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Posts Tagged ‘FDA approval’


Skin Regeneration Therapy One of First Tissue Engineering Products Evaluated by FDA

Reporter: Irina Robu, PhD

Under the provisions of 21st Century Cures Act the U.S. Food and Drug Administration approved StrataGraft regenerative skin tissue as the first product designated as a Regenerative Medicine Advanced Therapy (RMAT) produced by Mallinckrodt Pharmaceuticals. StrataGraft is shaped using unmodified NIKS cells grown under standard operating procedures since the continuous NIKS skin cell line has been thoroughly characterized. StrataGraft products are virus-free, non-tumorigenic, and offer batch-to-batch genetic consistency.

Passed in 2016, the 21st Century act allows FDA to grant accelerated review approval to products which meet an RMAT designation. The RMAT designation includes debates of whether priority review and/or accelerated approval would be suitable based on intermediate endpoints that would be reasonably likely to predict long-term clinical benefit.

The designation includes products

  • defined as a cell therapy, therapeutic tissue engineering product, human cell and tissue product, or any combination product using such therapies or products;
  • intended to treat, modify, reverse, or cure a serious or life-threatening disease or condition; and
  • preliminary clinical evidence indicates the drug has the potential to address unmet medical needs for such disease or condition.

According to Steven Romano, M.D., Chief Scientific Officer and Executive Vice President, Mallinckrodt “We are very pleased the FDA has determined StrataGraft meets the criteria for RMAT designation, as this offers the possibility of priority review and/or accelerated approval. The company tissue-based therapy is under evaluation in a Phase 3 trial to assess its efficacy and safety in the advancement of autologous skin regeneration of complex skin defects due to thermal burns that contain intact dermal elements.

SOURCE

https://www.rdmag.com/news/2017/07/skin-regeneration-therapy-one-first-be-evaluated-fda

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Clinical Trials Could Lead to FDA Approval for Artificial Pancreas

 Reported by: Irina Robu, PhD

Approximately 1.25 million American have type 1 diabetes accroding to the U.S. Centers for Disease Control and Prevention. A device that automatically monitors and regulates blood-sugar levels in people with type 1 diabetes developed by University of Virginia School of Medicine undergo two clinical trials starting early 2016.

The goal of the artificial pancreas is to eliminate the need for people with type 1 diabetes to stick their fingers multiple times daily to check their blood-sugar levels and to inject insulin manually.The artificial pancreas is designed to oversee and adjust insulin delivery as needed. At the center of the artificial pancreas platform is a reconfigured smartphone running advanced algorithms that is linked wirelessly to a blood-sugar monitor and an insulin pump, as well as a remote-monitoring site. People with the artificial pancreas can also access assistance via telemedicine.

Beneficial results from these long-term clinical trials examining how the artificial pancreas works in real-life settings could lead the U.S. Food and Drug Administration and other international regulatory groups to approve the device for use by people with type 1 diabetes, whose bodies do not produce enough insulin. The trials will conducted at nine locations in the U.S. and Europe sustained by a grant from the National Institute of Diabetes and Digestive and Kidney Diseases of the National Institutes of Health.

The first study – the International Diabetes Closed-Loop trial – will test technology developed at UVA by a research team led by Boris Kovatchev, director of the UVA Center for Diabetes Technology. That technology has been refined for clinical use by TypeZero Technologies, a startup company in Charlottesville that has licensed the UVA system.
The second trial will examine a new control algorithm developed by the team of Dr. Francis Doyle III at the Harvard John A. Paulson School of Engineering and Applied Sciences to test whether it further improves control of blood-sugar levels.

Along with UVA, the artificial pancreas will be tested at eight additional sites: Harvard University, Mount Sinai School of Medicine, Mayo Clinic, University of Colorado, Stanford University, University of Montpellier in France, University of Padova in Italy and Academic Medical Center at the University of Amsterdam in The Netherlands.

Source

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

 

Curator: Stephen J. Williams, Ph.D.

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

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

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

Ibrance structure

 

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

  1. 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.
  2. 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

 

graph_cell_cycle

 

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 Ki-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 p16INK4A; however, p16INK4A 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 p16INK4A 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.

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Notes

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.

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.

