed to have drugs absorbed or conjugated onto the particle surface, encapsulated inside the polymer/lipid or dissolved within the particle matrix. As a consequence, drugs can be protected from a critical environment or their unfavorable biopharmaceutical properties can be masked and replaced with the properties of nanomaterials. In addition, nanocarriers can be accumulated preferentially at tumor, inflammatory and infectious sites by virtue of the enhanced permeability and retention (EPR) effect. The EPR effect involves site-specific characteristics, not associated with normal tissues or organs, thus resulting in increased selective targeting. Based on those properties, nanodrug delivery systems offer many advantages,^[9–11] including:
      
      (Enlarge Image)
      
      Figure 1.
      
      Some nanotechnology-based drug delivery platforms, including a nanocrystal, liposome, polymeric micelle, protein-based nanoparticle, dendrimer, carbon nanotube and polymer–drug conjugate.
      NP: Nanoparticle.
      - Improving the stability of hydrophobic drugs, rendering them suitable for administration;
      - Improving biodistribution and pharmacokinetics, resulting in improved efficacy;
      - Reducing adverse effects as a consequence of favored accumulation at target sites;
      - Decreasing toxicity by using biocompatible nanomaterials.
      By adopting nanotechnology, fundamental changes in drug production and delivery are expected to affect approximately half of the worldwide drug production in the next decade, totaling approximately US$380 billion in revenue.^[12] Next, several main nanocarriers are briefly discussed.
      
      Nanocrystals
      
      One of the most obvious and important nanotechnology tools for product development is the opportunity to convert existing drugs with poor water solubility and dissolution rate into readily water-soluble dispersions by converting them into nanosized drugs.^[13,14] In other words, the drug itself may be formulated at a nanoscale such that it can function as its own ‘carrier’.^[15] Many approaches have been studied, but the most practical strategy involves reducing the drug particle size to nanometer range and stabilizing the drug NP surface with a layer of nonionic surfactants or polymeric macromolecules.^[16] By reducing the particle size of the active pharmaceutical ingredient, the drug’s surface area is increased considerably, thereby improving its solubility and dissolution and consequently increasing both the maximum plasma concentration and area under the curve. Once the drug is nanosized, it can be formulated into various dosage forms, such as oral, nasal and injectable. These nanocrystal drugs may have advantages over association colloids (micelle solutions) because the level of surfactant per amount of drug can be greatly minimized, using only the amount that is necessary to stabilize the solid–fluid interface.^[15]
      
      Furthermore, recent studies have shown that external agents, such as surfactants, for nanocrystal drug delivery can be eliminated. For example, a method was recently developed for the delivery of a hydrophobic photosensitizing anticancer drug in its pure form using nanocrystals.^[17] Synthesized by the reprecipitation method, the resulting drug nanocrystals were stable in aqueous dispersion, without the necessity of any additional stabilizer. These nanocrystals are uniform in size distribution with an average diameter of 110 nm. Such nanocrystals were efficiently taken up by tumor cells in vitro, and irradiation of such cells with visible light (665 nm) resulted in significant cell death. An in vivo study of the nanocrystal drug also showed significant efficacy compared with the conventional surfactant-based delivery system. These results illustrate the potential of pure drug nanocrystals for photodynamic therapy. As shown in Table 1 , a number of well-known drugs have already been commercialized using the nanocrystal approach.
      
      Organic Nanoplatforms
      
      Liposomes Liposomes are self-assembled artificial vesicles developed from amphiphilic phospholipids. These vesicles consist of a spherical bilayer structure surrounding an aqueous core domain, and their size can vary from 50 nm to several micrometers. Liposomes have attractive biological properties, including general biocompatibility, biodegradability, isolation of drugs from the surrounding environment and the ability to entrap both hydrophilic and hydrophobic drugs. Through the addition of agents to the lipid membrane, or the alteration of the surface chemistry, liposome properties, such as size, surface charge and functionality, can be easily tuned.
      
      Liposomes are the most clinically established nanosystems for drug delivery. Their efficacy has been demonstrated in reducing systemic effects and toxicity, as well as in attenuating drug clearance.^[18,19]Modified liposomes at the nanoscale have been shown to have excellent pharmacokinetic profiles for the delivery of DNA, antisense oligonucleotide, siRNA, proteins and chemotherapeutic agents.^[20]Examples of marketed liposomal drugs with higher efficacy and lower toxicity than their nonliposomal analogues are listed in Table 1 . Doxorubicin is an anticancer drug that is widely used for the treatment of various types of tumors. It is a highly toxic compound affecting not only tumor tissue, but also heart and kidney, a fact that limits its therapeutic applications. However, the development of doxorubicin enclosed in liposomes culminated in an approved nanomedical drug delivery system.^[21,22] This novel liposomal formulation has resulted in reduced delivery of doxorubicin to the heart and renal system, while elevating the accumulation in tumor tissue^[23,24] by the EPR effect. Furthermore, a number of liposomal drugs are currently being investigated, including anticancer agents, such as camptothecin^[25]and paclitaxel (PTX),^[26] as well as antibiotics, such as vancomycin^[27] and amikacin.^[28]
      
      Liposomes are also subject to some limitations, including low encapsulation efficiency, fast burst release of drugs, poor storage stability and lack of tunable triggers for drug release.^[29] Furthermore, since liposomes cannot usually permeate cells, drugs are released into the extracellular fluid.^[30] As such, many efforts have focused on improving their stability and increasing circulation half-life for effective targeting or sustained drug action.^[19,31] Surface modification is one method of conferring stability and structural integrity against a harsh bioenvironment after oral or parenteral administration.^[32] Surface modification can be achieved by attaching polyethylene glycol (PEG) units, which form a protective layer over the liposome surface (known as stealth liposomes) to slow down liposome recognition, or by attaching other polymers, such as poly(methacrylic acid-co-cholesteryl methacrylate)^[33] and poly(actylic acid),^[34] to improve the circulation time of liposomes in blood. To overcome the fast burst release of the chemotherapeutic drugs from liposomes, drugs such as doxorubicin may be encapsulated in the liposomal aqueous phase by an ammonium sulphate gradient.^[35] This strategy enables stable drug entrapment with negligible drug leakage during circulation, even after prolonged residence in the blood stream.^[36] Further efforts to improve control over the rate of release and drug bioavailability have been made by designing liposomes whose release is environmentally triggered. Accordingly, the drug release from liposome-responsive polymers, or hydrogel, is triggered by a change in pH, temperature, radiofrequency or magnetic field.^[37] Liposomes have also been conjugated with active-targeting ligands, such as antibodies^[38–40] or folate, for target-specific drug delivery.^[41]
      
      Polymeric NPs Polymeric NPs are colloidal particles with a size range of 10–1000 nm, and they can be spherical, branched or core–shell structures. They have been fabricated using biodegradable synthetic polymers, such as polylactide–polyglycolide copolymers, polyacrylates and polycaprolactones, or natural polymers, such as albumin, gelatin, alginate, collagen and chitosan.^[42] Various methods, such as solvent evaporation, spontaneous emulsification, solvent diffusion, salting out/emulsification-diffusion, use of supercritical CO₂ and polymerization, have been used to prepare the NPs.^[43]Advances in polymer science and engineering have resulted in the development of smart polymer (stimuli-sensitive polymer), which can change its physicochemical properties in response to environmental signals. Physical (temperature, ultrasound, light, electricity and mechanical stress), chemical (pH and ionic strength) and biological signals (enzymes and biomolecules) have been used as triggering stimuli. Various monomers having sensitivity to specific stimuli can be tailored to a homopolymer in response to a certain signal or copolymers answering multiple stimuli. The versatility of polymer sources and their easy combination make it possible to tune up polymer sensitivity in response to a given stimulus within a narrow range, leading to more accurate and programmable drug delivery.
      
      Polymeric nanocarriers can be categorized based on three drug-incorporation mechanisms. The first includes polymeric carriers that use covalent chemistry for direct drug conjugation (e.g., linear polymers). The second group includes hydrophobic interactions between drugs and nanocarriers (e.g., polymeric micelles from amphiphilic block copolymers). Polymeric nanocarriers in the third group include hydrogels, which offer a water-filled depot for hydrophilic drug encapsulation.
      
      Polymer–Drug Conjugates (Prodrugs) Many polymer–drug conjugates have been developed since the first combination reported in the 1970s.^[44,45] Conjugation of macromolecular polymers to drugs can significantly enhance the blood circulation time of the drugs. Especially, protein or peptide drugs, which can be readily digested inside the human body, can maintain their activity by conjugation of the water-soluble polymer PEG (PEGylation). For example, it was reported that PEGylated L-asparaginase increased its plasma half-life by up to 357 h.^[46] Without PEG, the half-life of natural L-asparaginase is only 20 h. In addition to PEGylation of proteins, small molecular anticancer drugs can also be PEGylated to improve their pharmacokinetics for cancer therapy. For instance, PEG-camptothecin (PROTHECAN®) has entered clinical trials for cancer therapy.^[47]
      
      Increasing the otherwise poor solubility of some drugs is another important function of polymer–drug conjugation. Specifically, conjugating water-soluble polymers to functional groups that already exist in the drug structure can significantly enhance the water solubility of the drug. Recently, a new category of polymer–drug conjugates called brush polymer–drug conjugates were prepared by ring-opening metathesis copolymerization.^[48] In this report, as PEG was employed as the brush polymer side chains, the conjugates exhibited significant water solubility. However, polymer–drug conjugates require chemical modification of the existing drugs; as a consequence, their production could cost more, and additional purification steps are needed. Moreover, polymers that are chemically conjugated with drugs are often considered new chemical entities owing to a pharmacokinetic profile distinct from that of the parent drugs. As such, additional US FDA approval is required, even though the parent drug has already been approved. Despite the variety of novel drug targets and sophisticated chemistries available, only four drugs (doxorubicin, camptothecin, PTX and platinate) and four polymers (N-[2-hydroxylpropyl]methacrylamide [HPMA] copolymer, poly-L-glutamic acid [PGA], PEG and dextran) have been used to develop polymer–drug conjugates.^[49–54] In addition to the commercially available polymer drugs listed in Table 1 , PGA-PTX (Xyotax™, CT-2103; Cell Therapeutics Inc./Chugai Pharmaceutical Co. Ltd.),^[55] PGA-camptothecin (CT-2106; Cell Therapeutics Inc.)^[56] and HPMA–doxorubicin (PK1/FCE-28068; Pfizer Inc./Cancer Research Campaign)^[57] are now in clinical trials. As an example, PK1 has been evaluated in clinical trials as an anticancer agent, and a Phase I evaluation has been completed in patients with several types of tumors resistant to prior therapy, such as chemotherapy or radiation. However, although the clinical results for HPMA–doxorubicin conjugates look promising, PEG-based conjugation remains the gold-standard in the field of polymeric drug delivery. In addition, polymer–drug conjugates are still limited by their nonbiodegradability and the fate of polymers after in vivoadministration.^[58]
      
      Polymeric Micelles Polymeric micelles are formed when amphiphilic surfactants or polymeric molecules spontaneously associate in aqueous medium to form core–shell structures. The inner core of a micelle, which is hydrophobic, is surrounded by a shell of hydrophilic polymers, such as PEG.^[59] Their hydrophobic core serves as a reservoir for poorly water-soluble and amphiphilic drugs; at the same time, their hydrophilic shell stabilizes the core, prolongs circulation time in blood and increases accumulation in tumor tissues.^[41] So far, a large variety of drug molecules have been incorporated into polymeric micelles, either by physical encapsulation^[60,61] or covalent attachment.^[62] Genexol-PM® (Samyang, Korea), PEG-poly(D,L-lactide)-PTX, employs cremophor-free polymeric micelles loaded with PTX drugs. It was found to have a three-times higher maximum tolerated dose in nude mice and two- to threefold higher levels of biodistribution, compared with those of pristine PTX, in various tissues, including tumors. A Phase I clinical trial has been evaluated in patients, and the results showed that Genexol-PM is superior to conventional PTX for the delivery of higher doses without additional toxicity.^[63] Recently, a series of novel dual targeting micellar delivery systems were developed based on the self-assembled hyaluronic acid-octadecyl (HA-C18) copolymer and folic acid-conjugated HA-C18 (FA-HA-C18). PTX was successfully encapsulated by HA-C18 and FA-HA-C18 polymeric micelles, with a high encapsulation efficiency of 97.3%. Since these copolymers are biodegradable, biocompatible and cell-specifically targetable, they become promising nanostructure carriers for hydrophobic anticancer drugs.^[64] In addition, stimuli-responsive drug-loaded micelles^[65–69] and multifunctional polymeric micelles containing imaging as well as therapeutic agents^[70–72] are now under active investigation with the potential to be the mainstream of the polymeric drug development in the near future. Furthermore, using computer simulation, the experimental preparation of drug-loaded polymeric micelles could be more efficiently guided, by providing insight into the mechanism of mesoscopic structures and serving as a complement to experiments.^[73]
      
      Hydrogel NPs In recent years, hydrogel NPs have gained considerable attention as one of the most promising nanoparticulate drug delivery systems owing to their unique properties. Hydrogels are cross-linked networks of hydrophilic polymers that can absorb and retain more than 20% of their weight in water, while at the same time, maintaining the distinct 3D structure of the polymer network. Swelling properties, network structure, permeability or mechanical stability of hydrogels can be controlled by external stimuli or physiological parameters.^[74–78] Hydrogels have been extensively studied for controlled release of therapeutics, stimuli-responsive release and applications in biological implants.^[75,79–81] However, the hydration response to changes in stimuli in most hydrogel systems is too slow for therapeutic applications. To overcome this limitation, further development of hydrogel structures at the micro- and nano-scale is needed.^[82] Recent reports showed some progress in micro- and nanogels of poly-N-isopropylacrylamide with ultrafast responses and attractive rheological properties.^[83,84] Ding et al. demonstrated that cisplatin-loaded polyacrylic acid hydrogel NPs could be implanted and plastered on tumor tissue.^[85] This hydrogel system exhibited superior efficacy in impeding tumor growth and prolonging lifespan in mice. The in vivo biodistribution assay also demonstrated that the hydrogel implant results in high concentration and retention of the drug. A multifunctional hybrid hydrogel was developed by combining the magnetic properties of NPs and the typical characteristics of the hydrogel. These hybrid hydrogels could be used to load a large number of drugs and transport them to the target site by the application of an external magnetic field.^[86] To improve the specificity of the hydrogel drug delivery systems, core–shell nanogels were developed, which utilize aptamers as the recognition element and near-infrared light as a triggering stimulus for drug delivery. In this system, gold (Au)–silver nanorods, which possess intense absorption bands in the near-infrared range, were coated with DNA cross-linked polymeric shells, so that drugs can be rapidly and controllably released upon the near-infrared irradiation.^[87] As the fate of hydrogel NPs after in vivo administration may be a concern for clinical applications, biodegradable hydrogel NPs with diameters of approximately 200 nm have been synthesized via inverse miniemulsion reversible addition–fragmentation chain-transfer polymerization of 2-(dimethylamino)ethyl methacrylate. A disulfide cross-linker was used to cross-link the NPs, so that the polymer network could be degraded to its constituent primary chains by exposure to a reductive environment. It is indicated that these biodegradable hydrogel NPs are currently being investigated for encapsulation and controlled release of siRNA.^[88] Although hydrogel NPs-based drugs are not commercially available, they have high possibility to be further developed for drug delivery systems in the future, owing to their highly biocompatible and effective drug-loading properties.
      
      Protein-based NPs Hydrophobic drugs, such as taxanes, are highly active and widely used in a variety of solid tumor therapies. Both PTX and docetaxel, which are the commercially available taxanes for clinical treatments, are hydrophobic. Because of their solubility problems, they have been formulated as suspensions with nonionic surfactants, such as Cremophor EL® (BASF Corp.) for PTX and Tween-80 (ICI Americas, Inc.) for docetaxel. However, these surfactants are associated with hypersensitivity reaction and toxic side effects to tissues. To decrease toxicity, albumin conjugated with PTX has been formulated, yielding NPs approximately 130 nm in size and approved by the FDA for breast cancer treatment.^[89–91] In addition to reduced toxicity, albumin–PTX has been found to bind with the albumin receptor (gp60) on endothelial cells, with further extravascular transport,^[92–94] resulting in an increase in drug concentration at tumor sites without hypersensitivity reactions. The albumin–PTX complex is approved in 38 countries for the treatment of metastatic breast cancer. Furthermore, Abraxane® is currently in various stages of investigation for the treatment of other cancers, such as metastatic breast cancer, non-small-cell lung cancer, malignant melanoma, pancreatic and gastric cancer.
      
      Dendrimers Dendrimers are synthetic, branched macromolecules that form a tree-like structure. Unlike most linear polymers, the chemical composition and molecular weight of dendrimers can be precisely controlled; hence, it is relatively easy to predict their biocompatibility and pharmacokinetics.^[95]Dendrimers are very uniform with extremely low polydispersities, and they are commonly created with dimensions incrementally grown in approximate nanometer steps from 1 to over 10 nm. Their globular structures and the presence of internal cavities enable drugs to be encapsulated within the macromolecule interior and are used to provide controlled release from the inner core.^[96] Although the small size (up to 10 nm) of dendrimers limits extensive drug incorporation, their dendritic nature and branching allows drug loading onto the outside surface of the structure^[97] via covalent binding or electrostatic interactions. Dendrimers can be synthesized by either divergent or convergent approaches. In the divergent approach, dendrimers are synthesized from the core and further built to other layers called generations. However, this method provides a low yield because the reactions that occur must be conducted on a single molecule processing a large number of equivalent reaction sites.^[98] In addition, a large amount of reagents is required for the latter stages of synthesis, resulting in complication of purification. For the convergent method, synthesis begins at the periphery of the dendrimer molecules and stops at the core. In this approach, each synthesized generation can be subsequently purified.^[98]
      
      Drug molecules associated with dendrimers can be utilized for cancer treatment,^[99] the enhancement of drug solubility and permeability (dendrimer–drug conjugates)^[100] and intracellular delivery.^[101] Some drugs can be physically encapsulated inside the dendrimer network or form linkages (either covalently or noncovalently) on the dendrimer surface.^[102] Furthermore, functionalization of the dendrimer surface with specific ligands can enhance potential targeting. For example, Myc et al. reported a polyamidoamine dendrimer conjugate containing FA as the targeting agent and methotroxate as the therapeutic agent.^[103] Cytotoxicity and specificity were tested with both FA receptor-expressing and nonexpressing cells. Both in vitro and in vivo results showed that the dendrimer conjugate was preferentially cytotoxic to the target cells. The polyamido amine dendrimer conjugated with an anti-prostate specific membrane antigen antibody was also demonstrated.^[104] The antibody–dendrimer conjugate specifically bound to anti-prostate specific membrane antigen-positive, but not negative, cell lines. However, dendrimer toxicity and immunogenicity are the main concerns when they are applied for drug delivery. Since the clinical experience with dendrimers has so far been limited, it is hard to tell whether the dendrimers are intrinsically ‘safe’ or ‘toxic’.
      
      Inorganic Platforms
      
      Au NPs Noble metal NPs, such as Au NPs, have emerged as a promising scaffold for drug and gene delivery in that they provide a useful complement to more traditional delivery vehicles. The combination of inertness and low toxicity,^[105] easy synthesis, very large surface area, well-established surface functionalization (generally through thiol linkages) and tunable stability provide Au NPs with unique attributes to enable new delivery strategies. Moreover, excess loading of pharmaceuticals on NPs allows ‘drug reservoirs’ to accumulate for controlled and sustained release, thereby maintaining the drug level within the therapeutic window. An Au NP with 2-nm core diameter could, in principle, be conjugated with 100 molecules to available ligands (n = 108) in the monolayer.^[106] Zubarev et al. have recently succeeded in coupling 70 PTX molecules, a chemotherapeutic drug, to an Au NP with a 2-nm core diameter.^[107] Efficient release of these therapeutic agents could be triggered by internal (e.g., glutathione^[108] or pH^[109]) or external (e.g., light^[110,111]) stimuli. In addition to serving as the carrier for drug delivery, Au NPs can also be imaged using contrast imaging techniques. Once the Au NPs are targeted to the diseased site, such as a tumor, hyperthermia treatment can be used for tumor destruction. For example, a recent study demonstrated that PEGylated Au NPs were employed for highly efficient drug delivery and in vivo photodynamic therapy of cancer.^[112] Compared with conventional photodynamic therapy drug delivery in vivo, PEGylated Au NPs accelerated the silicon phthalocyanine 4 administration by approximately two orders of magnitude without side effects in treated mice. The key issue that needs to be addressed with Au NPs is the engineering of the particle surface for optimized properties, such as bioavailability and nonimmunogenicity.
      
      Superparamagnetic NPs Magnetic NPs have been proposed as drug carriers with a push towards clinical trials.^[113] The superparamagnetic properties of iron (II) oxide particles can be used to guide microcapsules in place for delivery by external magnetic fields. Another advantage of using magnetic NPs is the ability to heat the particles after internalization, which is known as the hyperthermia effect. For example, Brazel et al. developed a grafted thermosensitive polymeric system by embedding FePt NPs in poly(N-isopropylacrylamide)-based hydrogels, which can be triggered to release the loaded drug by inducing an increase in temperature based on a magnetic thermal heating event.^[114] The grafted hydrogel system is also shown to exhibit a desirable positive thermal response with an increased drug diffusion coefficient for temperatures higher than physiological temperature.^[115]
      
      Besides being utilized for targeting and raising temperature, magnetic NPs can also affect the permeability of microcapsules by applying external oscillating magnetic fields and releasing encapsulated materials.^[116] For example, ferromagnetic Au-coated cobalt NPs (3 nm in diameter) were incorporated into the polymer walls of microcapsules. Subsequently, application of external alternating magnetic fields of 100–300 Hz and 1200 Oe strength disturbed the capsule wall structures and dramatically increased their permeability to macromolecules. This work supports the hypothesis that magnetic NPs embedded in polyelectrolyte capsules can be used for the controlled release of substances by applying an external magnetic field.
      
      The main benefits of superparamagnetic NPs over classical cancer therapies are minimal invasiveness, accessibility of hidden tumors and minimal side effects. Conventional heating of a tissue by, for example, microwaves or laser light results in the destruction of healthy tissue surrounding the tumor. However, targeted paramagnetic particles provide a powerful strategy for localized heating of cancerous cells.
      
      Ceramic NPs Ceramic NPs are particles fabricated from inorganic compounds with porous characteristics, such as silica, alumina and titania.^[117–119] Among these, silica NPs have attracted much research attention as a result of their biocompatibility and ease of synthesis, as well as surface modification.^{[120–122,301]} Furthermore, the well-established silane chemistry facilitates the cross-linking of drugs to silica particles.^[123,124] For example, recent breakthroughs in mesoporous silica NPs (MSNs) have brought new possibilities to this burgeoning area of research. MSNs contain hundreds of empty channels (mesopores) arranged in a 2D network of a honeycomb-like porous structure. In contrast to the low biocompatibility of other amorphous silica materials, recent studies have shown that MSNs exhibit superior biocompatibility at concentrations adequate for pharmacological applications.^[125,126]Once the vehicle is localized in the cytoplasm, it is desirable to have effective control over the release of drug molecules in order to reach pharmacologically effective levels. The ability to selectively functionalize the external particle and/or the interior nanochannel surface of MSNs is advantageous in achieving this goal.^[127,128] Different functional groups can be added by using this methodology, including, for example, functionalization with stimuli-responsive tethers that could be further attached to NPs (Au and iron [II] oxide). These NPs could work as gatekeepers and be removed by either intracellular or external triggers, such as changes in pH, reducing environment, enzymatic activity, light, electromagnetic field or ultrasound.^[128] The surface of MSNs can be engineered with cell-specific moieties, such as organic molecules, peptides, aptamers and antibodies, to achieve cell type or tissue specificity. Moreover, optical and magnetic contrast agents can be introduced to develop multipurpose drug delivery systems.
      
      These strategies demonstrated that the application of target-specific MSN vehicles in vitro is promising; however, the application in vivo has not yet been reported. These particles are not biodegradable; consequently, there is a concern that they may accumulate in the human body and cause harmful effects.^[117] For further in vivo applications, the biocompatibility, biodistribution, retention, degradation and clearance of MSNs must be systematically investigated.
      
      Carbon-based Nanomaterials Carbon-based nanomaterials have attracted particular interest because they can be surface functionalized for the grafting of nucleic acids, peptides and proteins. Carbon nanotubes (CNTs), fullerene, and nanodiamonds^[129] have been extensively studied for drug delivery applications.^[130] The size, geometry and surface characteristics of single-wall nanotubes (SWNTs), multiwall nanotubes and C₆₀ fullerenes make them appealing for drug carrier usage. For example, PTX-conjugated SWNTs have shown promise for in vivo cancer treatment. SWNT delivery of PTX affords markedly improved treatment efficacy over clinical Taxol (Bristol-Myers Squibb Co.), as evidenced by its ability to slow down tumor growth at a low PTX dose.^[131]
      
      However, the primary drawback of carbon-based nanomaterials appears to be their toxicity. Experiments have shown that CNTs can lead to cell proliferation inhibition and apoptosis. Although they are less toxic than carbon fibers and NPs, the toxicity of CNTs increases significantly when carbonyl, carboxyl and/or hydroxyl functional groups are present on their surface.^[132] Because of the reported toxicity of CNTs,^[133–137] studies involving their application for drug delivery are still being conducted.^[138–140] In order to promote the application of CNTs for drug delivery, researchers have functionalized their surface, rendering them benign.^[136] Unfortunately, concerns that functionalized CNTs may revert back to a toxic state if the functional group detaches has limited the pursuit of using these modified CNTs for biomedical applications.
      
      The toxicity of other forms of nanocarbons has also been reported.^{[132,140,141]} One study of human lung tumor cells showed that carbon NPs are even more toxic than multiwall nanotubes and carbon nanofibers.^[132] Given the mounting evidence demonstrating the toxicity of carbon NPs, the enthusiasm to develop carbon NPs for drug delivery has decreased significantly in recent years.
      
      Integrated Nanocomposite Particles
      
      A variety of nanoplatforms have been developed for a wide spectrum of applications, and each of these applications has unique advantages and limitations. By combining the specific function of each material, new hybrid nanocomposite materials can be fabricated. For instance, liposomes and polymeric NPs are the two most widely studied drug delivery platforms, and attempts have been made to combine the advantages of both systems. A recent study reported the use of nanocells consisting of nuclear poly(lactic-co-glycolic acid) NPs within an extranuclear PEGylated phospholipid envelope for temporal targeting of tumor cells and neovasculature.^[142] Moreover, liposomes are routinely coated with a hydrophilic polymer, such as PEG or poly(ethylene oxide), to improve the circulation time in vivo, which is another example of a liposome–polymer composite.^[143] Similarly, liposomal locked-in dendrimers, the combination of liposomes and dendrimers in one formulation, has resulted in higher drug loading and slower drug release from the composite, as compared with pure liposomes.^[144] Another LipoMag formulation, which consists of an oleic acid-coated magnetic nanocrystal core and a cationic lipid shell, was magnetically guided to deliver and silence genes in cells and tumors in mice.^[145]
      
      Targeting Strategies
      
      Two basic requirements should be realized in the design of nanocarriers to achieve effective drug delivery (Figure 2). First, drugs should be able to reach the desired tumor sites after administration with minimal loss to their volume and activity in blood circulation. Second, drugs should only kill tumor cells without harmful effects to healthy tissue.^[146] These requirements may be enabled using two strategies: passive and active targeting of drugs.^[147]
      
      (Enlarge Image)
      
      Figure 2.
      
      Passive and active targeting.
      By the enhanced permeability and retention effect, nanoparticles (NPs) can be passively extravasated through leaky vascularization, allowing their accumulation at the tumor region (A). In this case, drugs may be released in the extracellular matrix and then diffuse through the tissue. Active targeting (B) can enhance the therapeutic efficacy of drugs by the increased accumulation and cellular uptake of NPs through receptor-mediated endocytosis. NPs can be engineered to incorporate ligands that bind to endothelial cell surface receptors. In this case, the enhanced permeability and retention effect does not pertain, and the presence of leaky vasculature is not required.
      
      Passive Targeting
      
      Passive targeting takes advantage of the unique pathophysiological characteristics of tumor vessels, enabling nanodrugs to accumulate in tumor tissues. Typically, tumor vessels are highly disorganized and dilated with a high number of pores, resulting in enlarged gap junctions between endothelial cells and compromised lymphatic drainage. The ‘leaky’ vascularization, which refers to the EPR effect, allows migration of macromolecules up to 400 nm in diameter into the surrounding tumor region.^[147–149] One of the earliest nanoscale technologies for passive targeting of drugs was based on the use of liposomes. More advanced liposomes are coated with a synthetic polymer that protects the agents from immune destruction.^[150]
      
      Moreover, the EPR effect, the microenvironment surrounding tumor tissue, is different from that of healthy cells, a physiological phenomenon that also supports passive targeting. Based on the high metabolic rate of fast-growing tumor cells, they require more oxygen and nutrients. Consequently, glycolysis is stimulated to obtain extra energy, resulting in an acidic environment.^[151] Taking advantage of this, pH-sensitive liposomes have been designed to be stable at physiological pH 7.4, but degraded to release drug molecules at the acidic pH.^[152]
      
      Although passive targeting approaches form the basis of clinical therapy, they suffer from several limitations. Ubiquitously targeting cells within a tumor is not always feasible because some drugs cannot diffuse efficiently, and the random nature of the approach makes it difficult to control the process. The passive strategy is further limited because certain tumors do not exhibit an EPR effect, and the permeability of vessels may not be the same throughout a single tumor.^[153]
      
      Active Targeting
      
      One way to overcome the limitations of passive targeting is to attach affinity ligands (antibodies,^[154]peptides,^[155] aptamers^[156] or small molecules^[157] that only bind to specific receptors on the cell surface) to the surface of the nanocarriers by a variety of conjugation chemistries. Nanocarriers will recognize and bind to target cells through ligand–receptor interactions by the expression of receptors or epitopes on the cell surface. In order to achieve high specificity, those receptors should be highly expressed on tumor cells, but not on normal cells. Furthermore, the receptors should homogeneously express and should not be shed into the blood circulation. Internalization of targeting conjugates can also occur by receptor-mediated endocytosis after binding to target cells, facilitating drug release inside the cells. Based on the receptor-mediated endocytosis mechanism, targeting conjugates bind with their receptors first, followed by plasma membrane enclosure around the ligand–receptor complex to form an endosome. The newly formed endosome is transferred to specific organelles, and drugs could be released by acidic pH or enzymes. Although the active targeting strategy looks intriguing, nanodrugs currently approved for clinical use are relatively simple and generally lack active targeting or triggered drug release components. Moreover, nanodrugs currently under clinical development lack specific targeting. To fully explore the application of targeted drug delivery, we need to investigate whether the specific diseases are the correct application for targeting, whether the properties of the therapeutic drugs, as well as their site and mode of action, are suited for targeting and whether the delivery vehicles are optimal for product development.^[158]
      
      Key Factors Impacting Drug Delivery
      
      In order to achieve effective drug delivery, nanocarriers must have suitable circulation time to prevent the elimination of drugs before reaching their target. Based on previous investigations, size, shape and surface characteristics are key factors that impact the efficiency of drug delivery systems.
      
      Summary
      
      Nanotechnology is an emerging field with the potential to revolutionize drug delivery. Advances in this area have allowed some nanomedicines in the market to achieve desirable pharmacokinetic properties, reduce toxicity and improve patient compliance, as well as clinical outcomes. Integration of nanoparticulate drug delivery technologies in preformulation work not only accelerates the development of new therapeutic moieties, but also helps in the reduction of attrition of new molecular entities caused by undesirable biopharmaceutical and pharmacokinetic properties.
      
      Optimizing the integration of nanomaterials into drug delivery systems will require standardized metrics for their classification, as well as protocols for their handling. This will, in turn, result in a better understanding of the interactions of nanomaterials with biological systems, which will facilitate better engineering of their properties specific to biomedical applications. The development of such drug carriers will require a greater understanding of both the surface chemistry of nanomaterials and the interaction chemistry of these nanomaterials with biological systems. This can only be achieved through collaborative efforts among scientists in different disciplines. Those who work in this emerging field should have up-to-date information on related toxicology issues, potential health and safety risks and the regulatory environment that will impact patient use. Understanding both the benefits and the risks of these new nanotechnology applications will be essential to good decision-making for drug developers, regulators and ultimately the consumers and patients who will be the beneficiaries of new drug delivery technologies.
    5. Nanoparticles wrapped inside human platelet membranes serve as new vehicles for targeted drug delivery.

http://www.technologynetworks.com/news.aspx?ID=183111

Nanoparticles disguised as human platelets could greatly enhance the healing power of drug treatments for cardiovascular disease and systemic bacterial infections. These platelet-mimicking nanoparticles, developed by engineers at the University of California, San Diego, are capable of delivering drugs to targeted sites in the body — particularly injured blood vessels, as well as organs infected by harmful bacteria. Engineers demonstrated that by delivering the drugs just to the areas where the drugs were needed, these platelet copycats greatly increased the therapeutic effects of drugs that were administered to diseased rats and mice.

“This work addresses a major challenge in the field of nanomedicine: targeted drug delivery with nanoparticles,” said Liangfang Zhang, a nanoengineering professor at UC San Diego and the senior author of the study. “Because of their targeting ability, platelet-mimicking nanoparticles can directly provide a much higher dose of medication specifically to diseased areas without saturating the entire body with drugs.”

Schematic-of-platelet-nanoparticles-150915-f.jpg

The study is an excellent example of using engineering principles and technology to achieve “precision medicine,” said Shu Chien, a professor of bioengineering and medicine, director of the Institute of Engineering in Medicine at UC San Diego, and a corresponding author on the study. “While this proof of principle study demonstrates specific delivery of therapeutic agents to treat cardiovascular disease and bacterial infections, it also has broad implications for targeted therapy for other diseases such as cancer and neurological disorders,” said Chien.

