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Archive for the ‘Acute myelocytic leukemia’ Category


Blast crisis in myeloid leukemia and the activation of a microRNA-editing enzyme called ADAR1

Curator: Larry H. Bernstein, MD, FCAP

 

Fix to RNA-Editing Glitch May Defuse Blast Crisis

GEN News Highlights Jun 10, 2016   http://www.genengnews.com/gen-news-highlights/fix-to-rna-editing-glitch-may-defuse-blast-crisis/81252818/

The self-renewal of leukemia stem cells depends on the activation of a microRNA-editing enzyme called ADAR1. According to a new study, ADAR1 activation represents a unique therapeutic vulnerability in leukemia stem cells, which can give rise to blast crisis in chronic myeloid leukemia.     http://www.genengnews.com/Media/images/GENHighlight/thumb_Jun10_2016_ChronicMyeloidLeukemiaBloodCells6222419925.jpg

Few cancer mechanisms are as devastating as the generation of cancer stem cells, which arise in leukemia from white blood cell precursors. The mechanisms of this transition have been obscure, but the consequences are all too clear. Leukemia stem cells promote an aggressive, therapy-resistant form of disease called blast crisis.

Delving into the mechanisms by which leukemia stem cells are primed, a team of scientists at the University of California, San Diego (UCSD), uncovered a misfiring RNA-editing system. The main problem the scientists found was an enzyme called ADAR1 (adenosine deaminase acting on RNA1), which mediates post-transcriptional adenosine-to-inosine (A-to-I) RNA editing.

ADAR1 can edit the sequence of microRNAs (miRNAs), small pieces of genetic material. By swapping out just one miRNA building block for another, ADAR1 alters the carefully orchestrated system cells use to control which genes are turned on or off at which times.

ADAR1 is known to promote cancer progression and resistance to therapy. To study ADAR1, the UCSD team used human blast crisis chronic myeloid leukemia (CML) cells in the lab, and mice transplanted with these cells, to determine the enzyme’s role in governing leukemia stem cells.

The scientists, led by Catriona Jamieson, M.D., Ph.D., published their work June 9 in Cell Stem Cell, in an article entitled, “ADAR1 Activation Drives Leukemia Stem Cell Self-Renewal by Impairing Let-7 Biogenesis.” The article presented the first mechanistic link between pro-cancer inflammatory signals and RNA editing–driven reprogramming of precursor cells into leukemia stem cells.

The article describes how ADAR1-mediated A-to-I RNA editing is activated by Janus kinase 2 (JAK2) signaling and BCR-ABL1 signaling. Also, it indicated, in a model of blast crisis (BC) CML, that combined JAK2 and BCR-ABL1 inhibition prevents leukemia stem cell self-renewal commensurate with ADAR1 downregulation.

Essentially, the scientists were able to trace a series of molecular events: First, white blood cells with a leukemia-promoting gene mutation become more sensitive to signs of inflammation. That inflammatory response activates ADAR1. Then, hyper-ADAR1 editing slows down the miRNAs known as let-7. Ultimately, this activity increases cellular regeneration, or self-renewal, turning white blood cell precursors into leukemia stem cells.

“Lentiviral ADAR1 wild-type, but not an editing-defective ADAR1E912A mutant, induces self-renewal gene expression and impairs biogenesis of stem cell regulatory let-7 microRNAs,” wrote the author of the Cell Stem Cell article. “Combined RNA sequencing, qRT-PCR, CLIP-ADAR1, and pri-let-7 mutagenesis data suggest that ADAR1 promotes LSC generation via let-7 pri-microRNA editing andLIN28B upregulation.”

After learning how the ADAR1 system works, Dr. Jamieson’s team looked for a way to stop it. By inhibiting sensitivity to inflammation or inhibiting ADAR1 with a small-molecule tool compound, the researchers were able to counter ADAR1’s effect on leukemia stem cell self-renewal and restore let-7. Self-renewal of blast crisis CML cells was reduced by approximately 40% when treated with the small molecule called 8-Aza as compared to untreated cells.

“A small-molecule tool compound antagonizes ADAR1’s effect on LSC self-renewal in stromal co-cultures and restores let-7 biogenesis,” the study’s authors noted. “Thus, ADAR1 activation represents a unique therapeutic vulnerability in LSCs with active JAK2 signaling.”

“In this study, we showed that cancer stem cells co-opt a RNA editing system to clone themselves. What’s more, we found a method to dial it down,” said Dr. Catriona Jamieson. “Based on this research, we believe that detecting ADAR1 activity will be important for predicting cancer progression.

“In addition, inhibiting this enzyme represents a unique therapeutic vulnerability in cancer stem cells with active inflammatory signaling that may respond to pharmacologic inhibitors of inflammation sensitivity or selective ADAR1 inhibitors that are currently being developed.”

 

ADAR1 Activation Drives Leukemia Stem Cell Self-Renewal by Impairing Let-7 Biogenesis

Maria Anna Zipeto, Angela C. Court, Anil Sadarangani, Nathaniel P. Delos Santos, Larisa Balaian, Hye-Jung Chun, Gabriel Pineda, Sheldon R. Morris, Cayla N. Mason, Ifat Geron, Christian Barrett, Daniel J. Goff, Russell Wall, Maurizio Pellecchia, Mark Minden, Kelly A. Frazer, Marco A. Marra, Leslie A. Crews, Qingfei Jiang, Catriona H.M. Jamieson
Published online: June 9, 2016
  • JAK2 signaling activates ADAR1-mediated A-to-I RNA editing
  • JAK2 and BCR-ABL1 signaling converge on ADAR1 activation through STAT5a
  • ADAR1-mediated microRNA editing impairs let-7 biogenesis and enhances LSC self-renewal
  • JAK2 and BCR-ABL1 inhibition reduces ADAR1 expression and prevents LSC self-renewal

Post-transcriptional adenosine-to-inosine RNA editing mediated by adenosine deaminase acting on RNA1 (ADAR1) promotes cancer progression and therapeutic resistance. However, ADAR1 editase-dependent mechanisms governing leukemia stem cell (LSC) generation have not been elucidated. In blast crisis chronic myeloid leukemia (BC CML), we show that increased JAK2 signaling and BCR-ABL1 amplification activate ADAR1. In a humanized BC CML mouse model, combined JAK2 and BCR-ABL1 inhibition prevents LSC self-renewal commensurate with ADAR1 downregulation. Lentiviral ADAR1 wild-type, but not an editing-defective ADAR1E912A mutant, induces self-renewal gene expression and impairs biogenesis of stem cell regulatory let-7 microRNAs. Combined RNA sequencing, qRT-PCR, CLIP-ADAR1, and pri-let-7 mutagenesis data suggest that ADAR1 promotes LSC generation via let-7 pri-microRNA editing and LIN28Bupregulation. A small-molecule tool compound antagonizes ADAR1’s effect on LSC self-renewal in stromal co-cultures and restores let-7 biogenesis. Thus, ADAR1 activation represents a unique therapeutic vulnerability in LSCs with active JAK2 signaling.

 

Figure thumbnail fx1

 

 

https://ash.confex.com/ash/2015/webprogram/Paper85836.html

4014 Inflammatory Cytokine-Responsive ADAR1 Impairs Let-7 Biogenesis and Promotes Leukemia Stem Cell Generation

Chronic Myeloid Leukemia: Biology and Pathophysiology, excluding Therapy
Program: Oral and Poster Abstracts
Session: 631. Chronic Myeloid Leukemia: Biology and Pathophysiology, excluding Therapy: Poster III
Monday, December 7, 2015, 6:00 PM-8:00 PM
Hall A, Level 2 (Orange County Convention Center)

Maria Anna Zipeto, Ph.D1*, Angela Court Recart2*, Nathaniel Delos Santos3*, Qingfei Jiang, PhD4*, Leslie A Crews, PhD3* and Catriona HM Jamieson, MD, PhD3

1Sanford Consortium for Regenerative Medicine, University of California San Diego, La Jolla, CA
2University of California San Diego, LA JOLLA, CA
3Division of Regenerative Medicine, University of California, San Diego, La Jolla, CA
4University of California San Diego, La Jolla, CA

BackgroundIn advanced human malignancies, RNA sequencing (RNA-seq) has uncovered deregulation of adenosine deaminase acting on RNA (ADAR) editases that promote therapeutic resistance and leukemia stem cell (LSC) generation. Chronic myeloid leukemia (CML), an important paradigm for understanding LSC evolution, is initiated by BCR-ABL1 oncogene expression in hematopoietic stem cells (HSCs) but undergoes blast crisis (BC) transformation following aberrant self-renewal acquisition by myeloid progenitors harboring cytokine-responsive ADAR1 p150 overexpression. Emerging evidence suggests that adenosine to inosine editing at the level of primary (pri) or precursor (pre)-microRNA (miRNA), alters miRNA biogenesis and impairs biogenesis. However, relatively little is known about the role of inflammatory niche-driven ADAR1 miRNA editing in malignant reprogramming of progenitors into self-renewing LSCs.