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Footnotes

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

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References

  1. Toogood PL, et al. J Med Chem. 2005;48:2388–406. doi: 10.1021/jm049354h. [PubMed] [Cross Ref]
  2. Fry DW, et al. Mol Cancer Ther. 2004;3:1427–38. [PubMed]
  3. Flaherty KT, et al. Clin Cancer Res. 2012;18:568–76. doi: 10.1158/1078-0432.CCR-11-0509. [PubMed] [Cross Ref]
  4. Schwartz GK, et al. Br J Cancer. 2011;104:1862–8. doi: 10.1038/bjc.2011.177. [PMC free article] [PubMed] [Cross Ref]
  5. Leonard JP, et al. Blood. 2012;119:4597–607. doi: 10.1182/blood-2011-10-388298. [PubMed] [Cross Ref]
  6. Dean JL, et al. Oncogene. 2010;29:4018–32. doi: 10.1038/onc.2010.154. [PubMed] [Cross Ref]
  7. Stone S, et al. Cancer Res. 1996;56:3199–202. [PubMed]
  8. Roberts PJ, et al. J Natl Cancer Inst. 2012;104:476–87. doi: 10.1093/jnci/djs002. [PMC free article] [PubMed] [Cross Ref]
  9. 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, 3 Lisa M. Butler, 3 Wayne D. Tilley, 3 Agnieszka K. Witkiewicz, 4 , 2 ,* and Erik S. Knudsen 1 , 2 ,*

Author information ► Copyright and License information ►

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.

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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

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Introduction

Breast cancer is a highly heterogeneous disease.14 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.13 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.79 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

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

Author information ► Copyright and License information ►

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.

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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

 

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

 

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

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)

 

fda ibrance reviewers SAE comment

 

Other article in this Open Access Journal on Cell Cycle and Cancer Include:

 

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

 

 

 

 

 

 

 

 

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Curation of Recently Halted Oncology Trials Due to Serious Adverse Events – 2015

Curator: Stephen J. Williams, Ph.D.

The following is reports of oncology clinical trials in 2015 which have been halted for Serious Adverse Events (SAE), in most instances of an idiopathic nature. For comparison I have listed (as of this writing) the oncology drug approvals (8) for 2015. (from CenterWatch.com)

Oncology Drugs Approved in 2015

Farydak (panobinostat); Novartis; For the treatment of multiple myeloma, Approved February 2015

Ibrance (palbociclib); Pfizer; For the treatment of ER-positive, HER2-negative breast cancer, Approved February 2015

Lenvima (lenvatinib); Eisai; For the treatment of thyroid cancer, Approved February 2015

Lonsurf (trifluridine and tipiracil); Taiho Oncology; For the treatment of metastatic colorectal cancer , Approved September 2015

Odomzo (sonidegib); Novartis; For the treatment of locally advanced basal cell carcinoma, July 2015

Opdivo (nivolumab); Bristol-Myers Squibb; For the treatment of metastatic squamous non-small cell lung cancer, Approved March 2015

Unituxin (dinutuximab); United Therapeutics; For the treatment of pediatrics with high-risk neuroblastoma, Approved March 2015

Varubi (rolapitant); Tesaro; For the prevention of delayed nausea and vomiting associated with chemotherapy, Approved September 2015


Death Forces FDA to Place Clinical Hold on Advaxis (ADXS) Cancer Drug

from Biospace News

October 7, 2015
By Alex Keown, BioSpace.com Breaking News Staff

PRINCETON, N.J. – Following the death of a patient, the U.S. Food and Drug Administration (FDA) placed a hold on Advaxis (ADXS)’s experimental cancer treatment axalimogene filolisbac, which is currently in mid-stage trials.

In a statement issued this morning, Advaxis maintains the patient’s death was a result of the severity of her cancer and not due to the company’s experimental cancer treatment. It is seeking proof from the FDA that the drug was not a factor in the death. Still, the hold on the experimental cancer drug will cause the company to halt four clinical trials, Advaxis said. Other clinical trials, including those with the experimental ADXS-PSA and ADXS-HER2, are not affected by this hold. The company said it will continue to actively enroll and dose patients.

The FDA placed a hold on the drug on Oct. 2 after the company submitted a safety report to the regulatory agency that week. The drug is being developed to treat patients with persistent or recurrent metastatic (squamous or non-squamous cell) carcinoma of the cervix (PRmCC) who have progressed on at least one prior line of systemic therapy. Phase I trials released at the end of September showed treatment with axalimogene filolisbac resulted in a 38.5 percent 12-month overall survival rate in 26 patients. Patients typically fighting PRmCC who have failed at least one line of therapy have a typical survival rate of four to seven months.