The ins and outs of the platelet copycats

On the outside, platelet-mimicking nanoparticles are cloaked with human platelet membranes, which enable the nanoparticles to circulate throughout the bloodstream without being attacked by the immune system. The platelet membrane coating has another beneficial feature: it preferentially binds to damaged blood vessels and certain pathogens such as MRSA bacteria, allowing the nanoparticles to deliver and release their drug payloads specifically to these sites in the body.

Enclosed within the platelet membranes are nanoparticle cores made of a biodegradable polymer that can be safely metabolized by the body. The nanoparticles can be packed with many small drug molecules that diffuse out of the polymer core and through the platelet membrane onto their targets.

To make the platelet-membrane-coated nanoparticles, engineers first separated platelets from whole blood samples using a centrifuge. The platelets were then processed to isolate the platelet membranes from the platelet cells. Next, the platelet membranes were broken up into much smaller pieces and fused to the surface of nanoparticle cores. The resulting platelet-membrane-coated nanoparticles are approximately 100 nanometers in diameter, which is one thousand times thinner than an average sheet of paper.

This cloaking technology is based on the strategy that Zhang’s research group had developed to cloak nanoparticles in red blood cell membranes. The researchers previously demonstrated that nanoparticles disguised as red blood cells are capable of removing dangerous pore-forming toxins produced by MRSA, poisonous snake bites and bee stings from the bloodstream.

By using the body’s own platelet membranes, the researchers were able to produce platelet mimics that contain the complete set of surface receptors, antigens and proteins naturally present on platelet membranes. This is unlike other efforts, which synthesize platelet mimics that replicate one or two surface proteins of the platelet membrane.

“Our technique takes advantage of the unique natural properties of human platelet membranes, which have a natural preference to bind to certain tissues and organisms in the body,” said Zhang. This targeting ability, which red blood cell membranes do not have, makes platelet membranes extremely useful for targeted drug delivery, researchers said.

Platelet copycats at work

In one part of this study, researchers packed platelet-mimicking nanoparticles with docetaxel, a drug used to prevent scar tissue formation in the lining of damaged blood vessels, and administered them to rats afflicted with injured arteries. Researchers observed that the docetaxel-containing nanoparticles selectively collected onto the damaged sites of arteries and healed them.

When packed with a small dose of antibiotics, platelet-mimicking nanoparticles can also greatly minimize bacterial infections that have entered the bloodstream and spread to various organs in the body. Researchers injected nanoparticles containing just one-sixth the clinical dose of the antibiotic vancomycin into one of group of mice systemically infected with MRSA bacteria. The organs of these mice ended up with bacterial counts up to one thousand times lower than mice treated with the clinical dose of vancomycin alone.

“Our platelet-mimicking nanoparticles can increase the therapeutic efficacy of antibiotics because they can focus treatment on the bacteria locally without spreading drugs to healthy tissues and organs throughout the rest of the body,” said Zhang. “We hope to develop platelet-mimicking nanoparticles into new treatments for systemic bacterial infections and cardiovascular disease.”

6. Sponge-like nanoporous gold could be key to new devices to detect disease-causing agents in humans and plants, according to UC Davis researchers.

http://www.technologynetworks.com/news.aspx?ID=182663

A group from the UC Davis Department of Electrical and Computer Engineering have demonstrated that they could detect nucleic acids using nanoporous gold, a novel sensor coating material, in mixtures of other biomolecules that would gum up most detectors. This method enables sensitive detection of DNA in complex biological samples, such as serum from whole blood.

“Nanoporous gold can be imagined as a porous metal sponge with pore sizes that are a thousand times smaller than the diameter of a human hair,” said Erkin Şeker, assistant professor of electrical and computer engineering at UC Davis and the senior author on the papers. “What happens is the debris in biological samples, such as proteins, is too large to go through those pores, but the fiber-like nucleic acids that we want to detect can actually fit through them. It’s almost like a natural sieve.”

CoverArt_nanoporous_gold.png

Rapid and sensitive detection of nucleic acids plays a crucial role in early identification of pathogenic microbes and disease biomarkers. Current sensor approaches usually require nucleic acid purification that relies on multiple steps and specialized laboratory equipment, which limit the sensors’ use in the field. The researchers’ method reduces the need for purification.

“So now we hope to have largely eliminated the need for extensive sample clean-up, which makes the process conducive to use in the field,” Şeker said.

The result is a faster and more efficient process that can be applied in many settings.

The researchers hope the technology can be translated into the development of miniature point-of-care diagnostic platforms for agricultural and clinical applications.

“The applications of the sensor are quite broad ranging from detection of plant pathogens to disease biomarkers,” said Şeker.

For example, in agriculture, scientists could detect whether a certain pathogen exists on a plant without seeing any symptoms. And in sepsis cases in humans, doctors might determine bacterial contamination much more quickly than at present, preventing any unnecessary treatments.

7. Pushing the limits of lensless imaging

http://www.rdmag.com/news/2015/09/pushing-limits-lensless-imaging?

The Optical Society

To take a picture with this method, scientists fire an X-ray or extreme ultraviolet laser at a target. The light scatters off, and some of those photons interfere with one another and find their way onto a detector, creating a diffraction pattern. By analyzing that pattern, a computer then reconstructs the path those photons must have taken, which generates an image of the target material—all without the lens that’s required in conventional microscopy.

WASHINGTON — Using ultrafast beams of extreme ultraviolet light streaming at a 100,000 times a second, researchers from the Friedrich Schiller University Jena, Germany, have pushed the boundaries of a well-established imaging technique. Not only did they make the highest resolution images ever achieved with this method at a given wavelength, they also created images fast enough to be used in real time. Their new approach could be used to study everything from semiconductor chips to cancer cells.

The team will present their work at the Frontiers in Optics, The Optical Society’s annual meeting and conference in San Jose, California, USA, on October 22, 2015.

The researchers’ wanted to improve on a lensless imaging technique called coherent diffraction imaging, which has been around since the 1980s. To take a picture with this method, scientists fire an X-ray or extreme ultraviolet laser at a target. The light scatters off, and some of those photons interfere with one another and find their way onto a detector, creating a diffraction pattern. By analyzing that pattern, a computer then reconstructs the path those photons must have taken, which generates an image of the target material—all without the lens that’s required in conventional microscopy.

“The computer does the imaging part—forget about the lens,” explained Michael Zürch, Friedrich Schiller University Jena, Germany and lead researcher. “The computer emulates the lens.”

Without a lens, the quality of the images primarily depends on the radiation source. Traditionally, researchers use big, powerful X-ray beams like the one at the SLAC National Accelerator Laboratory in Menlo Park, CA, USA. Over the last 10 years, researchers have developed smaller, cheaper machines that pump out coherent, laser-like beams in the laboratory setting. While those machines are convenient from the cost perspective, they have drawbacks when reporting results.

The table-top machines are unable to produce as many photons as the big expensive ones which limits their resolution. To achieve higher resolutions, the detector must be placed close to the target material—similar to placing a specimen close to a microscope to boost the magnification. Given the geometry of such short distances, hardly any photons will bounce off the target at large enough angles to reach the detector. Without enough photons, the image quality is reduced.

Zürch and a team of researchers from Jena University used a special, custom-built ultrafast laser that fires extreme ultraviolet photons a hundred times faster than conventional table-top machines. With more photons, at a wavelength of 33 nanometers, the researchers were able to make an image with a resolution of 26 nanometers — almost the theoretical limit. “Nobody has achieved such a high resolution with respect to the wavelength in the extreme ultraviolet before,” Zürch said.

The ultrafast laser also overcame another drawback of conventional table-top light sources: long exposure times. If researchers have to wait for images, they can’t get real-time feedback on the systems they study. Thanks to the new high-speed light source, Zürch and his colleagues have reduced the exposure time to only about a second — fast enough for real-time imaging. When taking snapshots every second, the researchers reached a resolution below 80 nanometers.

The prospect of high-resolution and real-time imaging using such a relatively small setup could lead to all kinds of applications, Zürch said. Engineers can use this to hunt for tiny defects in semiconductor chips. Biologists can zoom in on the organelles that make up a cell. Eventually, he said, the researchers might be able to cut down on the exposure times even more and reach even higher resolution levels.

About FiO/LS

Frontiers in Optics (FiO) 2015 is The Optical Society’s (OSA) 99th Annual Meeting and is being held together with Laser Science, the 31th annual meeting of the American Physical Society (APS) Division of Laser Science (DLS). The two meetings unite the OSA and APS communities for five days of quality, cutting-edge presentations, in-demand invited speakers and a variety of special events spanning a broad range of topics in optics and photonics—the science of light—across the disciplines of physics, biology and chemistry. The exhibit floor will feature leading optics companies, technology products and programs.

About The Optical Society

Founded in 1916, The Optical Society (OSA) is a leading professional organization for scientists, engineers, students and entrepreneurs who fuel discoveries, shape real-life applications and accelerate achievements in the science of light. Through world-renowned publications, meetings and membership initiatives, OSA provides quality research, inspired interactions and dedicated resources for its extensive global network of optics and photonics experts. OSA is a founding partner of the National Photonics Initiative and the 2015 International Year of Light.

SOURCE: The Optical Society

8. Physicists determine three-dimensional positions of individual atoms for the first time
http://www.rdmag.com/news/2015/09/physicists-determine-three-dimensional-positions-individual-atoms-first-time?

Katherine Kornei, UCLA
The scientists were able to plot the exact coordinates of nine layers of atoms with a precision of 19 trillionths of a meter. Courtesy of Mary Scott and Jianwei (John) Miao/UCLAAtoms are the building blocks of all matter on Earth, and the patterns in which they are arranged dictate how strong, conductive or flexible a material will be. Now, scientists at UCLA have used a powerful microscope to image the three-dimensional positions of individual atoms to a precision of 19 trillionths of a meter, which is several times smaller than a hydrogen atom.

Their observations make it possible, for the first time, to infer the macroscopic properties of materials based on their structural arrangements of atoms, which will guide how scientists and engineers build aircraft components, for example. The research, led by Jianwei (John) Miao, a UCLA professor of physics and astronomy and a member of UCLA’s California NanoSystems Institute, is published September 21 in the online edition of the journal Nature Materials.

For more than 100 years, researchers have inferred how atoms are arranged in three-dimensional space using a technique called X-ray crystallography, which involves measuring how light waves scatter off of a crystal. However, X-ray crystallography only yields information about the average positions of many billions of atoms in the crystal, and not about individual atoms’ precise coordinates.

“It’s like taking an average of people on Earth,” Miao said. “Most people have a head, two eyes, a nose and two ears. But an image of the average person will still look different from you and me.”

Because X-ray crystallography doesn’t reveal the structure of a material on a per-atom basis, the technique can’t identify tiny imperfections in materials, such as the absence of a single atom. These imperfections, known as point defects, can weaken materials, which can be dangerous when the materials are components of machines like jet engines.

“Point defects are very important to modern science and technology,” Miao said.

Miao and his team used a technique known as scanning transmission electron microscopy, in which a beam of electrons smaller than the size of a hydrogen atom is scanned over a sample and measures how many electrons interact with the atoms at each scan position. The method reveals the atomic structure of materials because different arrangements of atoms cause electrons to interact in different ways.

However, scanning transmission electron microscopes only produce two-dimensional images. So, creating a 3-D picture requires scientists to scan the sample once, tilt it by a few degrees and re-scan it—repeating the process until the desired spatial resolution is achieved—before combining the data from each scan using a computer algorithm. The downside of this technique is that the repeated electron beam radiation can progressively damage the sample.

Using a scanning transmission electron microscope at the Lawrence Berkeley National Laboratory’s Molecular Foundry, Miao and his colleagues analyzed a small piece of tungsten, an element used in incandescent light bulbs. As the sample was tilted 62 times, the researchers were able to slowly assemble a 3-D model of 3,769 atoms in the tip of the tungsten sample.

The experiment was time consuming because the researchers had to wait several minutes after each tilt for the setup to stabilize.

“Our measurements are so precise, and any vibrations—like a person walking by—can affect what we measure,” said Peter Ercius, a staff scientist at Lawrence Berkeley National Laboratory and an author of the paper.

The researchers compared the images from the first and last scans to verify that the tungsten had not been damaged by the radiation, thanks to the electron beam energy being kept below the radiation damage threshold of tungsten.

Miao and his team showed that the atoms in the tip of the tungsten sample were arranged in nine layers, the sixth of which contained a point defect. The researchers believe the defect was either a hole in an otherwise filled layer of atoms or one or more interloping atoms of a lighter element such as carbon.

Regardless of the nature of the point defect, the researchers’ ability to detect its presence is significant, demonstrating for the first time that the coordinates of individual atoms and point defects can be recorded in three dimensions.

“We made a big breakthrough,” Miao said.

Miao and his team plan to build on their results by studying how atoms are arranged in materials that possess magnetism or energy storage functions, which will help inform our understanding of the properties of these important materials at the most fundamental scale.

“I think this work will create a paradigm shift in how materials are characterized in the 21st century,” he said. “Point defects strongly influence a material’s properties and are discussed in many physics and materials science textbooks. Our results are the first experimental determination of a point defect inside a material in three dimensions.”

The study’s co-authors include Rui Xu, Chien-Chun Chen, Li Wu, Mary Scott, Matthias Bartels, Yongsoo Yang and Michael Sawaya, all of UCLA; as well as Colin Ophus of Lawrence Berkeley National Laboratory; Wolfgang Theis of the University of Birmingham; Hadi Ramezani-Dakhel and Hendrik Heinz of the University of Akron; and Laurence Marks of Northwestern University.

This work was primarily supported by the U.S. Department of Energy’s Office of Basic Energy Sciences (grant DE-FG02-13ER46943 and contract DE-AC02—05CH11231).

9. An SDSU chemist has developed a technique to identify potential cancer drugs that are less likely to produce side effects.

http://www.technologynetworks.com/medchem/news.aspx?ID=183124

A class of therapeutic drugs known as protein kinase inhibitors has in the past decade become a powerful weapon in the fight against various life-threatening diseases, including certain types of leukemia, lung cancer, kidney cancer and squamous cell cancer of the head and neck. One problem with these drugs, however, is that they often inhibit many different targets, which can lead to side effects and complications in therapeutic use. A recent study by San Diego State University chemist Jeffrey Gustafson has identified a new technique for improving the selectivity of these drugs and possibly decreasing unwanted side effects in the future.

Why are protein kinase–inhibiting drugs so unpredictable? The answer lies in their molecular makeup.

Many of these drug candidates possess examples of a phenomenon known as atropisomerism. To understand what this is, it’s helpful to understand a bit of the chemistry at work. Molecules can come in different forms that have exactly the same chemical formula and even the same bonds, just arranged differently. The different arrangements are mirror images of each other, with a left-handed and a right-handed arrangement. The molecules’ “handedness” is referred to as chirality. Atropisomerism is a form of chirality that arises when the spatial arrangement has a rotatable bond called an axis of chirality. Picture two non-identical paper snowflakes tethered together by a rigid stick.

Some axes of chirality are rigid, while others can freely spin about their axis. In the latter case, this means that at any given time, you could have one of two different “versions” of the same molecule.

Watershed treatment

As the name suggests, kinase inhibitors interrupt the function of kinases—a particular type of enzyme—and effectively shut down the activity of proteins that contribute to cancer.

“Kinase inhibition has been a watershed for cancer treatment,” said Gustafson, who attended SDSU as an undergraduate before earning his Ph.D. in organic chemistry from Yale University, then working there as a National Institutes of Health poctdoctoral fellow in chemical biology.

“However, it’s really hard to inhibit a single kinase,” he explained. “The majority of compounds identified inhibit not just one but many kinases, and that can lead to a number of side effects.”

Many kinase inhibitors possess axes of chirality that are freely spinning. The problem is that because you can’t control which “arrangement” of the molecule is present at a given time, the unwanted version could have unintended consequences.

In practice, this means that when medicinal chemists discover a promising kinase inhibitor that exists as two interchanging arrangements, they actually have two different inhibitors. Each one can have quite different biological effects, and it’s difficult to know which version of the molecule actually targets the right protein.

“I think this has really been under-recognized in the field,” Gustafson said. “The field needs strategies to weed out these side effects.”

Applying the brakes

So that’s what Gustafson did in a recently published study. He and his colleagues synthesized atropisomeric compounds known to target a particular family of kinases known as tyrosine kinases. To some of these compounds, the researchers added a single chlorine atom which effectively served as a brake to keep the atropisomer from spinning around, locking the molecule into either a right-handed or a left-handed version.

When the researchers screened both the modified and unmodified versions against their target kinases, they found major differences in which kinases the different versions inhibited. The unmodified compound was like a shotgun blast, inhibiting a broad range of kinases. But the locked-in right-handed and left-handed versions were choosier.

“Just by locking them into one or another atropisomeric configuration, not only were they more selective, but they inhibited different kinases,” Gustafson explained.

If drug makers incorporated this technique into their early drug discovery process, he said, it would help identify which version of an atropisomeric compound actually targets the kinase they want to target, cutting the potential for side effects and helping to usher drugs past strict regulatory hurdles and into the hands of waiting patients.

11. ‘Nanocubes’ Make PSA Test Over 100 Times More Sensitive

http://www.mdtmag.com/news/2015/09/nanocubes-make-psa-test-over-100-times-more-sensitive?

A new catalyst that improves the sensitivity of the standard PSA test more than 100-fold, pictured above, is made of palladium nanocubes coated with iridium. (Credit: Xiaohu Xia, Michigan Technological University)

Say you’ve been diagnosed with prostate cancer, the second-leading cause of cancer death in men. You opt for surgery to remove your prostate. Three months later, a prostate surface antigen (PSA) test shows no prostate cells in your body. Everyone rejoices.

Until 18 months later, when another PSA test reveals that now prostate cells have reappeared. What happened?

The first PSA test yielded what’s known as a false negative result. It did not detect the handful of cells that remained after surgery and later multiplied. Now a chemist at Michigan Technological University has made a discovery that could, among other things, slash the numbers of false negatives in PSA tests.

Xiaohu Xia and his team, including researchers from Louisiana State University and the University of Texas at Dallas, have developed a new catalyst that could make lab tests like the PSA much more sensitive. And it may even speed up reactions that neutralize toxic industrial chemicals before they enter lakes and streams.

A paper on the research, “Pd-Ir Core-Shell Nanocubes: A Type of Highly Efficient and Versatile Peroxidase Mimic,” was published online Sept. 3 in ACS Nano. In addition to Xia, the coauthors are graduate students Jingtuo Zhang, Jiabin Liu and Haihang Ye and undergraduate Erin McKenzie of Michigan Tech; Moon J. Kim and Ning Lu of the University of Texas at Dallas; and Ye Xu and Kushal Ghale of Louisiana State University. The LSU team conducted theoretical calculations, and the UT Dallas team contributed high-resolution electron microscopy images.

Their new catalyst mimics the action of similar biochemicals found in nature, called peroxidases. “In animals and plants, these peroxidases are important– for example, they get rid of hydrogen peroxide, which is harmful to the organism,” said Xia, an assistant professor of chemistry at Michigan Tech. In medicine, peroxidases have become powerful tools for accelerating chemical reactions in diagnostic tests; a peroxidase found in the horseradish root is commonly used in the standard PSA test.

However, these natural peroxidases have drawbacks. They can be difficult to extract and purify. “And, they are made of protein, which isn’t very stable,” Xia explained. “At high temperatures, they cook, like meat.”

“Moreover, their efficiency is just fair,” he added. “We wanted to develop a mimic peroxidase that was substantially more efficient than the natural peroxidase, which would lead to a more-sensitive PSA test.”

Their new catalyst, made from nanoscale cubes of palladium coated with a few layers of iridium atoms, does just that. PSA tests Xia’s team conducted using the palladium-iridium catalyst were 110 times more sensitive than tests completed with the conventional peroxidase.

“After surgery, it’s vital to detect a tiny amount of prostate antigen, because otherwise you can get a false negative and perhaps delay treatment for cancer,” said Xia. “Our ultimate goal is to further refine our system for use in clinical diagnostic laboratories.”

Xia hopes that his mimic peroxidase will someday save lives through earlier detection of cancer and other maladies. He also plans to explore other applications, including how it compares with horseradish peroxidase in other catalytic reactions: breaking down toxic industrial-waste products like phenols into harmless substances.

Finally, the team wants to better understand why its palladium-iridium catalyst works so well. “We know the iridium coating is the key,” Xia said. “We think it makes the surface sticky, so the chemical reagents bind to it better.”

12. Using Proteomics To Understand How Genetic Mutations Rewire Cancer Cells

http://www.laboratorynetwork.com/doc/using-proteomics-to-understand-genetic-mutations-rewire-cancer-cells-0001?

SAN JOSE, Calif.–(BUSINESS WIRE)–Thermo Fisher Scientific and the Biotech Research and Innovation Center (BRIC) at the University of Copenhagen (UCPH) have shared results from two important scientific papers that advance understanding of how gene mutations drive cancer progression. The two landmark studies, published this week in the journal ; CELL, are some of the early results of the strategic collaboration between Thermo Fisher Scientific and the Linding Lab at BRIC, UCPH.

Using advanced Thermo Scientific Orbitrap Fusion mass spectrometry and next-generation sequencing technologies, researchers from the Universities of Copenhagen, Yale, Zurich, Rome and Tottori describe how specific cancer mutations target and damage the protein signaling networks within human cells on a global scale.

By developing advanced algorithms to integrate data from quantitative mass-spectrometry and next generation sequencing of tumor samples, the researchers have been able to uncover cancer-related changes to phosphorylation signaling networks. This new breakthrough allows researchers to identify the effects of mutations on the function of protein pathways in cancer for individual patients, even if those mutations are very rare.

Lead BRIC researcher Dr. Rune Linding said: “The identification of distinct changes within our tissues that could have the potential to help predict and treat cancer is a major step forward and we are confident that it can aid in the development of novel therapies and screening techniques.”

Since the human genome was decoded more than a decade ago, large scale cancer genome studies have successfully identified gene mutations in individual patients and tumors. However to develop improved cancer therapies, researchers need to explain and relate this genomic data to proteins, the targets of most pharmaceutical drugs. Creating this linkage provides powerful new insights into cancer biology and potential therapeutic approaches.

“The studies highlight the importance of integrating proteomics with genomics in future cancer studies and underscores the value of the broad technological expertise within Thermo Fisher,” said Ken Miller, vice president of research product marketing, life sciences mass spectrometry at Thermo Fisher. “It is becoming increasingly apparent that the genetic basis for each patient’s cancer is subtly, but importantly, different. This realization will inevitably lead to a need for tools to acquire and assess patient-specific information to develop highly personalized therapies with the potential for much greater efficacy. It is hoped that the novel approaches described in these studies, together with best-in-class enabling technologies such as the Orbitrap and Ion Torrent systems, will continue to improve our knowledge of cancer biology.”

The Biotech Research & Innovation Centre (BRIC) was established in 2003 by the Danish Ministry of Science, Technology and Innovation to form an elite centre in biomedical research.

The two studies will be available in advance online and printed in the 24th September issue of CELL, a premier journal in life and biological sciences. More information about the studies and links to media content can be found on http://www.lindinglab.science and http://www.bric.ku.dk. The work was supported by the European Research Council (ERC), the Lundbeck Foundation and Human Frontier Science Program.

13. Multi-Ancestry GWAS Uncovers a Dozen New Loci Linked to Blood Pressure

Sep 21, 2015

https://www.genomeweb.com/cardiovascular-disease/multi-ancestry-gwas-uncovers-dozen-new-loci-linked-blood-pressure?

NEW YORK (GenomeWeb) – In Nature Genetics, an international team described a dozen new loci influencing blood pressure patterns across individuals from multiple populations — a set that overlaps with variants implicated in epigenetic features of blood and other tissues.

Through a multi-stage genome-wide association study that relied on genotyping information for as many as 320,251 individuals of East Asian, South Asian, and European descent, the researchers focused in on SNPs at 12 blood pressure-associated sites in the genome, including loci previously linked to cardiac or metabolic functions.

In particular, the team saw blood pressure-linked variants in and around genes contributing to vascular smooth muscle and renal function. And a large proportion of the associated SNPs — or variants in linkage disequilibrium with them — turned up at sites already implicated in control of DNA methylation.

“We note an effect of genome-wide-associated sentinel SNPs on DNA methylation for traits in addition to blood pressure, suggesting that DNA methylation might have a wider role in linking common genetic variation to multiple phenotypes,” the study’s authors wrote.

More than a billion people around the world are affected by high blood pressure, the team explained, a condition that elevates the risk of heart disease, heart attack, stroke, and chronic kidney disease.

Because it occurs at especially high rates in East Asian and South Asian populations, the investigators reasoned that it might be possible to find both ancestry-specific and trans-ancestral genetic associations with high blood pressure.

The team started by analyzing imputed and directly genotyped SNPs in 31,516 individuals of East Asian ancestry, 35,352 individuals with European ancestry, and 33,126 individuals of South Asian descent, searching for variants associated with systolic blood pressure, diastolic blood pressure, pulse pressure, mean arterial pressure, and hypertension.

Through analyses on each population individually and in a meta-analysis of individuals from all three populations, the researchers initially identified 630 loci with suspected ties to at least one of the five blood pressure traits considered.

They then compared the top SNP at each site against data on as many as 87,205 individuals tested for various blood pressure traits for the International Consortium on Blood Pressure GWAS, narrowing in on 19 loci with potential ties to blood pressure that were not described in the past.

The team confirmed blood pressure associations for SNPs at 12 of the new loci through testing on another 48,268 East Asians, 68,456 Europeans, and 16,328 South Asians.

The analysis also verified almost two-dozen loci linked to blood pressure in the past and pointed to 17 sites in the genome with weaker ties to the traits of interest.

Variants at the 12 new loci seemed to have similar effects on the five traits in question, regardless of the population considered, while variants that first appeared to show population-specific effects in East Asians and Europeans did not pan out in replication testing.

By folding in linkage disequilibrium patterns for SNPs at the new blood pressure-associated sites, the researchers got a look at genes that fall near these linked SNPs — a collection that includes genes such as PDE3A, KCNK3, and PRDM6.

They also used these linkage patterns to look for overlap with DNA methylation-related SNPs, demonstrating that 28 of 35 SNPs at these loci seem to be linked to altered DNA methylation levels and related expression shifts in samples from thousands of Europeans or East Asians.

And the team saw similar effects in hundreds of cord blood samples subjected to methylation profiling, suggesting the effect is not simply a consequence of high blood pressure itself.

“The presence of these associations at an early stage of life, before substantial environmental exposure, lends support to the view that the sequence variants have a direct effect on DNA methylation and argues against reverse causation,” the study authors wrote.

14. Elabela, A New Human Embryonic Stem Cell Growth Factor

September 20, 2015 by mburatov

When embryonic stem cell lines are made, they are traditionally grown on a layer of “feeder cells” that secrete growth factors that keep the embryonic stem cells (ESCs) from differentiating and drive them to grow. These feeder cells are usually irradiated mouse fibroblasts that coat the culture dish, but do not divide. Mouse ESCs can be grown without feeder cells if the growth factor LIF is provided in the medium. LIF, however, is not the growth factor required by human ESCs, and therefore, designing culture media for human ESCs to help them grow without feeder cells has proven more difficult.

Having said that, several laboratories have designed media that can be used to derive human embryonic stem cells without feeder cells. Such a procedure is very important if such cells are to be used for therapeutic purposes, since animal cells can harbor difficult to detect viruses and unusual sugars on their cell surfaces that can also be transferred to human ESCs in culture. These unusual sugars can elicit a strong immune response against them, and for this reason, ESCs must be cultivated or derived under cell-free conditions. However, to design good cell-free culture media, we must know more about the growth factors required by ESCs.

To that end, Bruno Reversade from The Institute of Molecular and Cell Biology in Singapore and others have identified a new growth factor that human ESCs secrete themselves. This protein, ELABELA (ELA), was first identified as a signal for heart development. However, Reversade’s laboratory has discovered that ELA is also abundantly secreted by human ESCs and is required for human ESCs to maintain their ability to self-renew.

Reversade and others deleted the ELA gene with the CRISPR/Cas9 system, and they also knocked the expression of this gene down in other cells with small interfering RNAs. Alternatively, they also incubated human ESCs with antibodies against ELA, which neutralized ELA and prevented it from binding to the cell surface. However Ela was inhibited, the results were the same; reduced ESC growth, increased amounts of cell death, and loss of pluripotency.

How does ELA signal to cells to grow? Global signaling studies of growing human ESCs showed that ELA activates the PI3K/AKT/mTORC1 signaling pathway, which has been show in other work to be required for cell survival. By activating this pathway, ELA drives human ESCs through the cell-cycle progression, activates protein synthesis, and inhibits stress-induced apoptosis.

Interestingly, INSULIN and ELA have partially overlapping functions in human ESC culture medium, but only ELA seems to prime human ESCs toward the endoderm lineage. In the heart, ELA binds to the Apelin receptor APLNR. This receptor, however, is not expressed in human ESCs, which suggests that another receptor, whose identity remains unknown at the moment, binds ELA in human ESCs.

Thus ELA seems to act through an alternate cell-surface receptor, is an endogenous secreted growth factor in human

This paper was published in the journal Cell Stem Cell.

15. Multiwavelength TIRF Microscopy Enables Insight into Actin Filaments

http://www.photonics.com/Article.aspx?PID=1&AID=57707

Researchers at the University of California, San Francisco (UCSF) are combining multiple laser excitation wavelengths in total internal reflection fluorescence (TIRF) microscopy to investigate the binding dynamics of individual actin filaments.

DAN CALLEN, COHERENT INC.

TIRF microscopy provides a unique method of imaging isolated molecules and complexes in vitro. Additionally, the use of sensitive, low-noise cameras enables researchers to study this behavior in real time. A new plug-and-play method of combining several fiber-delivered, digitally modulated lasers into a single instrument, such as a TIRF microscope, now enables multiple labeled proteins to be imaged pseudosimultaneously at high frame rates. This article explores how multiwavelength excitation is being combined with TIRF microscopy in the laboratory of Dr. Dyche Mullins, a professor at UCSF, and how it’s being used to gain new insights into complex biochemical interactions that control the stability and function of actin filaments.

TIRF microscopy in single-filament studies

The Mullins Lab, located at UCSF’s Mission Bay campus, is widely recognized as a leading authority on the study of actin filaments. The protein filaments are fundamental to many processes in virtually every eukaryotic cell — they act as structural elements that enable movement of internal cargoes, amoeboid cell migration, cell division, etc. With these filaments playing so many different roles, it is not surprising that their combination of growth, branching, aggregation and movement involves many subtle control options, which are mediated by a range of different proteins. Sam Lord, the Mullins Lab’s microscope specialist, said, “One area of our research is studying how various proteins bind to actin filaments to enable aggregation, branching and other actions, and more specifically, how yet another set of proteins modulates these binding processes. Obviously, we do bulk studies in a cuvette that reveal overall kinetic data about these binding processes but we also want to image these processes in real time to study the structural biochemistry.” In order to do so, the lab uses TIRF microscopy to observe single actin filaments.

This process involves excitation light that is introduced into the sample region through either a glass slide or a cover slip. The microscope’s optics are configured so that the light hits the glass/sample interface beyond the critical angle, meaning that all of the light will undergo total internal reflection (TIR). However, even with TIR, some of the light’s electric field, called the evanescent wave, penetrates into the sample by an incredibly short distance — typically around 100 nm — beyond the interface. This means that TIRF microscopy can be used to selectively excite fluorescence in molecules and complexes that are adhered to the interface. However, because the light does not penetrate into the bulk (i.e., background) sample region, this methodology will not excite fluorescence from the huge backdrop of molecules freely floating within this medium.

TIRF microscopy is thus a 3D-resolved imaging technique. Its X-Y resolution is limited only by diffraction and/or the camera resolution, but the Z-axis sampling depth is much smaller than the diffraction limit. If there is sufficient signal for fast frame acquisition speeds, the important fourth dimension — time — enables dynamic processes, such as actin filament-protein binding, to be observed on a single filament or on a network of filaments, in real time.

In principle, both laser and nonlaser light sources may be used for fluorescence excitation in such TIRF-based applications. However, for experiments with naturally low signal levels, such as single-molecule monitoring, a laser beam’s extreme brightness is a critical advantage. In particular, a laser’s unique spatial brightness means that it is relatively simple to collimate and subsequently focus the beam into the sample with a narrow range of incidence angles, avoiding excitation of the bulk sample.

Through-objective TIRF microscopy

All TIRF microscope setups are based on one of two basic approaches: through-objective lens geometry or the prism-based method. In the former approach, light is directed in an off-axis geometry through an oil-immersion microscope objective so that the angle of incidence at the coverslip/sample interface is greater than the critical angle, as is shown schematically in Figure 1.

Figure 1. In TIRF microscopy, excitation light beyond the critical light is completely reflected. The evanescence of the light field at the refractive interface penetrates into the sample by about 100 nm, causing selective excitation of molecules and complexes adhered to this interface. TIRF microscopes are available with a choice of either through-objective excitation or prism excitation options.
In the prism-based method, the orientation of the sample is reversed with respect to the imaging objective. A light beam is introduced to the sample through a prism attached to the cover slip; the geometry of the prism ensures that the incidence angle at the sample is greater than the critical angle.

Depending on the type of experiment being performed, there are both advantages and disadvantages to each of the above methods. For example, the prism method limits physical access to the sample. As Lord explained, the Mullins Lab uses a Nikon microscope in the through-objective configuration with a very high numerical aperture (NA = 1.49) for several reasons. “For single-molecule studies, fluorescence signal strength is always a major challenge, particularly since we are following processes that need fast frame rates. So, we need a high-NA objective with a small working distance to maximize light collection efficiency. These objectives require a coverglass of precise thickness and the sample near the top of the coverslip to minimize aberrations.” Lord also stated that caution must be taken so the team does not introduce scattering and other losses due to viewing fluorescence through the bulk of the sample.