Methods

Primary normal and CML progenitors were FACS-purified and RNA-Seq analysis as well as qRT-PCR validation were performed according to published methods (Jiang, 2013). MiRNAs were extracted from purified CD34+ cells derived from CP, BC CML and cord blood by RNeasy microKit (QIAGEN) and let-7 expression was evaluated by qRT-PCR using miScript Primer assay (QIAGEN). CD34+ cord blood (n=3) were transduced with lentiviral human JAK2, let-7a, wt-ADAR1 and mutant ADAR1, which lacks a functional deaminase domain.  Because STAT signaling triggers ADAR1 transcriptional activation and both BCR-ABL1 and JAK2 activate STAT5a, nanoproteomics analysis of STAT5a levels was performed.  Engrafted immunocompromised RAG2-/-γc-/- mice were treated with a JAK2 inhibitor, SAR302503, alone or in combination with a potent BCR-ABL1 TKI Dasatinib, for two weeks followed by FACS analysis of human progenitor engraftment in hematopoietic tissues and serial transplantation.

Results

RNA-seq and qRT-PCR analysis in FACS purified BC CML progenitors revealed an over-representation of inflammatory pathway activation and higher levels of JAK2-dependent inflammatory cytokine receptors, when compared to normal and chronic phase (CP) progenitors. Moreover, RNA-seq and qRT-PCR analysis showed decreased levels of mature let-7 family of stem cell regulatory miRNA in BC compared to normal and CP progenitors. Lentiviral human JAK2 transduction of CD34+ progenitors led to an increase of ADAR1 transcript levels and to a reduction in let-7 family members. Interestingly, lentiviral human JAK2 transduction of normal progenitors enhanced ADAR1 activity, as revealed by RNA editing-specific qRT-PCR and RNA-seq analysis. Moreover, qRT-PCR analysis of CD34+ progenitors transduced with wt-ADAR1, but not mutant ADAR1 lacking functional deaminase activity, reduced let-7 miRNA levels. These data suggested that ADAR1 impairs let-7 family biogenesis in a RNA editing dependent manner. Interestingly, RNA-seq analysis confirmed higher frequency of A-to-I editing events in pri- and pre-let-7 family members in CD34+ BC compared to CP progenitors, as well as normal progenitors transduced with human JAK2 and ADAR1-wt, but not mutant ADAR1. Lentiviral ADAR1 overexpression enhanced CP CML progenitor self-renewal and decreased levels of some members of the let-7 family. In contrast, lentiviral transduction of human let-7a significantly reduced self-renewal of progenitors. In vivo treatments with Dasatinib in combination with a JAK2 inhibitor, significantly reduced self-renewal of BCR-ABL1 expressing BC progenitors in the bone marrow thereby prolonging survival of serially transplanted mice. Finally, a reduction in ADAR1 p150 transcripts was also noted following combination treatment only suggesting a role for ADAR1 in CSC propagation.

Conclusion

This is the first demonstration that intrinsic BCR-ABL oncogenic signaling and extrinsic cytokines signaling through JAK2 converge on activation of ADAR1 that drives LSC generation by impairing let-7 miRNA biogenesis. Targeted reversal of ADAR1-mediated miRNA editing may enhance eradication of inflammatory niche resident cancer stem cells in a broad array of malignancies, including JAK2-driven myeloproliferative neoplasms.

Disclosures: Jamieson: J&J: Research Funding ; GSK: Research Funding .

Interferon Receptor Signaling in Malignancy: a Network of Cellular Pathways Defining Biological Outcomes

Interferons (IFNs) are cytokines with important anti-proliferative activity and exhibit key roles in immune surveillance against malignancies. Early work initiated over 3 decades ago led to the discovery of IFN receptor activated Jak-Stat pathways and provided important insights into mechanisms for transcriptional activation of interferon stimulated genes (ISGs) that mediate IFN-biological responses. Since then, additional evidence has established critical roles for other receptor activated signaling pathways in the induction of IFN-activities. These include MAPK pathways, mTOR cascades and PKC pathways. In addition, specific microRNAs (miRNAs) appear to play a significant role in the regulation of IFN-signaling responses. This review focuses on the emerging evidence for a model in which IFNs share signaling elements and pathways with growth factors and tumorigenic signals, but engage them in a distinctive manner to mediate anti-proliferative and antiviral responses.

Because of their antineoplastic, antiviral, and immunomodulatory properties, recombinant interferons (IFNs) have been used extensively in the treatment of various diseases in humans (1). IFNs have clinical activity against several malignancies and are actively used in the treatment of solid tumors such as malignant melanoma and renal cell carcinoma; and hematological malignancies, such as myeloproliferative neoplasms (MPNs) (1). In addition, IFNs play prominent roles in the treatment of viral syndromes, such as hepatitis B and C (2). In contrast to their beneficial therapeutic properties, IFNs have been also implicated in the pathophysiology of certain diseases in humans. In many cases this involvement reflects abnormal activation of the endogenous IFN system, which has important roles in various physiological processes. Diseases in which dysregulation of the Type I IFN system has been implicated as a pathogenetic mechanism include autoimmune disorders such as systemic lupus erythematosous (3), Sjogren’s syndrome (3,4), dermatomyositis (5) and systemic sclerosis (3, 4). In addition, Type II IFN (IFNγ) overproduction has been implicated in bone marrow failure syndromes, such as aplastic anemia (6). There is also recent evidence for opposing actions of distinct IFN subtypes in the pathophysiology of certain diseases. For instance, a recent study demonstrated that there is an inverse association between IFNβ and IFNγ gene expression in human leprosy, consistent with opposing functions between Type I and II IFNs in the pathophysiology of this disease (7). Thus, differential targeting of components of the IFN-system, to either promote or block induction of IFN-responses depending on the disease context, may be useful in the therapeutic management of various human illnesses. The emerging evidence for the complex regulation of the IFN-system underscores the need for a detailed understanding of the mechanisms of IFN-signaling in order to target IFN-responses effectively and selectively.

It took over 35 years from the original discovery of IFNs in 1957 to the discovery of Jak-Stat pathways (8). The identification of the functions of Jaks and Stats dramatically advanced our understanding of the mechanisms of IFN-signaling and had a broad impact on the cytokine research field as a whole, as it led to the identification of similar pathways from other cytokine receptors (8). Subsequently, several other IFN receptor (IFNR)-regulated pathways were identified (9). As discussed below, in recent years there has been accumulating evidence that beyond Stats, non-Stat pathways play important and essential roles in IFN-signaling. This has led to an evolution of our understanding of the complexity associated with IFN receptor activation and how interacting signaling networks determine the relevant IFN response.

Interferons and their functions

The interferons are classified in 3 major categories, Type I (α, β, ω, ε, τ, κ, ν); Type II (γ) and Type III IFNs (λ1, λ2, λ3) (1, 9, 10). The largest IFN-gene family is the group of Type I IFNs. This family includes 14 IFNα genes, one of which is a pseudogene, resulting in the expression of 13 IFNα protein subtypes (1, 9). There are 3 distinct IFNRs that are specific for the 3 different IFN types. All Type I IFN subtypes bind to and activate the Type I IFNR, while Type II and III IFNs bind to and activate the Type II and III IFNRs, respectively (911). It should be noted that although all the different Type I IFNs bind to and activate the Type I IFNR, differences in binding to the receptor may account for specific responses and biological effects (9). For instance, a recent study provided evidence that direct binding of mouse IFNβ to the Ifnar1 subunit, in the absence of Ifnar2, regulates engagement of signals that control expression of genes specifically induced by IFNβ, but not IFNα (12). This recent discovery followed original observations from the 90s that revealed differential interactions between the different subunits of the Type I IFN receptor in response to IFNβ binding as compared to IFNα binding and partially explained observed differences in functional responses between different Type I IFNs (9).