Read full story here


FDA Halts Trial of Halozyme’s PEGPH20 for Pancreatic Cancer

Apr 9, 2014 Alex Philippidis

Halozyme Therapeutics acknowledged today that the FDA placed a formal clinical hold on its troubled Study 202 assessing its experimental drug PEGPH20 in patients with pancreatic cancer—less than a week after the company temporarily halted enrolling and dosing patients in the ongoing Phase II trial.

The agency told Halozyme it placed the clinical hold following the company’s pause in study activity. The trial’s independent data monitoring committee is evaluating data from the trial to learn why patients treated with PEGPH20 as well as nab-paclitaxel and gemcitabine saw a higher rate of blood clots and other thromboembolic events compared with patients treated with nab-paclitaxel and gemcitabine alone.

“We will be providing this information to the data monitoring committee and the FDA in parallel so they can complete their respective assessments,” Helen Torley, M.B. Ch.B., M.R.C.P., Halozyme’s president and CEO, said in a statement.

“Pancreatic cancer has one of the lowest survival rates of any cancer. We remain committed to evaluating PEGPH20 as a possible therapy to address this devastating disease,” Dr. Torley added.

As with Halozyme’s statement last week, the company’s latest remarks did not indicate when Halozyme expects to resume enrolling and dosing patients in Study 202, or how many patients had been enrolled and dosed when the temporary halt occurred.

The trial was envisioned as having 124 subjects, divided evenly between a treatment arm of PEGPH20 and nab-paclitaxel, and a gemcitabine arm, preceded by eight subject “run-in” phase assessing safety and tolerability, according to Study 202’s page on ClinicalTrials.gov (NCT01839487), last updated on January 27.

The study is one of two Phase II trials for PEGPH20; the other, SWOG, also aims to assess the drug for pancreatic cancer.

PEGPH20 is an investigational PEGylated form of Halozyme’s FDA-approved recombinant human hyaluronidase rHuPH20 (marketed as Hylenex®), designed to dramatically increases the half-life of the compound in the blood and allow for intravenous administration.

The temporary halt for Study 202 came two months after Halozyme publicly cited “potential acceleration of the PEGPH20 program” among several R&D programs for which it raised funds through a public offering of common stock that closed in February and generated approximately $107.8 million in net proceeds.

Read more at GenNEWS


FDA orders CytRx to halt patient enrollment after death of a cancer patient

CytRx ($CYTR) has run into an unexpected roadblock with its cancer drug conjugate aldoxorubicin, slamming the brakes on new patient recruitment in all their clinical trials after the FDA dropped a partial clinical hold on the program. According to the biotech the hold was forced by the death of a patient who was given the drug through a compassionate use program.

LA-based CytRx execs say that patients already enrolled in the studies will continue to receive the therapy as investigators added new safety measures, retooling trial protocols to include an “appropriate inclusion/exclusion criteria, an additional patient screening assessment and an evaluation of serum electrolytes prior to aldoxorubicin administration.” The patient who died, they added, had not qualified for any of its studies.

As it stands now, the biotech doesn’t know exactly how long the partial hold will last, but their announcement sought to calm jumpy investors, saying they expected to resolve the FDA’s demands “expeditiously” and can stick to their current timelines. CytRx says it expects to report preliminary results from their mid-stage study of Kaposi’s sarcoma in the second quarter of 2015 and preliminary results from the ongoing Phase II clinical trial of aldoxorubicin in glioblastoma multiforme in the first half of 2015. The company added that it is committed to completing enrollment in their Phase III trial by the end of next year.

hat reassurance appears to have helped with investors, who seemed to count this as more of a temporary setback than a catastrophe. Shares for CytRx were down about 9% in mid-morning trading.

Aldoxorubicin uses a linker molecule to attach to albumin in the blood and concentrate in tumors, where the acidic environment releases the chemotherapy doxorubicin in doses up to four times higher than what’s used now. Late last year their stock soared after their drug scored promising results for progression-free survival in a Phase IIb trial.

This case illustrates one reason why biotechs often quietly squirm under the pressure of compassionate use programs. They can be expensive to operate, time-consuming and raise fresh concerns when a patient dies or experiences a setback. On the other hand, if regulators take action like this following the death of an advanced stage cancer patient, there may have been something about the case that triggered broader concerns for the entire patient population


Clot risk in Lilly lung-cancer drug raises FDA concerns

July 7, 2015

Eli Lilly and Co.’s experimental lung cancer drug has raised concerns with U.S. regulators that it may increase patients’ risk of suffering potentially deadly blood clots.