Multiple, simultaneous laser wavelengths

As has been noted, the mechanisms controlling the binding of regulatory proteins to actin filaments are quite complex. To better understand these processes, the Mullins Lab increasingly has been using sophisticated, multiwavelength TIRF-based experiments. In order to image multiple fluorophores, Lord explained, “We can use either multiple sequenced lasers or a scope equipped with multiple cameras — we have setups for both arrangements.” He continued, “Multiple excitation wavelengths that sequence at high rates enable us to selectively image multiple, differently labeled targets using a microscope equipped with a single high-sensitivity camera, and ensures near-perfect image registration.”

When using multiple lasers, the two technical challenges are to perfectly coalign the lasers into the microscope objective and then to be able to switch between different wavelengths. In order to follow fast binding processes in real time, researchers typically must switch wavelengths between alternate camera frames to build up pseudosimultaneous (i.e., interleaved) videos at two or sometimes three laser wavelengths. This switching must be performed with no undesirable dead time (i.e., shifts in the beam path) and without using mechanical shutters or a complex and costly approach, such as an acousto-optic tunable filter.

Lord notes, “As recently as five years ago, we simply didn’t have low-cost options to conduct single molecule studies using multiple laser wavelengths pseudosimultaneously at the requisite frame rates (30 fps) in order to follow critical binding processes.” He added, “Digitally controllable diode or solid-state lasers, hardware sequencing electronics and quad-band optical filters make it possible to achieve nearly simultaneous multicolor imaging with a single camera.”

In 2014, the lab acquired several digitally modulatable smart lasers to enable multiwavelength TIRF microscopy. These lasers included Coherent’s fiber-pigtailed OBIS FP modules that operate at 488, 561 and 640 nm. The lab also acquired the OBIS Galaxy, which enables simple plug-and-play combining of up to eight fiber-coupled lasers into one, single-mode output fiber. As was detailed by Coherent’s Dan Callen and Matthias Schulze in BioPhotonics’ November 2014 issue (“Laser Combiner Enables Scanning Fluorescence Endoscopy,” www.photonics.com/A56915), this passive module enables lasers to be added or subtracted (i.e., hot-swapped) to any fiber-coupled instrument or setup in a few minutes or less via standard fiber connectors, such as FC/UFC and FC/APC connectors.

Figure 2. The OBIS Galaxy (shown with the top cover removed) allows plug-and-play combining of up to eight separate fiber coupled lasers into a single output fiber. Courtesy of Sam Lord.
The timing hardware setup at the Mullins Lab is very simple in design due to the fact that these smart lasers support direct digital modulation. In each experiment, the frame rate is set by the microscope’s high-sensitivity camera, which is an Andor DU897. The camera’s TTL output trigger pulses are processed in either a programmable Arduino board or an ESio controller, which then directs TTL pulses to fire one of the three lasers without any hardware or software delays. Alternating wavelengths typically are used in most experiments, although any sequence of wavelength frames easily can be programed using the Arduino and Micro-Manager software.¹

According to Lord, the flexibility of this arrangement supports future experimental setups that have even greater levels of complexity. In particular, he added, “We may well add a 405-nm laser option in the near future. If/when this arrives, we can simply plug it in and we are ready to go.”

Investigating modulation of actin binding processes

In the team’s work on the binding of actin filaments, this flexible TIRF setup enables the Mullins Lab to conduct experiments with several different approaches. For example, in typical two-wavelength experiments, the actin filament is labeled with one fluorophore, and the protein of interest is labeled with another fluorophore. The protein fluorophore only appears in the TIRF-produced images if/when it binds to the actin sitting on the cover slip. One use of the third wavelength is to image a second protein, which is labeled with a different fluorophore. The image sequences then may reveal, for example, whether the proteins are interspersed at different sites on the filament, or whether the second protein promotes filament growth or branching from a new site. Or, it may reveal that the second protein competitively displaces the first.

In a recently published study,² Mullins Lab researchers used their multilaser TIRF setup to investigate the details of control mechanisms associated with the binding of tropomyosins to actin filaments. Tropomyosins are coiled-coil proteins whose known functions are to bind actin filaments and thereby regulate multiple cytoskeletal functions — including actin network dynamics near the leading edge of motile cells.

Mullins explained, “The binding of tropomyosins to actin filaments is known to be fundamentally important in actin dynamics. But, we do not yet fully understand how this binding is regulated, especially near the leading edge of migrating cells. Why, for example, are filaments in the lamellum coated with tropomyosin while filaments in the adjacent lamellipod are not?” (Lamellum and lamellipod are distinct, actin-based substructures involved in cell migration.) He went on to state that, prior to his team’s latest studies, previous research demonstrated that tropomyosins inhibit actin nucleation by the Arp2/3 protein complex and that this, in turn, prevented filament severing by the protein cofilin.^3,4 “So, we have recently used TIRF and other methods to investigate if and how the Arp2/3 complex and cofilin in turn modulate the binding of tropomyosins to actin filaments,” he said.

Figure 3. TIRF images showing Tm1A binding preferentially to the pointed end of single actin filaments. The red signal is from Cy5 labeled Tm1A fluorescence excited at 640 nm, and the green signal is due to Alexa 488 labeled actin excited at 488 nm. Courtesy of J.Y. Hsiao, L.M. Goins, N.A. Petek, R.D. Mullins.
The team members studied these interactions in the specific case of nonmuscle Drosophila tropomyosin protein, Tm1A. They also compared some of these interactions in Tm1A to the same interactions in rabbit skeletal muscle tropomyosin, as other researchers previously have found that mammalian skeletal muscle tropomyosin is the least-effective Arp2/3 inhibitor.²

Data from dual-wavelength excitation produced by TIRF microscopy methodology when applied to single filaments is shown in Figure 3. This information shows that Tm1A preferentially binds near the pointed end of actin filaments. By comparing similar data that resulted from different experimental conditions, the researchers showed that pointed-end binding is dependent on the nucleotide state of the actin and the Tm1A concentration.

Although a complete evaluation of all of the research’s results, conclusions and wider implications falls outside the scope of this article, Mullins does summarize some of the key points. “Binding of cyto-skeletal tropomyosin to actin filaments turns out to be more complicated than previously appreciated. Both nucleation and spreading of tropomyosin are strongly influenced by the conformation of the actin filament and the presence of other regulatory proteins.” Mullins added that, based on TIRF-produced images and other collected data, “We have been able to propose a model where the cooperation of the severing activity of cofilin and tropomyosin binding helps establish the border between the lamellipod and lamellum.” The role of cofilin in the model referenced by Mullin is shown in Figure 4.

Figure 4. These images summarize the role of cofilin in the model proposed by Hsaio et al. [ref]. The branched actin network on the left shows the situation in the absence of cofilin, where tropomyosin binding is blocked by Arp2/3 branches. The branched actin network on the right illustrates that in the presence of cofilin, new pointed ends are created, which allows tropomyosin to bind. Once tropomyosin is bound, it protects the actin filaments from further cofilin severing, possibly resulting in the transition from the lamellipod to the lamellum. Courtesy of J.Y. Hsiao, L.M. Goins, N.A. Petek, R.D. Mullins.
In summation, TIRF microscopy is a well-established technique for imaging single molecular structures and protein complexes. This method also enables their respective dynamics to be observed in real time. By providing a method to rapidly switch between two or more excitation wavelengths, the latest lasers and laser-combining technologies are now enabling researchers to perform TIRF microscopy experiments with a greater number of separate labels. This capability is delivering unique insights into important and multifaceted processes in the study of cell biology.

Meet the author

Dan Callen is a product manager at Coherent Inc. in Santa Clara, Calif.; email: daniel.callen@coherent.com.

References

1. A.D. Edelstein et al. (2014). Advanced methods of microscope control using μManager software. J Biol Methods, Vol. 1, No. 2, e10.

2. J.Y. Hsiao et al. (2015). Arp2/3 complex and cofilin modulate binding of tropomyosin to branched actin networks. Curr Biol, pp. 1-10.

3. L. Blanchoin et al. (2001). Inhibition of the Arp2/3 complex-nucleated actin polymerization and branch formation by tropomyosin. Curr Biol, Vol. 11, No. 16, pp. 1300-1304.

4. J.H. Iwasa and R.D. Mullins (2007). Spatial and temporal relationships between actin-filament nucleation, capping and disassembly. Curr Biol, Vol. 17, No. 5, pp. 395-406.

18. Using QCLs for MIR-Based Spectral Imaging — Applications in Tissue Pathology

http://www.photonics.com/Article.aspx?PID=1&AID=57708

A quantum cascade laser (QCL) microscope allows for fast data acquisition, real-time chemical imaging and the ability to collect only spectral frequencies of interest. Due to their high-quality, highly tunable illumination characteristics and excellent signal-to-noise performance, QCLs are paving the way for the next generation of mid-infrared (MIR) imaging methodologies.

MICHAEL WALSH, UNIVERSITY OF ILLINOIS AT CHICAGO; MATTHEW BARRE & BENJAMIN BIRD, DAYLIGHT SOLUTIONS

H. Sreedhar^*1, V. Varma^*2, A. Graham³, Z. Richards¹, F. Gambacorata⁴, A. Bhatt¹,
P. Nguyen¹, K. Meinke¹, L. Nonn¹, G. Guzman¹, E. Fotheringham⁵, M. Weida⁵,
D. Arnone⁵, B. Mohar⁵, J. Rowlette⁵
Real-time, MIR chemical imaging microscopes could soon become powerful frontline screening tools for practicing pathologists. The ability to see differences in the biochemical makeup across a tissue sample greatly enhances a practioner’s ability to detect early stages of disease or disease variants. Today, this is accomplished much as it was 100 years ago — through the use of specially formulated stains and dyes in combination with white light microscopy. A new MIR, QCL-based microscope from Daylight Solutions enables real-time, nondestructive biochemical imaging of tissues without the need to perturb the sample with chemical or heat treatments, thus preserving the sample for follow-on fluorescence tagging, histochemical staining or other “omics” testing within the workflow.
MIR chemical imaging is a well-established absorbance spectroscopy technique; it senses the relative amount of light that molecules absorb due to their unique vibrational resonances falling within the MIR portion of the electromagnetic spectrum (i.e., wavelengths from approximately 2 to 15 µm). This absorption can be detected with a variety of MIR detector types and can provide detailed information about the sample’s chemical composition.

The most common instrument for this type of measurement is known as a Fourier transform infrared (FTIR) spectrometer. FTIR systems use a broadband MIR light source, known as a globar, to illuminate a sample; the absorption spectrum is generated by the use of interferometry. Throughout the past decade, FTIR systems have incorporated linear arrays and 2D focal plane arrays (FPAs) in a microscope configuration to enable a technique known as chemical imaging.

19. Inner Ear Undertakers

Support cells in the inner ear respond differently to two drugs that kill hair cells.

By Kerry Grens | September 1, 2015

http://www.the-scientist.com//?articles.view/articleNo/43824/title/Inner-Ear-Undertakers/

The paper
E.L. Monzack et al., “Live imaging the phagocytic activity of inner ear supporting cells in response to hair cell death,” Cell Death Differ, doi:10.1038/cdd.2015.48, 2015.

Killer drugs
A number of commonly used medications can cause hearing loss by killing off cochlear hair cells, which translate sound waves into neural activity. To understand how they die, Lisa Cunningham and Elyssa Monzack of the National Institute on Deafness and Other Communication Disorders and colleagues turned to the utricle, a vestibular inner-ear structure involved with balance whose hair cells are very similar to those in the cochlea, which are notoriously resistant to culturing when mature.

Body bags
The team developed a method to watch hair cells of whole mouse utricles die in real time after exposure to the chemotherapy drug cisplatin or the antibiotic neomycin. In response to the latter, supporting cells, glia-like neighbors of hair cells, appeared to form a phagosome around the corpses and engulf them. “You can see two, three, sometimes four supporting cells advancing simultaneously on that hair cell corpse,” says Cunningham—which suggests that the dying cell is giving off a specific and local signal.

Spilled guts
In contrast, cisplatin-induced hair cell death provoked hardly any phagocytic reaction from supporting cells, about half of which themselves succumbed. Cunningham says this could have clinical implications if dead hair cells then spill their cytoplasmic contents into the tissue, which can result in an immune response that can cause even further damage.

Distress call
Mark Warchol of Washington University in St. Louis says it will be important to identify the signal supporting cells are responding to after neomycin treatment. “There’s some molecular signal by which the hair cell causes [supporting cells] to execute this process. And with cisplatin, they’re just not capable of doing it.”

Pancreatic Cancer and Crossing Roads of Metabolism

Posted in Best evidence, Biomarkers & Medical Diagnostics, Calcium Signaling, Calmodulin Kinase and Contraction, Cancer and Current Therapeutics, CANCER BIOLOGY & Innovations in Cancer Therapy, Cancer Prevention: Research & Programs, Cancer Screening, Cell Biology, Signaling & Cell Circuits, Diabetes Mellitus, Diagnostic Immunology, Disease Biology, Drug Delivery Platform Technology, Gene Regulation, Gene Regulation and Evolution, Genetics & Innovations in Treatment, Genetics & Pharmaceutical, Genome Biology, Genomic Testing: Methodology for Diagnosis, Immunodiagnostics, Metabolism, Molecular Genetics & Pharmaceutical, Personal Health Applications: Tech Innovations serves HealhCare, Personalized and Precision Medicine & Genomic Research, Pharmaceutical Drug Discovery, Translational Research, Translational Science, tagged anti-cancer therapy, chemokines, D. Sag, Demet Sag, Diabetes, Dm, DM1, DM2, Dr. Demet Sag, Dr. Sag, Functional TransGenomics, GPCR, IL17, immunotheraphy, iNKT, NK, NKT, Pancreas, Pancreatic cancer, pregnancy, TM1, TM2 on March 18, 2015| Leave a Comment »

Pancreatic Cancer and Crossing Roads of Metabolism

Curator: Demet Sag, PhD

PART I: Pancreatic Cancer

Intro
What is Pancreas cancer
What are the current and possible applications for treatment and early diagnosis
How pancreatic cancer is related to obesity, overweight, BMI, diabetes
Genetics of Pancreatic Cancer

PART II : Translational Research on Molecular Genetics Studies at Immune Response Mechanism

Natural Killer Cells
IL-17
Chemokines

search_result- pancreatic cancer clinical trial studies

https://clinicaltrials.gov/ct2/results?term=Pancreatic+Cancer&Search=Search pc 1

PART I: Pancreatic Cancer

Introduction:

Our body works a s a system even during complex diseases that is sometimes forgotten. From nutrition to basic immune responses since we are born we start to change how we respond and push the envelope to keep hemostasis in our body.

During this time additional factors also increase or decrease the rate of changes such as life style, environment, inherited as well acquired genetic make-up, types of infections, weight and stress only some of them. As a result we customized our body so deserve a personalized medicine for a treatment. Customized approach is its hype with developing technology to analyze data and compare functional genomics of individuals.

However, still we need the basic cell differentiation to solve the puzzle to respond well and connect the dots for physiological problems. At the stem of the changes there is a cell that respond and amplify its reaction to gain a support to defend at its best . Thus, in this review I like to make a possible connection for pancreatic cancer, obesity-diabetes and innate immune response through natural killer cells.

Pancreatic cancer is one of the most lethal malignancies. Pancreatic cancer is one of the most difficult cancers to treat. Fewer than 5% of patients survive more than 5 years after diagnosis. The 5-year survival rate is despite therapeutic improvements still only 6%. More than 80% of the pancreatic tumors are classified as pancreatic ductal adenocarcinoma (PDA).

When cells in the pancreas that secrete digestive enzymes (acinar cells) turn into duct-like structures, pancreatic cancer can develop. Oncogenic signaling – that which causes the development of tumors – can influence these duct-like cells to form lesions that are a cancer risk.

Crossing roads

The recent publication brought up the necessity to understand how pancreatic cancer and IL17 are connected.

Schematic diagram showing the central role of IL-17B–IL-17RB signaling in pancreatic cancer metastasis.

Adapted from an illustration by Heng-Hsiung Wu and colleagues

http://jem.rupress.org/content/212/3/284/F2.large.jpg

Simply, obesity and diabetes increases the risks of cancers, cardiovascular disease, hypertension, and type-2 DM. There is a very big public health concern as obesity epidemic, the incidence of diabetes is increasing globally, with an estimated 285 million people, or 6.6% of the population from 20 to 79 years of age, affected this is especially more alarming as child obesity is on the rise.

According to a World Health Organization (WHO) report showing that 400 million people are obese in the world, with a predicted increase to 700 million by 2015 and in the US, 30–35 percent of adults are obese. In addition, high BMI and increased risk of many common cancers, such as liver, endometrium, breast, pancreas, and colorectal cancers have a linear increasing relationship.

The BMI is calculated by dividing body weight in kilograms by height squared in meters kg/m²). The current standard categories of BMI are as follows: underweight, <18.5; normal weight, 18.5–24.9; overweight, 25.0–29.9; obese, 30.0–34.9; and severely obese, > or = 35.0).

Furthermore, natural killer cells not only control innate immune responses but have function in other immune responses that was not recognized well before.

Recently, there have been reports regarding Natural Killer cells on was about the function of IL17 that is produced by iNKT, a subtype of NK, for a possible drug target. In addition, regulation of receptors that are up or downregulated by NK cells for a precise determination between compromised cells and healthy cells.

Therefore, instead of sole reliance on SNPs, or GWAS for early diagnostics or only organ system base pathology, compiling the overall health of the system is necessary for a proper molecular diagnostics and targeted therapies.

What is Pancreas cancer

SNAP SHOT:

Incidence

It is a rare type of cancer.
20K to 200K US cases per year

Medically manageable

Treatment can help

Requires a medical diagnosis

lab tests or imaging
spreads rapidly and has a poor prognosis.
treatments may include: removing the pancreas, radiation, and chemotherapy.

Ages affected; even though person may develop this cancer from age 0 to 60+ there is a high rate of incidence after age 40.

People may experience:

Pain: in the abdomen or middle back
Whole body: nausea, fatigue, or loss of appetite
Also common: yellow skin and eyes, fluid in the abdomen, weight loss, or dark urine
The pancreas secretes enzymes that aid digestion and hormones that help regulate the metabolism of sugars.

Prescription

Chemotherapy regimen by injection: Irinotecan, Gemcitabine (Gemzar), Oxaliplatin (Eloxatin)
Other treatments: Leucovorin by injection, Fluorouracil by injection (Adrucil)

Also common

Chemotherapy regimen: Gemcitabine-Oxaliplatin regimen, Docetaxel-Gemcitabine regimen
Procedures: Radiation therapy, Pancreatectomy, surgery to remove pancreatic tumors

Specialists

Radiologist: Uses images to diagnose and treat disease within the body.
Oncologist: Specializes in cancer.
Palliative medicine: Focuses on improving quality of life for terminally ill patients.
General surgeon: Performs a range of surgeries on the abdomen, skin, breast, and soft tissue.
Gastroenterologist: Focuses on the digestive system and its disorders.

What are the current and possible applications for treatment and early diagnosis

Diagnostics

Several imaging techniques are employed in order to see if cancer exists and to find out how far it has spread. Common imaging tests include:

Ultrasound – to visualize tumor
Endoscopic ultrasound (EUS) – thin tube with a camera and light on one end
Abdominal computerized tomography (CT) scans – to visualize tumor
Endoscopic retrograde cholangiopancreatography (ERCP) – to x-ray the common bile duct
Angiogram – to x-ray blood vessels
Barium swallows to x-ray the upper gastrointestinal tract
Magnetic resonance imaging (MRI) – to visualize tumor
Positron emission tomography (PET) scans – useful to detect if disease has spread

New solutions in Diagnostics;

The study, published in Nature Communications, suggests that targeting the gene in question – protein kinase D1 (PKD1) – could lead to new ways of halting the development of one of the most difficult tumors to treat.

“As soon as pancreatic cancer develops, it begins to spread, and PKD1 is key to both processes. Given this finding, we are busy developing a PKD1 inhibitor that we can test further,” says the study’s co-lead investigator, Dr. Peter Storz.

Do we have new markers?

Is it possible check the cancer along with glucose levels or insulin at the point of care or companion diagnostics?

Therapy

New Solutions in Therapies

ABRAXANE (paclitaxel formulated as albumin bound nanoparticles; nab-paclitaxel), in combination with gemcitabine, has been recommended for use within NHS Scotland by the Scottish Medicines Consortium (SMC) for the treatment of metastatic adenocarcinoma of the pancreas.

The SMC decision is based on results from the MPACT (Metastatic Pancreatic Adenocarcinoma Clinical Trial) study, published in the October 2013 edition of the New England Journal of Medicine, which demonstrated an increase in median overall survival of 1.8 months when compared to gemcitabine alone [(8.5 months vs. 6.7 months respectively) (HR 0.72; 95% CI 0.62 to 0.83 P<0.001)].

Updated results from post-hoc analysis of the MPACT trial based on an extended data cut-off (8 months) at the time the trial was closed demonstrated an increase in the median overall survival benefit of 2.1 months when compared to gemcitabine alone [(8.7 months vs. 6.6 months respectively) (HR 0.72,95% CI = 0.62 to 0.83, P<.001)].

Using radioactive bacteria to stop the spread of pancreatic cancer – scientists from Albert Einstein College of Medicine of Yeshiva University used bacteria to carry radioisotopes commonly used in cancer treatment directly into pancreatic cancer cells. They found in animal experiments that the incidence of secondary tumors went down dramatically – i.e. the cancer was much less likely to spread (metastasize).

Targeting stroma is another approached that is followed by TGen to potentially extend patient survival in all cases including advanced cases based on a report at Clinical Cancer Research, published online by the American Association for Cancer Research. Thus this eliminates one of the limiting factor to reach tumor cells and destroying the accumulation of stroma — the supporting connective tissue that includes hyaluronan and few other collagen types.

One of the study leaders, Andrew Biankin, a Cancer Research UK scientist at the University of Glasgow in the UK said that “Being able to identify which patients would benefit from platinum-based treatments would be a game-changing moment for treating pancreatic cancer, potentially improving survival for a group of patients.”

In the journal Nature, the international team- including scientists from Cancer Research UK showed the evidence of large chunks of DNA being shuffled around, which they were able to classify according to the type of disruption they created in chromosomes.

The study concludes there are four subtypes of pancreatic cancer, depending on the frequency, location and types of DNA rearrangement. It terms the subtypes: stable, locally rearranged, scattered and unstable.

Can we develop an immunotherapy?

Genetics of Pancreatic Cancer

There are many ongoing studies to develop diagnostics technologies and treatments. However, the etiology of PC is not well understood. Pancreas has dual functions that include 2% of endocrine hormone secretion and 98% exocrine secretion, enzymes, to help digestion. As a result, pancreatic cancer is related to obesity, overweight, diabetes.

First, eliminating the risk factors can be the simplest path. Next approach is dropping the obesity and diabetes to prevent the occurrence of cancers since in the U.S. population, 50 percent are overweight, 30 percent are medically obese and 10 percent have diabetes mellitus (DM). Tobacco smoking, alcohol consumptions, chronic pancreatitis, and genetic risk factors, have been recognized as potential risk factors for the development and progression of PC.

Many studies showed that the administration of anti-diabetic drugs such as metformin and thiazolidinediones (TZD) class of PPAR-γ agonists decreases the risk of cancers. Thus, these agents are thought to be the target to diagnose or cure PC.

Type 2 diabetes mellitus has been associated with an increased risk of several human cancers, such as liver, pancreatic, endometrial, colorectal, breast, and bladder cancer. The majority of the data show that metformin therapy decreases, while insulin secretagog drugs slightly increase the risk of certain types of cancers in type 2 diabetes.

Metformin can decrease cell proliferation and induce apoptosis in certain cancer cell lines. Endogenous and exogenous (therapy induced) hyperinsulinemia may be mitogenic and may increase the risk of cancer in type 2 diabetes. Type 2 diabetes mellitus accounts for more than 95% of the cases.

In PDA these cells have been reported to express specific genes such as Aldh1 or CD133. To date, more than 20 case-control studies and cohort and nested case-control studies with information on the association between diabetes and pancreatic cancer, BMI and cancer, and obesity and cancer have been reported.

Meta analysis and cohort studies:

Meta studies for Diabetes and PC

Most of the diabetes and PC studies were included in two meta-analyses, in 1995 and in 2005, investigating the risk of pancreatic cancer in relation to diabetes.

The first meta-analysis, conducted in 1995, included 20 of these 40 published case-control and cohort studies and reported an overall estimated relative risk (RR) of pancreatic cancer of 2.1 with a 95% confidence interval (CI) of 1.6-2.8. These values were relatively unchanged when the analyses were restricted to patients who had diabetes for at least 5 years (RR, 2.0 [95% CI, 1.2-3.2]).

The second meta-analysis, which was conducted in 2005, included 17 case-control and 19 cohort and nested case-control studies published from 1996 to 2005 and demonstrated an overall odds ratio (OR) for pancreatic cancer of 1.8 and 95% CI of 1.7-1.9 . Individuals diagnosed with diabetes within 4 years before their pancreatic cancer diagnosis had a 50% greater risk of pancreatic cancer than did those diagnosed with diabetes more than 5 years before their cancer diagnosis (OR, 2.1 [95% CI, 1.9-2.3] versus OR, 1.5 [95% CI, 1.3-1.8]; P = 0.005).

In a recent pooled analysis of 2192 patients with pancreatic cancer and 5113 cancer-free controls in three large case-control studies conducted in the United States (results of two of the three studies were published after 2005),
Risk estimates decreased as the number of years with diabetes increased.
Individuals with diabetes for 2 or fewer, 3-5, 6-10, 11-15, or more than 15 years had ORs (95% CIs) of 2.9 (2.1-3.9), 1.9 (1.3-2.6), 1.6 (1.2-2.3), 1.3 (0.9-2.0), and 1.4 (1.0-2.0), respectively (P < 0.0001 for trend).

Meta Studies between BMI and PC

Meta studies in 2003 and 2008 showed a week positive association between BMI and PC. In 2003, a meta-analysis of six case-control and eight prospective studies including 6,391 PC cases 2% increase in risk per 1 kg/m² increase in BMI. In 2008, 221 datasets, including 282,137 incidence of cancer cases with 3,338,001 subjects the results were similar RR, 1.12; CI, 1.02–1.22.

In 2007, 21 prospective studies handled , 10 were from the United States, 9 were from Europe, and 2 were from Asia and studies was conducted including 3,495,981 individuals and 8,062 PC cases. There was no significant difference between men and women and the estimated summary risk ratio (RR) per 5 kg/m² increase in BMI was 1.12 (95% CI, 1.06–1.17) in men and women combined.

This study concluded that concluded that there was a positive association between BMI and risk of PC, per a 5 kg/m² increase in BMI may be equal to a 12% increased risk of PC.

The location and type of the obesity may also signal for a higher risk. The recent Women’s Health Initiative study in the United States among 138,503 postmenopausal showed that women central obesity in relation to PC (n=251) after average of 7.7 years of follow-up duration demonstrated that central adiposity is related to developing PC at a higher risk. Based on their result “women in the highest quintile of waist-to-hip ratio have a 70 percent (95% CI, 10–160%) greater risk of PC compared with women in the lowest quintile”
Age of obesity or being overweight versus risk of developing PC was also examined.

Regardless of their DM status they were at risk and decreased their survival even more so among men than women between age of 14-59.

overweight 14 to 39 years (highest odds ratio [OR], 1.67; 95% CI, 1.20–2.34) or

obese 20 to 49 years (highest OR, 2.58; 95% CI, 1.70–3.90) , independent of DM status.

This association was different between men and women from the ages of 14 to 59:

stronger in men (adjusted OR, 1.80; 95% CI, 1.45–2.23)

weaker in women (adjusted OR, 1.32; 95% CI, 1.02–1.70).

The effect of BMI , obesity and overweight had reduced overall survival of PC regardless of disease stage and tumor resection status

high BMI (= or > 25) 20 to 49 years , an earlier onset of PC by 2 to 6 years.

obese patients: hazard ratio, 1.86, 95% CI, 1.35–2.56).

overweight or obese 30 to 79 years, in the year prior to recruitment

overweight patients: hazard ratio, 1.26, 95% CI, 0.94–1.69;

Similarly, the authors concluded that:

Being overweight or obese during early adulthood was associated with a greater risk of PC and a younger age of disease onset, whereas obesity at an older age was associated with a lower overall survival in patients diagnosed with PC.
More recently, several large prospective cohort studies with a long duration of follow-up has been conducted in the U.S. showing a positive association between high BMI and the risk of PC (adjusted RR 1.13–1.54), suggesting the role of obesity and overweight with higher risk in the development and eventual death due to PC.
Although the role of smoking and gender in the association of obesity and PC is not clear, the new evidence strongly supports a positive association of high BMI with increased risk of PC, consistent with the majority of early findings; however, all recent studies strongly suggest that obesity and overweight are independent risk factor of PC.
Diabetes was associated with a 1.8-fold increase in risk of pancreatic cancer (95% CI, 1.5-2.1).

How pancreatic cancer is related to obesity, overweight, BMI, diabetes

Connections in Physiology and Pathology:

Altogether cumulative data suggest that DM has a three-fold increased risk for the development of PC and a two-fold risk for biliary cancer insulin resistance and abnormal glucose metabolism, even in the absence of diabetes, is associated with increased risk for the development of PC. Obesity alters the metabolism towards insulin resistance through affecting gene expression of inflammatory cytokines, adipose hormones such as adipokines, and PPAR-γ.

Furthermore, adiponectin also pointed out to be a negative link factor for cancers such as colon, breast, and PC. Therefore, insulin resistance is one of the earliest negative effects of obesity, early altered glucose metabolism, chronic inflammation, oxidative stress and decreased levels of adipose hormone adiponectin and PPAR-γ, key regulators for adipogenesis.

Potential pathways directly linking obesity and diabetes to pancreatic cancer. Obesity and diabetes cause mutiple alterations in glucose and lipid hemastasis, microenvironments, and immune responses, which result in the activation of several oncogenic signaling pathways.

These deregulations increase cell survival and proliferation, eventually leading to the development and progression of pancreatic cancer. ROS, reactive oxygen species; IGF-1, insulin-like growth factor-1; IR, insulin receptors; IGF-1R, insulin-like growth factor-1 receptors; TNFR, tumor necrosis factor receptors; TLR, Toll-like receptors; HIF-1α, hypoxia-inducible factor-α1; AMPK, AMP kinase; IKK, IκB kinase; PPAR-γ, peroxisome proliferator-activated receptor-γ; VEGF, vascular endothelial growth factor; MAPK, MAP kinase; mTOR, mammalian target of rapamycin; TSC, tuberous sclerosis complex; Akt, protein kinase B. PI3K, phosphoinositide-3-kinase; STAT3, activator of transcription-3; JNK, c-Jun NH2-terminal kinase.

Top six pathways interacting with obesity or diabetes in modifying the risk of pancreatic cancer are Chemokine Signaling, Pathways in cancer, Cytokine-cytokine receptor interaction, Calcium signaling pathway. MAPK signaling pathway.

This analysis showed

GNGT2,
RELA,
TIAM1,
CBLC,
IFNA13,
IL22RA1,
IL2RA
GNAS,
MAP2K7,
DAPK3,
EPAS1 and
FOS as contributor genes.

Furthermore, top overrepresented canonical pathways, including

Role of RIG1-like Receptors in Antiviral Innate Immunity,
Role of PI3K/AKT Signaling in the Pathogenesis of Influenza, and
Molecular Mechanisms of Cancer

in genes interacting with risk factors (P < 10⁻⁸) are

TRAF6,
RELA,
IFNA7,
IFNA4,
NFKB2,
IFNA10,
IFNA16,
NFKB1,
IFNA1/IFNA13,
IFNA5,
IFNA14,
IFNA,
GSK3B,
IFNA16,
IFNA14,
TP53,
FYN,
ARHGEF4,
GNAS,
CYCS ,
AXIN1,
ADCY4,
PRKAR2A,
ARHGEF1 ,
CDC42,
RAC,3
SIN3A,
RB1,
FOS ,
CDH1,
NFKBIA,
GNAT1,
PAK3,
RHOA,
RASGRP1,
PIK3CD,
BMP6,
CHEK2, and

KEGG code	Pathway description	Risk factor	No. of genes/genes with marginal effect^a	No. of SNPs/eigenSNPs in the interaction analysis^b	*P_{G x E}*^c	Major contributing genes^d
hsa04062^e	Chemokine Signaling^e	Obesity	175/27	695/181	3.29 × 10⁻⁶	GNGT2 RELA TIAM1
hsa05200	Pathways in cancer	Obesity	315/37	806/212	5.35 × 10⁻⁴	CBLC RELA
hsa04060	Cytokine-cytokine receptor interaction	Obesity	247/36	422/149	6.97 × 10⁻⁴	IFNA13 IL22RA1 IL2RA
hsa04020	Calcium signaling pathway	Diabetes	171/24	759/190	1.57 × 10⁻⁴	GNAS
hsa04010	MAPK signaling pathway	Diabetes	260/32	523/154	3.56 × 10⁻⁴	FOS MAP2K7
hsa05200	Pathways in cancer	Diabetes	315/37	806/212	4.46 × 10⁻⁴	DAPK3 EPAS1 FOS

^aNumber of genes making up the pathway/ number of genes survived the PCA-LRT (P ≤ 0.10).

^bNumber of SNPs in the “reconstructed” pathways/number of principal components for LRT.

^cP value was estimated by LRT in logistic regression model with adjustment of age, sex, study site, pack years(continuous), obesity or diabetes as appropriate, and five principal components for population structure.

^dGenes with P_{G x E} ≤ 0.05 in logistic regression and P ≤ 0.10 in PCA-LRT.