A common property of all IFNs, independently of type and subtype, is the induction of antiviral effects in vitro and in vivo (1). Because of their potent antiviral properties, IFNs constitute an important element of the immune defense against viral infections. There is emerging information indicating that specificity of the antiviral response is cell type dependent and/or reflects specific tissue expression of certain IFNs. As an example, a recent comparative analysis of the involvement of the Type I IFN system as compared to the Type III IFN system in antiviral protection against rotavirus infection of intestinal epithelial cells demonstrated an almost exclusive requirement for IFNλ (Type III IFN) (13). The antiviral effects of IFNα have led to the introduction of this cytokine in the treatment of hepatitis C and B in humans (2) and different viral genotypes have been associated with response or failure to IFN-therapy (14).

Most importantly, IFNs exhibit important antineoplastic effects, reflecting both direct antiproliferative responses mediated by IFNRs expressed on malignant cells, as well as indirect immunomodulatory effects (15). IFNα and its pegylated form (peg IFNα) have been widely used in the treatment of several neoplastic diseases, such as hairy cell leukemia (HCL), chronic myeloid leukemia (CML), cutaneous T cell lymphoma (CTCL), renal cell carcinoma (RCC), malignant melanoma, and myeloproliferative neoplasms (MPNs) (1, 16). Although the emergence of new targeted therapies and more effective agents have minimized the use of IFNs in the treatment of diseases like HCL and CML, IFNs are still used extensively in the treatment of melanoma, CTCL and MPNs (1, 16, 17). Notably, recent studies have provided evidence for long lasting molecular responses in patients with polycythemia vera (PV), essential thrombocytosis (ET) and myelofibrosis (MF) who were treated with IFNα (16). Beyond their inhibitory properties on malignant hematopoietic progenitors, IFNs are potent regulators of normal hematopoiesis (9) and contribute to the regulation of normal homeostasis in the human bone marrow (18). Related to its effects in the central nervous system, IFNβ has clinical activity in multiple sclerosis (MS) and has been used extensively for the treatment of patients with MS (19). The immunoregulatory properties of Type I IFNs include key roles in the control of innate and adaptive immune responses, as well as positive and negative effects on the activation of the inflammasome (15). Dysregulation of the Type I IFN response is seen in certain autoimmune diseases, such as Aicardi-Goutières syndrome (20). In fact, self-amplifying Type I IFN-production is a key pathophysiological mechanism in autoimmune syndromes (21). There is also emerging evidence that IFNλ may contribute to the IFN signature in autoimmune diseases (3).

Jak-Stat pathways

Jak kinases and DNA binding Stat-complexes

Tyrosine kinases of the Janus family (Jaks) are associated in unique combinations with different IFNRs and their functions are essential for IFN-inducible biological responses. Stats are transcriptional activators whose activation depends on tyrosine phosphorylation by Jaks (8, 9). In the case of the Type I IFN receptor, Tyk2 and Jak1 are constitutively associated with the IFNAR1 and IFNAR2 subunits, respectively (8, 9) (Fig. 1). For the Type II IFN receptor, Jak1 and Jak2 are associated with the IFNGR1 and IFNGR2 receptor subunits, respectively (8, 9) (Fig. 1). Finally, in the case of the Type III IFNR, Jak1 and Tyk2 are constitutively associated with the IFN-λR1 and IL-10R2 receptor chains, respectively (10) (Fig. 1). Upon engagement of the different IFNRs by the corresponding ligands, the kinase domains of the associated Jaks are activated and phosphorylate tyrosine residues in the intracellular domains of the receptor subunits that serve as recruitmenst sites for specific Stat proteins. Subsequently, the Jaks phosphorylate Stat proteins that form unique complexes and translocate to the nucleus where they bind to specific sequences in the promoters of ISGs to initiate transcription. A major Stat complex in IFN-signaling is the interferon stimulated gene factor 3 (ISGF3) complex. This IFN-inducible complex is composed or Stat1, Stat2 and IRF9 and regulates transcription by binding to IFN stimulated response elements (ISRE) in the promoters of a large group of IFN stimulated genes (ISGs) (8, 9). ISGF3 complexes are induced during engagement of the Type I and III IFN receptors, but not in response to activation of Type II IFN receptors (810) (Table 1). Beyond ISGF3, several other Stat-complexes involving different Stat homodimers or heterodimers are activated by IFNs and bind to IFNγ-activated (GAS) sequences in the promoters of groups of ISGs (8, 9). Such GAS binding complexes are induced by all different IFNs (I, II and III), although there is variability in the engagement and utilization of different Stats by the different IFN-receptors (Table 1). It should also be noted that engagement of certain Stats, such as Stat4 and Stat6, is cell type-specific and may be relevant for tissue specific functions (9). The significance of different Stat binding complexes in the induction of Type I and II IFN responses was in part addressed in a study in which Stat1 cooperative DNA binding was disrupted by generating knock-in mice expressing cooperativity-deficient STAT1 (22). As expected, Type II IFN-induced gene transcription and antibacterial responses were essentially lost in these mice, but Type I IFN-dependent recruitment of Stat1 to ISRE elements and antiviral responses were not affected (22), demonstrating the existence of important differences in Stat1 cooperative DNA binding between Type I and II IFN signaling.

Type I, II, III interferon receptors subunits, associated kinases of the Janus family, and effector Stat-pathways. Note: Stat:Stat reflects multiple potential Stat:Stat compexes, as outlined in Table 2.

Table 1

Different Stat-DNA binding complexes induced by Type I, II and III IFNs.

Serine phosphorylation of Stats

The nuclear translocation of Stat-proteins occurs after their activation, following phosphorylation on specific sites by Jak kinases (8, 9). It is well established that phosphorylation on tyrosine 701 is required for activation of Stat1 and phosphorylation on tyrosine 705 is required for activation of Stat3 (8, 9). Beyond tyrosine phosphorylation, phosphorylation on serine 727 in the Stat1 and Stat3 transactivation domains is required for full and optimal transcriptional activation of ISGs (8, 9). There is evidence that serine phosphorylation occurs after the phosphorylation of Stat1 on tyrosine 701 and that translocation to the nucleus and recruitment to the chromatin are essential in order for Stat1 to undergo serine 727 phosphorylation (23). Several IFN-dependent serine kinases for Stat1 have been described, raising the possibility that this phosphorylation occurs in a cell type specific manner. After the original demonstration that protein kinase C (PKC) delta (PKCδ) is a serine kinase for Stat1 and is required for optimal transcriptional activation in response to IFNα (24), extensive work has confirmed the role of this PKC isoform in the regulation of serine 727 phosphorylation in Stat1 and has been extended to different cellular systems (2529) (Table 2). In the Type II IFN system five different serine kinases for the transactivation domain (TAD) of Stat1/phosphorylation on serine 727 have been demonstrated in different cell systems.  …..

Serine phosphorylation of Stats

The nuclear translocation of Stat-proteins occurs after their activation, following phosphorylation on specific sites by Jak kinases (8, 9). It is well established that phosphorylation on tyrosine 701 is required for activation of Stat1 and phosphorylation on tyrosine 705 is required for activation of Stat3 (8, 9). Beyond tyrosine phosphorylation, phosphorylation on serine 727 in the Stat1 and Stat3 transactivation domains is required for full and optimal transcriptional activation of ISGs (8, 9). There is evidence that serine phosphorylation occurs after the phosphorylation of Stat1 on tyrosine 701 and that translocation to the nucleus and recruitment to the chromatin are essential in order for Stat1 to undergo serine 727 phosphorylation (23). Several IFN-dependent serine kinases for Stat1 have been described, raising the possibility that this phosphorylation occurs in a cell type specific manner. After the original demonstration that protein kinase C (PKC) delta (PKCδ) is a serine kinase for Stat1 and is required for optimal transcriptional activation in response to IFNα (24), extensive work has confirmed the role of this PKC isoform in the regulation of serine 727 phosphorylation in Stat1 and has been extended to different cellular systems (2529) (Table 2). In the Type II IFN system five different serine kinases for the transactivation domain (TAD) of Stat1/phosphorylation on serine 727 have been demonstrated in different cell systems. ….

Protein tyrosine phosphatases with regulatory effects on Jak-Stat pathways in IFN-signaling.
…….