The drug, known as necitumumab, improved patients’ overall chances of survival, yet people taking the medicine also experienced more risk, Food and Drug Administration staff said in a report Tuesday. Indianapolis-based Lilly is seeking to sell the medicine to treat a subset of the most common type of lung cancer.

FDA advisers will meet Thursday to discuss the risks and benefits of necitumumab for patients with advanced squamous non-small cell lung cancer, in combination with chemotherapy. The FDA is expected to decide if Lilly can sell the drug by the end of the year.

While the safety of necitumumab reflects that of similar drugs, the increased danger of clotting “in this already high risk population is of concern,” FDA staff wrote.

One study showed that out of 538 patients taking necitumumab and chemotherapy, 9 percent experienced a serious clot, compared with 5 percent of 541 patients given only chemotherapy, according to the staff report.

Squamous lung cancer accounts for 25 percent to 30 percent of all lung cancer, according to the American Cancer Society.

Patients in a clinical trial who took necitumumab lived a median of 11.5 months, 1.6 months longer than those who got only chemotherapy, the FDA staff report said.

Opdivo Side Effects Center (as seen on Rxlist.com) (NOTE:TRIAL NOT HALTED)

Last reviewed on RxList 10/05/2015

Opdivo (nivolumab) is a human monoclonal antibody used to treat patients with unresectable or metastatic melanoma and disease progression following ipilimumab and, if BRAF V600 mutation positive, a BRAF inhibitor; and to treat metastatic squamous non-small cell lung cancer with progression on or after platinum-based chemotherapy. Common side effects of Opdivo include fatigue, rash, itching, cough, upper respiratory tract infection, swelling of the extremities, shortness of breath, muscle pain, decreased appetite, nausea, vomiting, constipation, diarrhea, weakness, swelling, fever, abdominal pain, chest pain, joint pain, and weight loss.


Opdivo FDA Prescribing Information: Side Effects
(Adverse Reactions)

Clinical Trials Experience

Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in clinical practice.

The data described in the WARNINGS AND PRECAUTIONS section and below reflect exposure to OPDIVO in Trial 1, a randomized trial in patients with unresectable or metastatic melanoma and in Trial 3, a single-arm trial in patients with metastatic squamous non-small cell lung cancer (NSCLC).

Clinically significant adverse reactions were evaluated in a total of 691 patients enrolled in Trials 1, 3, or an additional dose finding study (n=306) administering OPDIVO at doses of 0.1 to 10 mg/kg every 2 weeks [see WARNINGS AND PRECAUTIONS].

Unresectable or Metastatic Melanoma

The safety of OPDIVO was evaluated in Trial 1, a randomized, open-label trial in which 370 patients with unresectable or metastatic melanoma received OPDIVO 3 mg/kg every 2 weeks (n=268) or investigator’s choice of chemotherapy (n=102), either dacarbazine 1000 mg/m² every 3 weeks or the combination of carboplatin AUC 6 every 3 weeks plus paclitaxel 175 mg/m² every 3 weeks [see Clinical Studies]. The median duration of exposure was 5.3 months (range: 1 day to 13.8+ months) with a median of eight doses (range: 1 to 31) in OPDIVO-treated patients and was 2 months (range: 1 day to 9.6+ months) in chemotherapy treated patients. In this ongoing trial, 24% of patients received OPDIVO for greater than 6 months and 3% of patients received OPDIVO for greater than 1 year.

In Trial 1, patients had documented disease progression following treatment with ipilimumab and, if BRAF V600 mutation positive, a BRAF inhibitor. The trial excluded patients with autoimmune disease, prior ipilimumab-related Grade 4 adverse reactions (except for endocrinopathies) or Grade 3 ipilimumab-related adverse reactions that had not resolved or were inadequately controlled within 12 weeks of the initiating event, patients with a condition requiring chronic systemic treatment with corticosteroids ( > 10 mg daily prednisone equivalent) or other immunosuppressive medications, a positive test for hepatitis B or C, and a history of HIV.

The study population characteristics in the OPDIVO group and the chemotherapy group were similar: 66% male, median age 59.5 years, 98% white, baseline ECOG performance status 0 (59%) or 1 (41%), 74% with M1c stage disease, 73% with cutaneous melanoma, 11% with mucosal melanoma, 73% received two or more prior therapies for advanced or metastatic disease, and 18% had brain metastasis. There were more patients in the OPDIVO group with elevated LDH at baseline (51% vs. 38%).