^ePathways remained significant after Bonferroni correction (P < 1.45 × 10⁻⁴)

Top overrepresented canonical pathways in genes interacting with risk factors (P < 10⁻⁸)

Biological process	Risk factor	P Value^a	Ratio^b	Contributing genes
Role of RIG1-like Receptors in Antiviral Innate Immunity	Obesity	6.71 × 10⁻¹¹	12/49 (0.25)	TRAF6 RELA IFNA7 IFNA4 NFKB2 IFNA10 IFNA16 NFKB1 IFNA1/IFNA13 IFNA5 IFNA14 IFNA6
Role of PI3K/AKT Signaling in the Pathogenesis of Influenza	Obesity	8.64 × 10⁻⁹	12/74 (0.12)	RELA IFNA7 IFNA4 NFKB2 GSK3B IFNA10 IFNA16 NFKB1 IFNA1/IFNA13 IFNA5 IFNA14 IFNA6
Molecular Mechanisms of Cancer	Diabetes	1.03 × 10⁻⁹	24/378 (0.063)	TP53 FYN ARHGEF4 GNAS CYCS AXIN1 ADCY4 PRKAR2A ARHGEF1 CDC42 RAC3 SIN3A RB1 FOS CDH1 NFKBIA GNAT1 PAK3 RHOA RASGRP1 PIK3CD BMP6 CHEK2 E2F2

^aCalculated using Fisher’s exact test (right-tailed).

^bNumber of genes interacting with a risk factor of interest (P ≤ 0.05) in a given pathway divided by total number of genes making up that pathway.

Pancreatic Cancer and Diabetes:

We conclude that diabetes type II has a fundamental influence on pancreatic ductal adenocarcinoma by stimulating cancer cell proliferation, while metformin inhibits cancer cell proliferation. Chronic inflammation had only a minor effect on the pathophysiology of an established adenocarcinoma.

Diabetes increases tumor size and proliferation of carcinoma cells
Diabetes does not decrease cell death in carcinomas
Diabetes II like syndrome reduces the number of Aldh1⁺cells within the tumor
Metformin decreases tumor size and proliferation of carcinoma cells

Much is known about factors increasing the likelihood to develop PDA. Identified risk factors include among others chronic pancreatitis, long lasting diabetes, and obesity. Patients with chronic and especially hereditary pancreatitis have a very high relative risk of developing pancreatic cancer of 13.3 and 69.0, respectively. Patients with diabetes and obesity have a moderately increased relative risk of 1.8 and 1.3. These studies indicate that a substantial number of patients with PDA also suffer from local inflammation or diabetes.

http://www.biomedcentral.com/1471-2407/15/51/figure/F3?highres=y

http://www.biomedcentral.com/content/figures/s12885-015-1047-x-4.jpg

Potential mechanisms underlying the associations of diabetes and cancer.

AdipoR1/R2, adiponectin receptor 1/2;
AMPK, 5′-AMPactivated protein kinase;
IGF-1, insulin-like growth factor-1;
IGF-1R, insulin-like growth factor-1 receptor;
IKK, IκA;B kinase; IR, insulin receptor;
IRS-1, insulin receptor substrate-1;
MAPK, mitogen-activated-protein-kinase;
mTOR, mammalian target of rapamycin;
NF-κA;B, nuclear factor-κA;B;
ObR, leptin receptor;
PAI-1, plasminogen activator inhibitor-1;
PI3-K, phosphatidylinositol 3-kinase;
ROS, Reactive oxygen species;
TNF-α, tumor necrosis factor- α;
TNF-R1, tumor necrosis factor-receptor 1;
uPA, urokinase-type plasminogen activator;
uPAR, urokinase-type plasminogen activator receptor;
VEGF, vascular endothelial growth factor;
VEGFR, vascular endothelial growth factor receptor.

http://www.ncbi.nlm.nih.gov/core/lw/2.0/html/tileshop_pmc/tileshop_pmc_inline.html?title=Click%20on%20image%20to%20zoom&p=PMC3&id=3238796_nihms-277874-f0001.jpg

Type 2 diabetes mellitus is likely the third modifiable risk factor for pancreatic cancer after cigarette smoking and obesity. The relationship between diabetes and pancreatic cancer is complex. Diabetes or impaired glucose tolerance is present in more than 2/3rd of pancreatic cancer patients.

Epidemiological investigations have found that long-term type 2 diabetes mellitus is associated with a 1.5-fold to 2.0-fold increase in the risk of pancreatic cancer. A causal relationship between diabetes and pancreatic cancer is also supported by findings from prediagnostic evaluations of glucose and insulin levels in prospective studies.

Insulin resistance and associated hyperglycemia, hyperinsulinemia, and inflammation have been suggested to be the underlying mechanisms contributing to development of diabetes-associated pancreatic cancer.

Stem Cells

http://www.ncbi.nlm.nih.gov/core/lw/2.0/html/tileshop_pmc/tileshop_pmc_inline.html?title=Click%20on%20image%20to%20zoom&p=PMC3&id=3410675_nihms295920f1.jpg

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3932318/

“A study by Permert et al.using glucose tolerance tests in patients with newly diagnosed pancreatic cancer showed that 75% of patients met criteria for diabetes. Pannala et al. used fasting blood glucose values or previous use of antidiabetic medications to define diabetes in patients with pancreatic cancer (N.=512) and age-matched control non-cancer subjects attending primary care clinics (N.=933) “

Distribution of fasting blood glucose among pancreatic cancer cases and controls. From Pannala et al.

“ They reported a nearly seven-fold higher prevalence of diabetes in pancreatic cancer patients compared to controls (47% vs. 7%). In a retrospective study using similar criteria, Chari et al. found the prevalence of diabetes in pancreatic cancer patients to be 40%. ^{http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3932318/}”

Relationship between type 2 diabetes and risk of pancreatic cancer in case-control and nested case control studies. “Diamond: point estimate representing study-specific relative risks or summary relative risks with 95% CIs. Horizontal lines: represent 95% confidence intervals (CIs). Test for heterogeneity among studies: P<0.001, I2=93.6%. 1, cohort studies (N.=27) use incidence or mortality rate as the measurements of relative risk; 2, cohort studies (N.=8) use standardized incidence/mortality rate as the measurement of relative risk. From Benet al.”

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3932318/

Table II

Sensitivity and specificity for biomarkers for pancreatic cancer.

Biomarker	Study	Sensitivity	Specificity	N.
CA19-9	Goonetilleke ⁶⁸	79	82	Meta-analysis
	Steinberg ⁶⁹	81	90	Meta-analysis
CA125	Duraker ⁸⁵	57	78	123
	Haguland ⁸⁶	45	76	95
CEA	Ni ⁸⁷	45	75	68
	Haglund ⁸⁶	54	76	95
	Zhao ⁸⁸	25	86	143
	Duraker ⁸⁵	39	91	123
SPan-1	Kiriyama ⁷⁴	81	76	64
	Chung ⁸⁹	92	83	67
	Kobayashi ⁹⁰	82	85	200
Du-PAN 2	Satake ⁸³	48	85	239
	Sawabu ⁹¹	72	94	32
	Kawa ⁹²	64	–	200

PART II: Targets for Immunomodulation to develop a therapy

Natural Killer Cells:

Natural Killer cells usually placed under non-specific immune response as a first defend mechanism during innate immunity. NKs responses to innate immune reactions but not only viruses but also bacteria and parasitic infections develop a new line of defense. These reactions involve amplification of many cytokines based on the specific infection or condition. Thus, these activities help NKs to evolve.

However, their functions proven to be more than innate immune response since from keeping the pregnancy term to prevent recurrent abortions to complex diseases such as cancer, diabetes and cardiovascular conditions they have roles thorough awakening chemokines and engaging them specifically with their receptors to activate other immune cells. For example, there is a signaling mechanism connection between NKs and DCs to respond attacks. Furthermore, there are interactions between various types of immune cells and they are specific for example between NK and Tregs.

During pregnancy there is a special kind of interaction between NK cells and Tregs.

There can be several reasons such as to protect pregnancy from the immunosuppressive environment so then the successful implantation of the embryo and tolerance of the mother to the embryo can be established. In normal pregnancy, these cells are not killers, but rather provide a microenvironment that is pregnancy compatible and supports healthy placentation.

During cancer development tumors want to build a microenvironment through an array of highly orchestrated immune elements to generate a new environment against the host. In normal pregnancy, decidua, the uterine endometrium, is critical for the development of placental vasculature.

This is the region gets thicks and thin during female cycles to prevent or accept pregnancies. As a result, mother nature created that 70% of all human decidual lymphocytes are NK cells, defined as uterine or decidual NK (dNK) cells.

The NK cell of decidua (dNK) and peripheral blood NK cells are different since dNK cells are characterized as CD56^brightCD16⁻CD3⁻, express killer cell immunoglobulin-like receptors and exhibit low killing capacity despite the presence of cytolytic granules, and a higher frequency of CD4⁺CD25^bright

The lesson learn here is that pregnancy and mammary tissue are great examples of controlling cellular differentiation and growth since after pregnancy all these cells go back to normal state.

Understanding these minute differences and relations to manipulate gene expression may help to:

Develop better biomaterials to design long lasting medical devices and to deliver vaccines without side effects.
Generate safer vaccines as NKcells are the secret weapons in DC vaccination and studying their behavior together with T-cell activation in vaccinated individuals might predict clinical outcome.
Establish immunotherapies based on interactions between NK cells and Tregs for complex diseases not only cancer, but also many more such as autoimmune disorder, transplants, cardiovascular, diabetes.

Trascription factors are the silence players of the gene expression that matches input to output as a cellular response either good or bad but this can be monitored and corrected with a proper meical device or diagnostics tool to provide successful treatment regimen.

Therefore, the effects of Tregs on NK during gene regulation analyzed and compared among other living organisms for concerved as well as signature sequence targets even though the study is on human.
Unfortunatelly we can’t mutate the human for experimental purposes so comparative developmental studies now its widely called stem cell biology with a system biology approach may help to establish the pathway.

NK and T reg regulation share a common interest called T box proteins. These proteins are conserved and also play role in development of heart at very early development, embryology. What is shared among all T-box is simply lie behind the capacity for DNA binding through the T-box domain and transcriptional regulatory activity, which plays a role in controlling the expression of developmental gene in all animal species.

The Special T box protein: T-bet

The first identified T-box protein was Brachyury (T). in a nut shell

The T-box domain is made up of about 180 amino-acid residues that includes a specific sequence of DNA
called T-box domain, TCACACCT between residues 135 and 326 in mouse.

However, T-bet which is the T-box protein expressed in T cells and also called as TBX21 is quite conserved in 18 members of the T-box protein (TBX) family
since it has a crucial dual role during development and for coordination of both innate and adaptive immune responses.

T-Bet was originally cloned for its role in Th1 lineage, it has a role in Th2 development, too.

The whole mechanism based on direct activation and modulation mechanisms in that T-Bet directly activates IFN-γ gene transcription and enhances development of Th1 cells at the same time modulates IL-2 and Th2 cytokines in an IFN-γ-independent manner that creates an attenuation of Th2 cell development.

Thus, certain lipids ligands or markers can be utilized during vaccine design to steer the responses for immune therapies against autoimmune diseases. As a result, tumors can be removed and defeated by manipulating NKs action.

INKT:

NKT has functions in diabetes, asthma. One cell type that has been proposed to contribute immensely to the development of asthma is NKT cells, which constitute a small population of lymphocytes that express markers of both T cells (T-cell receptor, TCR) and NK cells (e.g., NK1.1, NKG2D). NKT cells can be subdivided into at least three subtypes, based on their TCR. Type I NKT cells or invariant NKT (iNKT) cells express invariant TCR chains (V14–J18 in mice and V24–J18 in humans) coupled with a limited repertoire of V chains (V8, V7 and V2 in mice and V11 in humans).

The studies in the past decade showed the protective mechanism of NKT cells during the development of Type 1 diabetes can be complex.

First, NKT cells can impair the differentiation of anti-islet reactive T cells into Th1 effector cells in a cell–cell contact dependent manner, which did not require Th2 cytokine production or CD1d recognition.
Second, NKT cells accumulating in the pancreas can indirectly suppress diabetogenic CD4⁺T cells via IFN-γ production.
Last, anergic iNKT cells induced by protracted αGalCer stimulation can induce the production of noninflammatory DCs, which inhibit diabetes development in an Ag-specific fashion.

These findings point to an important protective role for NKT cells during autoimmune pathogenesis in the pancreas.

A crucial role has been suggested for invariant natural killer T cells (iNKT) in regulating the development of asthma, a complex and heterogeneous disease characterized by airway inflammation and airway hyperreactivity (AHR).

iNKT cells constitute a unique subset of T cells responding to endogenous and exogenous lipid antigens, rapidly secreting a large amount of cytokines, which amplify both innate and adaptive immunity.

IL17:

Terashima A et al (2008) identified a novel subset of natural killer T (NKT) cells that expresses the interleukin 17 receptor B (IL-17RB) for IL-25 (also known as IL-17E) and is essential for the induction of Airway hypersensitive reaction (AHR). IL-17RB is preferentially expressed on a fraction of CD4(+) NKT cells but not on other splenic leukocyte populations tested.

They strongly suggested that IL-17RB(+) CD4(+) NKT cells play a crucial role in the pathogenesis of asthma.

NKT connection can be established between through targeting IL17 and IL17RB. There is a functional specialization of interleukin-17 family members. Interleukin-17A (IL-17A) is the signature cytokine of the recently identified T helper 17 (Th17) cell subset. IL-17 has six family members (IL-17A to IL-17F).

Although IL-17A and IL-17F share the highest amino acid sequence homology, they perform distinct functions; IL-17A is involved in the development of autoimmunity, inflammation, and tumors, and also plays important roles in the host defenses against bacterial and fungal infections, whereas IL-17F is mainly involved in mucosal host defense mechanisms. IL-17E (IL-25) is an amplifier of Th2 immune responses.

There is no one easy answer for the role of IL-17 in pancreatic cancer as there are a number of unresolved issues and but it can be only suggested that pro-tumorigenic IL-17 activity is confined to specific subsets of patients with pancreatic cancer since there is a increased expression of IL-17RB in these patients about ∼40% of pancreatic cancers presented on their histochemical staining (IHC- immunohistochemistry.

IL17 and breast cancer:

In addition, during breast cancer there is an increased signaling of interleukin-17 receptor B (IL-17RB) and IL-17B. They promoted tumor formation in breast cancer cells in vivo and even created acinus formation in immortalized normal mammary epithelial cells in vitro cell culture assays.

Furthermore, the elevated expression of IL-17RB not only present itself stronger than HER2 for a better prognosis but also brings the shortest survival rate if patients have increased IL-17RB and HER2 levels.
However, decreased level of IL-17RB in trastuzumab-resistant breast cancer cells significantly reduced their tumor growth. This may prompt a different independent role for IL-17RB and HER2 in breast cancer development.
In addition, treatment with antibodies specifically against IL-17RB or IL-17B effectively attenuated tumorigenicity of breast cancer cells.

These results suggest that the amplified IL-17RB/IL-17B signaling pathways may serve as a therapeutic target for developing treatment to manage IL-17RB-associated breast cancer.

IL 17 and Asthma:

A requirement for iNKT cells has also been shown in a model of asthma induced with air pollution, ozone and induced with respiratory viruses chronic asthma studied in detail. In these studies specific types of NKT cells found to that specific types of NK and receptors trigger of asthma symptoms. Taken together, these studies indicate that both Th2 cells (necessary for allergen-specific responses) and iNKT cells producing IL-4 and IL-13 are required for the development of allergen-induced AHR.

Although CD4⁺ IL-4/IL-13-producing iNKT cells (in concert with antigen-specific Th2 cells) are crucial in allergen-induced AHR, NK1.1^–IL-17-producing iNKT cells have a major role in ozone-induced AHR.

A main question in iNKT cell biology involves the identification of lipid antigens that can activate iNKT cells since this allow to identify which microorganisms to attack as a result, the list of microorganisms that produce lipids that activate iNKT cells is rapidly growing.

Invariant natural killer T cells (iNKT) cell function in airway hyperreactivity (AHR). iNKT cells secrete various cytokines, including Th2 cytokines, which have direct effects on hematopoietic cells, airway smooth muscle cells, and goblet cells. Alternatively, iNKT cells could regulate other cell types that are known to be involved in asthma pathogenesis, e.g., neutrophils and alveolar macrophages.

http://www.nature.com/mi/journal/v2/n5/images/mi200996f1.jpg

Chemokines:

Chemokines have a crucial role in organogenesis of various organs including lymph nodes, arising from their key roles in stem cell migration. Moreover, most homeostatic chemokines can control the movement of lymphocytes and dendritic cells and eventually adaptive immunity. Chemokines are heparin-binding proteins with 4 cysteine residues in the conserved positions.

The human chemokine system has about 48 chemokines. They are subgrouped based on:

Number of cysteines
Number of amino acid separating cysteines
Presence or absence of ELR motif includes, 3-amino acid sequence, glutamic acid-leucine-arginine
functionally classified as inflammatory, homeostatic, or both, based on their expression patterns

Chemokines are structurally divided into 4 subgroups :CXC, CC, CX3C, and C. X represent an aminoacid so the first 2 cysteines are separated by 1 is grouped as CXC and 3 amino acids is called CX3C chemokines but in CC the first 2 cysteines are adjacent. In the C chemokines there is no second and fourth cysteines.

Various types of inflammatory stimuli induce abundantly the expression of inflammatory chemokines to induce the infiltration of inflammatory cells such as granulocytes and monocytes/macrophages.

inflammatory chemokines are CXC chemokines with ELR motif and CCL2.
homeostatic chemokines are expressed constitutively in specific tissues or cells.

Chemokines exert their biological activities by binding their corresponding receptors, which belong to G-protein coupled receptor (GPCR) with 7-span transmembrane portions. Thus, the target cell specificity of each chemokine is determined by the expression pattern of its cognate receptor .

Moreover, chemokines can bind to proteoglycans and glycosaminoglycans with a high avidity, because the carboxyl-terminal region is capable of binding heparin.

Consequently, most chemokines are produced as secretory proteins, but upon their secretion, they are immobilized on endothelium cells and/or in extracellular matrix by interacting with proteoglycans and glycosaminoglycans. The immobilization facilitates the generation of a concentration gradient, which is important for inducing the target cells to migrate in a directed way.

The human chemokine system.

Chemokine receptor	Chemokines	Receptor expression in
Chemokine receptor	Chemokines	Leukocytes	Epithelium	Endothelium
CXCR1	CXCL6, 8	PMN	+	−
CXCR2	CXCL1, 2, 3, 5, 6, 7, 8	PMN	+	+
CXCR3	CXCL4, 9, 10, 11	Th1, NK	−	+
CXCR4	CXCL12	Widespread	+	+
CXCR5	CXCL13	B	−	−
CXCR6	CXCL16	Activated T	+	−
CXCR7 (ACKR3)	CXCL12, CXCL11	Widespread	+	+
Unknown	CXCL14 (acts on monocytes)
CCR1	CCL3, 4, 5, 7, 14, 15, 16, 23	Mo, Mϕ, iDC, NK	+	+
CCR2	CCL2, 7, 8, 12, 13	Mo, Mϕ, iDC, NK activated T, B	+	+
CCR3	CCL5, 7, 11, 13, 15, 24, 26, 28	Eo, Ba, Th2	−	+
CCR4	CCL2, 3, 5, 17, 22	iDC, Th2, NK, T, Mϕ	−	−
CCR5	CCL3, 4, 5, 8	Mo, Mϕ, NK, Th1 activated T	+	−
CCR6	CCL20	iDC, activated T, B	+	−
CCR7	CCL19, 21	mDC, Mϕ, naïve T activated T	+	−
CCR8	CCL1, 4, 17	Mo, iDC, Th2, Treg	−	−
CCR9	CCL25	T	+	−
CCR10	CCL27, 28	Activated T, Treg	+	−
Unknown	CCL18 (acts on mDC and naïve T)
CX3CR1	CX3CL1	Mo, iDC, NK, Th1	+	−
XCR1	XCL1, 2	T, NK	−	−
Miscellaneous	Scavenger receptors for chemokines
Duffy antigen (ACKR1)	CCL2, 5, 11, 13, 14
	CXCL1, 2, 3, 7, 8
D6 (ACKR2)	CCL2, 3, 4, 5, 7, 8, 12
	CCL13, 14, 17, 22
CCRRL1 (ACKR4)	CCL19, CCL21, CCL25

Leukocyte anonyms are as follows. Ba: basophil, Eo: eosinophil, iDC: immature dendritic cell, mDC: mature dendritic cell, Mo: monocyte, Mϕ: macrophage, NK: natural killer cell, Th1: type I helper T cell, Th2: type II helper T cell, and Treg: regulatory T cell.

There are differences between human liver and peripheral NK cells. Regulation of NK cell functions by CD226, CD96 and TIGIT.close. CD226 binding to CD155 or CD112 at the cell surface of transformed or infected cells triggers cytotoxic granule exocytosis and target cell lysis by natural killer (NK) cells. TIGIT, CD226, CD96 and CRTAM ligand specificity and signalling.close.

Regulation of NK cell-mediated cancer immunosurveillance through CD155 expression.close. CD155 is frequently overexpressed by cancer cells.

pc10

	Liver NK cells	Circulating NK cells	References
CD3-CD56+	30.6% (11.6–51.3%)	12.8% (1–22%)	17
CD56^bright/total NK cell	~50%	~10%	¹⁸^,¹⁹
CD56^dim/total NK cell	~50%	~90%	¹⁸^,¹⁹
CD27	high	low	²⁰^,²¹
CD16	−	+	¹⁸^,²²
CD69	+/−, higher	+/−	¹⁶
Chemokine receptor	CCR7 and CXCR3 (CD56^bright)	CXCR1, CX3CR1 (CD56^dim)	¹³^,²³
Inhibitory receptor (NKG2A)	high	low	²⁴
Natural cytotoxicity	higher	high	¹⁸^,¹⁹
TRAIL	high	low	1
Perforin, Granzyme B	high	low	²
Cytokine production	high (MIP-1α/β, IL-10, TNF-α, TNF-β, IFN-γ, GM-CSF)	low (TNF-α, TNF-β, IFN-γ, GM-CSF, IL-10)	¹⁸
ADCC	–	high	²⁵

In conclusion, having to develop precise early diagnostics is about determining the overlapping genes as key among diabetes, obesity, overweight and pancreas functions even pregnancy can be suggested.

It seems feasible to develop an immunotherapy for pancreatic cancer with the focus on chemokines and primary signaling between iNKT and Tregs such as one of the recent plausable target IL-17 and IL17 RB.

References:

Heng-Hsiung Wu,^{1et al}Targeting IL-17B–IL-17RB signaling with an anti–IL-17RB antibody blocks pancreatic cancer metastasis by silencing multiple chemokines. Published March 2, 2015 // JEM vol. 212 no. 3 333-349

MUNIRAJ¹andS. T. CHARI²Minerva Gastroenterol Dietol. 2012 Dec; 58(4): 331–345.PMCID: PMC3932318

Beaudoin L. et al. NKT cells inhibit the onset of diabetes by impairing the development of pathogenic T cells specific for pancreatic β cells. Immunity. 2002;17:725–736.

Wang J, Cho S, Ueno A, et al. Ligand-dependent induction of noninflammatory dendritic cells by anergic invariant NKT cells minimizes autoimmune inflammation.J. Immunol. 2008;181:2438–2445.

Lee HH, Meyer EH, Goya S, et al. Apoptotic cells activate NKT cells through T cell Ig-like mucin-like-1 resulting in airway hyper-reactivity. J. Immunol.2010;185:5225–5235.

Huang CK¹, et al ⁶. Autocrine/paracrine mechanism of interleukin-17B receptor promotes breast tumorigenesis through NF-κB-mediated antiapoptotic pathway. Oncogene. 2014 Jun 5;33(23):2968-77.

Terashima A¹ et al A novel subset of mouse NKT cells bearing the IL-17 receptor B responds to IL-25 and contributes to airway hyperreactivity. J Exp Med. 2008 Nov 24;205(12):2727-33.

Isaksson B et al. Lifestyle factors and pancreatic cancer risk: a cohort study from the Swedish Twin Registry. Int J Cancer. 2002;98:480–482.

Larsson SC et al Overall obesity, abdominal adiposity, diabetes and cigarette smoking in relation to the risk of pancreatic cancer in two Swedish population-based cohorts. Br J Cancer.2005;93:1310–1315.

Michaud DS et al Physical activity, obesity, height, and the risk of pancreatic cancer. JAMA.2001;286:921–929.

Patel AV et al Obesity, recreational physical activity, and risk of pancreatic cancer in a large U.S. Cohort.Cancer Epidemiol Biomarkers Prev. 2005;14:459–466.

Rapp K et al Obesity and incidence of cancer: a large cohort study of over 145,000 adults in Austria. Br J Cancer. 2005;93:1062–1067.

Shibata A et al. A prospective study of pancreatic cancer in the elderly. Int J Cancer. 1994;58:46–49.

Howe GR, Jain M, Miller AB. Dietary factors and risk of pancreatic cancer: results of a Canadian population-based case-control study. Int J Cancer.1990;45:604–608.

Nilsen TI, Vatten LJ. A prospective study of lifestyle factors and the risk of pancreatic cancer in Nord-Trondelag, Norway. Cancer Causes Control.2000;11:645–652.

Zatonski W et al Nutritional factors and pancreatic cancer: a case-control study from south-west Poland. Int J Cancer. 1991;48:390–394.

Berrington de GA et al A meta-analysis of obesity and the risk of pancreatic cancer. Br J Cancer. 2003;89:519–523.

Larsson SC, Orsini N, Wolk A. Body mass index and pancreatic cancer risk: A meta-analysis of prospective studies. Int J Cancer. 2007;120:1993–1998.

Renehan AG et al Body-mass index and incidence of cancer: a systematic review and meta-analysis of prospective observational studies. Lancet. 2008;371:569–578.

Luo J et al Obesity and risk of pancreatic cancer among postmenopausal women: the Women’s Health Initiative (United States) Br J Cancer. 2008;99:527–531.

Li D et al Body mass index and risk, age of onset, and survival in patients with pancreatic cancer.JAMA. 2009;301:2553–2562.

Jiao L et al . Body mass index, effect modifiers, and risk of pancreatic cancer: a pooled study of seven prospective cohorts. Cancer Causes Control. 2010;21:1305–1314.

Johansen D et al Metabolic factors and the risk of pancreatic cancer: a prospective analysis of almost 580,000 men and women in the Metabolic Syndrome and Cancer Project. Cancer Epidemiol Biomarkers Prev. 2010;19:2307–2317.

Godsland IF. Insulin resistance and hyperinsulinaemia in the development and progression of cancer. Clin Sci (Lond) 2010;118:315–332. Kahn BB, Flier JS. Obesity and insulin resistance. J Clin Invest. 2000;106:473–481.

Pisani P. Hyper-insulinaemia and cancer, meta-analyses of epidemiological studies. Arch Physiol Biochem. 2008;114:63–70.

Jazet IM, Pijl H, Meinders AE. Adipose tissue as an endocrine organ: impact on insulin resistance. Neth J Med. 2003;61:194–212.

Kahn SE, Hull RL, Utzschneider KM. Mechanisms linking obesity to insulin resistance and type 2 diabetes. Nature. 2006;444:840–846.

Shoelson et al Obesity related hyperinsulinaemia and hyperglycaemia and cancer development. Arch Physiol Biochem. 2009;115:86–96.

Boyd DB. Insulin and cancer. Integr Cancer Ther. 2003;2:315–329.

Fisher WE, Boros LG, Schirmer WJ. Insulin promotes pancreatic cancer: evidence for endocrine influence on exocrine pancreatic tumors. J Surg Res.1996;63:310–313.

P Matangkasombut¹^,², et al Natural killer T cells and the regulation of asthma Mucosal Immunology (2009) 2, 383–392;

Tahir SM, Cheng O, Shaulov A, et al. Loss of IFN-γ production by invariant NK T cells in advanced cancer. J. Immunol. 2001;167:4046–4050.

Motohashi S, Kobayashi S, Ito T, et al. Preserved IFN-α production of circulating Vα24 NKT cells in primary lung cancer patients. Int. J. Cancer.2002;102:159–165.

Toura I, Kawano T, Akutsu Y, Nakayama T, Ochiai T, Taniguchi M. Cutting edge: inhibition of experimental tumor metastasis by dendritic cells pulsed with α-galactosylceramide. J. Immunol. 1999;163:2387–2391.

Chang DH, Osman K, Connolly J, et al. Sustained expansion of NKT cells and antigen-specific T cells after injection of α-galactosyl-ceramide loaded mature dendritic cells in cancer patients. J. Exp. Med. 2005;201:1503–1517.

Ambrosino E, Terabe M, Halder RC, et al. Cross-regulation between type I and type II NKT cells in regulating tumor immunity: a new immunoregulatory axis. J. Immunol. 2007;179:5126–5136. uncovered a new immunoregulatory axis where vNKT cells can inhibit the antitumor activity of iNKT cells and CD8⁺ T cells

Crowe NY, Coquet JM, Berzins SP, et al. Differential antitumor immunity mediated by NKT cell subsets in vivo. J. Exp. Med. 2005;202:1279–1288.

Novak J, Beaudoin L, Park S, et al. Prevention of Type 1 diabetes by invariant NKT cells is independent of peripheral CD1d expression. J. Immunol.2007;178:1332–1340.

Everhart J, Wright D. Diabetes mellitus as a risk factor for pancreatic cancer. A meta-analysis. JAMA. 1995;273:1605–9.

Huxley R et al Type-II diabetes and pancreatic cancer: a meta-analysis of 36 studies. Br J Cancer. 2005;92:2076–83.

Ben Q, Xu M, Ning X, Liu J, Hong S, Huang W, et al. Diabetes mellitus and risk of pancreatic cancer: A meta-analysis of cohort studies. Eur J Cancer.2011;47:1928–37.

Clinic, Mayo. “Mayo researchers identify gene that pushes normal pancreas cells to change shape.”Medical News Today. MediLexicon, Intl., 24 Feb. 2015. Web.10 Mar. 2015.

James D. Byrne et al Local iontophoretic administration of cytotoxic therapies to solid tumors

Sci Transl Med 4 February 2015: Vol. 7, Issue 273, p. 273ra14 Sci. Transl. Med. DOI: 10.1126/scitranslmed.3009951, published online 4 February 2015, abstract.

Mayo Clinic news release, accessed 20 February 2015 via Newswise.

Additional source: ACS, What are the key statistics about pancreatic cancer?, accessed 20 February 2015.

Additional source: ACS, What is pancreatic cancer?, accessed 20 February 2015.

Scottish Medicines Consortium. Treatment Assessment. February 2015

NHS England. Cancer Drugs Fund list Version 3. Available at http://www.england.nhs.uk/wp-content/uploads/2015/01/ncdf-list-dec14.pdf . Last accessed January 2015

NHS England. Cancer Drugs Fund: Albumin-bound paclitaxel decision summary. Available athttp://www.england.nhs.uk/wp-content/uploads/2015/01/ncdf-summ-albumin-pac.pdf. Accessed February 2015

Cancer Research UK. Pancreatic cancer key stats. Available athttp://www.cancerresearchuk.org/cancer-info/cancerstats/keyfacts/pancreatic-cancer/cancerstats-key-facts-on-pancreatic-cancer. Accessed February 2015

Cancer Research UK. Statistics and outlook for pancreatic cancer. Available athttp://www.cancerresearchuk.org/about-cancer/type/pancreatic-cancer/treatment/statistics-and-outlook-for-pancreatic-cancer Accessed February 2015

ISD Scotland. Cancer statistics: Pancreatic Cancer. Available at http://www.isdscotland.org/Health-Topics/Cancer/Cancer-Statistics/Pancreatic/ Accessed February 2015

Von Hoff DD, et al. Increased Survival in Pancreatic Cancer with nab-Paclitaxel plus Gemcitabine. N Engl J Med. 2013;369:1691 – 1703. Available at:http://www.nejm.org/doi/full/10.1056/NEJMoa1304369 Accessed February 2015

Goldstein D et al. nab-Paclitaxel plus gemcitabine for metastatic pancreatic cancer: long-term survival from a phase III trial. JNCI J Ntal Cancer Inst, 2015, 1-10. DOI: 10.1093/jnci/dju413. Accessed February 2015

The Translational Genomics Research Inst. “TGen study: Destroying tumor material that ‘cloaks’ cancer cells could benefit patients.” Medical News Today. MediLexicon, Intl., 27 Feb. 2015. Web. 10 Mar. 2015.

Mol Carcinog. 2012 Jan; 51(1): 64–74. doi: 10.1002/mc.20771

Mendonça FM¹, de Sousa FR¹, Barbosa AL¹, Martins SC¹, Araújo RL¹, Soares R², Abreu C¹. Metabolism. 2015 Metabolic syndrome and risk of cancer: which link? Feb;64(2):182-9.

Huang CK¹, et al Autocrine/paracrine mechanism of interleukin-17B receptor promotes breast tumorigenesis through NF-κB-mediated antiapoptotic pathway. Oncogene. 2014 Jun 5;33(23):2968-77.

Jiao L et al Dietary consumption of advanced glycation end products andpancreatic cancer in the prospective NIH-AARP Diet and Health Study.

Cancer. 2014 Dec 1;120(23):3669-75. doi: 10.1002/cncr.28863. Epub 2014 Oct 14. Clinical and pathologic features of familial pancreatic cancer.

The Rockefeller University Press, doi: 10.1084/jem.20141702 Cancer Lett. 2015 Jan 28;356(2 Pt A):281-8. doi: 10.1016/j.canlet.2014.03.028. Epub 2014 Apr 2.

Humphris JL¹, et al Australian Pancreatic Cancer Genome Initiative Br J Cancer. 2014 Nov 25;111(11):2180-6. doi: 10.1038/bjc.2014.525. Epub 2014 Oct 2.

Søreide K¹, Sund M². Epidemiological-molecular evidence of metabolic reprogramming on proliferation, autophagy and cell signaling in pancreas cancer. Am J Clin Nutr. 2015 Jan;101(1):126-34. doi: 10.3945/ajcn.114.098061. Epub 2014 Nov 19.

Lin CC¹, et al .Independent and joint effect of type 2 diabetes and gastric and hepatobiliary diseases on risk of pancreatic cancer risk: 10-year follow-up of population-based cohort.