MicroRNAs (miRs) and the IFN response

IFN-inducible JAK-STAT, MAPK and mTOR signaling cascades are also regulated potentially by microRNAs (miRs). miRs are important regulators of post-transcriptional events, leading to inhibition of mRNA translation or mRNA degradation (105). In recent years it has become apparent that the direct regulation of STAT activity by mIRs has profound effects on consequent gene expression, specifically in the context of cytokine-inducible events (106). Pertinent for this review of IFN-inducible STAT activation, miR-145, miR-146A and miR-221/222 target STAT1 and miR-221/222 target STAT2 (106). Numerous studies describe different miRs that target STAT3: mIR-17, miR-17-5p, mIR-17-3p, mIR-18a, miR-19b, mIR-92-1, miR-20b, Let-7a, miR-106a, miR-106-25, miR-106a-362 and miR-125b (106) (Fig. 4). mIR-132, miR-212 and miR-200a have been implicated in negatively regulating STAT4 expression in human NK cells (107) and miR-222 has been shown to regulate STAT5 expression (108). In addition, JAK-STAT signaling is affected by miR targeting of suppressors of cytokine signaling (SOCS) proteins. miR-122 and miR-155 targeting of SOCS1 releases the inhibition of STAT1 (and STAT5a/b) (109111), and mIR-19a regulation of SOCS1 and SOCS3 effectively prolongs activation of both STAT1 and STAT3 (112). There is also evidence that miR-155 targets the inositol phosphatase SHIP1, effectively prolonging/inducing IFN-γ expression (113). Much of the evidence associated with miRs prolonging JAK-STAT activation relates to cancer studies, where tumor-secreted miRs promote cell migration and angiogenesis by prolonging JAK-STAT activation (114). miR-145 targeting of SOCS7 affects nuclear translocation of STAT3 and has been associated with enhanced IFNβ production (115). Beyond inhibition of SOCS proteins, miRs may influence the expression of other inhibitory factors associated with JAK-STAT signaling, and miR-301a and miR-18a have been shown to inhibit PIAS3, a negative regulator of STAT3 activation (116). There is also the potential for STATS to directly regulate miR gene expression. STAT5 suppresses expression of miR15/16 (117) and there is evidence that there are potential STAT3 binding sites in the promoters of about 200 miRs (118). Viewed altogether, there is compelling evidence for miR-STAT interactions, yet few studies have considered the contributions of miRs to IFN-inducible JAK-STAT signaling.

Targeting and regulation of various proteins known to be involved in IFN-signaling by different miRNAs.  ….

Evolution of our understanding of IFN-signals and future perspectives

A substantial amount of knowledge has accumulated since the original discovery of the Jak-Stat pathway in the early 90s. It is now clear that several key signaling cascades are essential for the induction of Type I, II and III IFN-responses. The original view that IFN-signals can be transmitted from the cell surface to the nucleus in two simple steps involving tyrosine phosphorylation of Stat proteins (8) now appears somewhat simplistic, as it has been established that modifications of Jak-Stat signals by other pathways and/or simultaneous engagement of other essential complementary cellular cascades is essential for induction of ISG transcriptional activation, mRNA translation, protein expression and subsequent induction of IFN-responses. Such pathways include PKC and MAP kinase pathways and mTORC1 and mTORC2-dpendent signaling cascades.

Over the next decade our understanding of the mechanisms by which IFN-signals are induced will likely continue to evolve, with the anticipated outcome that it will be possible exploit this new knowledge for translational-therapeutic purposes. For instance, selective targeting of kinase-elements of the IFN-pathway with kinase inhibitors may be useful in the treatment of autoimmune diseases where dysregulated/excessive Type I IFN production contributes to the pathophysiology of disease. On the other hand, efforts to promote the induction of specific IFN-signals, may lead to novel, less toxic, therapeutic interventions for a variety of viral infectious diseases and neoplastic disorders.

Exploring the RNA World in Hematopoietic Cells Through the Lens of RNA-Binding Proteins

The discovery of microRNAs has renewed interest in post-transcriptional modes of regulation, fueling an emerging view of a rich RNA world within our cells that deserves further exploration. Much work has gone into elucidating genetic regulatory networks that orchestrate gene expression programs and direct cell fate decisions in the hematopoietic system. However, the focus has been to elucidate signaling pathways and transcriptional programs. To bring us one step closer to reverse engineering the molecular logic of cellular differentiation, it will be necessary to map post-transcriptional circuits as well and integrate them in the context of existing network models. In this regard, RNA-binding proteins (RBPs) may rival transcription factors as important regulators of cell fates and represent a tractable opportunity to connect the RNA world to the proteome. ChIP-seq has greatly facilitated genome-wide localization of DNA-binding proteins, helping us to understand genomic regulation at a systems level. Similarly, technological advances such as CLIP-seq allow transcriptome-wide mapping of RBP binding sites, aiding us to unravel post-transcriptional networks. Here, we review RBP-mediated post-transcriptional regulation, paying special attention to findings relevant to the immune system. As a prime example, we highlight the RBP Lin28B, which acts as a heterochronic switch between fetal and adult lymphopoiesis.

The basis of cellular differentiation and function can be represented as integrated circuits that are genetically programmed. Identification of the master regulators within these complex circuits that can switch on or off a genetic program will enable us to reprogram cells to suit biomedical needs. A remarkable example was the discovery by Takahashi and Yamanaka (1) that somatic cells could be reprogrammed into induced pluripotent stem (iPS) cells via the ectopic expression of four key transcription factors. Interestingly, a specific set of microRNAs (miRNAs) could also mediate this reprogramming (2, 3), revealing a powerful layer of post-transcriptional regulation that is able to override a pre-existing transcriptional program (4). Similarly, miR-9 and miR-124 were sufficient to mediate transdifferentiation of human fibroblasts into neurons (5). Accordingly, we are enamored by the RNA world and pay special attention in our investigations to regulatory non-coding RNAs (ncRNAs), particularly miRNAs and long non-coding RNAs (lncRNAs) and how they integrate with known genetic regulatory networks (Fig. 1). With the exception of certain ribozymes, regulatory RNAs generally do not work alone. Instead, they are physically organized as RNA-protein (RNP) complexes. Operationally, RNA-binding proteins (RBPs) and their interactome work in concert as post-transcriptional networks, or RNA regulons, in response to developmental and environmental cues (6). Inspired by this concept and other pioneering studies in the worm, we recently demonstrated that a single RBP Lin28 was sufficient to reprogram adult hematopoietic progenitors to adopt fetal-like properties (7). We discuss these and related findings, which begin to disentangle the complex functions of RBPs in the context of recent advances in post-transcriptional regulation, starting with the discovery of miRNAs.

Fig. 1

Updated model of gene regulation that integrates RBPs and ncRNAs

The Lin28/let-7 circuit: from worm development to lymphopoiesis

Inspiration from the worm

Working in C. elegans, Ambros and Horvitz (8) identified a set of genes that control developmental timing, a category that they termed heterochronic genes. Heterochrony is a term coined by evolutionary biologists and popularized by the worm community to denote events that either positively or negatively regulate developmental timing in multicellular organisms. The discovery of two heterochronic genes, lin-4 and lin-28, which encode a miRNA and RBP respectively, is particularly relevant to this review. The lineage (lin) mutants were previously identified and named because they displayed abnormalities in cell lineage differentiation. Furthermore, some of them were considered heterochronic, as adult mutants harbored immature characteristics (retarded phenotype) or, conversely, larval mutants displayed adult characteristics (precocious phenotype). It was not until 1993 that lin-4 was characterized molecularly, because contrary to popular expectations, the gene did not encode a protein but instead a small RNA now appreciated as the first miRNA to be discovered (9). The lin-4 miRNA acts in part by inhibiting the expression of the LIN-14 transcription factor through imperfect basepairing to sites in the 3′ untranslated region (UTR) of lin-14 mRNA (9, 10). However, it was not apparent initially whether lin-4 or lin-14 is evolutionarily conserved, potentially relegating these findings to be relevant only to the worm. Interestingly, Lin28, a gene conserved in mammals, was later identified to be a direct target of the lin-4 miRNA (11). Lin28 loss-of-function resulted in a precocious phenotype, whereas gain-of-function resulted in a retarded phenotype; thus, Lin28 acts as a heterochronic switch during C. elegans larval development (11).

The possibility that lin-4 may be an oddity of the worm was dissolved with the discovery of the second miRNA, again in C. elegans, let-7 (12). Unlike lin-4, the evolutionary conservation of let-7 from sea urchin to human was quickly appreciated (13). Importantly, expression analysis showed that let-7 expression is temporally regulated from molluscs to vertebrates in all three major clades of bilaterian animals, implying that its role as a developmental timekeeper is conserved (14). This established miRNAs as a field unto its own that has progressed rapidly with the identification of Drosha, Dgcr8, Dicer, and Argonaute (Ago) RBPs as core components of the miRNA pathway (15). Orthologs of lin-4were eventually found in mammals (mir-125a, -b-1, and -b-2) (16) along with hundreds of novel miRNAs from numerous organisms (17). We now recognize that miRNAs, in complex with the RBP Ago, frequently bind their cognate targets via imperfect complementarity to evolutionarily conserved sequences in 3′ UTRs (1820) and mediate post-transcriptional repression (21).