OPDIVO was discontinued for adverse reactions in 9% of patients. Twenty-six percent of patients receiving OPDIVO had a drug delay for an adverse reaction. Serious adverse reactions occurred in 41% of patients receiving OPDIVO. Grade 3 and 4 adverse reactions occurred in 42% of patients receiving OPDIVO. The most frequent Grade 3 and 4 adverse reactions reported in 2% to less than 5% of patients receiving OPDIVO were abdominal pain, hyponatremia, increased aspartate aminotransferase, and increased lipase.


FDA Approves Eisai’s LENVIMA™ (lenvatinib) for the Treatment of Patients with Locally Recurrent or Metastatic, Progressive, Radioactive Iodine-Refractory Differentiated Thyroid Cancer

– Press release from Eisai (NOTE: TRIAL NOT HALTED)

Feb 13, 2015

WOODCLIFF LAKE, N.J., Feb. 13, 2015 /PRNewswire/ — Eisai Inc. announced today that the U.S. Food and Drug Administration (FDA) approved the company’s receptor tyrosine kinase inhibitor LENVIMA™ (lenvatinib) for the treatment of locally recurrent or metastatic, progressive, radioactive iodine-refractory differentiated thyroid cancer (RAI-R DTC). LENVIMA was approved following a priority review by the FDA, which is designated for drugs the FDA believes have the potential to provide a significant improvement in the treatment of a serious condition. LENVIMA demonstrated a statistically significant progression-free survival (PFS) prolongation and response rate in patients with progressive, differentiated thyroid cancer who had become refractory to radioactive iodine (RAI) therapy.

In the clinical trial, adverse events led to dose reductions in 68% of patients who received LENVIMA and 5% of patients who received placebo. Some patients will need to discontinue treatment for serious adverse reactions. In the trial, 18% of patients treated with LENVIMA and 5% who received placebo discontinued treatment. The most common adverse reactions (at least 10%) that resulted in dose reductions of LENVIMA were hypertension (13%), proteinuria (11%), decreased appetite (10%), and diarrhea (10%).

AstraZeneca halts a pair of lung cancer trials over a safety scare

From October 9, 2015 | By of FierceBiotech

“AstraZeneca ($AZN) is pressing pause on trials combining two of its most important pipeline cancer treatments after tracking reports of lung disease, halting enrollment as it gathers more information.

The company is testing a combination of AZD9291 and durvalumab, formerly MEDI4736, in two studies involving patients with non-small cell lung cancer. Late last month, AstraZeneca hit the brakes on enrollment in both trials due to an increase in reports of interstitial lung disease, which can lead to dangerous scarring and impaired pulmonary function. The pauses are temporary, the company stressed in an emailed statement, and patients already enrolled in the study will be given new consent forms to ensure they understand the risks before choosing whether keep getting treatment.”

Other posts on this site on Cytotoxicity and Cancer include

Novel Approaches to Cancer Therapy [11.1]

Misfolded Proteins – from Little Villains to Little Helpers… Against Cancer

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

A Synthesis of the Beauty and Complexity of How We View Cancer

Good and Bad News Reported for Ovarian Cancer Therapy

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Dompe’ Receives FDA orphan drug designation for rhNGF in the treatment of Neurotrophic Keratitis (NK).

Reporter: Stephen J Williams, PhD

 

The U.S. FDA granted Dompe’ an orphan drug designation for rhNGF (recombinant human nerve growth factor) in the treatment of Neurotrophic Keratitis (NK).

Neurotrophic Keratitis (NK) is a rare, degenerative corneal disease caused by an impairment of corneal innervation (the distribution or supply of nerves), leading to a decrease or absence of corneal sensation and dysfunction of the corneal epithelium and abnormal corneal epithelial healing. The development of persistent epithelial defects or corneal ulcers can result in vision loss.

Severe NK is consistently recognized by clinicians as a serious condition lacking a highly effective treatment option.

The epidemiology of NK has not been well-defined. The estimated prevalence of patients with moderate-to-severe NK (stage 2-3) is less than 1 person in 5,000 globally.

Clinical trials in the U.S. are expected to begin in the next few months in leading research centers.

Dompé will be present at the American Association of Ophthalmology Annual meeting (Chicago, October 18-21). Currently, the enrollment is ongoing for the company’s Phase II trial with rhNGF in the treatment of NK.
Background – Dompé and its R&D

  • Dompé is a leading Italian biopharmaceutical company (with headquarters in Milan) committed to the development of innovative treatment solutions for rare, often orphan, diseases that have a high social impact, in areas where unmet treatment needs still exist.
  • The Company focuses its R&D activities in diabetes, ophthalmology, oncology and organ transplants.
  • The R&D activities are carried out in the Dompé biotech plant located in L’Aquila (Abruzzo), which has an internationally recognized expertise in the field of rare diseases.  
  • This year (2014), Dompé opened an office in New York, staffed with scientists and R&D teams in order to carry out and coordinate the scientific activities in the U.S.