Wang Z¹ et al Metformin is associated with reduced risk of pancreatic cancer in patients with type 2 diabetes mellitus: a systematic review and meta-analysis. Diabetes Res Clin Pract. 2014 Oct;106(1):19-26. doi: 10.1016/j.diabres.2014.04.007. Epub 2014 Apr 18.

Preziosi G¹, Oben JA², Fusai G³. Obesity and pancreatic cancer. Surg Oncol. 2014 Jun;23(2):61-71. doi: 10.1016/j.suronc.2014.02.003. Epub 2014 Mar 12.

Berger NA¹. Obesity and cancer pathogenesis. Ann N Y Acad Sci. 2014 Apr;1311:57-76. doi: 10.1111/nyas.12416.

De Souza AL¹, Saif MW. Diabetes and pancreatic cancer. JOP. 2014 Mar 10;15(2):118-20. doi: 10.6092/1590-8577/2286.

Timofte D et al Metabolic disorders in patients operated for pancreatic cancer. Rev Med Chir Soc Med Nat Iasi. 2014 Apr-Jun;118(2):392-8.

Lowenfels AB, Maisonneuve P. Epidemiologic and etiologic factors of pancreatic cancer. Hematol Oncol Clin North Am. 2002;16:1–16.

Lowenfels AB, Sullivan T, Fiorianti J, Maisonneuve P. The epidemiology and impact of pancreatic diseases in the United States. Curr Gastroenterol Rep.2005;7:90–95.

Michaud DS. Epidemiology of pancreatic cancer. Minerva Chir. 2004;59:99–111.

Schuster DP. Obesity and the Development of Type 2 Diabetes: the Effects of Fatty Tissue Inflamation. Dovepress; 2010. pp. 253–262.

WHO. World Health Organization Fact Sheet for World Wide Prevalence of Obesity. 2006. http://www.who.int/mediacentre/factsheets/fs311/en/index.html.

Chang S et al, State ranks of incident cancer burden due to overweight and obesity in the United States, 2003. Obesity (Silver Spring) 2008;16:1636–1650.

Lewis L. Lanie Evolutionary struggles between NK cells and viruses Nature Reviews Immunology 8, 259-268 (April 2008) | doi:10.1038/nri2276

Seth, S. et al. The murine pan T cell marker CD96 is an adhesion receptor for CD155 and nectin-1. Biochem. Biophys. Res. Commun. 364, 959–965 (2007).

de Andrade et al DNAM-1 control of natural killer cells functions through nectin and nectin-like proteins. Immunol. Cell Biol. 92, 237–244 (2014).

Orange, J. S. Formation and function of the lytic NK-cell immunological synapse. Nature Rev. Immunol. 8, 713–725 (2008).

Lagrue, K. et al. The central role of the cytoskeleton in mechanisms and functions of the NK cell immune synapse. Immunol. Rev. 256, 203–221 (2013).

Vyas, Y. M. et al. Spatial organization of signal transduction molecules in the NK cell immune synapses during MHC class I-regulated noncytolytic and cytolytic interactions. J. Immunol. 167, 4358–4367 (2001).

Shibuya, K. et al. CD226 (DNAM-1) is involved in lymphocyte function-associated antigen 1 costimulatory signal for naive T cell differentiation and proliferation. J. Exp. Med. 198,1829–1839 (2003).

Lozano, E. et al The CD226/CD155 interaction regulates the proinflammatory (T_H1/T_H17)/anti-inflammatory (T_H2) balance in humans. J. Immunol. 191, 3673–3680 (2013).

Maier, M. K. et al. The adhesion receptor CD155 determines the magnitude of humoral immune responses against orally ingested antigens. Eur. J. Immunol. 37, 2214–2225(2007).

Pende, D. et al. Expression of the DNAM-1 ligands, Nectin-2 (CD112) and poliovirus receptor (CD155), on dendritic cells: relevance for natural killer-dendritic cell interaction.Blood 107, 2030–2036 (2006).

O’Leary et al T cell- and B cell-independent adaptive immunity mediated by natural killer cells. Nature Immunol. 7, 507–516(2006).

Sanchez-Correa, B. et al. Decreased expression of DNAM-1 on NK cells from acute myeloid leukemia patients. Immunol. Cell Biol. 90, 109–115 (2012).

Mamessier, E. et al. Human breast cancer cells enhance self tolerance by promoting evasion from NK cell antitumor immunity. J. Clin. Invest. 121, 3609–3622 (2011).

Nakai, R. et al. Overexpression of Necl-5 correlates with unfavorable prognosis in patients with lung adenocarcinoma. Cancer Sci. 101, 1326–1330 (2010).

Tane, S. et al. The role of Necl-5 in the invasive activity of lung adenocarcinoma. Exp. Mol. Pathol. 94, 330–335 (2013).

Sloan, K. E. et al. CD155/PVR plays a key role in cell motility during tumor cell invasion and migration. BMC Cancer 4, 73 (2004)

Chan, C. J., Smyth, M. J. & Martinet, L. Molecular mechanisms of natural killer cell activation in response to cellular stress. Cell Death Differ. 21, 5–14 (2014).

Li, M. et al. T-cell immunoglobulin and ITIM domain (TIGIT) receptor/poliovirus receptor (PVR) ligand engagement suppresses interferon-γ production of natural killer cells via β-arrestin 2-mediated negative signaling. J. Biol. Chem. 289, 17647–17657 (2014).

Guma, M. et al. Imprint of human cytomegalovirus infection on the NK cell receptor repertoire. Blood 104, 3664–3671 (2004).

Sharma S. Natural killer cells and regulatory T cells in early pregnancy loss.

Int J Dev Biol. 2014;58(2-4):219-29. doi: 10.1387/ijdb.140109ss. Review.

Mukaida N, Sasaki S, Baba T. Chemokines in cancer development and progression and their potential as targeting molecules for cancer treatment. Mediators Inflamm. 2014;2014:170381. doi: 10.1155/2014/170381. Epub 2014 May 22. Review.

Van Elssen CH, Oth T, Germeraad WT, Bos GM, Vanderlocht J. Natural killer cells: the secret weapon in dendritic cell vaccination strategies.Clin Cancer Res. 2014 Mar 1;20(5):1095-103. doi: 10.1158/1078-0432.CCR-13-2302. Review.

Gardner AB, Lee SK, Woods EC, Acharya AP. Biomaterials-based modulation of the immune system. Biomed Res Int. 2013;2013:732182. doi: 10.1155/2013/732182. Epub 2013 Sep 22. Review.

Pedroza-Pacheco I, Madrigal A, Saudemont A. Interaction between natural killer cells and regulatory T cells: perspectives for immunotherapy. Cell Mol Immunol. 2013 May;10(3):222-9. doi: 10.1038/cmi.2013.2. Epub 2013 Mar 25. Review.

Lindau D, Gielen P, Kroesen M, Wesseling P, Adema GJ. The immunosuppressive tumour network: myeloid-derived suppressor cells, regulatory T cells and natural killer T cells. Immunology. 2013 Feb;138(2):105-15. doi: 10.1111/imm.12036. Review.

Tian Z, Chen Y, Gao B.Natural killer cells in liver disease. Hepatology. 2013 Apr;57(4):1654-62. doi: 10.1002/hep.26115. Review.

Joyce S, Girardi E, Zajonc DM. J NKT cell ligand recognition logic: molecular basis for a synaptic duet and transmission of inflammatory effectors. Immunol. 2011 Aug 1;187(3):1081-9. doi: 0.4049/jimmunol.1001910. Review.

Diana J, Gahzarian L, Simoni Y, Lehuen A. Innate immunity in type 1 diabetes. Discov Med. 2011 Jun;11(61):513-20. Review.

Wu L, Van Kaer L.Natural killer T cells in health and disease. Front Biosci (Schol Ed). 2011 Jan 1;3:236-51. Review.

Cantorna MT. Why do T cells express the vitamin D receptor? Ann N Y Acad Sci. 2011 Jan;1217:77-82. doi: 10.1111/j.1749-6632.2010.05823.x. Epub 2010 Nov 29. Review.

Key Papers:

These papers, Gilfian et all and Iguchi-Manaka et al, were the first to show the role of CD226 in NK cell- and CD8⁺ T cell-mediated tumour immunosurveillance using Cd226^−/− mice.

Gilfillan, S.et al. DNAM-1 promotes activation of cytotoxic lymphocytes by nonprofessional antigen-presenting cells and tumors. J. Exp. Med. 205, 2965–2973 (2008).
Iguchi-Manaka, A.et al. Accelerated tumor growth in mice deficient in DNAM-1 receptor. Exp. Med. 205, 2959–2964 (2008).

Johnston, R. J. et al. The immunoreceptor TIGIT regulates antitumor and antiviral CD8⁺ T cell effector function. Cancer Cell 26, 923–937 (2014).
This study shows that TIGIT is expressed by PD1⁺ exhausted tumour-infiltrating T cells and that targeting these receptors with monoclonal antibodies represents a promising strategy to restore CD8⁺ T cell functions in cancer or in chronic infectious disease.

Khakoo, S. I. et al. HLA and NK cell inhibitory receptor genes in resolving hepatitis C virus infection. Science 305, 872–874 (2004).

Fang, M. et al. CD94 is essential for NK cell-mediated resistance to a lethal viral disease.Immunity 34, 579–589 (2011).
This study using CD94-deficient mice shows that the activating receptor formed by CD94 and NKG2E is essential for the resistance of C57BL/6 mice to mousepox.

Pradeu, T., Jaeger, S. & Vivier, E. The speed of change: towards a discontinuity theory of immunity? Nature Rev. Immunol. 13, 764–769 (2013).
This is an outstanding review on the formulation of a new immune paradigm ‘the discontinuity theory’

Further Reading:

Vol 13, No 4 (2012): July – p. 330-469	Molecular Biology of Pancreatic Cancer: How Useful Is It in Clinical Practice?	ABSTRACT HTML PDF
George H Sakorafas, Vasileios Smyrniotis

Vol 13, No 4 (2012): July – p. 330-469	Endoscopic Findings of Upper Gastrointestinal Lesions in Patients with Pancreatic Cancer	ABSTRACT HTML PDF
Koushiro Ohtsubo, Hiroyuki Watanabe, Hisatsugu Mouri, Kaname Yamashita, Kazuo Yasumoto, Seiji Yano

Vol 13, No 5 (2012): September – p. 470-547	Two Avirulent, Lentogenic Strains of Newcastle Disease Virus Are Cytotoxic for Some Human Pancreatic Tumor Lines In Vitro	ABSTRACT HTML PDF
Robert J Walter, Bashar M Attar, Asad Rafiq, Megan Delimata, Sooraj Tejaswi

Vol 14, No 3 (2013): May – p. 221-303	Duration of Diabetes and Pancreatic Cancer in a Case-Control Study in the Midwest and the Iowa Women’s Health Study (IWHS) Cohort	ABSTRACT HTML PDF
Sarah A Henry, Anna E Prizment, Kristin E Anderson

Vol 16, No 1 (2015): January – p. 1-99	Endoscopic Management of Pain in Pancreatic Cancer	ABSTRACT HTML PDF
Parit Mekaroonkamol, Field F Willingham, Saurabh Chawla

Vol 14, No 2 (2013): March – p. 109-220	Advancements in the Management of Pancreatic Cancer: 2013	ABSTRACT HTML PDF
Muhammad Wasif Saif

Vol 15, No 5 (2014): September – p. 413-540	New-onset Diabetes: A Clue to the Early Diagnosis of Pancreatic Cancer	ABSTRACT HTML PDF
Suresh T Chari

Vol 13, No 5 (2012): September – p. 470-547	Effects of Porcine Pancreatic Enzymes on the Pancreas of Hamsters. Part 2: Carcinogenesis Studies	ABSTRACT HTML PDF
Fumiaki Nozawa, Mehmet Yalniz, Murat Saruc, Jens Standop, Hiroshi Egami, Parviz M Pour

Vol 14, No 5 (2013): September – p. 475-527	Synchronous Triple Cancers of the Pancreas, Stomach, and Cecum Treated with S-1 Followed by Pancrelipase Treatment of Pancreatic Exocrine Insufficiency	ABSTRACT HTML PDF
Koushiro Ohtsubo, Daisuke Ishikawa, Shigeki Nanjo, Shinji Takeuchi, Tadaaki Yamada, Hisatsugu Mouri, Kaname Yamashita, Kazuo Yasumoto, Toshifumi Gabata, Osamu Matsui, Hiroko Ikeda, Yasushi Takamatsu, Sakae Iwakami, Seiji Yano

Vol 13, No 1 (2012): January – p. 1-123	Newcastle Disease Virus LaSota Strain Kills Human Pancreatic Cancer Cells in Vitro with High Selectivity	ABSTRACT HTML PDF
Robert J Walter, Bashar M Attar, Asad Rafiq, Sooraj Tejaswi, Megan Delimata

Vol 13, No 3 (2012): May – p. 252-329	Rare Solid Tumors of the Pancreas as Differential Diagnosis of Pancreatic Adenocarcinoma	ABSTRACT HTML PDF
Sabine Kersting, Monika S Janot, Johanna Munding, Dominique Suelberg, Andrea Tannapfel, Ansgar M Chromik, Waldemar Uhl, Uwe Bergmann

Vol 14, No 4 (2013): July – p. 304-474	A Proteomic Comparison of Formalin-Fixed Paraffin-Embedded Pancreatic Tissue from Autoimmune Pancreatitis, Chronic Pancreatitis, and Pancreatic Cancer	ABSTRACT HTML PDF SUPPL. TABLES 1-4 (PDF)
Joao A Paulo, Vivek Kadiyala, Scott Brizard, Peter A Banks, Hanno Steen, Darwin L Conwell

Vol 13, No 4 (2012): July – p. 330-469	Highlights on the First Line Treatment of Metastatic Pancreatic Cancer	ABSTRACT HTML PDF
Krishna S Gunturu, Jamie Jarboe, Muhammad Wasif Saif

Vol 14, No 2 (2013): March – p. 109-220	Pancreatic Cancer: Updates on Translational Research and Future Applications	ABSTRACT HTML PDF
Evangelos G Sarris, Konstantinos N Syrigos, Muhammad Wasif Saif

Vol 14, No 4 (2013): July – p. 304-474	Pancreatic Cancer: What About Screening and Detection?	ABSTRACT HTML PDF
Froso Konstantinou, Kostas N Syrigos, Muhammad Wasif Saif

Vol 14, No 4 (2013): July – p. 304-474	Diabetes and Pancreatic Cancer	ABSTRACT HTML PDF
Najla Hatem El-Jurdi, Muhammad Wasif Saif

Vol 13, No 5 (2012): September – p. 470-547	Effects of Porcine Pancreatic Enzymes on the Pancreas of Hamsters. Part 1: Basic Studies	ABSTRACT HTML PDF
Murat Saruc, Fumiaki Nozawa, Mehmet Yalniz, Atsushi Itami, Parviz M Pour

Vol 14, No 2 (2013): March – p. 109-220	Analysis of Endoscopic Pancreatic Function Test (ePFT)-Collected Pancreatic Fluid Proteins Precipitated Via Ultracentrifugation	ABSTRACT HTML PDF SUPPL.(XLS) SUPPL.(PDF)
Joao A Paulo, Vivek Kadiyala, Aleksandr Gaun, John F K Sauld, Ali Ghoulidi, Peter A Banks, Hanno Steen, Darwin L Conwell

Vol 16, No 1 (2015): January – p. 1-99	Regulation Mechanisms of the Hedgehog Pathway in Pancreatic Cancer: A Review	ABSTRACT HTML PDF
Kim Christin Honselmann, Moritz Pross, Carlo Maria Felix Jung, Ulrich Friedrich Wellner, Steffen Deichmann, Tobias Keck, Dirk Bausch

Vol 14, No 5S (2013): September (Suppl.) – p. 528-602	History of Previous Cancer in Patients Undergoing Resection for Pancreatic Adenocarcinoma	ABSTRACT PDF
*Francesca Gavazzi, Maria Rachele Angiolini, Cristina Ridolfi, Maria Carla Tinti, Marco Madonini, Marco Montorsi, Alessandro Zerbi*

Vol 13, No 4 (2012): July – p. 330-469	Molecular Biology of Pancreatic Cancer: How Useful Is It in Clinical Practice?	ABSTRACT HTML PDF
George H Sakorafas, Vasileios Smyrniotis

Vol 13, No 4 (2012): July – p. 330-469	Endoscopic Findings of Upper Gastrointestinal Lesions in Patients with Pancreatic Cancer	ABSTRACT HTML PDF
Koushiro Ohtsubo, Hiroyuki Watanabe, Hisatsugu Mouri, Kaname Yamashita, Kazuo Yasumoto, Seiji Yano

Vol 13, No 5 (2012): September – p. 470-547	Two Avirulent, Lentogenic Strains of Newcastle Disease Virus Are Cytotoxic for Some Human Pancreatic Tumor Lines In Vitro	ABSTRACT HTML PDF
Robert J Walter, Bashar M Attar, Asad Rafiq, Megan Delimata, Sooraj Tejaswi

Vol 14, No 3 (2013): May – p. 221-303	Duration of Diabetes and Pancreatic Cancer in a Case-Control Study in the Midwest and the Iowa Women’s Health Study (IWHS) Cohort	ABSTRACT HTML PDF
Sarah A Henry, Anna E Prizment, Kristin E Anderson

Vol 16, No 1 (2015): January – p. 1-99	Endoscopic Management of Pain in Pancreatic Cancer	ABSTRACT HTML PDF
Parit Mekaroonkamol, Field F Willingham, Saurabh Chawla

Vol 14, No 2 (2013): March – p. 109-220	Advancements in the Management of Pancreatic Cancer: 2013	ABSTRACT HTML PDF
Muhammad Wasif Saif

Vol 15, No 5 (2014): September – p. 413-540	New-onset Diabetes: A Clue to the Early Diagnosis of Pancreatic Cancer	ABSTRACT HTML PDF
Suresh T Chari

Vol 13, No 5 (2012): September – p. 470-547	Effects of Porcine Pancreatic Enzymes on the Pancreas of Hamsters. Part 2: Carcinogenesis Studies	ABSTRACT HTML PDF
Fumiaki Nozawa, Mehmet Yalniz, Murat Saruc, Jens Standop, Hiroshi Egami, Parviz M Pour

Vol 14, No 5 (2013): September – p. 475-527	Synchronous Triple Cancers of the Pancreas, Stomach, and Cecum Treated with S-1 Followed by Pancrelipase Treatment of Pancreatic Exocrine Insufficiency	ABSTRACT HTML PDF
Koushiro Ohtsubo, Daisuke Ishikawa, Shigeki Nanjo, Shinji Takeuchi, Tadaaki Yamada, Hisatsugu Mouri, Kaname Yamashita, Kazuo Yasumoto, Toshifumi Gabata, Osamu Matsui, Hiroko Ikeda, Yasushi Takamatsu, Sakae Iwakami, Seiji Yano

Vol 13, No 1 (2012): January – p. 1-123	Newcastle Disease Virus LaSota Strain Kills Human Pancreatic Cancer Cells in Vitro with High Selectivity	ABSTRACT HTML PDF
Robert J Walter, Bashar M Attar, Asad Rafiq, Sooraj Tejaswi, Megan Delimata

Vol 13, No 3 (2012): May – p. 252-329	Rare Solid Tumors of the Pancreas as Differential Diagnosis of Pancreatic Adenocarcinoma	ABSTRACT HTML PDF
Sabine Kersting, Monika S Janot, Johanna Munding, Dominique Suelberg, Andrea Tannapfel, Ansgar M Chromik, Waldemar Uhl, Uwe Bergmann

Vol 14, No 4 (2013): July – p. 304-474	A Proteomic Comparison of Formalin-Fixed Paraffin-Embedded Pancreatic Tissue from Autoimmune Pancreatitis, Chronic Pancreatitis, and Pancreatic Cancer	ABSTRACT HTML PDF SUPPL. TABLES 1-4 (PDF)
Joao A Paulo, Vivek Kadiyala, Scott Brizard, Peter A Banks, Hanno Steen, Darwin L Conwell

Vol 13, No 4 (2012): July – p. 330-469	Highlights on the First Line Treatment of Metastatic Pancreatic Cancer	ABSTRACT HTML PDF
Krishna S Gunturu, Jamie Jarboe, Muhammad Wasif Saif

Vol 14, No 2 (2013): March – p. 109-220	Pancreatic Cancer: Updates on Translational Research and Future Applications	ABSTRACT HTML PDF
Evangelos G Sarris, Konstantinos N Syrigos, Muhammad Wasif Saif

Vol 14, No 4 (2013): July – p. 304-474	Pancreatic Cancer: What About Screening and Detection?	ABSTRACT HTML PDF
Froso Konstantinou, Kostas N Syrigos, Muhammad Wasif Saif

Vol 14, No 4 (2013): July – p. 304-474	Diabetes and Pancreatic Cancer	ABSTRACT HTML PDF
Najla Hatem El-Jurdi, Muhammad Wasif Saif

Vol 13, No 5 (2012): September – p. 470-547	Effects of Porcine Pancreatic Enzymes on the Pancreas of Hamsters. Part 1: Basic Studies	ABSTRACT HTML PDF
Murat Saruc, Fumiaki Nozawa, Mehmet Yalniz, Atsushi Itami, Parviz M Pour

Vol 14, No 2 (2013): March – p. 109-220	Analysis of Endoscopic Pancreatic Function Test (ePFT)-Collected Pancreatic Fluid Proteins Precipitated Via Ultracentrifugation	ABSTRACT HTML PDF SUPPL.(XLS) SUPPL.(PDF)
Joao A Paulo, Vivek Kadiyala, Aleksandr Gaun, John F K Sauld, Ali Ghoulidi, Peter A Banks, Hanno Steen, Darwin L Conwell

Vol 16, No 1 (2015): January – p. 1-99	Regulation Mechanisms of the Hedgehog Pathway in Pancreatic Cancer: A Review	ABSTRACT HTML PDF
Kim Christin Honselmann, Moritz Pross, Carlo Maria Felix Jung, Ulrich Friedrich Wellner, Steffen Deichmann, Tobias Keck, Dirk Bausch

Vol 14, No 5S (2013): September (Suppl.) – p. 528-602	History of Previous Cancer in Patients Undergoing Resection for Pancreatic Adenocarcinoma	ABSTRACT PDF
*Francesca Gavazzi, Maria Rachele Angiolini, Cristina Ridolfi, Maria Carla Tinti, Marco Madonini, Marco Montorsi, Alessandro Zerbi*

Patents

1. www.uspto.gov

http://www.uspto.gov/web/patents/patog/week10/OG/html/1412-2/US08974784-20150310.html

Anti-pancreatic cancer antibodies: David M. Goldenberg, Mendham, NJ (US); Hans J. Hansen, Picayune, MS (US); Chien-Hsing Chang, Downingtown, PA (US); …

2. www.uspto.gov

http://www.uspto.gov/web/patents/patog/week42/OG/html/1407-3/US08865413-20141021.html

A method of diagnosing pancreatic cancer in a human, the method comprising detecting the level of golgi apparatus protein 1 in a sample from the …

3. www.uspto.gov

http://www.uspto.gov/web/patents/patog/week10/OG/html/1412-2/US08974802-20150310.html

A method for the treatment of pancreatic cancer, which comprises the administration to a human patient with pancreatic cancer of an effective …

4. www.uspto.gov

http://www.uspto.gov/web/patents/patog/week50/OG/html/1409-3/US08912191-20141216.html

A method of treatment of melanoma, colorectal cancer, or pancreatic cancerwherein the treatment inhibits the progress of, reduces the rate of …

5. www.uspto.gov

http://www.uspto.gov/web/patents/patog/week10/OG/html/1412-2/US08975401-20150310.html

A method of treating a cancer selected from breast cancer, hepatocellular carcinoma … gastric carcinoma, leukemia and pancreatic cancer in a subject …

6. www.uspto.gov

http://www.uspto.gov/web/patents/patog/week42/OG/html/1407-3/US08865173-20141021.html

Treatments for pancreatic cancer metastases: Suzanne M. Spong, San Francisco, CA (US); Thomas B. Neff, Atherton, CA (US); and Stephen J. Klaus, San …

7. www.uspto.gov

http://www.uspto.gov/web/patents/patog/week48/OG/html/1409-1/US08901093-20141202.html

Custom vectors for treating and preventing pancreatic cancer: Dennis L. Panicali, Acton, MA (US); Gail P. Mazzara, Winchester, MA (US); Linda R. …

8. www.uspto.gov

http://www.uspto.gov/web/patents/patog/week09/OG/html/1412-1/US08969366-20150303.html

A method for treating a disease selected from the group consisting of melanoma, stomach cancer, liver cancer, colorectal cancer, pancreatic …

9. Drug composition cytotoxic for pancreatic cancer cells

http://www.uspto.gov/web/patents/patog/week13/OG/html/1401-1/US08685941-20140401.html

Drug composition cytotoxic for pancreatic cancer cells: James Turkson, Orlando, Fla. (US) Assigned to University of Central Florida Research …

10. [PDF] J. John Shimazaki, Esq. 1539 Lincoln Way, Suite 204

http://www.uspto.gov/web/offices/com/sol/foia/tac/2.66/74713131.pdf

John Shimazaki, Esq. 1539 Lincoln Way, Suite 204 … containing the Of fice Action because Applicant™s president™s father was ill withpancreatic…

11. [PDF] Written Comments on Genetic Diagnostic Testing Study

http://www.uspto.gov/aia_implementation/gen_e_lsi_20130207.pdf

Page 5 of 23 extracolonic cancers of LS include liver cancer, pancreatic cancer, gall bladder duct cancer, prostate cancer, sarcomas, thyroid cancer …

12. Detection of digestive organ cancer, gastric cancer …

http://www.uspto.gov/web/patents/patog/week02/OG/html/1410-2/US08932990-20150113.html

Detection of digestive organ cancer, gastric cancer, colorectal cancer, pancreatic cancer, and biliary tract cancer by gene expression profiling

13. www.uspto.gov

http://www.uspto.gov/web/patents/patog/week06/OG/html/1399-2/US08648112-20140211.html

wherein said cancer is selected from the group consisting of a sarcoma, … a nervous system cancer, prostate cancer, pancreatic cancer, and colon can …

14. Treatment of hyperproliferative diseases with vinca …

http://www.uspto.gov/web/patents/patog/week45/OG/html/1408-2/US08883775-20141111.html

A method of treating or ameliorating a hyperproliferative disorder selected from the group consisting of glioblastoma, lung cancer, breast cancer . …

15. www.uspto.gov

http://www.uspto.gov/web/patents/patog/week30/OG/html/1404-5/US08791125-20140729.html

A method for treating a Weel kinase mediated cancer selected from the group consisting of breast cancer, lung cancer, pancreatic cancer, colon …

16. www.uspto.gov

http://www.uspto.gov/web/patents/patog/week08/OG/html/1411-4/US08962891-20150224.html

wherein said proliferative disorder is breast cancer or pancreatic cancer. …

17. Immunoconjugates, compositions for making them, and …

http://www.uspto.gov/web/patents/patog/week40/OG/html/1407-1/US08852599-20141007.html

A method for treating a cancer in a subject suffering from such cancer, … pancreatic cancer, ovarian cancer, lymphoma, colon cancer, mesothelioma, …

18. www.uspto.gov

http://www.uspto.gov/web/patents/patog/week11/OG/html/1400-3/US08673898-20140318.html

A method of treating cancer, … lung cancer, melanoma, neuroblastomas, oral cancer, ovarian cancer, pancreatic cancer, prostate cancer , rectal cance …

19. www.uspto.gov

http://www.uspto.gov/web/patents/patog/week43/OG/html/1407-4/US08871744-20141028.html

A method for treating a subject having breast cancer, ovarian cancer, or pancreatic cancer in need of therapy thereof comprising administering to …

20. [PDF] Pamela Scudder <pscudder@windstream.net> Sent: Saturday …

http://www.uspto.gov/sites/default/files/aia_implementation/gene-comment-scudder.pdf

My daughter died of ovarian cancer. My other daughter and many … (mutation) is known to cause a higher incidence of pancreatic (for instance) cancer …

21. Methods of treating cancer using pyridopyrimidinone …

http://www.uspto.gov/web/patents/patog/week48/OG/html/1409-1/US08901137-20141202.html

A method of treating pancreatic cancer which method comprises administering to a patient a therapeutically effective amount of a compound that is:

22. Heteroaryl substituted pyrrolo[2,3-B]pyridines and pyrrolo …

http://www.uspto.gov/web/patents/patog/week02/OG/html/1410-2/US08933086-20150113.html

A method of treating pancreatic cancer in a patient, comprising administering to said patient a therapeutically effective amount of a compound …

23. www.uspto.gov

http://www.uspto.gov/web/patents/patog/week49/OG/html/1409-2/US08906934-20141209.html

… wherein the cell proliferative disorder is selected from the group consisting of cervical cancer, colon cancer, ovarian cancer, pancreatic cancer, …

24. www.uspto.gov

http://www.uspto.gov/web/patents/patog/week32/OG/html/1405-2/US08802703-20140812.html

A method of inhibiting MEK in a cancer cell selected from the group consisting of human melanoma cells and human pancreatic cancer cells …

25. Antibody-based arrays for detecting multiple signal …

http://www.uspto.gov/web/patents/patog/week08/OG/html/1399-4/US08658388-20140225.html

A method for performing a multiplex, high-throughput immunoassay for facilitating a cancer diagnosis, the method comprising:

26. www.uspto.gov

http://www.uspto.gov/web/patents/patog/week48/OG/html/1409-1/US08901147-20141202.html

A method for the treatment of colorectal cancer, lung cancer, breast cancer, prostatecancer, urinary cancer, kidney cancer, and pancreatic …

27. Patentee Index – United States Patent and Trademark Office

http://www.uspto.gov/web/patents/patog/week16/OG/patentee/alphaY.htm

Yamaue, Hiroki; to Onco Therapy Science, Inc. Combination therapy for pancreatic cancer using an antigenic peptide and chemotherapeutic agent 08703713 …

28. Patentee Index – United States Patent and Trademark Office

http://www.uspto.gov/web/patents/patog/week48/OG/patentee/alphaP_Utility.htm

… The Custom vectors for treating and preventing pancreatic cancer … system and apparatus for control of pancreatic beta cell function to improve …

29. Patentee Index – United States Patent and Trademark Office

http://www.uspto.gov/web/patents/patog/week16/OG/patentee/alphaW.htm

Whatcott, Cliff; and Han, Haiyong, to Translational Genomics Research Institute, The Therapeutic target for pancreatic cancer cells 08703736 Cl. …

30. Patentee Index – United States Patent and Trademark Office

http://www.uspto.gov/web/patents/patog/week10/OG/patentee/alphaG.htm

Goldenberg, David M.; Hansen, Hans J.; Chang, Chien-Hsing; and Gold, David V., to Immunomedics, Inc. Anti-pancreatic cancer antibodies 08974784 Cl. …

31. Patentee Index – United States Patent and Trademark Office

http://www.uspto.gov/web/patents/patog/week42/OG/patentee/alphaD.htm

… Narayan, Vaibhav; and Patterson, Scott, to Celera Corporation Pancreatic cancertargets and uses thereof 08865413 Cl. 435-7.1. Domsch, Matthew L.; …

32. [PDF] 15 March 2005 – United States Patent and Trademark Office

http://www.uspto.gov/web/trademarks/tmog/20050315_OG.pdf

15 March 2005 – United States Patent and Trademark Office

33. www.uspto.gov

http://www.uspto.gov/web/patents/patog/week10/OG/html/1412-2/US08975248-20150310.html

Combinations of therapeutic agents for treating cancer: … myeloma, colorectal adenocarcinoma, cervical carcinoma and pancreatic carcinoma, …

34. Patentee Index – United States Patent and Trademark Office

http://www.uspto.gov/web/patents/patog/week05/OG/patentee/alphaG_Utility.htm

… Inc. Medium-chain length fatty acids, salts and triglycerides in combination with gemcitabine for treatment of pancreatic cancer 08946190 Cl. …

35. Patentee Index – United States Patent and Trademark Office

http://www.uspto.gov/web/patents/patog/week13/OG/patentee/alphaT_Utility.htm

Turkson, James; to University of Central Florida Research Foundation, Inc. Drug composition cytotoxic for pancreatic cancer cells 08685941 Cl. 514-49.