…..

One diverse group of RBPs appreciated to be important in the immune system, even before the discovery of miRNAs, is distinguished by their ability to bind to AU-rich elements (AREs) often found in 3′ UTRs of genes involved in inflammation, growth, and survival. Such RBPs are known as ARE-BPs and have been implicated in mRNA decay, alternative splicing, translation, as well as both alleviating and enhancing miRNA-mediated mRNA repression (104107). Genetic inactivation of several ARE-BPs have been linked to aberrant cytokine expression due to impaired ARE-mediated decay (5, 108111) (Table 1). In addition, deficiency of HuR and AUF1 has uncovered a pro-survival role for both in lymphocytes (112, 113), while ectopic expression of Tis11b (ZFP36L1) negatively regulates erythropoiesis by down-regulating Stat5b mRNA stability (114). The KH-type splicing regulatory protein (KSRP) originally identified as an alternative-splicing factor is a multi-functional RBP. It has been shown to associate with both Drosha and Dicer complexes to positively regulate the biogenesis of a subset of miRNAs including mir-155 and let-7 (73, 108, 115120). In addition, KSRP, like many other ARE-BPs, mediate selective decay of mRNAs by recruitment of exosome complexes to mRNA targets (121) and constitutes a prime example of a multi-functional RBP.

……

Biological processes involved in the development and function of the immune system require programmed changes in protein production and constitute prime candidates for post-transcriptional regulation. While the ENCODE project initially aimed to identify all functional elements in the human DNA sequence, recent discoveries centered around miRNAs and multi-tasking RBPs, such as Lin28, have highlighted the need for a similar systematic effort in mapping post-transcriptional functional elements within the transcriptome. Integration of genomic, transcriptomic, and proteomic data remains a daunting but necessary task to achieve understanding of the full impact of genetic programs and the enigmatic roles of regulatory RNAs. Mastering the science of (re)programming cell fates promises to unleash the potential of stem cells for Regenerative Medicine.

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Monitoring AML with “cell specific” blood test

Larry H. Bernstein, MD, FCAP, Curator

LPBI

 

‘Liquid Biopsy’ Blood Test Replaces Painful Bone Marrow Biopsy for Leukemia

Mon, 01/11/2016  by BioFluidica, Inc.  http://www.mdtmag.com/news/2016/01/liquid-biopsy-blood-test-replaces-painful-bone-marrow-biopsy-leukemia

 

BioFluidica, Inc. has released the clinical data for minimal residual disease detection in Acute Myeloid Leukemia (AML) patients using circulating leukemic cells selected from blood. The data was published in the peer reviewed journal the Analyst (141 (2016) 640). AML is a rapidly developing leukemic disease with ~20,000 cases reported in 2015 with a 5-year survival rate of only 25%.

The goal of this study was to detect early stages of disease relapse following stem cell transplantation. Currently AML relapse is detected using bone marrow biopsy samples that are painful for the patient and using existing commercial tests, limits the frequency of testing and thus resulting in poor outcomes for AML patients. The paper describes that using BioFluidica’s analytical technology relapse could be detected nearly 2 months earlier than conventional tests. In addition, test frequency could be significantly increased using BioFluidica’s technology compared to tests requiring bone marrow biopsies.

Professor Steven A. Soper, the scientific founder of BioFluidica and co-author of the paper with Dr. Paul Armistead, a hematologist, both at the University of North Carolina states that “the use of a blood test compared to a bone marrow biopsy would be a tremendous advancement in diagnostic capability that can dramatically improve the survival rate of patients with AML.”

BioFluidica is developing innovative technologies for the isolation and analysis of rare, circulating biomarkers in the blood. The company’s first platform has the capacity to isolate circulating tumor cells, exosomes and cfDNA from the blood with unprecedented recovery and purity. The technology is based on patented microfluidics designs which has been clinically validated for 6 different cancer types including Colorectal, Pancreatic Ductal Adenocarcinoma, Ovarian, Breast, Multiple Myeloma and AML. Additionally, stroke detection and infectious disease identification have also obtained clinical validation using the BioFluidica test. The company was cofounded by Dr. Soper who is currently a Professor in Biomedical Engineering and Chemistry at the University of North Carolina at Chapel Hill (UNC-CH). He is also Director of a new center on the UNC-CH campus, Center for BioModular Multi-scale Systems for Precision Medicine, focused on developing new tools for the molecular analysis of circulating biomarkers.

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Chemotherapy in AML

Curator: Larry H. Bernstein, MD, FCAP

 

 

Sorafenib Showed Efficacy as Chemotherapy Add-On in AML
Results from the phase II SORAML trial indicated that adding sorafenib to standard chemotherapy for younger patients with acute myeloid leukemia was effective, but also resulted in increased toxicity

Reduced-Intensity HSCT Extends Remission in Older AML Patients
The use of reduced-intensity conditioning HSCT as a method to maintain remission was effective in a select group of older patients with acute myeloid leukemia

 

Sorafenib Showed Efficacy as Chemotherapy Add-On in AML

– See more at: http://www.cancernetwork.com/leukemia-lymphoma/sorafenib-showed-efficacy-chemotherapy-add-aml

 

Results from the phase II SORAML trial indicated that adding sorafenib to standard chemotherapy for younger patients with acute myeloid leukemia (AML) was effective, but also resulted in increased toxicity.

 

The drug increased event-free survival and reduced need for salvage therapy and allogeneic stem cell transplantation, but also produced worse grade 3 or higher fever, diarrhea, bleeding, cardiac events, and rash compared with placebo.

“After a decade of assessing the potential of kinase inhibitors in acute myeloid leukemia, their use in combination with standard treatment is becoming an important option for newly diagnosed younger patients,” wrote Christoph Röllig, MD, of Medizinische Klinik und Poliklinik I, Universitätsklinikum der Technischen Universität in Dresden, Germany, and colleagues in Lancet Oncology.

Patients age 18 to 60 years were enrolled in the phase II study between 2009 and 2011. All patients had to have newly diagnosed, treatment-naive AML and a performance status of 0–2. Patients were randomly assigned to 2 cycles of induction daunorubicin plus cytarabine followed by 3 cycles of high-dose cytarabine consolidation therapy plus either sorafenib 400 mg twice daily (n = 134) or placebo (n = 133).

With a median follow-up of 3 years, the researchers found that adding sorafenib to standard chemotherapy significantly improved event-free survival, from a median of 9 months with placebo to a median of 21 months with sorafenib. Patients assigned sorafenib had a 3-year event-free survival rate of 40% compared with 22% for patients assigned placebo (P = .013).

“The improvement in event-free survival and relapse-free survival is significant and clinically relevant since salvage treatment with or without allogeneic stem cell transplantation could be prevented or substantially delayed by sorafenib treatment,” the researchers wrote.

At 3 years, 63% of patients assigned sorafenib and 56% of patients assigned placebo were still alive, and the median overall survival was not reached in either group. Patients assigned sorafenib had fewer relapses after complete remission compared with placebo (54 vs 34) and, therefore, fewer allogeneic stem cell transplantations were required among patients assigned sorafenib (31 vs 18).

Finally, withdrawal from the trial due to adverse events was more common among patients assigned sorafenib (24% vs 12%).

In an editorial published with the study, Naval Daver, MD, and Marina Konopleva, MD, PhD, of the University of Texas MD Anderson Cancer Center in Houston, pointed out that these results contrast findings by Serve et al who found that “the addition of sorafenib to standard chemotherapy in patients older than 60 years with acute myeloid leukemia resulted in increased toxicity and early mortality,” without improved antileukemic efficacy compared with placebo, suggesting that older patients were unable to tolerate the toxicities associated with the addition of sorafenib to standard chemotherapy.

Daver and Konopleva agreed with Röllig and colleagues, writing that the lack of improvement in overall survival despite an improvement in event-free survival requires “further investigation to develop future strategies that will improve overall survival.”