 

Dompé commitment in ophthalmology – rhNGF

  • In ophthalmology, Dompé is promoting the research and development of Nerve Growth Factor (NGF), a soluble protein that stimulates the growth, maintenance and survival of neurons, whose discovery led to Prof. Rita Levi Montalcini being awarded the Nobel Prize in 1986.
  • Recombinant human Nerve Growth Factor (rhNGF) has been studied and produced exclusively at Dompé’s production site in L’Aquila, Italy, and is undergoing an international Phase II trial, called “REPARO”, to evaluate its efficacy and safety in the treatment of Neurotrophic Keratitis, a rare orphan disease. The trial is being conducted in 39 centers and nine European countries.

The medicine recently has been designated an orphan drug for the treatment of Retinitis Pigmentosa (RP), a severe, genetic rare disease that can lead to blindness for which there is currently no treatment available. A clinical trial in the EU, involving patients with RP, started in the first quarter of 2014 with the enrolment of the first patient.

SOURCE

From: Gail Thornton <gailsthornton@yahoo.com>
Reply-To: Gail Thornton <gailsthornton@yahoo.com>
Date: Wed, 23 Jul 2014 07:02:05 -0700
To: Aviva Lev-Ari <avivalev-ari@alum.berkeley.edu>
Subject: Dompe’ Receives FDA orphan drug designation for rhNGF

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Larry H Bernstein, MD, FCAP, Reporter and curator

αllbβ3 Antagonists As An Example of Translational Medicine Therapeutics

http://phrmaceuticalintelligence.com/2013-10-12/larryhbern_BS-Coller/αllbβ3 Antagonists As An Example of Translational Medicine Therapeutics

by Barry S. Coller, MD
Rockefeller University

Introduction

This article is a segment in several articles about platelets, platelet function, and advances in applying the surge of knowledge to therapy.  In acute coronary syndromes, plaque rupture leads to thrombotic occlusion.  We have also seen that the development of a plaque occurs in 3 stages, only the last of which involves plaque rupture.  Platelets interact with the vascular endothelium, and platelet-endothelial as well as platelet-platelet interactions are known to be important in atherogenesis.  We learned that platelets are derived from megakaryocytes that break up and these elements are released into the blood stream.  It has recently been discovered that platelets can replicate in the circulation.  The turnover of platelets is rapid, and platelets sre stored at room temperature with shaking, and are viable for perhaps only 3-4 days once they are received in the blood bank for use.  In cardiology, the identification, isolation, and characterization of GPIIb/IIIa from the platelet was a huge advance in the potential for coronary intervention, and that potential became of paramount importance with the introduction of GPIIb/IIIa inhibitors as a standard in coronary vascular therapeutic procedures.   The following manuscript by Barry Coller, at Rockefeller University,  is a presentation of the GPIIb/IIIa story as an excellent example of Translational Medicine.

Search for GPIIb/IIIa inhibitor of the (anti-αIIb133 (GPIIb/IIIa) receptor)

The deliberate search for drugs to inhibit the αIIb133 (GPIIb/IIIa) receptor ushered in the era of rationally designed antiplatelet therapy and thus represents an important milestone in the evolution of antiplatelet drug development. The selection of the αIIb133 receptor as a therapeutic target rested on a broad base of basic and clinical research conducted by many investigators in the 1960s and 1970s working in the fields of platelet physiology, the rare bleeding disorder Glanzmann thrombasthenia, platelet membrane glycoproteins, integrin receptors, coronary artery pathology, and experimental thrombosis. Thus, αIIb133 was found to mediate platelet aggregation by virtually all of the physiology agonists (e.g., ADP, epinephrine, and thrombin) through a mechanism in which platelet activation by these agents results in a change in the conformation of the receptor. This is followed by increased affinity of the receptor for the multivalent ligands fibrinogen and von Willebrand factor, both of which are capable of binding to receptors on two platelets simultaneously, producing platelet crosslinking and aggregation. At about the same time, experimental studies demonstrated platelet thrombus formation at sites of vascular injury, and biochemical studies in humans demonstrated evidence of platelet activation during acute ischemic cardiovascular events.