36. Patentee Index – United States Patent and Trademark Office

http://www.uspto.gov/web/patents/patog/week31/OG/patentee/alphaG_Utility.htm

… David M., to Immunomedics, Inc. Anti-mucin antibodies for early detection and treatment of pancreatic cancer 08795662 Cl. 424-130.1. Gold, …

37. [PDF] www.uspto.gov

http://www.uspto.gov/web/trademarks/tmog/20110816_OG.pdf

http://www.uspto.gov

38. Patentee Index – United States Patent and Trademark Office

http://www.uspto.gov/web/patents/patog/week29/OG/patentee/alphaG.htm

Goggins, Michael G.; and Sato, Norihiro, to Johns Hopkins University, The Aberrantly methylated genes in pancreatic cancer 08785614 Cl. 536-24.3. …

39. www.uspto.gov

http://www.uspto.gov/web/patents/patog/week46/OG/html/1408-3/US08889697-20141118.html

wherein said cancer is pancreatic cnacer, chronic myelogenous leukemia (CML), acute myelogenous leukemia (AML), acute lymphoblastic leukemia (ALL …

40. Patentee Index – United States Patent and Trademark Office

http://www.uspto.gov/web/patents/patog/week39/OG/patentee/alphaM_Utility.htm

Malafa, Mokenge P.; and Sebti, Said M., to University of South Florida Delta-tocotrienol treatment and prevention of pancreatic cancer 08846653 Cl. …

41. Patentee Index – United States Patent and Trademark Office

http://www.uspto.gov/web/patents/patog/week02/OG/patentee/alphaK_Utility.htm

… Taro, to National University Corporation Kanazawa University Detection of digestive organ cancer, gastric cancer, colorectal cancer, pancreatic …

42. Patentee Index – United States Patent and Trademark Office

http://www.uspto.gov/web/patents/patog/week11/OG/patentee/alphaK_Utility.htm

Kirn, David; to Sillajen Biotherapeutics, Inc. Oncolytic vaccinia virus cancer therapy 08980246 Cl. 424-93.2. Kirn, Larry J.; …

43. Patentee Index – United States Patent and Trademark Office

http://www.uspto.gov/web/patents/patog/week39/OG/patentee/alphaM_Utility.htm

Malafa, Mokenge P.; and Sebti, Said M., to University of South Florida Delta-tocotrienol treatment and prevention of pancreatic cancer 08846653 Cl. …

44. Patentee Index – United States Patent and Trademark Office

http://www.uspto.gov/web/patents/patog/week35/OG/patentee/alphaS_Utility.htm

list of patentees to whom patents were issued on the 2nd day of september, 2014 and to whom reexamination certificates were issued during the week …

45. Patentee Index – United States Patent and Trademark Office

http://www.uspto.gov/web/patents/patog/week42/OG/patentee/alphaS.htm

… Therapeutics Inc. Compounds and compositions for stabilizing hypoxia inducible factor-2 alpha as a method for treating cancer 08865748 Cl. …

46. [PDF] Paper No. 12 UNITED STATES PATENT AND TRADEMARK OFFICE …

http://www.uspto.gov/sites/default/files/ip/boards/bpai/decisions/prec/bhide.pdf

high incidence of ras involvement, such as colon and pancreatic tumors. By … withcancer or pre-cancerous states will serve to treat or palliate the …

47. CPC Scheme – C07K PEPTIDES – United States Patent and …

http://www.uspto.gov/web/patents/classification/cpc/html/cpc-C07K.html

PEPTIDES (peptides in … Cancer-associated SCM-recognition factor, CRISPP} [2013‑01] … Kazal type inhibitors, e.g. pancreatic secretory inhibitor, …

48. Class Definition for Class 514 – DRUG, BIO-AFFECTING AND …

http://www.uspto.gov/web/patents/classification/uspc514/defs514.htm

… compound X useful as an anti-cancer … certain rules as to patent … Cystic fibrosis is manifested by faulty digestion due to a deficiency of pa …

49. United States Patent and Trademark Office

http://www.uspto.gov/web/patents/classification/cpc/html/cpc-G01N_3.html

Cancer-associated SCM-recognition factor, CRISPP . G01N 2333/4748. . . . . … Bovine/basic pancreatic trypsin inhibitor (BPTI, aprotinin) G01N …

50. Class Definition for Class 530 – CHEMISTRY: NATURAL RESINS …

http://www.uspto.gov/web/patents/classification/uspc530/defs530.htm

CLASS 530 , CHEMISTRY: NATURAL … Typically the processes of this subclass include solvent extraction of pancreatic … as well as with some forms of …

51. CPC Definition – A61K PREPARATIONS FOR MEDICAL, DENTAL, OR …

http://www.uspto.gov/web/patents/classification/cpc/html/defA61K.html

PREPARATIONS FOR MEDICAL, DENTAL, OR TOILET PURPOSES … i.e. Pancreatic stem cells are classified in A61K 35/39, … preparations containing cancer a …

52. Class 530: CHEMISTRY: NATURAL RESINS OR DERIVATIVES …

http://www.uspto.gov/web/offices/ac/ido/oeip/taf/def/530.htm

Typically the processes of this subclass include solvent extraction of pancreatic … 828 for cancer -associated proteins … provided for in Class …

53. United States Patent and Trademark Office

http://www.uspto.gov/web/patents/classification/cpc/html/cpc-G01N_1.html

Home page of the United States Patent and … Pancreatic cells} G01N 33/5073 … – relevant features relating to a specifically defined cancer are …

54. TBD – United States Patent and Trademark Office

http://www.uspto.gov/web/patents/classification/shadowFiles/defs514sf.htm?514_971&S&10E&10F

class 514, drug, bio-affecting and body treating compositions …

55. Patentee Index – United States Patent and Trademark Office

http://www.uspto.gov/web/patents/patog/week47/OG/patentee/alphaN_Utility.htm

… Dale E., to Buck Institute for Age Research, The Reagents and methods for cancertreatment and … useful for diagnosis and treatment of pancreati …

56. United States Patent and Trademark Office

http://www.uspto.gov/web/patents/classification/cpc/html/cpc-C12Y_2.html

Pancreatic ribonuclease (3.1.27.5) C12Y 301/27006. . Enterobacter ribonuclease (3.1.27.6) C12Y 301/27007. . Ribonuclease F (3.1.27.7) C12Y 301/27008. …

57. Patentee Index – United States Patent and Trademark Office

http://www.uspto.gov/web/patents/patog/week01/OG/patentee/alphaI_Utility.htm

Institute for Cancer Research: See … and Segev, Hanna, to Technion Research & Development Foundation Limited Populations of pancreatic …

58. Patentee Index – United States Patent and Trademark Office

http://www.uspto.gov/web/patents/patog/week53/OG/patentee/alphaC.htm

Cancer Research Technology Limited: See–Collins, Ian; Reader, John Charles; Klair, Suki; Scanlon, Jane; Addison, Glynn; and Cherry, Michael 08618121 …

59. Patentee Index – United States Patent and Trademark Office

http://www.uspto.gov/web/patents/patog/week12/OG/patentee/alphaP_Utility.htm

… to University Health Network Cyclic inhibitors of carnitine palmitoyltransferase and treating cancer … progenitor cells and pancreatic endocrine …

60. Patentee Index – United States Patent and Trademark Office

http://www.uspto.gov/web/patents/patog/week47/OG/patentee/alphaI.htm

… to King Fahd University of Petroleum and Minerals Cytotoxic compounds for treatingcancer … or preventing a pancreatic dysfunction 08894972 Cl …

61. Patentee Index – United States Patent and Trademark Office

http://www.uspto.gov/web/patents/patog/week50/OG/patentee/alphaC.htm

… and Taylor-Papadimitriou, Joyce, to Københavns Universitet Generation of a cancer-specific … to CuRNA, Inc. Treatment of pancreatic …

62. Patentee Index – United States Patent and Trademark Office

http://www.uspto.gov/web/patents/patog/week29/OG/patentee/alphaP_Utility.htm

… to Cedars-Sinai Medical Center Drug delivery of temozolomide for systemic based treatment of cancer … Pancreatic enzyme compositions and …

63. Class 424: DRUG, BIO-AFFECTING AND BODY TREATING …

http://www.uspto.gov/web/offices/ac/ido/oeip/taf/def/424.htm

… a disclosed or even specifically claimed utility (i.e., compound X having an attached radionuclide useful as an anti-cancer diagnostic or …

64. Patentee Index – United States Patent and Trademark Office

http://www.uspto.gov/web/patents/patog/week25/OG/patentee/alphaT_Utility.htm

… Chang-Jer, to Gold Nanotech Inc. Physical nano-complexes for preventing and treating cancer and … and protective solution for protecting pancrea …

65. Patentee Index – United States Patent and Trademark Office

http://www.uspto.gov/web/patents/patog/week27/OG/patentee/alphaA_Utility.htm

… Thomas T., to Penn State Research Foundation, The In vivo photodynamic therapy ofcancer via a near infrared … of pancreatic beta-cells by …

66. Patentee Index – United States Patent and Trademark Office

http://www.uspto.gov/web/patents/patog/week32/OG/patentee/alphaB_Utility.htm

Birnie, Richard; to University of York, The Cancer vaccine 08802619 Cl. 514-1. Birtwhistle, Daniel P.; Long, James R.; and Reinke, Robert E., …

67. Patentee Index – United States Patent and Trademark Office

http://www.uspto.gov/web/patents/patog/week20/OG/patentee/alphaC_Utility.htm

… to Cornell University Method for treating cancer 08729133 Cl. 514-673 … methods for promoting the generation of PDX1+ pancreatic cells …

68. Patentee Index – United States Patent and Trademark Office

http://www.uspto.gov/web/patents/patog/week49/OG/patentee/alphaL_Utility.htm

… Kurt, to Abbvie Biotherapeutics Inc. Compositions against cancer antigen LIV-1 and uses … H., to Amylin Pharmaceuticals, LLC Pancreatic …

69. Patentee Index – United States Patent and Trademark Office

http://www.uspto.gov/web/patents/patog/week11/OG/patentee/alphaS_Utility.htm

… Kenji; and Matsuda, Hirokazu, to Kyoto University Molecular probe for imaging ofpancreatic islets and use … use in the treatment of cancer …

70. Patentee Index – United States Patent and Trademark Office

http://www.uspto.gov/web/patents/patog/week36/OG/patentee/alphaK.htm

… Emi; Matsumi, Chiemi; and Saitoh, Yukie, to Actgen Inc Antibody having anti-cancer … The Plectin-1 targeted agents for detection and treatment …

71. Patentee Index – United States Patent and Trademark Office

http://www.uspto.gov/web/patents/patog/week53/OG/patentee/alphaK.htm

list of patentees to whom patents were issued on the 31th day of december, 2013 and to whom reexamination certificates were issued during the week …

72. Patentee Index – United States Patent and Trademark Office

http://www.uspto.gov/web/patents/patog/week40/OG/patentee/alphaK_Utility.htm

… Uemoto, Shinji; and Kawaguchi, Yoshiya, to Kyoto University Method of culturingpancreatic islet-like tissues by a … of breast cancer 08853183 …

Clinical Trials:

Region Name

Number of Studies

World

1824

Africa [map]

Central America [map]

East Asia [map]

179

Japan

[studies]

Europe [map]

444

Middle East [map]

North America

1189

Canada [map]

102

[studies]

Mexico

[studies]

United States [map]

1144

[studies]

Alabama	60	[studies]
Alaska	4	[studies]
Arizona	107	[studies]
Arkansas	23	[studies]
California	235	[studies]
Colorado	79	[studies]
Connecticut	51	[studies]
Delaware	15	[studies]
District of Columbia	36	[studies]
Florida	187	[studies]
Georgia	77	[studies]
Hawaii	15	[studies]
Idaho	11	[studies]
Illinois	139	[studies]
Indiana	94	[studies]
Iowa	51	[studies]
Kansas	39	[studies]
Kentucky	48	[studies]
Louisiana	46	[studies]
Maine	11	[studies]
Maryland	189	[studies]
Massachusetts	142	[studies]
Michigan	116	[studies]
Minnesota	114	[studies]
Mississippi	14	[studies]
Missouri	91	[studies]
Montana	27	[studies]
Nebraska	42	[studies]
Nevada	32	[studies]
New Hampshire	25	[studies]
New Jersey	64	[studies]
New Mexico	27	[studies]
New York	230	[studies]
North Carolina	111	[studies]
North Dakota	22	[studies]
Ohio	136	[studies]
Oklahoma	41	[studies]
Oregon	54	[studies]
Pennsylvania	180	[studies]
Rhode Island	23	[studies]
South Carolina	72	[studies]
South Dakota	23	[studies]
Tennessee	115	[studies]
Texas	212	[studies]
Utah	36	[studies]
Vermont	11	[studies]
Virginia	69	[studies]
Washington	83	[studies]
West Virginia	12	[studies]
Wisconsin	74	[studies]
Wyoming	9	[studies]

North Asia [map]

Pacifica [map]

South America [map]

South Asia [map]

Southeast Asia [map]

Search Results for ‘pancreas cancer’

Genomics and Epigenetics: Genetic Errors and Methodologies – Cancer and Other Diseases on March 25, 2015 | Read Full Post »

@Mayo Clinic: Inhibiting the gene, protein kinase D1 (PKD1), and its protein could stop spread of this form of Pancreatic Cancer on February 24, 2015 Read Full Post »

The Changing Economics of Cancer Medicine: Causes for the Vanishing of Independent Oncology Groups in the US on November 26, 2014 | Read Full Post »

Autophagy-Modulating Proteins and Small Molecules Candidate Targets for Cancer Therapy: Commentary of Bioinformatics Approaches on September 18, 2014 | Read Full Post »

New Immunotherapy Could Fight a Range of Cancers on June 4, 2014 Read Full Post »

Locally Advanced Pancreatic Cancer: Efficacy of FOLFIRINOX on June 1, 2014 Read Full Post »

ipilimumab, a Drug that blocks CTLA-4 Freeing T cells to Attack Tumors @DM Anderson Cancer Center on May 28, 2014 | Read Full Post »

NIH Study Demonstrates that a New Cancer Immunotherapy Method could be Effective against a wide range of Cancers on May 12, 2014 |

Cancer Research: Curations and Reporting Posted in on May 6, 2014 | Read Full Post »

Cancer Research: Curations and Reporting: Aviva Lev-Ari, PhD, RN on April 20, 2014 | Read Full Post »

Prologue to Cancer – e-book Volume One – Where are we in this journey? on April 13, 2014 | Read Full Post »

Epilogue: Envisioning New Insights in Cancer Translational Biology on April 4, 2014 | Read Full Post »

A Synthesis of the Beauty and Complexity of How We View Cancer

on March 26, 2014 Read Full Post »

Pancreatic Cancer Diagnosis: Four Novel Histo-pathologies Screening Characteristics offers more Reliable Identification of Cellular Features associated with Cancer

on November 13, 2013 | Read Full Post »

What`s new in pancreatic cancer research and treatment?

on October 21, 2013 | Read Full Post »

Family History of Cancer may increase the Risk of Close Relatives developing the Same Type of Cancer as well as Different Types

on July 25, 2013 Read Full Post »

2013 Perspective on “War on Cancer” on December 23, 1971

on July 5, 2013 Read Full Post »

Mesothelin: An early detection biomarker for cancer (By Jack Andraka) on April 21, 2013 | Read Full Post »

Pancreatic Cancer: Genetics, Genomics and Immunotherapy

on April 11, 2013 | Read Full Post »

New methods for Study of Cellular Replication, Growth, and Regulation on March 25, 2015 Read Full Post »

Diet and Diabetes on March 2, 2015 | Read Full Post »

Neonatal Pathophysiology on February 22, 2015 | Read Full Post »

Endocrine Action on Midbrain on February 12, 2015 | Read Full Post »

Gastrointestinal Endocrinology on February 10, 2015 | Read Full Post »

Parathyroids and Bone Metabolism on February 10, 2015 | Read Full Post »

Pancreatic Islets on February 8, 2015 | Read Full Post »

Pituitary Neuroendocrine Axis on February 4, 2015 |Read Full Post »

Highlights in the History of Physiology on December 28, 2014 | Read Full Post »

Outline of Medical Discoveries between 1880 and 1980 on December 3, 2014 | Read Full Post »

Diagnostics Industry and Drug Development in the Genomics Era: Mid 80s to Present on November 21, 2014 Read Full Post »

Implantable Medical Devices to 2015 – Industry Market Research, Market Share, Market Size, Sales, Demand Forecast, Market Leaders, Company Profiles, Industry Trends on November 17, 2014 | Read Full Post »

Pharmacological Action of Steroid Hormones on October 27, 2014 | Read Full Post »

Metabolomics Summary and Perspective on October 16, 2014 | Read Full Post »

Pancreatic Tumors take nearly 20 years to become Lethal after the first Genetic Perturbations – Discovery @ The Johns Hopkins University on October 15, 2014 |Read Full Post »

Isoenzymes in cell metabolic pathways on October 6, 2014 | Read Full Post »

Metformin, thyroid-pituitary axis, diabetes mellitus, and metabolism on September 28, 2014 | Read Full Post »

Carbohydrate Metabolism on August 13, 2014 | Read Full Post »

A Primer on DNA and DNA Replication on July 29, 2014 | Read Full Post »

The Discovery and Properties of Avemar – Fermented Wheat Germ Extract: Carcinogenesis Suppressor on June 7, 2014 | Read Full Post »

Previous Articles posted on Prostate Cancer

@Mayo Clinic: Inhibiting the gene, protein kinase D1 (PKD1), and its protein could stop spread of this form of Pancreatic Cancer	2012pharmaceutical		2015/02/24 Published
Thymoquinone, an extract of nigella sativa seed oil, blocked pancreatic cancer cell growth and killed the cells by enhancing the process of programmed cell death.	larryhbern	2014/07/15 Published
Moringa Oleifera Kills 97% of Pancreatic Cancer Cells in Vitro	larryhbern	2014/06/21 Published
The Gonzalez protocol: Worse than useless for pancreatic cancer	sjwilliamspa	2014/06/17 Published
An alternative approach to overcoming the apoptotic resistance of pancreatic cancer	2012pharmaceutical	2014/06/03 Published
Locally Advanced Pancreatic Cancer: Efficacy of FOLFIRINOX	2012pharmaceutical	2014/06/01 Published
Consortium of European Research Institutions and Private Partners will develop a microfluidics-based lab-on-a-chip device to identify Pancreatic Cancer Circulating Tumor Cells (CTC) in blood	2012pharmaceutical	2014/04/10 Published
Pancreatic Cancer Diagnosis: Four Novel Histo-pathologies Screening Characteristics offers more Reliable Identification of Cellular Features associated with Cancer	2012pharmaceutical	2013/11/13 Published
What`s new in pancreatic cancer research and treatment?	2012pharmaceutical	2013/10/21 Published
Pancreatic Cancer: Genetics, Genomics and Immunotherapy	tildabarliya	2013/04/11 Published
Pancreatic cancer genomes: Axon guidance pathway genes – aberrations revealed	2012pharmaceutical	2012/10/24 Published
Biomarker tool development for Early Diagnosis of Pancreatic Cancer: Van Andel Institute and Emory University	2012pharmaceutical	2012/10/24 Published
Personalized Pancreatic Cancer Treatment Option	2012pharmaceutical	2012/10/16 Published
Battle of Steve Jobs and Ralph Steinman with Pancreatic cancer: How we lost	ritusaxena	2012/05/21 Published
Early Biomarker for Pancreatic Cancer Identified	pkandala	2012/05/17 Published
Usp9x: Promising therapeutic target for pancreatic cancer	ritusaxena	2012/05/14 Published
War on Cancer Needs to Refocus to Stay Ahead of Disease Says Cancer Expert	sjwilliamspa	2015/03/27 Published
Antibiotics that target mitochondria effectively eradicate cancer stem cells, across multiple tumor types: Treating cancer like an infectious disease	2012pharmaceutical	2015/02/15 Published
Pancreatic Islets	larryhbern	2015/02/08 Publ

Vol 13, No 4 (2012): July – p. 330-469	Molecular Biology of Pancreatic Cancer: How Useful Is It in Clinical Practice?	ABSTRACT HTML PDF
George H Sakorafas, Vasileios Smyrniotis

Vol 13, No 4 (2012): July – p. 330-469	Endoscopic Findings of Upper Gastrointestinal Lesions in Patients with Pancreatic Cancer	ABSTRACT HTML PDF
Koushiro Ohtsubo, Hiroyuki Watanabe, Hisatsugu Mouri, Kaname Yamashita, Kazuo Yasumoto, Seiji Yano

Vol 13, No 5 (2012): September – p. 470-547	Two Avirulent, Lentogenic Strains of Newcastle Disease Virus Are Cytotoxic for Some Human Pancreatic Tumor Lines In Vitro	ABSTRACT HTML PDF
Robert J Walter, Bashar M Attar, Asad Rafiq, Megan Delimata, Sooraj Tejaswi

Vol 14, No 3 (2013): May – p. 221-303	Duration of Diabetes and Pancreatic Cancer in a Case-Control Study in the Midwest and the Iowa Women’s Health Study (IWHS) Cohort	ABSTRACT HTML PDF
Sarah A Henry, Anna E Prizment, Kristin E Anderson

Vol 16, No 1 (2015): January – p. 1-99	Endoscopic Management of Pain in Pancreatic Cancer	ABSTRACT HTML PDF
Parit Mekaroonkamol, Field F Willingham, Saurabh Chawla

Vol 14, No 2 (2013): March – p. 109-220	Advancements in the Management of Pancreatic Cancer: 2013	ABSTRACT HTML PDF
Muhammad Wasif Saif

Vol 15, No 5 (2014): September – p. 413-540	New-onset Diabetes: A Clue to the Early Diagnosis of Pancreatic Cancer	ABSTRACT HTML PDF
Suresh T Chari

Vol 13, No 5 (2012): September – p. 470-547	Effects of Porcine Pancreatic Enzymes on the Pancreas of Hamsters. Part 2: Carcinogenesis Studies	ABSTRACT HTML PDF
Fumiaki Nozawa, Mehmet Yalniz, Murat Saruc, Jens Standop, Hiroshi Egami, Parviz M Pour

Vol 14, No 5 (2013): September – p. 475-527	Synchronous Triple Cancers of the Pancreas, Stomach, and Cecum Treated with S-1 Followed by Pancrelipase Treatment of Pancreatic Exocrine Insufficiency	ABSTRACT HTML PDF
Koushiro Ohtsubo, Daisuke Ishikawa, Shigeki Nanjo, Shinji Takeuchi, Tadaaki Yamada, Hisatsugu Mouri, Kaname Yamashita, Kazuo Yasumoto, Toshifumi Gabata, Osamu Matsui, Hiroko Ikeda, Yasushi Takamatsu, Sakae Iwakami, Seiji Yano

Vol 13, No 1 (2012): January – p. 1-123	Newcastle Disease Virus LaSota Strain Kills Human Pancreatic Cancer Cells in Vitro with High Selectivity	ABSTRACT HTML PDF
Robert J Walter, Bashar M Attar, Asad Rafiq, Sooraj Tejaswi, Megan Delimata

Vol 13, No 3 (2012): May – p. 252-329	Rare Solid Tumors of the Pancreas as Differential Diagnosis of Pancreatic Adenocarcinoma	ABSTRACT HTML PDF
Sabine Kersting, Monika S Janot, Johanna Munding, Dominique Suelberg, Andrea Tannapfel, Ansgar M Chromik, Waldemar Uhl, Uwe Bergmann

Vol 14, No 4 (2013): July – p. 304-474	A Proteomic Comparison of Formalin-Fixed Paraffin-Embedded Pancreatic Tissue from Autoimmune Pancreatitis, Chronic Pancreatitis, and Pancreatic Cancer	ABSTRACT HTML PDF SUPPL. TABLES 1-4 (PDF)
Joao A Paulo, Vivek Kadiyala, Scott Brizard, Peter A Banks, Hanno Steen, Darwin L Conwell

Vol 13, No 4 (2012): July – p. 330-469	Highlights on the First Line Treatment of Metastatic Pancreatic Cancer	ABSTRACT HTML PDF
Krishna S Gunturu, Jamie Jarboe, Muhammad Wasif Saif

Vol 14, No 2 (2013): March – p. 109-220	Pancreatic Cancer: Updates on Translational Research and Future Applications	ABSTRACT HTML PDF
Evangelos G Sarris, Konstantinos N Syrigos, Muhammad Wasif Saif

Vol 14, No 4 (2013): July – p. 304-474	Pancreatic Cancer: What About Screening and Detection?	ABSTRACT HTML PDF
Froso Konstantinou, Kostas N Syrigos, Muhammad Wasif Saif

Vol 14, No 4 (2013): July – p. 304-474	Diabetes and Pancreatic Cancer	ABSTRACT HTML PDF
Najla Hatem El-Jurdi, Muhammad Wasif Saif

Vol 13, No 5 (2012): September – p. 470-547	Effects of Porcine Pancreatic Enzymes on the Pancreas of Hamsters. Part 1: Basic Studies	ABSTRACT HTML PDF
Murat Saruc, Fumiaki Nozawa, Mehmet Yalniz, Atsushi Itami, Parviz M Pour

Vol 14, No 2 (2013): March – p. 109-220	Analysis of Endoscopic Pancreatic Function Test (ePFT)-Collected Pancreatic Fluid Proteins Precipitated Via Ultracentrifugation	ABSTRACT HTML PDF SUPPL.(XLS) SUPPL.(PDF)
Joao A Paulo, Vivek Kadiyala, Aleksandr Gaun, John F K Sauld, Ali Ghoulidi, Peter A Banks, Hanno Steen, Darwin L Conwell

Vol 16, No 1 (2015): January – p. 1-99	Regulation Mechanisms of the Hedgehog Pathway in Pancreatic Cancer: A Review	ABSTRACT HTML PDF
Kim Christin Honselmann, Moritz Pross, Carlo Maria Felix Jung, Ulrich Friedrich Wellner, Steffen Deichmann, Tobias Keck, Dirk Bausch

Vol 14, No 5S (2013): September (Suppl.) – p. 528-602	History of Previous Cancer in Patients Undergoing Resection for Pancreatic Adenocarcinoma	ABSTRACT PDF
*Francesca Gavazzi, Maria Rachele Angiolini, Cristina Ridolfi, Maria Carla Tinti, Marco Madonini, Marco Montorsi, Alessandro Zerbi*

Vol 13, No 4 (2012): July – p. 330-469	Molecular Biology of Pancreatic Cancer: How Useful Is It in Clinical Practice?	ABSTRACT HTML PDF
George H Sakorafas, Vasileios Smyrniotis

Vol 13, No 4 (2012): July – p. 330-469	Endoscopic Findings of Upper Gastrointestinal Lesions in Patients with Pancreatic Cancer	ABSTRACT HTML PDF
Koushiro Ohtsubo, Hiroyuki Watanabe, Hisatsugu Mouri, Kaname Yamashita, Kazuo Yasumoto, Seiji Yano

Vol 13, No 5 (2012): September – p. 470-547	Two Avirulent, Lentogenic Strains of Newcastle Disease Virus Are Cytotoxic for Some Human Pancreatic Tumor Lines In Vitro	ABSTRACT HTML PDF
Robert J Walter, Bashar M Attar, Asad Rafiq, Megan Delimata, Sooraj Tejaswi

Vol 14, No 3 (2013): May – p. 221-303	Duration of Diabetes and Pancreatic Cancer in a Case-Control Study in the Midwest and the Iowa Women’s Health Study (IWHS) Cohort	ABSTRACT HTML PDF
Sarah A Henry, Anna E Prizment, Kristin E Anderson

Vol 16, No 1 (2015): January – p. 1-99	Endoscopic Management of Pain in Pancreatic Cancer	ABSTRACT HTML PDF
Parit Mekaroonkamol, Field F Willingham, Saurabh Chawla

Vol 14, No 2 (2013): March – p. 109-220	Advancements in the Management of Pancreatic Cancer: 2013	ABSTRACT HTML PDF
Muhammad Wasif Saif

Vol 15, No 5 (2014): September – p. 413-540	New-onset Diabetes: A Clue to the Early Diagnosis of Pancreatic Cancer	ABSTRACT HTML PDF
Suresh T Chari

Vol 13, No 5 (2012): September – p. 470-547	Effects of Porcine Pancreatic Enzymes on the Pancreas of Hamsters. Part 2: Carcinogenesis Studies	ABSTRACT HTML PDF
Fumiaki Nozawa, Mehmet Yalniz, Murat Saruc, Jens Standop, Hiroshi Egami, Parviz M Pour

Vol 14, No 5 (2013): September – p. 475-527	Synchronous Triple Cancers of the Pancreas, Stomach, and Cecum Treated with S-1 Followed by Pancrelipase Treatment of Pancreatic Exocrine Insufficiency	ABSTRACT HTML PDF
Koushiro Ohtsubo, Daisuke Ishikawa, Shigeki Nanjo, Shinji Takeuchi, Tadaaki Yamada, Hisatsugu Mouri, Kaname Yamashita, Kazuo Yasumoto, Toshifumi Gabata, Osamu Matsui, Hiroko Ikeda, Yasushi Takamatsu, Sakae Iwakami, Seiji Yano

Vol 13, No 1 (2012): January – p. 1-123	Newcastle Disease Virus LaSota Strain Kills Human Pancreatic Cancer Cells in Vitro with High Selectivity	ABSTRACT HTML PDF
Robert J Walter, Bashar M Attar, Asad Rafiq, Sooraj Tejaswi, Megan Delimata

Vol 13, No 3 (2012): May – p. 252-329	Rare Solid Tumors of the Pancreas as Differential Diagnosis of Pancreatic Adenocarcinoma	ABSTRACT HTML PDF
Sabine Kersting, Monika S Janot, Johanna Munding, Dominique Suelberg, Andrea Tannapfel, Ansgar M Chromik, Waldemar Uhl, Uwe Bergmann

Vol 14, No 4 (2013): July – p. 304-474	A Proteomic Comparison of Formalin-Fixed Paraffin-Embedded Pancreatic Tissue from Autoimmune Pancreatitis, Chronic Pancreatitis, and Pancreatic Cancer	ABSTRACT HTML PDF SUPPL. TABLES 1-4 (PDF)
Joao A Paulo, Vivek Kadiyala, Scott Brizard, Peter A Banks, Hanno Steen, Darwin L Conwell

Vol 13, No 4 (2012): July – p. 330-469	Highlights on the First Line Treatment of Metastatic Pancreatic Cancer	ABSTRACT HTML PDF
Krishna S Gunturu, Jamie Jarboe, Muhammad Wasif Saif

Vol 14, No 2 (2013): March – p. 109-220	Pancreatic Cancer: Updates on Translational Research and Future Applications	ABSTRACT HTML PDF
Evangelos G Sarris, Konstantinos N Syrigos, Muhammad Wasif Saif

Vol 14, No 4 (2013): July – p. 304-474	Pancreatic Cancer: What About Screening and Detection?	ABSTRACT HTML PDF
Froso Konstantinou, Kostas N Syrigos, Muhammad Wasif Saif

Vol 14, No 4 (2013): July – p. 304-474	Diabetes and Pancreatic Cancer	ABSTRACT HTML PDF
Najla Hatem El-Jurdi, Muhammad Wasif Saif

Vol 13, No 5 (2012): September – p. 470-547	Effects of Porcine Pancreatic Enzymes on the Pancreas of Hamsters. Part 1: Basic Studies	ABSTRACT HTML PDF
Murat Saruc, Fumiaki Nozawa, Mehmet Yalniz, Atsushi Itami, Parviz M Pour

Vol 14, No 2 (2013): March – p. 109-220	Analysis of Endoscopic Pancreatic Function Test (ePFT)-Collected Pancreatic Fluid Proteins Precipitated Via Ultracentrifugation	ABSTRACT HTML PDF SUPPL.(XLS) SUPPL.(PDF)
Joao A Paulo, Vivek Kadiyala, Aleksandr Gaun, John F K Sauld, Ali Ghoulidi, Peter A Banks, Hanno Steen, Darwin L Conwell

Vol 16, No 1 (2015): January – p. 1-99	Regulation Mechanisms of the Hedgehog Pathway in Pancreatic Cancer: A Review	ABSTRACT HTML PDF
Kim Christin Honselmann, Moritz Pross, Carlo Maria Felix Jung, Ulrich Friedrich Wellner, Steffen Deichmann, Tobias Keck, Dirk Bausch

Vol 14, No 5S (2013): September (Suppl.) – p. 528-602	History of Previous Cancer in Patients Undergoing Resection for Pancreatic Adenocarcinoma	ABSTRACT PDF
*Francesca Gavazzi, Maria Rachele Angiolini, Cristina Ridolfi, Maria Carla Tinti, Marco Madonini, Marco Montorsi, Alessandro Zerbi*

See more at http://personalizedmedicine.partners.org/Education/Personalized-Medicine-Conference/Program.aspx#sthash.qGbGZXXf.dpuf

11:30AM 11/13/2014 – Role of Genetics and Genomics in Pharmaceutical Development @10th Annual Personalized Medicine Conference at the Harvard Medical School, Boston

Posted in Academic Publishing, Conference Coverage with Social Media, Personalized and Precision Medicine & Genomic Research, Pharmaceutical Analytics, Pharmaceutical Drug Discovery, Pharmaceutical Industry Competitive Intelligence, Pharmaceutical R&D Investment, Pharmacodynamics and Pharmacokinetics, Pharmacogenomics, Scientific & Biotech Conferences: Press Coverage, tagged Alzheimer's Disease Neuroimaging Initiative, anti-cancer therapy, companion diagnostics, imaging agent, imaging-based diagnosis, oncology on November 13, 2014| Leave a Comment »

11:30AM 11/13/2014 – 10th Annual Personalized Medicine Conference at the Harvard Medical School, Boston

Reporter: Aviva Lev-Ari, PhD, RN

REAL TIME Coverage of this Conference by Dr. Aviva Lev-Ari, PhD, RN – Director and Founder of LEADERS in PHARMACEUTICAL BUSINESS INTELLIGENCE, Boston http://pharmaceuticalintelligence.com

11:30 a.m. – Keynote Speaker – Role of Genetics and Genomics in Pharmaceutical Development

Role of Genetics and Genomics in Pharmaceutical Development

There was a time when pharmaceutical companies attempted to develop drugs that could be used to treat large populations of individuals diagnosed with a particular disease. These drugs were used to treat large groups of patients and were not always effective for all patients. The paradigm of drug development is changing where highly targeted drugs that would be highly effective in specific sub populations of patients are becoming the new norm. Dr. Skovronsky will describe how the pharmaceutical industry as a whole and Lilly in particular is taking advantage of the new knowledge about the genetic basis of disease to develop highly effective therapies.