 

Sorafenib and novel multikinase inhibitors in AML

Naval Daver, Marina Konopleva

The Lancet Oncology 2015.          DOI: http://dx.doi.org/10.1016/S1470-2045(15)00454-4

Induction chemotherapy can produce complete remission in most (50–70%) patients with acute myeloid leukaemia.1 However, between 50% and 80% of patients relapse, and only 20–30% achieve long-term disease-free survival.

 

Reduced-Intensity HSCT Extends Remission in Older AML Patients

– See more at: http://www.cancernetwork.com/leukemia-lymphoma/reduced-intensity-hsct-extends-remission-older-aml-patients

 

The use of reduced-intensity conditioning hematopoietic stem cell transplantation (HSCT) as a method to maintain remission was effective in a select group of older patients with acute myeloid leukemia (AML), resulting in a nonrelapse mortality (NRM) similar to that seen in younger patients, according to the results of the phase II Cancer and Leukemia Group B 100103/Blood and Marrow Transplant Clinical Trial Network 0502 trial. 

 

“Of critical importance, for the first time (to the best of our knowledge), favorable results in transplantation of older patients have been obtained in a multicenter cooperative group setting, which makes the results more likely to be generalizable,” wrote Steven M. Devine, MD, of the Ohio State University in Columbus, Ohio, and colleagues in the Journal of Clinical Oncology.

According to the study, although patients aged older than 60 have complete remission rates of 50% to 60%, many will ultimately relapse. HSCT is associated with lower rates of relapse compared with chemotherapy in younger patients, but has been considered too toxic for older patients.

This study looked at the use of reduced-intensity conditioning HSCT in an older patient population aged 60 to 74 years. It included 114 patients with AML who were in first complete remission. The median age of patients was 65 years. A little more than half of the patients received transplants from unrelated donors and were given rabbit antithymocyte globulin (ATG) for graft-versus-host disease (GVHD) prophylaxis.

At follow-up, 71 patients had died. The median follow-up of the 43 surviving patients was 1,602 days. At 2 years, the rate of disease-free survival (DFS) was 42% and overall survival (OS) was 48%. Among patients who had unrelated donors, the 2-year DFS was 40% and the OS was 50%.

“The 2-year DFS and OS rates in this group compare favorably to those in studies of conventional chemotherapy–based approaches to remission consolidation in which DFS and OS rates beyond 2 years are typically below 20%,” the researchers wrote.

The NRM at 2 years was 15% and was not different among those patients with related vs unrelated donors. Forty-four percent of patients relapsed at 2 years.

“The 44% relapse rate at 2 years was high, although relapse rates approaching 80% to 90% have been observed in older patients after conventional chemotherapy, suggesting a potential graft-versus-leukemia effect,” the researchers wrote. “Interpretation of our trial results is limited somewhat by lack of consistent knowledge of the mutational status of the patients at diagnosis or of disease burden at complete remission by minimal residual disease assessment.”

There was a cumulative incidence of grades 2 to 4 GVHD of 9.6% and of grade 3 to 4 GVHD of 2.6% at 100 days. The incidence of GVHD did not vary by donor type. Chronic GVHD occurred in 28% of patients.

Devine and colleagues noted that these rates were lower than they anticipated.

“The incorporation of rabbit ATG into the conditioning regimen for all patients, including recipients with matched sibling donors, may have contributed to the relatively low rates of GVHD and NRM, as has been observed in previous studies,” they wrote.

 

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Cancer Companion Diagnostics

Curator: Larry H. Bernstein, MD, FCAP

 

Companion Diagnostics for Cancer: Will NGS Play a Role?

Patricia Fitzpatrick Dimond, Ph.D.

http://www.genengnews.com/insight-and-intelligence/companion-diagnostics-for-cancer/77900554/

Companion diagnostics (CDx), in vitro diagnostic devices or imaging tools that provide information essential to the safe and effective use of a corresponding therapeutic product, have become indispensable tools for oncologists.  As a result, analysts expect the global CDx market to reach $8.73 billion by 2019, up from from $3.14 billion in 2014.

Use of CDx during a clinical trial to guide therapy can improve treatment responses and patient outcomes by identifying and predicting patient subpopulations most likely to respond to a given treatment.

These tests not only indicate the presence of a molecular target, but can also reveal the off-target effects of a therapeutic, predicting toxicities and adverse effects associated with a drug.

For pharma manufacturers, using CDx during drug development improves the success rate of drugs being tested in clinical trials. In a study estimating the risk of clinical trial failure during non-small cell lung cancer drug development in the period between 1998 and 2012 investigators analyzed trial data from 676 clinical trials with 199 unique drug compounds.

The data showed that Phase III trial failure proved the biggest obstacle to drug approval, with an overall success rate of only 28%. But in biomarker-guided trials, the success rate reached 62%. The investigators concluded from their data analysis that the use of a CDx assay during Phase III drug development substantially improves a drug’s chances of clinical success.

The Regulatory Perspective

According to Patricia Keegen, M.D., supervisory medical officer in the FDA’s Division of Oncology Products II, the agency requires a companion diagnostic test if a new drug works on a specific genetic or biological target that is present in some, but not all, patients with a certain cancer or disease. The test identifies individuals who would benefit from the treatment, and may identify patients who would not benefit but could also be harmed by use of a certain drug for treatment of their disease. The agency classifies companion diagnosis as Class III devices, a class of devices requiring the most stringent approval for medical devices by the FDA, a Premarket Approval Application (PMA).

On August 6, 2014, the FDA finalized its long-awaited “Guidance for Industry and FDA Staff: In Vitro Companion Diagnostic Devices,” originally issued in July 2011. The final guidance stipulates that FDA generally will not approve any therapeutic product that requires an IVD companion diagnostic device for its safe and effective use before the IVD companion diagnostic device is approved or cleared for that indication.

Close collaboration between drug developers and diagnostics companies has been a key driver in recent simultaneous pharmaceutical-CDx FDA approvals, and partnerships between in vitro diagnostics (IVD) companies have proliferated as a result.  Major test developers include Roche Diagnostics, Abbott Laboratories, Agilent Technologies, QIAGEN), Thermo Fisher Scientific, and Myriad Genetics.

But an NGS-based test has yet to make it to market as a CDx for cancer.  All approved tests include PCR–based tests, immunohistochemistry, and in situ hybridization technology.  And despite the very recent decision by the FDA to grant marketing authorization for Illumina’s MiSeqDx instrument platform for screening and diagnosis of cystic fibrosis, “There still seems to be a number of challenges that must be overcome before we see NGS for targeted cancer drugs,” commented Jan Trøst Jørgensen, a consultant to DAKO, commenting on presentations at the European Symposium of Biopathology in June 2013.

Illumina received premarket clearance from the FDA for its MiSeqDx system, two cystic fibrosis assays, and a library prep kit that enables laboratories to develop their own diagnostic test. The designation marked the first time a next-generation sequencing system received FDA premarket clearance. The FDA reviewed the Illumina MiSeqDx instrument platform through its de novo classification process, a regulatory pathway for some novel low-to-moderate risk medical devices that are not substantially equivalent to an already legally marketed device.

Dr. Jørgensen further noted that “We are slowly moving away from the ‘one biomarker: one drug’ scenario, which has characterized the first decades of targeted cancer drug development, toward a more integrated approach with multiple biomarkers and drugs. This ‘new paradigm’ will likely pave the way for the introduction of multiplexing strategies in the clinic using gene expression arrays and next-generation sequencing.”

The future of CDxs therefore may be heading in the same direction as cancer therapy, aimed at staying ahead of the tumor drug resistance curve, and acknowledging the reality of the shifting genomic landscape of individual tumors. In some cases, NGS will be applied to diseases for which a non-sequencing CDx has already been approved.

Illumina believes that NGS presents an ideal solution to transforming the tumor profiling paradigm from a series of single gene tests to a multi-analyte approach to delivering precision oncology. Mya Thomae, Illumina’s vice president, regulatory affairs, said in a statement that Illumina has formed partnerships with several drug companies to develop a universal next-generation sequencing-based oncology test system. The collaborations with AstraZeneca, Janssen, Sanofi, and Merck-Serono, announced in 2014 and 2015 respectively, seek to  “redefine companion diagnostics for oncology  focused on developing a system for use in targeted therapy clinical trials with a goal of developing and commercializing a multigene panel for therapeutic selection.”

On January 16, 2014 Illumina and Amgen announced that they would collaborate on the development of a next-generation sequencing-based companion diagnostic for colorectal cancer antibody Vectibix (panitumumab). Illumina will develop the companion test on its MiSeqDx instrument.