Our own studies initially focused on platelet-fibrinogen interactions using an assay in which normal platelets agglutinated fibrinogen-coated beads. The agglutination was enhanced with platelet activators. Platelets from patients with Glanzmann thrombasthenia, who lack the αIIb133 receptor, did not agglutinate the beads. We adapted this assay to a microtiter plate system to identify monoclonal antibodies that inhibited platelet-fibrinogen interactions and then demonstrated that these antibodies bound to αIIb133. They were also more potent inhibitors of platelet aggregation than any known antiplatelet agent and produced a pattern of aggregation that was virtually identical to that found using platelets from patients with Glanzmann thrombasthenia.

I recognized the theoretical potential of using an antibody to inhibit platelets in vivo but also recognized the challenges and limitations. Since experimental models of thrombosis had been developed in the dog, and since the antibody we initially worked with did not react with dog platelets, we had to go back to our original samples to identify an antibody (7E3) that reacted with dog platelets in addition to human platelets. Since coating platelets with immunoglobulins results in their rapid elimination of the platelets from the circulation, and since the clearance is mediated by the immunoglobulin Fc region, we prepared F(ab’)2 fragments of 7E3 for our in vivo studies. Additional challenges included preparing large quantities of antibody on a very limited budget and purifying the antibodies so they contained only minimal amounts of endotoxin. With the small amount of 7E3-F(ab’)2 we initially prepared, we were able to show dose response inhibition of platelet aggregation in three dogs, achieving greater inhibition than with aspirin or ticlopidine, the only antiplatelet agents approved for human use at that time. We also devised an assay using radiolabeled 7E3 to quantify the percentage of platelet αIIbβ3 receptors that were blocked when a specific dose of 7E3-F(ab’)2 was administered in vivo. This allowed us to directly measure the effect of the agent on its target receptor on its target cell.

I considered two criteria most important in selecting the initial animal models in which to test the efficacy and safety of administering 7E3-F(ab’)2:

  • 1) the model had to convincingly simulate a human vascular disease, and
  • 2) aspirin had to have failed to produce complete protection from thrombosis.

The latter criterion was particularly important because I planned to stop this line of research if the 7E3-F(ab’)2 was not more efficacious than aspirin.

Ultimately, we collaborated with Dr. John Folts of the University of Wisconsin, who had developed a dog model of unstable angina by attaching a short cylindrical ring to partially occlude a coronary artery and using a hemostat to induce vascular injury. Pretreatment of the animal with 7E3-F(ab’)2 was more effective than aspirin or any other compound Dr. Folts had previously tested in preventing platelet thrombus formation, as judged by its effects on the characteristic repetitive cycles of platelet deposition and embolization. Electron microscopy of the vessels confirmed the reduction in platelet thrombi by 7E3-F(ab’)2, with only a monolayer of platelets typically deposited.

Dr. Chip Gold and his colleagues at Massachusetts General Hospital had developed a dog model to assess the effects of tissue plasminogen activator (t-PA) on experimental thrombi induced in the dog coronary artery. Although t-PA was effective in lysing the thrombi, the blood vessels rapidly reoccluded with new thrombi that were rich in platelets. Aspirin could not prevent reocclusion, whereas 7E3-F(ab’)2 not only prevented reocclusion, but also increased the speed of reperfusion by t-PA.

The next steps in drug development could not be performed in my laboratory because they required resources far in excess of those in my grant from the National Heart, Lung, and Blood Institute to study basic platelet physiology. As a result, in 1986 the Research Foundation of the State University of New York licensed the 7E3 antibody to Centocor, Inc., a new biotechnology company specializing in the diagnostic and therapeutic application of monoclonal antibodies.

Subsequent Development of 7E3

The subsequent development of 7E3 as a therapeutic agent required extensive collaboration among myself, a large number of outstanding scientists at Centocor, and many leading academic cardiologists. Many decisions and hurdles remained for us, including the decision to develop a mouse/human chimeric 7E3 Fab (c7E3 Fab); the design and execution of the toxicology studies; the assessment of the potential toxicity of 7E3 crossreactivity with αVβ3; the development of sensitive and specific assays to assess immune responses to c7E3 Fab; the design, execution, and analysis of the Phase I, II, and III studies; and the preparation, submission, and presentation of the Product Licensing  Application to the Food and Drug Administration, and comparable documents to European and Scandinavian agencies.