Role of Genetics and Genomics in Pharmaceutical Development

Daniel Skovronsky, M.D., Ph.D.
Vice President of Tailored Therapeutics, Lilly

@EliLillyCo

@LillyHealth

Alzheimer’s Disease

early detection
how do drugs work in Alzheimer’s Disease (AD) – difficult to conduct Clinical Trials
Personalized the treatment as early on as possible: looking inside the brain and track the disease
images of the pathology of AD – Amyloid imaging using agents
diagnostics test on autopsy of AD brains after death
Risk of Progression
amyloid deposition over time – Dynamics of accumulations
Autopsy of brains of AD: MANY AD patients have negative scans
Clinical Trial definition of AD: 22% did not have amyloid — WERE TREATED WITH ANTI Amyloid DRUGS (22% Solanezumab, 16% Bapineuzumab)
1/2 have DX of AD and treated with targeted drug — have negative Scans for Amyloid deposits — NOT PROGRESSING
those progressing are those with Positive Scans
18 month and 36 month – Progression of Amyloid — Only at Positive scans
A4 Trial Dx Florbetapir
Rx solanezumab – symptomatic dementia vs AD
Markers o=for the disease – Neural degeneration – Tau in temporal lobe
Treat patient with start of Tau — avoid progression to amyloid deposition

CANCER

Companion Diagnostics (CD) vs Therapeutics – start to find the biomarkers at the same time: Drug and Diagnostics
DNA, RNA, Protein
Diagnostics –>> translation
CLIA lab at Eli Lilly for companion diagnostics
Biomarker Negative vs Positive ans a spectrum of results
Immunohistochemistry (IHC) for protein expression – simple assay, complicated test
two different agent at two different albs — give two different diagnostics
Tumor heterogeneity: Glioblastoma
Tissue scarce resource — it is separated in time Biopsy taken at different times
Detection of chromosomal – Liquid Biopsy – Exosomes
mRNA, miRNA
Summary: Prime key porters to quickly bring therapies to patients

– See more at: http://personalizedmedicine.partners.org/Education/Personalized-Medicine-Conference/Program.aspx#sthash.qGbGZXXf.dpuf

1:45PM 11/12/2014 – Panel Discussion – Oncology @10th Annual Personalized Medicine Conference at the Harvard Medical School, Boston

Posted in Academic Publishing, Conference Coverage with Social Media, Personalized and Precision Medicine & Genomic Research, Scientific & Biotech Conferences: Press Coverage, tagged #endcancer, #meded, anti-cancer therapy, Big data, biochemotherapy, Bioinformatics, Chemogenomics, genomic drug development, genomics, health outcomes research, Huntsman Intermountain, MD Anderson Cancer center, medical education, Medical Ethics, oncology, Personalized medicine, Targeted therapy on November 12, 2014| Leave a Comment »

1:45PM 11/12/2014 – 10th Annual Personalized Medicine Conference at the Harvard Medical School, Boston

Reporter: Aviva Lev-Ari, PhD, RN

REAL TIME Coverage of this Conference by Dr. Aviva Lev-Ari, PhD, RN – Director and Founder of LEADERS in PHARMACEUTICAL BUSINESS INTELLIGENCE, Boston http://pharmaceuticalintelligence.com

1:45 p.m. Panel Discussion – Oncology

Oncology

There has been a remarkable transformation in our understanding of the molecular genetic basis of cancer and its treatment during the past decade or so. In depth genetic and genomic analysis of cancers has revealed that each cancer type can be sub-classified into many groups based on the genetic profiles and this information can be used to develop new targeted therapies and treatment options for cancer patients. This panel will explore the technologies that are facilitating our understanding of cancer, and how this information is being used in novel approaches for clinical development and treatment.

Oncology

Opening Speaker & Moderator:

Lynda Chin, M.D.
Department Chair, Department of Genomic Medicine
MD Anderson Cancer Center @MDAnderson #endcancer

Who pays for personalized medicine?
potential of Big data, analytics, Expert systems, so not each MD needs to see all cases, Profile disease to get same treatment
business model: IP, Discovery, sharing, ownership — yet accelerate therapy
security of healthcare data
segmentation of patient population
management of data and tracking innovations
platforms to be shared for innovations
study to be longitudinal,
How do we reconcile course of disease with personalized therapy
phenotyping the disease vs a Patient in wait for cure/treatment

Panelists:

Roy Herbst, M.D., Ph.D. @DrRoyHerbstYale

Ensign Professor of Medicine and Professor of Pharmacology;
Chief of Medical Oncology, Yale Cancer Center and Smilow Cancer Hospital @YaleCancer

Development new drugs to match patient, disease and drug – finding the right patient for the right Clinical Trial

match patient to drugs
partnerships: out of 100 screened patients, 10 had the gene, 5 were able to attend the trial — without the biomarker — all 100 patients would participate for the WRONG drug for them (except the 5)
patients wants to participate in trials next to home NOT to have to travel — now it is in the protocol
Annotated Databases – clinical Trial informed consent – adaptive design of Clinical Trial vs protocol
even Academic MD can’t read the reports on Genomics
patients are treated in the community — more training to MDs
Five companies collaborating – comparison of 6 drugs in the same class
if drug exist and you have the patient — you must apply personalized therapy

Lincoln Nadauld, M.D., Ph.D.
Director, Cancer Genomics, Huntsman Intermountain Cancer Clinic @lnadauld @intermountain

@Stanford, all patients get Tumor profiles Genomic results, interpretation – deliver personalized therapy
Outcomes from Genomics based therapies
Is survival superior
Targeted treatment – Health economic impact is cost lower or not for same outcome???
genomic profiling of tumors: Genomic information changes outcome – adverse events lower
Path ways and personalized medicine based on Genomics — integration not yet been worked out

Question by Moderator: Data Management

Platform development, clinical knowledge system,
build consortium of institutions to share big data – identify all patients with same profile

Liver Toxicity halts Clinical Trial of IAP Antagonist for Advanced Solid Tumors

Posted in Biological Networks, Gene Regulation and Evolution, Biomarkers & Medical Diagnostics, BioSimilars, CANCER BIOLOGY & Innovations in Cancer Therapy, Cancer Prevention: Research & Programs, Cell Biology, Signaling & Cell Circuits, Chemical Biology and its relations to Metabolic Disease, Chemical Genetics, Computational Biology/Systems and Bioinformatics, Disease Biology, Small Molecules in Development of Therapeutic Drugs, FDA Regulatory Affairs, Genetics & Innovations in Treatment, Genome Biology, Health Economics and Outcomes Research, Health Law & Patient Safety, Human Immune System in Health and in Disease, Liver & Digestive Diseases Research, Personalized and Precision Medicine & Genomic Research, tagged AAV, adverse effects, anti-cancer therapy, Apoptosis, Aviva Lev-Ari, Cancer - General, DILI, Drug development, drug induced liver injury, Food and Drug Administration, health, hepatoxicity, IAP, idiosyncratic, inflammation, inhibitor of apoptosis, novartis, renal cancer, SMA, Spinal muscular atrophy, toxicology, Zolgensma on November 25, 2013| Leave a Comment »

Liver Toxicity halts Clinical Trial of IAP Antagonist for Advanced Solid Tumors

Curator: Stephen J. Williams, Ph.D.

UPDATED 8/12/2022

Athough not related to IAP Antagonists this update does report 2 deaths from IDILI or idiosynchratic drug induced liver injury from a gene therapy trial using an AAV (adeno associated virus) targeting the disease spinal muscular atrophy. Please see below after reading about IDILI.

A recent press release on FierceBiotech reported the FDA had put a halt on a phase 1 study for advanced refractory solid tumors and lymphomas of Curis Inc. oral inhibitor of apoptosis (IAP) antagonist CUDC-427. The FDA placed the trial on partial clinical hold following reports of a death of a patient from severe liver failure. The single-agent, dose escalation Phase 1 study was designed to determine the maximum tolerated dose and recommended doses for a Phase 2 trial. The press release can be found at:

http://www.fiercebiotech.com/press-releases/curis-reports-third-quarter-2013-financial-results-and-provides-cudc-427-de.

According to the report one patient with breast cancer that had metastasized to liver, lungs, bone, and ovaries developed severe hepatotoxicity as evidenced by elevated serum transaminase activities (AST and ALT) and hyper-billirubinemia. Serum liver enzyme activities did not attenuate upon discontinuation of CUDC-427. This was unlike prior experience to the CUDC-427 drug, in which decreased hepatic function was reversed upon drug discontinuation. The patient died from liver failure one month after discontinuation of CUDC-427.

It was noted that no other patient had experienced such a serious, irreversible liver dysfunction.

Although any incidence of hepatotoxicity can be cause for concern, the incidence of IDIOSYNCRATIC IRREVERSIBLE HEPATOTOXICITY warrants a higher scrutiny.

Four general concepts can explain toxicity profiles and divergences between individuals:

Toxicogenomics: Small differences in the genetic makeup between individuals (such as polymorphisms (SNP) could result in differences in toxicity profile for a drug. This ais a serious possibility as only one patient presented with such irreversible liver damage
Toxicodynamics: The toxicologic effect is an extension of the pharmacologic mechanism of action (or lack thereof: could there have been alternate signaling pathways activated in this patient or noncanonical mechanism)
Toxicokinetic: The differences in toxicological response due to differences in absorption, distribution, metabolism, excretion etc. (kinetic parameters)
Idiosyncratic: etiology is unknown; usually a minority of adverse effects

Since there is not enough information to investigate toxicogenomic or toxicokinetic mechanisms for this compound, the rest of this post will investigate the possible mechanisms of hepatotoxicity due to IAP antagonists and clues from other clinical trials which might shed light on a mechanism of toxicity (toxicodynamic) or idiosyncratic events.

Therefore this post curates the current understanding of drug-induced liver injury (DILI), especially focusing on a type of liver injury referred to as idiosyncratic drug-induced liver injury (IDILI) in the context of:

Targeted and newer chemotherapies such as IAP antagonists
Current concepts of mechanisms of IDILI including:

i) Inflammatory responses provoked by presence of disease

ii) Cellular stresses, provoked by disease, uncovering NONCANONICAL toxicity pathways

iii) Pharmacogenomics risk factors of IDILI

Eventually this post aims to stimulate the discussion:

Given inflammation, genetic risk factors, and cellular stresses (seen in clinical setting) have been implicated in idiosyncratic drug-induced liver injury from targeted therapies, should preclinical hepatotoxicity studies also be conducted in the presence of the metastatic disease?
Does inflammation and cellular stress from clinical disease unmask NONCANONICAL pharmacologic and/or toxicological mechanisms of action?

Classification of types of Cellular Liver injury: A listing of types of cellular injury is given for review

I. Hepatic damage after Acute Exposure

A. Cytotoxic (Necrotic): irreversible cell death characterized by loss of cell membrane integrity, intracellular swelling, nuclear shrinkage (pyknosis) and eventual cytoplasmic breakdown of nuclear DNA (either by a process known as karyolysis or karyorhexus) localized inflammation as a result of release of cellular constituents. Intracellular ATP levels are commonly seen in necrotic death. Necrosis, unlike apoptosis, does not require a source of ATP. A nice review by Yoshihide Tsujimoto describing and showing (by microscopy) the differences between apoptosis and necrosis can be found here.

B. Cholestatic: hepatobiliary dysfunction with bile stasis and accumulation of bile salts. Cholestatic injury can result in lipid (particularly cholesterol) accumulation in cannicular membranes resulting in decreased permeability of the membrane, hyperbillirubinemia and is generally thought to result in metabolic defects.

C. Lipid Peroxidation: free radical generation producing peroxide of cellular lipids, generally resulting in a cytotoxic cell death

II. Hepatic damage after Chronic Exposure

A. Chirrotic: Chronic morphologic alteration of the liver characterized by the presence of septae of collagen distributed throughout the major portion of the liver; Forms fibrous sheaths altering hepatic blood flow, resulting in a necrotic process with scar tissue; Alteration of hepatic metabolic systems.

B. Carcinogenesis

III. Idiosyncratic Drug Induced Liver Injury

The aforementioned mechanisms of hepatotoxicity are commonly referred to as the “intrinsic” (or end target-organ) toxicity mechanisms. Idiosyncratic drug-induced liver injury (IDILI) is not well understood but can be separated into allergic and nonallergic reactions. Although the risk of acute liver failure associated with idiosyncratic hepatotoxins is low (about 1 in ten thousand patients) there are more than 1,000 drugs and herbal products associated with this type of toxic reaction. Idiosyncratic drug induced liver failure usually gets a black box warning from the FDA. Idiosyncratic drug-induced liver injury differs from “intrinsic” toxicity in that IDILI:

Happens in a minority of patients (susceptible patients)
Not reproducible in animal models
Not dose-dependent
Variable time of onset
Variable liver pathology (not distinctive lesions)
Not related to drug’s pharmacologic mechanism of action (trovafloxacin IDILI vs. levofloxacin)

A great review in Perspectives in Pharmacology written by Robert Roth and Patricia Ganey at Michigan State University explains these differences between intrinsic and idiosyncratic drug-induced hepatotoxicity[1] (however authors do note that there are many similarities between the two mechanisms). It is felt that drug sensitivity (allergic) and inflammatory responses (nonallergic) may contribute to the occurrence of IDILI. For instance lipopolysaccharide (LPS) form bacteria can potentiate acetaminophen toxicity. In fact animal models of IDILI have been somewhat successful:

co-treatment of rats and mice with nontoxic doses of trovafloxacin (casues IDILI in humans) and LPS resulted in marked hepatotoxicity while no hepatotoxicity seen with levofloxacin plus LPS[2]
correlates well with incidence of human IDILI (adapted from a review Inflammatory Stress and Idiosyncratic Hepatotoxicity: Hints from Animal Models (in Pharmacology Reviews)[3]. Idiosyncratic injury damage has been reported for diclofenac, halothane, and sulinac. These drugs also show hepatotoxicity in the LPS model for IDILI.
Roth and Ganey suggest the reason why idiosyncratic hepatotoxicity is not seen in most acute animal toxicity studies is that, in absence of stress/inflammation IDILI occurrence is masked by lethality but stress/inflammation shifts increases sensitivity to liver injury at a point before lethality is seen

Figure. Idiosyncratic toxic responses of the liver. In the absence of stress and/or genetic factors, drug exposure may result in an idiosyncratic liver injury (IDILI) at a point (or dose) beyond the therapeutic range and lethal exposure for that drug. Preclinical studies, usually conducted at sublethal doses, would not detect DILI . Stress and/or genetic factors sensitize the liver to toxic effects of the drug (synergism) and DILI is detected at exposure levels closer to therapeutic range. Note IDILI is not necessarily dose-dependent but cellular stress (like ROS or inflammation) may expose NONCANONICAL mechanisms of drug action or toxicity which result in IDILI. Model adapted from Roth and Ganey.

What Stress factors contribute to IDILI?

Various stresses including inflammation from bacterial, viral infections ,inflammatory cytokines and stress from reactive oxygen (ROS) have been suggested as mechanisms for IDILI.

Inflammation/Cytokines (also discussed in other sections of this post): Inflammation has long been associated with human cases of DILI. Many cytokines and inflammatory mediators have been implicated including TNFα, IL7, TGFβ, and IFNϒ (viral infection) leading some to conclude that serum measurement of cytokines could be a potential biomarker for DILI[4]. In addition, ROS (see below) is generated from inflammation and also considered a risk factor for DILI[5].
Reactive Oxygen (ROS)/Reactive Metabolites: Oxidative stress, either generated from reactive drug metabolites or from mitochondrial sources, has been shown to be involved in apoptotic and necrotic cell death. Both alterations in the enzymes involved in the generation of and protection from ROS have been implicated in increased risk to DILI including (as discussed further) alterations in mitochondrial superoxide dismutase 2 (SOD2) and glutathione S-transferases. Both ROS and inflammatory cytokines can promote JNK signaling, which has been implicated in DILI[6].

Dr. Neil Kaplowitz suggested that we:

“develop a unifying hypothesis that involves underlying genetic or acquired mitochondrial abnormalities as a major determinant of susceptibility for a number of drugs that target mitochondria and cause DILI. The mitochondrial hypothesis, implying gradually accumulating and initially silent mitochondrial injury in heteroplasmic cells which reaches a critical threshold and abruptly triggers liver injury, is consistent with the findings that typically idiosyncratic DILI is delayed (by weeks or months), that increasing age and female gender are risk factors and that these drugs are targeted to the liver and clearly exhibit a mitochondrial hazard in vitro and in vivo. New animal models (e.g., the Sod2(+/-) mouse) provide supporting evidence for this concept. However, genetic analyses of DILI patient samples are needed to ultimately provide the proof-of-concept”[7].

Figures. Mechanisms of Drug-Induced Liver Injury and Factors related to the occurrence of DILI (used with permission from Oxford Press; reference [7])

To this end, Dr. Brett Howell and other colleagues at the Hamner-UNC Institute for Drug Safety Sciences (IDSS) developed an in-silico model of DILI ( the DILISym™ model)which is based on depletion of cellular ATP and reactive metabolite formation as indices of DILI.

Have there been Genetic Risk Factors identified for DILI?

Candidate-gene-associated studies (CGAS) have been able to identify several genetic risk factors for DILI including:

Uridine Diphosphate Glucuronosyltransferase 2B7 (UGT2B7): variant increased susceptibility to diclofenac-induced DILI
Adenosine triphosphate-binding cassette C2 (ABCC2) variant ABCC-24CT increased susceptibility to diclofenac-induced DILI
Glutathione S-transferase (GSTT1): patients with a double GSTT1-GSTM1 null genotype had a significant 2.7 fold increased risk of DILI from nonsteroidal anti-inlammatory agents, troglitazone and tacrine. GSTs are involved in the detoxification of phase 1 metabolites and also protect against cellular ROS.

Although these CGAS confirmed these genetic risk factors, Stefan Russman suggests a priori genome-wide association studies (GWAS) might provide a more complete picture of genetic risk factors for DILI as CGAS is limited due to

Candidate genes are selected based on current mechanisms and knowledge of DILI so genetic variants with no known knowledge of or mechanistic information would not be detected
Many CGAS rely on analysis of a limited number of SNP and did not consider intronic regions which may control gene expression

A priori GWAS have the advantage of being hypothesis-free, and although they may produce a high number of false-positives, new studies of genetic risk factors of ximelagatran, flucioxaciliin and diclofenac-induced liver injury are using a hybrid approach which combines the whole genome and unbiased benefits of GWAS with the confirmatory and rational design of CGAS[8-10].

Even though idiosyncratic DILI is rare, the severity, unpredictable onset, and unknown etiology and risk factors have prompted investigators such as Stefan Russmann from University Hospital Zurich and Ignazio Grattagliano from University of Bari to suggest:

Identification of risk factors for rare idiosyncratic hepatotoxicity requires special networks that contribute to data collection and subsequent identification of environmental as well as genetic risk factors for clinical cases of idiosyncratic DILI[11].

Therefore, a DILI network project (DILIN) had been developed to collect samples and detailed genetic and clinical data on IDILI cases from multiple medical centers. The project aims to identify the upstream and downstream genetic risk factors for IDILI[12]. Please see a SlideShare presentation here of the goals of the DILI network project.

Drs Colin Spraggs and Christine Hunt had reviewed possible genetic risk factors of DILI seen with various tyrosine kinase inhibitors (TKIs) including Lapatinib (Tykerb/Tyverb©, a dual inhibitor of HER2/EGFR heterodimer) and paopanib (Votrient©; a TKI that targets VEGFR1,2,3 and PDGFRs)[13].

From a compilation of studies:

Elevation in serum bilirubin during treatment with lapatinib and pazopanib are associated with UGT1A1 polymorphism related to Gilbert’s syndrome (a clinically benign syndrome)
Anecdotal evidence shows that polymorphisms of lapatinib and pazopanib metabolizing enzymes may contribute to differences seen in onset of DILI
Pazopanib-induced elevations of ALT correlate with HFE variants, suggesting alterations in iron transport may predispose to DILI
Strong correlations between lapatinib-induced DILI and class II HLA locus suggest inflammatory stress response important in DILI

Note that these clinical findings were not evident from the preclinical tox studies. According to the European Medicines Agency assessment report for Tykerb states: “the major findings in repeat dose toxicity studies were attributed to lapatinib pharmacology (epithelial effect in skin and GI system. The toxic events occurred at exposures close to the human exposure at the recommended dose. Repeat-dose toxicity studies did not reveal important safety concerns than what would be expected from the mode of action”.

However, it should be noted that in high dose repeat studies in mice and rats, severe lethality was seen with hematologic, gastrointestinal toxicities in combination with altered blood chemistry parameters and yellowing of internal organs.

IAP Antagonists, Mechanism of Action, and Clinical Trials:

A few IAP antagonists which are in early stage development include:

Norvatis IAP Inhibitor LCL161: at 2012 San Antonia Breast Cancer Symposium, a phase 1 trial in triple negative breast cancer showed promising results when given in combination with paclitaxel.
Ascenta Therapeutics IAP inhibitor AT-406 in phase 1 in collaboration with Debiopharm S.A. showed antitumor efficacy in xenograft models of breast, pancreatic, prostate and lung cancer. The development of this compound is described in a paper by Cai et. al.

National Cancer Institute sponsored trials using antagonists of IAPs include

Phase II Study of Birinapant for Advanced Ovarian, Fallopian Tube, and Peritoneal Cancer (NCI-12-C-0191). Principle Investigator: Dr. Christina Annunziata. See the protocol summary. More open trials for this drug are located here. Closed trials including safety studies can be found here.
A Phase 1 non-randomized dose escalation study to determine maximum tolerated dose (MTD) and characterize the safety for the TetraLogic compound TL32711 had just been completed. Results have not been published yet.
Closed Clinical trials with the IAP antagonist HGS1029 in advanced solid tumors determined that weekly i.v. administration of HGS1029 reported a safety issue for primary outcome measures

A great review on IAP proteins and their role as regulators of apoptosis and potential targets for cancer therapy [14] can be found as a part of a Special Issue in Experimental Oncology “Apoptosis: Four Decades Later”. Human IAPs (inhibitors of apoptosis) consist of eight proteins involved in cell death, immunity, inflammation, cell cycle, and migration including:

In general, IAP proteins are directly involved in inhibiting apoptosis by binding and directly inhibiting the effector cysteine protease caspases (caspase 3/7) ultimately responsible for the apoptotic process [15]. IAPs were actually first identified in baculoviral genomes because of their ability to suppress host-cell death responses during viral infection [16]. IAP proteins are often overexpressed in cancers [17].

Apoptosis is separated into two pathways, defined by the initial stress or death signal and the caspases involved:

Extrinsic pathway: initiated by TNFα and death ligand FasLigand; involves caspase-8; process inhibited by IAP1/2
Intrinsic pathway: initiated by DNA damage, irradiation, chemotherapeutics; mitochondrial pathway involving caspase 9 and cytochrome c release from mitochondria; mitochondria also releases SMAC/DIABLO, which binds and inhibits XIAP (XIAP inhibits the Intrinsic apoptotic pathway.

Intrinsic and Extrinsic pathways of apoptosis. Figure photocredit (wikidot.com)

The Curis IAP antagonist (and others) is a SMAC small molecule mimetic. It is interesting to note [18, 19] that IAP antagonists can result in death by

Apoptosis: an IAP antagonist in presence of competent TNFα signaling
Necrosis: seen with IAP inhibitors in cells with altered TNFα signaling or with presence of caspase inhibitors

IAPs are also involved in the regulation of signaling pathways such as:

NF-ΚB signaling pathway

NF-ΚB is a “rapid-acting” transcription factor which has been found to be overexpressed in various cancers. Under most circumstances NF-ΚB translocation to the nucleus results in transcription of genes related to cell proliferation and survival. NF-ΚB signaling is broken down in two pathways

Canonical: Canonical pathway can be initiated (for example in inflammation) when TNF-α binds its receptors activating death domains (TRADD)
Noncanonical: since requires new protein synthesis takes longer than canonical signaling. Can be initiated by other TNF like ligands like CD40

IAP1/2 is a negative regulator of the noncanonical NF-ΚB signaling pathway by promoting proteosomal degradation of the TRAF signaling complex. A wonderfully annotated list of NF-ΚB target genes can be found on the Thomas Gilmore lab site at Boston University at http://www.bu.edu/nf-kb/gene-resources/target-genes/ .

NF-ΚB has been considered a possible target for chemotherapeutic development however Drs. Veronique Baud and Michael Karin have pondered the utility of IAP antagonists as a good target in their review: Is NF-ΚB a good target for cancer therapy?: Hopes and pitfalls [20]. The authors discuss issues such that IAP antagonism induced both the classical and noncanonical NF-ΚB pathway thru NIK stabilization, resulting in stabilization of NF-ΚB signaling and thereby undoing any chemotherapeutic effect which would be desired.

AKT signaling

IAPs have been shown to interact with other proteins including a report that SIAP regulates AKT activity and caspase-3-dependent cleavage during cisplatin-induced apoptosis in human ovarian cancer cells and could be another mechanism involved in cisplatin resistance[21]. In addition there have been reports that IAPs can regulate JNK and MAPK signaling.

Therefore, IAPs are involved in CANONICAL and NONCANONICAL pathways.

IAPs can Regulate Pro-Inflammatory Cytokines

A recent 2013 JBC paper [22]showed that IAPs and their antagonists can regulate spontaneous and TNF-induced proinflammatory cytokine and chemokine production and release

IAP required for production of multiple TNF-induced proinflammatory mediators
IAP antagonism decreased TNF-mediated production of chemokines and cytokines
But increased spontaneous release of chemokines

In addition Rume Damgaard and Mads Gynd-Hansen have suggested that IAP antagonists may be useful in treating inflammatory diseases like Crohn’s disease as IAPs regulate innate and acquired immune responses[23].

Toxicity profiles of IAP antagonists

NOTE: In a paper in Toxicological Science from 2012[24], Rebecca Ida Erickson form Genentech reported on the toxicity profile of the IAP antagonist GDC-0152 from a study performed in dogs and rats. A dose-dependent toxicity profile from i.v. administration was consistent with TNFα-mediated toxicity with

Elevated plasma cytokines and an inflammatory leukogram
Increased serum transaminases
Inflammatory infiltrate and apoptosis/necrosis in multiple tissues

In a related note, a similar type of fatal idiosyncratic hepatotoxicity was reported in a 62 year-old man treated with the Raf kinase inhibitor sorafenib for renal cell carcinoma[25]: Fatal case of sorafenib-associated idiosyncratic hepatotoxicity in the adjuvant treatment of a patient with renal cell carcinoma; Case Report in BMC Cancer.

At week four after initiation of sorafenib treatment, the patient noticed increasing fatigue, malaise, gastrointestinal discomfort and abdominal rash. Although treatment was discontinued, jaundice developed and blood test revealed an acute hepatitis with

Elevated serum ALT
Elevated serum alkaline phosphatase
Increased prothrombin time
Increased LDH

…elevated levels seen in the case with the aforementioned IAP antagonist. Autopsy revealed

Lobular hepatitis
Mononuclear cell infiltrate
Hepatocyte necrosis

These findings are in line with a drug-induced inflammation and IDILI. In addition to hepatotoxicity, renal insufficiency developed in this patient. The authors had suggested the death was probably due to “an idiosyncratic allergic reaction to sorafenib manifesting as hepatotoxicity with associated renal impairment”. The authors also noted that genome wide association studies of idiosyncratic drug-induced liver injury support involvement of major histocompatibility complex (MHC) polymorphisms[26]. MHC involvement has also been associated with lapatanib and pazopanib hepatotoxicity [27, 28].

Curis has been involved in another novel oncology therapeutic, a first in class.

Last year Roche and Genentech had won approval for a Hedgehog pathway inhibitor vismodegib for treatment of advanced basal cell carcinoma (reported at FierceBiotech©). Vismodegib was initially developed in collaboration with Curis, Inc. The hedgehog signaling pathway, which controls the function of Gli factors (involved in stem cell differentiation), is overactive in advanced basal cell carcinoma as well as other cancer types.

As an additional reference, the FDA National Center for Toxicological Research has developed THE LIVER TOXICITY KNOWLEDGE BASE (LTKB).

“The LTKB is a project designed to study drug-induced liver injury (DILI). Liver toxicity is the most common cause for the discontinuation of clinical trials on a drug, as well as the most common reason for an approved drug’s withdrawal from the marketplace. Because of this, DILI has been identified by the FDA’s Critical Path Initiatives as a key area of focus in a concerted effort to broaden the agency’s knowledge for better evaluation tools and safety biomarkers.”

A nice SlideShow of Toxicity of Targeted Therapies can be found here: http://www.slideshare.net/RashaHaggag/toxicities-of-targeted-therapies

Also please note that ALL GENES in this article are linked to their GENECARD

UPDATED 8/12/2022

Zolgensma Gene Therapy Linked to 2 Deaths in SMA Patients, Novartis Reports

August 12, 2022

Victoria Johnson

Source: https://www.cgtlive.com/view/zolgensma-gene-therapy-linked-to-2-deaths-in-sma-patients-novartis-reports

The 2 deaths, due to acute liver failure, occurred in patients treated in Kazakhstan and Russia.

Two children with spinal muscular atrophy (SMA) have died after being treated with onasemnogene abeparvovec (Zolgensma; Novartis) from acute liver failure, a known safety risk of the therapy.¹

Novartis has updated the FDA and other regulatory agencies in countries that Zolgensma is approved in, including Russia and Kazakhstan, where the deaths occurred. The company will also update the labeling of Zolgensma to include the deaths.

“While this is important safety information, it is not a new safety signal and we firmly believe in the overall favorable risk/benefit profile of Zolgensma, which to date has been used to treat more than 2300 patients worldwide across clinical trials, managed access programs, and in the commercial setting,” Novartis said in an emailed statement to BioPharma Dive.²

Zolgensma’s labeling includes the risk of liver injury and instructs clinicians to assess liver function before treatment and to manage liver enzyme counts with steroid treatment. The 2 deaths occurred 5 to 6 weeks after the one-time infusion and 1 to 10 days after corticosteroid treatment was tapered, according to an initial report from Stat News.¹

An FDA advisory committee meeting that took place last fall identified risks of adeno associated virus (AAV) gene therapies including, specifically, Zolgensma.² The committee recommended caution, but nothing that would hinder gene therapy development.

Zolgensma, which was approved in the US in May 2019, just recently demonstrated further positive data from SPR1NT (NCT03505099), a phase 3 multicenter, single-arm trial on its effect in presymptomatic children with SMA in 2 articles published in Nature Medicine.^3,4

All children in both the type 1 and type 2 cohorts achieved the ability to independently sit and most achieved other age-appropriate milestones including standing and walking. None of the children in the study required respiratory support or nutritional support, and there were no serious treatment-related adverse events observed.

“The robust data from both the 2- and 3-copy SPR1NT cohorts are being published together for the first time, further supporting the significant and clinically meaningful benefit of Zolgensma in presymptomatic babies with SMA,” Shephard Mpofu, MD, SVP, chief medical officer, Novartis Gene Therapies, said in a previous statement.⁵ “When treated with Zolgensma prior to the onset of symptoms, not only did all 29 patients enrolled in SPR1NT survive, but were thriving—breathing and eating on their own, with most even sitting, standing, and walking without assistance.”

REFERENCE

1. Silverman E. Novartis reports two children died from acute liver failure after treatment with Zolgensma gene therapy. STAT. August 11, 2022. https://www.statnews.com/pharmalot/2022/08/11/novartis-zolgensma-liver-failure-gene-therapy-death/

2. Pagliarulo N. Novartis reports deaths of two patients treated with Zolgensma gene therapy. BioPharma Dive. August 12, 2022. https://www.biopharmadive.com/news/novartis-zolgensma-patient-death-liver-injury/629542/

3. Strauss KA, Farrar MA, Muntoni F, et al. Onasemnogeneabeparvovec for presymptomatic infants with two copies of SMN2 at risk for spinal muscular atrophy type 1: the Phase III SPR1NT trial. Nat Med. Published online June 17, 2022. doi:10.1038/s41591-022-01866-42

4. Strauss KA, Farrar MA, Muntoni F, et al. Onasemnogeneabeparvovec for presymptomatic infants with three copies of SMN2 at risk for spinal muscular atrophy: the Phase III SPR1NT trial. Nat Med. Published online June 17, 2022.doi: 10.1038/s41591-022-01867-3

5. Novartis announces Nature Medicine publication of Zolgensma data demonstrating age-appropriate milestones when treating children with SMA presymptomatically. News release. Novartis. June 17, 2022. https://firstwordpharma.com/story/5597735

REFERENCES

1. Roth RA, Ganey PE: Intrinsic versus idiosyncratic drug-induced hepatotoxicity–two villains or one? The Journal of pharmacology and experimental therapeutics 2010, 332(3):692-697.

2. Waring JF, Liguori MJ, Luyendyk JP, Maddox JF, Ganey PE, Stachlewitz RF, North C, Blomme EA, Roth RA: Microarray analysis of lipopolysaccharide potentiation of trovafloxacin-induced liver injury in rats suggests a role for proinflammatory chemokines and neutrophils. The Journal of pharmacology and experimental therapeutics 2006, 316(3):1080-1087.

3. Deng X, Luyendyk JP, Ganey PE, Roth RA: Inflammatory stress and idiosyncratic hepatotoxicity: hints from animal models. Pharmacological reviews 2009, 61(3):262-282.

4. Laverty HG, Antoine DJ, Benson C, Chaponda M, Williams D, Kevin Park B: The potential of cytokines as safety biomarkers for drug-induced liver injury. European journal of clinical pharmacology 2010, 66(10):961-976.

5. Schwabe RF, Brenner DA: Mechanisms of Liver Injury. I. TNF-alpha-induced liver injury: role of IKK, JNK, and ROS pathways. American journal of physiology Gastrointestinal and liver physiology 2006, 290(4):G583-589.

6. Seki E, Brenner DA, Karin M: A liver full of JNK: signaling in regulation of cell function and disease pathogenesis, and clinical approaches. Gastroenterology 2012, 143(2):307-320.

7. Kaplowitz N: Drug-induced liver injury. Clinical infectious diseases : an official publication of the Infectious Diseases Society of America 2004, 38 Suppl 2:S44-48.

8. Kindmark A, Jawaid A, Harbron CG, Barratt BJ, Bengtsson OF, Andersson TB, Carlsson S, Cederbrant KE, Gibson NJ, Armstrong M et al: Genome-wide pharmacogenetic investigation of a hepatic adverse event without clinical signs of immunopathology suggests an underlying immune pathogenesis. The pharmacogenomics journal 2008, 8(3):186-195.

9. Aithal GP, Ramsay L, Daly AK, Sonchit N, Leathart JB, Alexander G, Kenna JG, Caldwell J, Day CP: Hepatic adducts, circulating antibodies, and cytokine polymorphisms in patients with diclofenac hepatotoxicity. Hepatology 2004, 39(5):1430-1440.

10. Daly AK, Aithal GP, Leathart JB, Swainsbury RA, Dang TS, Day CP: Genetic susceptibility to diclofenac-induced hepatotoxicity: contribution of UGT2B7, CYP2C8, and ABCC2 genotypes. Gastroenterology 2007, 132(1):272-281.