In 2012, the agency approved Qiagen’s Therascreen KRAS RGQ PCR Kit to identify best responders to Erbitux (cetuximab), another antibody drug in the same class as Vectibix. The label for Vectibix, an EGFR-inhibiting monoclonal antibody, restricts the use of the drug for those metastatic colorectal cancer patients who harbor KRAS mutations or whose KRAS status is unknown.

The U.S. FDA, Illumina said, hasn’t yet approved a companion diagnostic that gauges KRAS mutation status specifically in those considering treatment with Vectibix.  Illumina plans to gain regulatory approval in the U.S. and in Europe for an NGS-based companion test that can identify patients’ RAS mutation status. Illumina and Amgen will validate the test platform and Illumina will commercialize the test.

Treatment Options

Foundation Medicine says its approach to cancer genomic characterization will help physicians reveal the alterations driving the growth of a patient’s cancer and identify targeted treatment options that may not have been otherwise considered.

FoundationOne, the first clinical product from Foundation Medicine, interrogates the entire coding sequence of 315 cancer-related genes plus select introns from 28 genes often rearranged or altered in solid tumor cancers.  Based on current scientific and clinical literature, these genes are known to be somatically altered in solid cancers.

These genes, the company says, are sequenced at great depth to identify the relevant, actionable somatic alterations, including single base pair change, insertions, deletions, copy number alterations, and selected fusions. The resultant fully informative genomic profile complements traditional cancer treatment decision tools and often expands treatment options by matching each patient with targeted therapies and clinical trials relevant to the molecular changes in their tumors.

As Foundation Medicine’ s NGS analyses are increasingly applied, recent clinical reports describe instances in which comprehensive genomic profiling with the FoundationOne NGS-based assay result in diagnostic reclassification that can lead to targeted drug therapy with a resulting dramatic clinical response. In several reported instances, NGS found, among the spectrum of aberrations that occur in tumors, changes unlikely to have been discovered by other means, and clearly outside the range of a conventional CDx that matches one drug to a specific genetic change.

TRK Fusion Cancer

In July 2015, the University of Colorado Cancer Center and Loxo Oncology published a research brief in the online edition of Cancer Discovery describing the first patient with a tropomyosin receptor kinase (TRK) fusion cancer enrolled in a LOXO-101 Phase I trial. LOXO-101 is an orally administered inhibitor of the TRK kinase and is highly selective only for the TRK family of receptors.

While the authors say TRK fusions occur rarely, they occur in a diverse spectrum of tumor histologies. The research brief described a patient with advanced soft tissue sarcoma widely metastatic to the lungs. The patient’s physician submitted a tumor specimen to Foundation Medicine for comprehensive genomic profiling with FoundationOne Heme, where her cancer was demonstrated to harbor a TRK gene fusion.

Following multiple unsuccessful courses of treatment, the patient was enrolled in the Phase I trial of LOXO-101 in March 2015. After four months of treatment, CT scans demonstrated almost complete tumor disappearance of the largest tumors.

The FDA’s Elizabeth Mansfield, Ph.D., director, personalized medicine staff, Office of In Vitro Diagnostics and Radiological Health, said in a recent article,  “FDA Perspective on Companion Diagnostics: An Evolving Paradigm” that “even as it seems that many questions about co-development have been resolved, the rapid accumulation of new knowledge about tumor biology and the rapid evolution of diagnostic technology are challenging FDA to continually redefine its thinking on companion diagnostics.” It seems almost inevitable that a consolidation of diagnostic testing should take place, to enable a single test or a few tests to garner all the necessary information for therapeutic decision making.”

Whether this means CDx testing will begin to incorporate NGS sequencing remains to be seen.

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Platelet Transfusions

Larry H. Bernstein, MD, FCAP, Curator

LPBI

Platelet Transfusion: A Clinical Practice Guideline From the AABB

Richard M. Kaufman, MD; Benjamin Djulbegovic, MD, PhD; Terry Gernsheimer, MD; Steven Kleinman, MD,
Alan T. Tinmouth, MD; Kelley E. Capocelli, MD; Mark D. Cipolle, MD, PhD; Claudia S. Cohn, MD, PhD; et al.

Ann Intern Med. 2015;162(3):205-213. http://dx.doi.org:/10.7326/M14-1589

Annals of Internal Medicine 3 February 2015, Vol 162, No. 3>

Approximately 2.2 million platelet doses are transfused annually in the United States (1). A high proportion of these platelet units are transfused prophylactically to reduce the risk for spontaneous bleeding in patients who are thrombocytopenic after chemotherapy or hematopoietic progenitor cell transplantation (HPCT) (13). Unlike other blood components, platelets must be stored at room temperature, limiting the shelf life of platelet units to only 5 days because of the risk for bacterial growth during storage. Therefore, maintaining hospital platelet inventories is logistically difficult and highly resource-intensive (45). Platelet transfusion is associated with several risks to the recipient (Table 1), including allergic reactions and febrile nonhemolytic reactions. Sepsis from a bacterially contaminated platelet unit represents the most frequent infectious complication from any blood product today (8). In any situation where platelet transfusion is being considered, these risks must be balanced against the potential clinical benefits.

Background: The AABB (formerly, the American Association of Blood Banks) developed this guideline on appropriate use of platelet transfusion in adult patients.

Methods: These guidelines are based on a systematic review of randomized, clinical trials and observational studies (1900 to September 2014) that reported clinical outcomes on patients receiving prophylactic or therapeutic platelet transfusions. An expert panel reviewed the data and developed recommendations using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) framework.

Recommendation 1: The AABB recommends that platelets should be transfused prophylactically to reduce the risk for spontaneous bleeding in hospitalized adult patients with therapy-induced hypoproliferative thrombocytopenia. The AABB recommends transfusing hospitalized adult patients with a platelet count of 10 × 109 cells/L or less to reduce the risk for spontaneous bleeding. The AABB recommends transfusing up to a single apheresis unit or equivalent. Greater doses are not more effective, and lower doses equal to one half of a standard apheresis unit are equally effective. (Grade: strong recommendation; moderate-quality evidence)

Recommendation 2: The AABB suggests prophylactic platelet transfusion for patients having elective central venous catheter placement with a platelet count less than 20 × 109 cells/L. (Grade: weak recommendation; low-quality evidence)

Recommendation 3: The AABB suggests prophylactic platelet transfusion for patients having elective diagnostic lumbar puncture with a platelet count less than 50 × 109 cells/L. (Grade: weak recommendation; very-low-quality evidence)

Recommendation 4: The AABB suggests prophylactic platelet transfusion for patients having major elective nonneuraxial surgery with a platelet count less than 50 × 109 cells/L. (Grade: weak recommendation; very-low-quality evidence)

Recommendation 5: The AABB recommends against routine prophylactic platelet transfusion for patients who are nonthrombocytopenic and have cardiac surgery with cardiopulmonary bypass. The AABB suggests platelet transfusion for patients having bypass who exhibit perioperative bleeding with thrombocytopenia and/or evidence of platelet dysfunction. (Grade: weak recommendation; very-low-quality evidence)

Recommendation 6: The AABB cannot recommend for or against platelet transfusion for patients receiving antiplatelet therapy who have intracranial hemorrhage (traumatic or spontaneous). (Grade: uncertain recommendation; very-low-quality evidence)

Table 1. Approximate Per-Unit Risks for Platelet Transfusion in the United States

Approximate_Per-Unit_Risks_for_Platelet_Transfusion_in_the_United_States

Approximate_Per-Unit_Risks_for_Platelet_Transfusion_in_the_United_States

Clinical and laboratory aspects of platelet transfusion therapy
Literature review current through: Sep 2015. | This topic last updated: Jun 12, 2015.

INTRODUCTION — Hemostasis depends on an adequate number of functional platelets, together with an intact coagulation (clotting factor) system. This topic covers the logistics of platelet use and the indications for platelet transfusion in adults. The approach to the bleeding patient, refractoriness to platelet transfusion, and platelet transfusion in neonates are discussed elsewhere.

(See “Approach to the adult patient with a bleeding diathesis”.)

(See “Refractoriness to platelet transfusion therapy”.)

(See “Clinical manifestations, evaluation, and management of neonatal thrombocytopenia”, section on ‘Platelet transfusion’.)

PLATELET COLLECTION — There are two ways that platelets can be collected: by isolation from a unit of donated blood, or by apheresis from a donor in the blood bank.