Based on the results of the 2,099 patient EPIC trial, in which conjunctive treatment with a bolus plus infusion of c7E3 Fab significantly reduced the risk of developing an ischemic complication (death, myocardial infarction, or need for urgent intervention) after coronary artery angioplasty or atherectomy in patients at high risk of such complications, the Food and Drug Administration approved the conjunctive use of c7E3 Fab (generic name, abciximab) in high-risk angioplasty and atherectomy on December 22, 1994. Since then it has been administered to more than 2.5 million patients in the U.S., Europe, Scandinavia, and Asia. Its optimal role in treating cardiovascular disease continues to evolve in response to the introduction of new anticoagulants, antiplatelet agents, stents, and procedures.

Extended Investigations

We have also been able to apply the monoclonal antibodies we prepared to αIIb33 to the prenatal detection of Glanzmann thrombasthenia, and have used the antibodies as probes for characterizing both the biogenesis of the receptor and the conformational changes that the receptor undergoes with activation. We have been able to precisely map the 7E3 epitope on 33, providing additional insights into the mechanism by which it prevents ligand binding. We have also exploited the ability of another antibody to αIIb33 to stabilize the receptor complex in order to facilitate production of crystals of the αIIb33 headpiece; the x-ray diffraction properties of these crystals were studied in collaboration with Dr. Timothy Springer’s group at Harvard and provide the first structural information on the receptor.

In landmark studies in the 1980s, Pierschbacher and Ruoslahti demonstrated the importance of the arginine-aspartic acid (RGD) sequence in the interaction of the integrin α531 with fibronectin, and they went on to show that peptides with the RGD sequence could inhibit this interaction. Subsequent studies by many groups demonstrated that these peptides could also inhibit the interaction of platelet αIIb33 with fibrinogen and von Willebrand factor. Dr. David Phillip and Dr. Robert Scarbrough led the team at Cor Therapeutics that made a cyclic pentapeptide with high selectivity for αIIb33 over αV33 by patterning their compound on the KGD sequence in the snake venom barbourin. The resulting antiplatelet agent, eptifibatide, received FDA approval in May 1998. At Merck, Dr. Robert Gould led the team that developed the nonpeptide RGD-mimetic tirofiban, which also is selective for αIIb33 compared to αV33. It also received FDA approval in May 1998. Our recent x-ray crystallographic studies in collaboration with Dr. Springer’s group provided structural information on the mechanisms and sites of binding of these drugs with αIIb33.

Translation of Basic Science into Therapy

Many important elements and an enormous amount of good fortune were needed for the translation of the basic science information about platelet aggregation into the drug abciximab, including, but not limited to:

  • 1) the support of basic studies of platelet physiology by the National Institutes of Health in my laboratory and many other laboratories,
  • 2) the creation and ongoing funding of a core facility available to all faculty members to prepare monoclonal antibodies at the State University of New York at Stony Brook under the direction of Dr. Arnold Levine,
  • 3) the 1988 Bayh-Dole Act and its subsequent amendments, and the expertise of the Technology Transfer Office at Stony Brook in licensing 7E3 to Centocor, which then provided the capital and additional expertise required for its development, and
  • 4) the expert and enthusiastic collaboration by two large and disciplined cooperative groups of interventional cardiologists (TAMI, EPIC) under the dynamic leadership of Drs. Eric Topol and Rob Califf,

tirofiban, that were eager to test the safety and efficacy of the 7E3 derivatives. Although the translation of each new scientific discovery into improved health via novel preventive, diagnostic, or therapeutic strategies requires the blazing of a unique path, optimizing these elements and similar ones may allow the path to be shorter and/or to be traversed more easily, at a lower cost, or in a shorter period of time.

 

Related articles in Pharmaceutical Intelligence:

Platelets in Translational Research – 1   Larry H. Bernstein, MD, FCAP
https://pharmaceuticalintelligence.com/10-6-2013/larryhbern/Platelets_in_Translational_Research-1
Platelets in Translational Research – 2  Larry H. Bernstein, MD, FCAP
http://phramaceuticalintelligence.com/2013-10-7/larryhbern/Platelets-in-Translational-Research-2/

Do Novel Anticoagulants Affect the PT/INR? The Cases of XARELTO (rivaroxaban) and PRADAXA (dabigatran)
Vivek Lal, MBBS, MD, FCIR, Justin D Pearlman, MD, PhD, FACC and Aviva Lev-Ari, PhD, RN
https://pharmaceuticalintelligence.com/2013/09/23/do-novel-anticoagulants-affect-the-ptinr-the-cases-of-xarelto-rivaroxaban-and-pradaxa-dabigatran/

 

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