11. Russmann S, Kullak-Ublick GA, Grattagliano I: Current concepts of mechanisms in drug-induced hepatotoxicity. Current medicinal chemistry 2009, 16(23):3041-3053.

12. Fontana RJ, Watkins PB, Bonkovsky HL, Chalasani N, Davern T, Serrano J, Rochon J: Drug-Induced Liver Injury Network (DILIN) prospective study: rationale, design and conduct. Drug safety : an international journal of medical toxicology and drug experience 2009, 32(1):55-68.

13. Spraggs CF, Xu CF, Hunt CM: Genetic characterization to improve interpretation and clinical management of hepatotoxicity caused by tyrosine kinase inhibitors. Pharmacogenomics 2013, 14(5):541-554.

14. de Almagro MC, Vucic D: The inhibitor of apoptosis (IAP) proteins are critical regulators of signaling pathways and targets for anti-cancer therapy. Experimental oncology 2012, 34(3):200-211.

15. Deveraux QL, Takahashi R, Salvesen GS, Reed JC: X-linked IAP is a direct inhibitor of cell-death proteases. Nature 1997, 388(6639):300-304.

16. Crook NE, Clem RJ, Miller LK: An apoptosis-inhibiting baculovirus gene with a zinc finger-like motif. Journal of virology 1993, 67(4):2168-2174.

17. Tamm I, Kornblau SM, Segall H, Krajewski S, Welsh K, Kitada S, Scudiero DA, Tudor G, Qui YH, Monks A et al: Expression and prognostic significance of IAP-family genes in human cancers and myeloid leukemias. Clinical cancer research : an official journal of the American Association for Cancer Research 2000, 6(5):1796-1803.

18. Laukens B, Jennewein C, Schenk B, Vanlangenakker N, Schier A, Cristofanon S, Zobel K, Deshayes K, Vucic D, Jeremias I et al: Smac mimetic bypasses apoptosis resistance in FADD- or caspase-8-deficient cells by priming for tumor necrosis factor alpha-induced necroptosis. Neoplasia 2011, 13(10):971-979.

19. He S, Wang L, Miao L, Wang T, Du F, Zhao L, Wang X: Receptor interacting protein kinase-3 determines cellular necrotic response to TNF-alpha. Cell 2009, 137(6):1100-1111.

20. Baud V, Karin M: Is NF-kappaB a good target for cancer therapy? Hopes and pitfalls. Nature reviews Drug discovery 2009, 8(1):33-40.

21. Asselin E, Mills GB, Tsang BK: XIAP regulates Akt activity and caspase-3-dependent cleavage during cisplatin-induced apoptosis in human ovarian epithelial cancer cells. Cancer research 2001, 61(5):1862-1868.

22. Kearney CJ, Sheridan C, Cullen SP, Tynan GA, Logue SE, Afonina IS, Vucic D, Lavelle EC, Martin SJ: Inhibitor of apoptosis proteins (IAPs) and their antagonists regulate spontaneous and tumor necrosis factor (TNF)-induced proinflammatory cytokine and chemokine production. The Journal of biological chemistry 2013, 288(7):4878-4890.

23. Damgaard RB, Gyrd-Hansen M: Inhibitor of apoptosis (IAP) proteins in regulation of inflammation and innate immunity. Discovery medicine 2011, 11(58):221-231.

24. Erickson RI, Tarrant J, Cain G, Lewin-Koh SC, Dybdal N, Wong H, Blackwood E, West K, Steigerwalt R, Mamounas M et al: Toxicity profile of small-molecule IAP antagonist GDC-0152 is linked to TNF-alpha pharmacology. Toxicological sciences : an official journal of the Society of Toxicology 2013, 131(1):247-258.

25. Fairfax BP, Pratap S, Roberts IS, Collier J, Kaplan R, Meade AM, Ritchie AW, Eisen T, Macaulay VM, Protheroe A: Fatal case of sorafenib-associated idiosyncratic hepatotoxicity in the adjuvant treatment of a patient with renal cell carcinoma. BMC cancer 2012, 12:590.

26. Daly AK: Drug-induced liver injury: past, present and future. Pharmacogenomics 2010, 11(5):607-611.

27. Spraggs CF, Budde LR, Briley LP, Bing N, Cox CJ, King KS, Whittaker JC, Mooser VE, Preston AJ, Stein SH et al: HLA-DQA1*02:01 is a major risk factor for lapatinib-induced hepatotoxicity in women with advanced breast cancer. Journal of clinical oncology : official journal of the American Society of Clinical Oncology 2011, 29(6):667-673.

28. Xu CF, Reck BH, Goodman VL, Xue Z, Huang L, Barnes MR, Koshy B, Spraggs CF, Mooser VE, Cardon LR et al: Association of the hemochromatosis gene with pazopanib-induced transaminase elevation in renal cell carcinoma. Journal of hepatology 2011, 54(6):1237-1243.

Other articles on the site about Toxicology and Pharmacology of New Classes of Cancer Chemotherapy include:

FDA Guidelines For Developmental and Reproductive Toxicology (DART) Studies for Small Molecules

Gamma Linolenic Acid (GLA) as a Therapeutic tool in the Management of Glioblastoma

DNA Methultransferases – Implications to Epigenetic Regulation and Cancer Therapy Targeting: James Shen, PhD

Molecular Profiling in Cancer Immunotherapy: Debraj GuhaThakurta, PhD

AT13148 – A Novel Oral Multi-AGC Kinase Inhibitor Has Potent Antitumor Activity

Targeting Mitochondrial-bound Hexokinase for Cancer Therapy

Breast Cancer, drug resistance, and biopharmaceutical targets

Ubiquitin-Proteosome pathway, Autophagy, the Mitochondrion, Proteolysis and Cell Apoptosis: Part III

Ubiquinin-Proteosome pathway, autophagy, the mitochondrion, proteolysis and cell apoptosis

http://pharmaceuticalintelligence.com/2013/12/23/calmodulin-and-protein-kinase-c-drive-the-ca2-regulation-of-hormone-and-neurotransmitter-release-that-triggers-ca2-stimulated-exocytosis/

Sensors and Signaling in Oxidative Stress

Posted in CANCER BIOLOGY & Innovations in Cancer Therapy, Cancer Prevention: Research & Programs, Cardiovascular Research, Cell Biology, Signaling & Cell Circuits, Chemical Biology and its relations to Metabolic Disease, Chemical Genetics, Cytoskeleton, Disease Biology, Small Molecules in Development of Therapeutic Drugs, Frontiers in Cardiology and Cardiovascular Disorders, Genome Biology, Genomic Testing: Methodology for Diagnosis, Metabolomics, Molecular Genetics & Pharmaceutical, Myocardial metabolism, Myocardial ischemia, myocardial perfusion, Myocardial adenine nucleotide metabolism, Pharmacogenomics, Population Health Management, Genetics & Pharmaceutical, tagged anti-cancer therapy, ATPase, Aviva Lev-Ari, Cancer - General, Cardiovascular disease, drug resistance, Heart Failure, Inrf2, James W. Kaspar, Keap1, Larry H. Bernstein, Mutagenesis, NF-κB, NFE2L2, Nrf2, oxidative stress, Reactive oxygen species, somatic mutation, Suresh K. Niture, Vascular smooth muscle on November 1, 2013| Leave a Comment »

Sensors and Signaling in Oxidative Stress

Author and Curator: Larry H. Bernstein, MD, FCAP

Article XI Sensors and Signaling in Oxidative Stress

Image created by Adina Hazan 06/30/2021

This is article ELEVEN in the following series on Calcium Role in Cardiovascular Diseases

Part I: Identification of Biomarkers that are Related to the Actin Cytoskeleton
Larry H Bernstein, MD, FCAP
http://pharmaceuticalintelligence.com/2012/12/10/identification-of-biomarkers-
that-are-related-to-the-actin-cytoskeleton/

Part II: Role of Calcium, the Actin Skeleton, and Lipid Structures in Signaling and Cell Motility
Larry H. Bernstein, MD, FCAP, Stephen Williams, PhD and Aviva Lev-Ari, PhD, RN
http://pharmaceuticalintelligence.com/2013/08/26/role-of-calcium-the-actin-
skeleton-and-lipid-structures-in-signaling-and-cell-motility/

Part III: Renal Distal Tubular Ca2+ Exchange Mechanism in Health and Disease
Larry H. Bernstein, MD, FCAP, Stephen J. Williams, PhD
and Aviva Lev-Ari, PhD, RN
http://pharmaceuticalintelligence.com/2013/09/02/renal-distal-tubular-ca2-
exchange-mechanism-in-health-and-disease/

Part IV: The Centrality of Ca(2+) Signaling and Cytoskeleton Involving Calmodulin Kinases and
Ryanodine Receptors in Cardiac Failure, Arterial Smooth Muscle, Post-ischemic Arrhythmia,
Similarities and Differences, and Pharmaceutical Targets
Larry H Bernstein, MD, FCAP, Justin Pearlman, MD, PhD, FACC and Aviva Lev-Ari, PhD, RN
http://pharmaceuticalintelligence.com/2013/09/08/the-centrality-of-ca2-signaling-and-cytoskeleton-
involving-calmodulin-kinases-and-ryanodine-receptors-in-cardiac-failure-arterial-smooth-muscle-
post-ischemic-arrhythmia-similarities-and-differen/

Part V: Ca2+-Stimulated Exocytosis: The Role of Calmodulin and Protein Kinase C in Ca2+ Regulation of Hormone and Neurotransmitter

Larry H Bernstein, MD, FCAP and Aviva Lev-Ari, PhD, RN

Part VI: Calcium Cycling (ATPase Pump) in Cardiac Gene Therapy: Inhalable Gene Therapy for Pulmonary
Arterial Hypertension and Percutaneous Intra-coronary Artery Infusion for Heart Failure: Contributions by Roger J. Hajjar, MD
Aviva Lev-Ari, PhD, RN
http://pharmaceuticalintelligence.com/2013/08/01/calcium-molecule-in-cardiac-gene-therapy-inhalable-gene-therapy-
for-pulmonary-arterial-hypertension-and-percutaneous-intra-coronary-artery-infusion-for-heart-failure-contributions-by-roger-j-hajjar/

Part VII: Cardiac Contractility & Myocardium Performance: Ventricular Arrhythmias and Non-ischemic Heart Failure –
Therapeutic Implications for Cardiomyocyte Ryanopathy (Calcium Release-related Contractile Dysfunction) and Catecholamine Responses
Justin Pearlman, MD, PhD, FACC, Larry H Bernstein, MD, FCAP and Aviva Lev-Ari, PhD, RN
http://pharmaceuticalintelligence.com/2013/08/28/cardiac-contractility-myocardium-performance-ventricular-arrhythmias-
and-non-ischemic-heart-failure-therapeutic-implications-for-cardiomyocyte-ryanopathy-calcium-release-related-contractile/

Part VIII: Disruption of Calcium Homeostasis: Cardiomyocytes and Vascular Smooth Muscle Cells:
The Cardiac and Cardiovascular Calcium Signaling Mechanism
Justin Pearlman, MD, PhD, FACC, Larry H Bernstein, MD, FCAP and Aviva Lev-Ari, PhD, RN
http://pharmaceuticalintelligence.com/2013/09/12/disruption-of-calcium-homeostasis-cardiomyocytes-and-vascular-smooth-
muscle-cells-the-cardiac-and-cardiovascular-calcium-signaling-mechanism/

Part IX: Calcium-Channel Blockers, Calcium Release-related Contractile Dysfunction
(Ryanopathy) and Calcium as Neurotransmitter Sensor
Justin Pearlman, MD, PhD, FACC, Larry H Bernstein, MD, FCAP and Aviva Lev-Ari, PhD, RN
http://pharmaceuticalintelligence.com/2013/09/16/calcium-channel-blocker-calcium-as-neurotransmitter-sensor-
and-calcium-release-related-contractile-dysfunction-ryanopathy/

Part X: Synaptotagmin functions as a Calcium Sensor: How Calcium Ions Regulate the fusion of
vesicles with cell membranes during Neurotransmission
Larry H Bernstein, MD, FCAP and Aviva Lev-Ari, PhD, RN
http://pharmaceuticalintelligence.com/2013/09/10/synaptotagmin-functions-as-a-calcium-sensor-how-calcium-ions-
regulate-the-fusion-of-vesicles-with-cell-membranes-during-neurotransmission/

Part XI: Sensors and Signaling in Oxidative Stress
Larry H. Bernstein, MD, FCAP
http://pharmaceuticalintelligence.com/2013/11/01/sensors-and-signaling-in-oxidative-stress/

Part XII: Atherosclerosis Independence: Genetic Polymorphisms of Ion Channels Role in the Pathogenesis of Coronary Microvascular Dysfunction and Myocardial Ischemia (Coronary Artery Disease (CAD))

Larry H Bernstein, MD, FCAP and Aviva Lev-Ari, PhD, RN

http://pharmaceuticalintelligence.com/2013/12/21/genetic-polymorphisms-of-ion-channels-have-a-role-in-the-pathogenesis-of-coronary-microvascular-dysfunction-and-ischemic-heart-disease/

This important article on oxidative stress was published in Free Radical Biol. and Med.

Nrf2:INrf2(Keap1) Signaling in Oxidative Stress

James W. Kaspar, Suresh K. Niture, and Anil K. Jaiswal^*Department of Pharmacology, University of Maryland School of Medicine, Baltimore, MD

Free Radic Biol Med. 2009 Nov; 47(9): 1304–1309. http://dx.doi.org/10.1016/j.freeradbiomed.2009.07.035

Nrf2:INrf2(Keap1) are cellular sensors of chemical and radiation induced oxidative and electrophilic stress. Nrf2 is a nuclear transcription factor that controls the expression and coordinated induction of a battery of defensive genes encoding detoxifying enzymes and antioxidant proteins. This is a mechanism of critical importance for cellular protection and cell survival. Nrf2 is retained in the cytoplasm by an inhibitor INrf2. INrf2 functions as an adapter for Cul3/Rbx1 mediated degradation of Nrf2. In response to oxidative/electrophilic stress, Nrf2 is switched on and then off by distinct early and delayed mechanisms. Oxidative/electrophilic modification of INrf2cysteine151 and/or PKC phosphorylation of Nrf2serine40 results in

the escape or release of Nrf2 from INrf2.

Nrf2 is stabilized and

translocates to the nucleus,
forms heterodimers with unknown proteins, and
binds antioxidant response element (ARE) that
leads to coordinated activation of gene expression.
It takes less than fifteen minutes from the time of exposure to switch on nuclear import of Nrf2. This is followed by activation of a delayed mechanism that controls switching off of Nrf2 activation of gene expression. GSK3β phosphorylates Fyn at unknown threonine residue(s) leading to nuclear localization of Fyn. Fyn phosphorylates Nrf2tyrosine568
resulting in nuclear export of Nrf2, binding with INrf2 and
degradation of Nrf2.

The switching on and off of Nrf2 protects cells against free radical damage, prevents apoptosis and promotes cell survival.

Introduction

Oxidative stress is induced by a vast range of factors including xenobiotics, drugs, heavy metals and ionizing radiation. Oxidative stress leads to the generation of Reactive Oxygen Species (ROS) and electrophiles. ROS and electrophiles generated can have a profound impact on survival, growth development and evolution of all living organisms [1,2] ROS include

both free radicals, such as the superoxide anion and the hydroxyl radical, and
oxidants such as hydrogen peroxide [3].

ROS and electrophiles can cause diseases such as cancer, cardiovascular complications, acute and chronic inflammation, and neurodegenerative diseases [1]. Therefore, it is obvious that

cells must constantly labor to control levels of ROS, preventing them from accumulation.

Much of what we know about the mechanisms of protection against oxidative stress has come from the study of prokaryotic cells [4,5]. Prokaryotic cells utilize transcription factors OxyR and SoxRS to sense the redox state of the cell, and

during oxidative stress these factors induce the expression of nearly eighty defensive genes [5].

Eukaryotic cells have similar mechanisms to protect against oxidative stress [Fig. 1; ref. 3,6–9]. Initial effect of oxidative/electrophilic stress leads to activation of a battery of defensive gene expression that leads to detoxification of chemicals and ROS and prevention of free radical generation and cell survival [Fig. 1].

Fig. 1. Chemical and radiation exposure and coordinated induction of defensive genes.

Of these genes, some are enzymes such as NAD(P)H:quinine oxidoreductase 1 (NQO1), NRH:quinone oxidoreductase 2 (NQO2), glutathione S-transferase Ya subunit (GST Ya Subunit), heme oxygenase 1 (HO-1), and γ-glutamylcysteine synthetase (γ-GCS), also known as glutamate cysteine ligase (GCL). Other genes have end products that regulate a wide variety of cellular activities including

signal transduction,
proliferation, and
immunologic defense reactions.

There is a wide variety of factors associated with the cellular response to oxidative stress. For example,

NF-E2 related factor 2 (Nrf2),
heat shock response activator protein 1, and
NF-kappaB promote cell survival,

whereas activation of c-jun, N-terminal kinases (JNK), p38 kinase and TP53 may lead to cell cycle arrest and apoptosis [10]. The Nrf2 pathway is regarded as the most important in the cell to protect against oxidative stress. [3,6–9]. It is noteworthy that accumulation of ROS and/or electrophiles leads to oxidative/electrophile stress,

membrane damage,
DNA adducts formation and
mutagenicity [Fig. 1].

These changes lead to degeneration of tissues and premature aging, apoptotic cell death, cellular transformation and cancer.

Antioxidant Response Element and Nrf2

Promoter analysis identified a cis-acting enhancer sequence designated as the antioxidant response element (ARE) that

controls the basal and inducible expression of antioxidant genes in response to xenobiotics, antioxidants, heavy metals and UV light [11].

The ARE sequence is responsive to a broad range of structurally diverse chemicals apart from β-nafthoflavone and phenolic antioxidants [12]. Mutational analysis revealed GTGACA***GC to be the core sequence of the ARE [11,13–14]. This core sequence is present in all Nrf2 downstream genes that respond to antioxidants and xenobiotics [3,6–9]. Nrf2 binds to the ARE and regulates ARE-mediated antioxidant enzyme genes expression and induction in response to a variety of stimuli including antioxidants, xenobiotics, metals, and UV irradiation [6,15–21].

Nrf2 is ubiquitously expressed in a wide range of tissue and cell types [22–24] and belongs to a subset of basic leucine zipper genes (bZIP) sharing a conserved structural domain designated as a cap’n’collar domain which is highly conserved in Drosphila transcription factor CNC (Fig. 2; ref. 25].

Fig. 2. Schematic Presentation of Various Domains of Nrf (Nrf1, Nrf2, Nrf3) and INrf2

Nrf, NF-E2 Related Factor; INrf2, Inhibitor of Nrf2; NTR, N-Terminal Region; BTB, Broad complex, Tramtrack, Bric-a-brac; IVR, Intervening/linker Region; DGR, Kelch domain/ diglycine repeats; CTR, C-Terminal Region.

The basic region, just upstream of the leucine zipper region,

is responsible for DNA binding [3] and
the acidic region is required for transcriptional activation.

ARE-mediated transcriptional activation requires heterodimerization of Nrf2 with other bZIP proteins including Jun (c-Jun, Jun-D, and Jun-B) and small Maf (MafG, MafK, MafF) proteins [18– 20,26–27].

Initial evidence demonstrating the role of Nrf2 in antioxidant-induction of detoxifying enzymes came from studies on

the role of Nrf2 in ARE-mediated regulation of NQO1 gene expression [17].

Nrf2 was subsequently shown to be involved in

the transcriptional activation of other ARE-responsive genes such as
- GST Ya, γ-GCS, HO-1, antioxidants, proteasomes, and drug transporters [3,6–9,28–33].

Overexpression of Nrf2 cDNA was shown to upregulate the expression and induction of the NQO1 gene in response to antioxidants and xenobiotics [17]. In addition, Nrf2-null mice exhibited a marked

decrease in the expression and induction of NQO1,
indicating that Nrf2 plays an essential role in the in vivo regulation of NQO1 in response to oxidative stress [26].

The importance of this transcription factor in upregulating ARE-mediated gene expression has been demonstrated by several in vivo and in vitro studies [reviewed in ref. 3]. The results indicate that Nrf2 is an important activator of phase II antioxidant genes [3,8].

Negative Regulation of Nrf2 mediated by INrf2

A cytosolic inhibitor (INrf2), also known as Keap1 (Kelch-like ECH-associating protein 1), of Nrf2 was identified and reported [Fig. 2; ref. 34–35]. INrf2, existing as a dimer [36], retains Nrf2 in the cytoplasm. Analysis of the INrf2 amino acid sequence and domain structure-function analyses have revealed that

INrf2 has a BTB (broad complex, tramtrack, bric-a-brac)/ POZ (poxvirus, zinc finger) domain and
a Kelch domain [34–35] also known as the DGR domain (Double glycine repeat) [37].

Keap1 has three additional domains/regions:

the N-terminal region (NTR),
the invervening region (IVR), and
the C-terminal region (CTR) [8].

The BTB/POZ domain has been shown to be

a protein-protein interaction domain.

In the Drosophila Kelch protein, and in IPP,

the Kelch domain binds to actin [38–39]
allowing the scaffolding of INrf2 to the actin cytoskeleton
- which plays an important role in Nrf2 retention in the cytosol [40].

The main function of INrf2 is to serve as

an adapter for the Cullin3/Ring Box 1 (Cul3/Rbx1) E3 ubiquitin ligase complex [41–43].

Cul3 serves as a scaffold protein that forms the E3 ligase complex with Rbx1 and recruits a cognate E2 enzyme [8].

INrf2

via its N-terminal BTB/POZ domain binds to Cul3 [44] and
via its C-terminal Kelch domain binds to the substrate Nrf2

leading to the ubiquitination and degradation of Nrf2 through the 26S proteasome [45–49].

Under normal cellular conditions, the cytosolic INrf2/Cul3-Rbx1 complex is constantly degrading Nrf2. When a cell is exposed to oxidative stress Nrf2 dissociates from the INrf2 complex, stabilizes and translocates into the nucleus leading to activation of ARE-mediated gene expression [3,6–9]. An alternative theory is that Nrf2 in response to oxidative stress escapes INrf2 degradation, stabilizes and translocates in the nucleus [49–50]. We suggested the theory of escape of Nrf2 from INrf2 [49] and similar suggestion was also made in another report [50]. However, the follow up studies in our laboratory could not support the escape theory. Escape theory is a possibility but has to be proven by experiments before it can be adapted. Therefore, we will use the release of Nrf2 from INrf2 in the rest of this review.

Numerous reports have suggested that

any mechanism that modifies INrf2 and/or Nrf2 disrupting the Nrf2:INrf2 interaction will result in the upregulation of ARE-mediated gene expression.

A model Nrf2:INrf2 signaling from antioxidant and xenobiotic to activation of ARE-mediated defensive gene expression is shown in Fig. 3.

Fig. 3. Nrf2 signaling in ARE-mediated coordinated activation of defensive genes

Since the metabolism of antioxidants and xenobiotics results in the generation of ROS and electrophiles [51], it is thought that these molecules might act as second messengers, activating ARE-mediated gene expression. Several protein kinases including PKC, ERK, MAPK, p38, and PERK [49,52– 56] are known to modify Nrf2 and activate its release from INrf2. Among these mechanisms,

oxidative/electrophilic stress mediated phosphorylation of Nrf2 at serine40 by PKC is necessary for Nrf2 release from INrf2, but
is not required for Nrf2 accumulation in the nucleus [49,52–53].

In addition to post-translational modification in Nrf2, several crucial residues in INrf2 have also been proposed to be important for activation of Nrf2. Studies based on

the electrophile mediated modification,
location and
mutational analyses revealed
- that three cysteine residues, Cys151, Cys273 and Cys288 are crucial for INrf2 activity [50].

INrf2 itself undergoes ubiquitination by the Cul3 complex, via a proteasomal independent pathway,

which was markedly increased in response to phase II inducers such as antioxidants [57].

It has been suggested that normally INrf2 targets Nrf2 for ubiquitin mediated degradation but

electrophiles may trigger a switch of Cul3 dependent ubiquitination from Nrf2 to INrf2 resulting in ARE gene induction.

The redox modulation of cysteines in INrf2

might be a mechanism redundant to the phosphorylation of Nrf2 by PKC, or that
the two mechanisms work in concert.

In addition to cysteine151 modification,

phosphorylation of Nrf2 has also been shown to play a role in INrf2 retention and release of Nrf2.

Serine104 of INrf2 is required for dimerization of INrf2, and

mutations of serine104 led to the disruption of the INrf2 dimer leading to the release of Nrf2 [36].

Recently, Eggler at al. demonstrated that modifying specific cysteines of the electrophile-sensing human INrf2 protein is insufficient to disrupt binding to the Nrf2 domain Neh2 (58). Upon introduction of electrophiles, modification of INrf2C151 leads to a change in the conformation of the BTB domain by means of perturbing the homodimerization site, disrupting Neh2 ubiquitination, and causing ubiquitination of INrf2. Modification of INrf2 cysteines by electrophiles does not lead to disruption of the INrf2–Nrf2 complex. Rather, the switch of ubiquitination from Nrf2 to INrf2 leads to Nrf2 nuclear accumulation.

More recently, our laboratory demonstrated that phosphorylation and de-phosphorylation of tyrosine141 in INrf2 regulates its stability and degradation, respectively [59]. The de-phosphorylation of tyrosine141 caused destabilization and degradation of INrf2 leading to the release of Nrf2. Furthermore, we showed that prothymosin-α mediates nuclear import of the INrf2/Cul3-Rbx1 complex [60]. The INrf2/Cul3-Rbx1 complex inside the nucleus exchanges prothymosin-α with Nrf2 resulting in degradation of Nrf2. These results led to the conclusion that prothymosin-α mediated nuclear import of INrf2/Cul3-Rbx1 complex leads to ubiquitination and degradation of nuclear Nrf2 presumably to regulate nuclear level of Nrf2 and rapidly switch off the activation of Nrf2 downstream gene expression. An auto-regulatory loop also exists within the Nrf2 pathway [61]. An ARE was identified in the INrf2 promoter that facilitates Nrf2 binding causing induction of the INrf2 gene. Nrf2 regulates INrf2 by controlling its transcription, and INrf2 controls Nrf2 by serving as an adaptor for degradation.

Other Regulatory Mediators of Nrf2

Bach1 (BTB and CNC homology 1, basic leucine zipper transcription factor 1) is a transcription repressor [62] that is ubiquitously expressed in tissues [63–64] and distantly related to Nrf2 [8]. In the absence of cellular stress, Bach1 heterodimers with small Maf proteins [65] that bind to the (ARE) [66] repressing gene expression. In the presence of oxidative stress, Bach1 releases from the ARE and is replaced by Nrf2. Bach1 competes with Nrf2 for binding to the ARE leading to suppression of Nrf2 downstream genes [66].

Nuclear import of Nrf2, from time of exposure to stabilization, takes roughly two hours [67]. This is followed by activation of a delayed mechanism involving Glycogen synthase kinase 3 beta (GSK3f3) that controls switching off of Nrf2 activation of gene expression (Fig. 3). GSK3f3 is a multifunctional serine/threonine kinase, which plays a major role in various signaling pathways [68]. GSK3f3 phosphorylates Fyn, a tyrosine kinase, at unknown threonine residue(s) leading to nuclear localization of Fyn [69]. Fyn phosphorylates Nrf2 tyrosine 568 resulting in nuclear export of Nrf2, binding with INrf2 and degradation of Nrf2 [70].

The negative regulation of Nrf2 by Bach1 and GSK3f3/Fyn are important in repressing Nrf2 downstream genes that were induced in response to oxidative/electrophilic stress. The tight control of Nrf2 is vital for the cells against free radical damage, prevention of apoptosis and cell survival [3,6–9,70].

Nrf2 in Cytoprotection, Cancer and Drug Resistance

Nrf2 is a major protective mechanism against xenobiotics capable of damaging DNA and initiating carcinogenesis [71]. Inducers of Nrf2 function as blocking agents that prevents carcinogens from reaching target sites, inhibits parent molecules undergoing metabolic activation, or subsequently preventing carcinogenic species from interacting with crucial cellular macromolecules, such as DNA, RNA, and proteins [72]. A plausible mechanism by which blocking agents impart their chemopreventive activity is the induction of detoxification and antioxidant enzymes [73]. Oltipraz, 3H-1,2,-dithiole-3-thione (D3T), Sulforaphane, and Curcumin can be considered potential chemopreventive agents because

these compounds have all been shown to induce Nrf2 [74–81].

Studies have shown a role of Nrf2 in protection against cadmium and manganese toxicity [82]. Nrf2 also plays an important role in reduction of methyl mercury toxicity [83]. Methylmercury activates Nrf2 and the activation of Nrf2 is essential for reduction of methylmercury by facilitating its excretion into extracellular space. In vitro and in vivo studies have shown a role of Nrf2 in neuroprotection and protection against Parkinson’s disease [84– 86]. Disruption of Nrf2 impairs the resolution of hyperoxia-induced acute lung injury and inflammation in mice [87]. Nrf2-knockout mice were more prone to

tumor growth when exposed to carcinogens such as benzo[a]pyrene, diesel exhaust, and N-nitrosobutyl (4-hydroxybutyl) amine [88–90].

INrf2/Nrf2 signaling is also shown to regulate oxidative stress tolerance and lifespan in Drosophila [91].

A role of Nrf2 in drug resistance is suggested based on its property to induce detoxifying and antioxidant enzymes (92–97). The loss of INrf2 (Keap1) function is shown to

lead to nuclear accumulation of Nrf2, activation of metabolizing enzymes and drug resistance (95).

Studies have reported mutations resulting in dysfunctional INrf2 in lung, breast and bladder cancers (96–100). A recent study reported that somatic mutations also occur in the coding region of Nrf2, especially in cancer patients with a history of smoking or suffering from squamous cell carcinoma (101). These mutations abrogate its interaction with INrf2 and nuclear accumulation of Nrf2. This gives advantage to

cancer cell survival and
undue protection from anti-cancer treatments.

However, the understanding of the mechanism of Nrf2 induced drug resistance remains in its infancy. In addition, the studies on Nrf2 regulated downstream pathways that contribute to drug resistance remain limited.

Future Perspectives

Nrf2 creates a new paradigm in cytoprotection, cancer prevention and drug resistance. Considerable progress has been made to better understand all mechanisms involved within the intracellular pathways regulating Nrf2 and its downstream genes. Preliminary studies demonstrate that

deactivation of Nrf2 is as important as activation of Nrf2.

Further studies are needed to better understand the negative regulation of Nrf2. Also better understanding of the negative regulation of Nrf2 could help design a new class of effective chemopreventive compounds not only targeting Nrf2 activation, but also

targeting the negative regulators of Nrf2.

Abbreviations:

Nrf2 NF-E2 related factor 2; INrf2 Inhibitor of Nrf2 also known as Keap1; ROS Reactive oxygen species.

References (1-15 of 101)

1. Breimer LH. Molecular Mechanisms of oxygen radical carcinogenesis and mutagenesis: the role of DNA base damage. Mol Carcinog 1990;3:188–197. [PubMed: 2206282]

2. Meneghini R. Iron homeostasis, oxidative stress, and DNA damage. Free Radic Biol Med 1997;23:783– 792. [PubMed: 9296456]

3. Jaiswal AK. Nrf2 signaling in coordinated activation of antioxidant gene expression. Free Radic Biol Med 2004;36:1199–1207. [PubMed: 15110384]

4. Bauer CE, Elsen S, Bird TH. Mechanisms for redox control of gene expression. Annu Rev Microbiol 1999;53:495–523. [PubMed: 10547699]

5. Zheng M, Storz G. Redox sensing by prokaryotic transcription factors. Biochem Pharm 2000;59:1–6. [PubMed: 10605928]

6. Dhakshinamoorthy S, Long DJ II, Jaiswal AK. Antioxidant regulation of genes encoding enzymes that detoxify xenobiotics and carcinogens. Current Topics in Cellular Regulation 2000;36:201–206. [PubMed: 10842753]

7. Zhang DD. Mechanistic studies of the Nrf2-Keap1 signaling pathway. Drug Metab Rev 2006;38:769– 789. [PubMed: 17145701]

8. Kobayashi M, Yamamoto M. Nrf2-Keap1 regulation of cellular defense mechanisms against electrophiles and reactive oxygen species. Adv Enzyme Regul 2006;46:113–140. [PubMed: 16887173]

9. Copple IM, Goldring CE, Kitteringham NR, Park BK. The Nrf2-Keap1 defense pathway: role in protection against drug-induced toxicity. Toxicology 2008;246:24–33. [PubMed: 18083283]

10. Halliwell, B.; Gutteridge, JMC. Free radicals in biology and medicine. Vol. 4. Oxford University Press; 2007.

11. Rushmore TH, Morton MR, Pickett CB. The antioxidant responsive element. Actiavtion by oxidative stress and identification of the DNA consensus sequence required for functional activity. J Biol Chem 1991;266:11632–11639. [PubMed: 1646813]
12. Rushmore TH, King RG, Paulson KE, Pickett CB. Regulation of glutathione S-transferase Ya subunit gene expression: identification of a unique xenobiotics-responsive element controlling inducible expression by planar aromatic compounds. Proc Natl Acad Sci USA 1990;87:3826–3830. [PubMed: 2160079]
13. Xie T, Belinsky M, Xu Y, Jaiswal AK. ARE and TRE-mediated regulation of gene expression: response to xenobiotics and antioxidants. J Biol Chem 1995;270:6894–6900. [PubMed: 7896838]

Rushmore TH, Pickett CB. Glutathione S-transferases, structures, regulation, and therapeutic implications. J Biol Chem 1993;268:11475–11478. [PubMed: 8505281]

15. Jaiswal AK. Regulation of genes encoding NAD(P)H:quinone oxidoreductases. Free Radic Biol Med 2000;29:254–252. [PubMed: 11035254]