Pooled platelets – A single unit of platelets can be isolated from every unit of donated blood, by centrifuging the blood within the closed collection system to separate the platelets from the red blood cells (RBC). The number of platelets per unit varies according to the platelet count of the donor; a yield of 7 x 1010platelets is typical [1]. Since this number is inadequate to raise the platelet count in an adult recipient, four to six units are pooled to allow transfusion of 3 to 4 x 1011 platelets per transfusion [2]. These are called whole blood-derived or random donor pooled platelets.

Advantages of pooled platelets include lower cost and ease of collection and processing (a separate donation procedure and pheresis equipment are not required). The major disadvantage is recipient exposure to multiple donors in a single transfusion and logistic issues related to bacterial testing.

Apheresis (single donor) platelets – Platelets can also be collected from volunteer donors in the blood bank, in a one- to two-hour pheresis procedure. Platelets and some white blood cells are removed, and red blood cells and plasma are returned to the donor. A typical apheresis platelet unit provides the equivalent of six or more units of platelets from whole blood (ie, 3 to 6 x 1011platelets) [2]. In larger donors with high platelet counts, up to three units can be collected in one session. These are called apheresis or single donor platelets.

Advantages of single donor platelets are exposure of the recipient to a single donor rather than multiple donors, and the ability to match donor and recipient characteristics such as HLA type, cytomegalovirus (CMV) status, and blood type for certain recipients. (See ‘Ordering platelets’ below.)

Issues related to the effects of platelet pheresis on the donor are covered elsewhere. (See “Blood donor screening: Procedures and processes to enhance safety for the blood recipient and the blood donor”, section on ‘Apheresis platelet donors’.)

Both pooled and apheresis platelets contain some white blood cells (WBC) that were collected along with the platelets. These WBC can cause febrile non-hemolytic transfusion reactions (FNHTR), alloimmunization, and transfusion-associated graft-versus-host disease (ta-GVHD) in some patients.

Platelet products also contain plasma, which can be implicated in adverse reactions including transfusion-related acute lung injury (TRALI) and anaphylaxis. (See‘Complications of platelet transfusion’ below.)

Several strategies are used to prevent the complications associated with WBC and plasma contamination of platelets. (See ‘Ordering platelets’ below.)

Platelets concentrates also contain a small number of red blood cells (RBCs) that express Rh antigens on their surface (platelets do not express Rh antigens). The small numbers of RBCs in apheresis platelets negates the issue of Rh alloimmunization in most patients. However, blood banks avoid giving platelets from Rh+ donors to Rh female patients because of the potential risk of Rh alloimmunization and subsequent hemolytic disease of the newborn. (See “Overview of Rhesus D alloimmunization in pregnancy”.)

PLATELET STORAGE AND PATHOGEN REDUCTION — Platelets are stored at room temperature, because cold induces clustering of von Willebrand factor receptors on the platelet surface and morphological changes of the platelets, leading to enhanced clearance by hepatic macrophages and reduced platelet survival in the recipient [3-6].

All cells are more metabolically active at room temperature, so platelets are stored in bags that allow oxygen and carbon dioxide gas exchange. Citrate is included to prevent clotting and maintain proper pH, and dextrose is added as an energy source [2].

A disadvantage of room temperature storage is the increased growth of bacteria compared with blood products stored in the refrigerator or freezer. (See‘Complications of platelet transfusion’ below.)

Strategies for reducing exposure to contaminating pathogens include:

Donor screening for bloodborne pathogens (see “Blood donor screening: Laboratory testing”, section on ‘Infectious disease screening’ and “Blood donor screening: Procedures and processes to enhance safety for the blood recipient and the blood donor”, section on ‘Protection of the recipient’)

Proper skin sterilization techniques during collection, and discarding the first 15 to 30 mL of blood collected, which is most likely to be contaminated by skin bacteria

Performing tests to screen for bacterial contamination, such as automated culture-based assays, and rapid point-of-issue tests (see “Transfusion-transmitted bacterial infection”, section on ‘Detection of contamination’)

Using blood products that have been subjected to pathogen inactivation or reduction treatment (not available in the United States) (see “Pathogen inactivation of blood products”, section on ‘Pathogen inactivation of platelets’and “Preparation of blood components”, section on ‘Pathogen reduction’)

The shelf life of platelets stored at room temperature is five days because of the bacterial infection risk that increases in relationship to the storage duration. This short shelf life contributes to the greater sensitivity of platelet inventory to shortages.

INDICATIONS FOR PLATELET TRANSFUSION — Platelets can be transfused therapeutically (ie, to treat active bleeding or in preparation for an invasive procedure that would cause bleeding), or prophylactically (ie, to prevent spontaneous bleeding).

Actively bleeding patient — Actively bleeding patients with thrombocytopenia should be transfused with platelets immediately to keep platelet counts above50,000/microL in most bleeding situations, and above 100,000/microL if there is disseminated intravascular coagulation or central nervous system bleeding. (See“Clinical features, diagnosis, and treatment of disseminated intravascular coagulation in adults”, section on ‘Treatment’ and “Spontaneous intracerebral hemorrhage: Treatment and prognosis”, section on ‘Initial treatment’.).

Other factors contributing to bleeding should also be addressed. These include:

Surgical or anatomic defect

Fever

Infection or inflammation

Coagulopathy

Acquired or inherited platelet function defect

The dose and frequency of platelet transfusions will depend on the platelet count and the severity of bleeding. (See ‘Dose’ below.)

Preparation for an invasive procedure — Platelets are transfused in preparation for an invasive procedure if the thrombocytopenia is severe and the risks of bleeding are deemed high. Most of the data used to determine bleeding risk come from retrospective studies of patients who are afebrile and have thrombocytopenia but not coagulopathy [7]. Typical platelet count thresholds that are used for some common procedures are as follows:

Neurosurgery or ocular surgery – 100,000/microL

Most other major surgery – 50,000/microL

Endoscopic procedures – 50,000/microL for therapeutic procedures;20,000/microL for low risk diagnostic procedures (see “Endoscopic procedures in patients with disorders of hemostasis”, section on ‘Procedure-related bleeding risk’)

Central line placement – 20,000/microL [8]

Lumbar puncture – 10,000 to 20,000/microL in patients with hematologic malignancies and greater than 40,000 to 50,000 in patients without hematologic malignancies, but lower in patients with immune thrombocytopenia (ITP) [9-11]

Epidural anesthesia – 80,000/microL [11]

Bone marrow aspiration/biopsy20,000/microL

Prevention of spontaneous bleeding — Prophylactic transfusion is used to prevent spontaneous bleeding in patients at high risk of bleeding. The threshold for prophylactic transfusion varies depending on the patient and on the clinical scenario. (See ‘Specific clinical scenarios’ below.)

Predicting spontaneous bleeding — There are no ideal tests for predicting who will bleed spontaneously [12]. Studies of patients with thrombocytopenia suggest that patients can bleed even with platelet counts greater than 50,000/microL [13]. However, bleeding is much more likely at platelet counts less than 5000/microL. Among individuals with platelet counts between 5000/microL and 50,000/microL,clinical findings can be helpful in decision-making regarding platelet transfusion.

The platelet count at which a patient bled previously can be a good predictor of future bleeding.

Petechial bleeding and ecchymoses are generally not thought to be predictive of serious bleeding, whereas mucosal bleeding and epistaxis (so-called “wet” bleeding) are thought to be predictive.

Coexisting inflammation, infection, and fever also increase bleeding risk.

The underlying condition responsible for a patient’s thrombocytopenia also may help in estimating the bleeding risk. As an example, some patients with ITP often tolerate very low platelet counts without bleeding, while patients with some acute leukemias that are associated with coagulopathy (eg, acute promyelocytic leukemia) can have bleeding at higher platelet counts (eg, 30,000 to 50,000/microL). (See ‘Specific clinical scenarios’ below.)

Compared with adults, children with bone marrow suppression may be more likely to experience bleeding at the same degree of thrombocytopenia. In a secondary subgroup analysis of the PLADO trial, in which patients were randomly assigned to different platelet doses, children had more days of bleeding, more severe bleeding, and required more platelet transfusions than adults with similar platelet counts [14]. However, these findings do not suggest a different threshold for platelet transfusion in children, as the increased risk of bleeding was distributed across a wide range of platelet counts.

Tests for platelet-dependent hemostasis (ie, bleeding time, thromboelastography, and other point of care tests) are generally not used to predict bleeding in thrombocytopenic patients. (See “Platelet function testing”, section on ‘The in vivo bleeding time’ and “Platelet function testing”, section on ‘Instruments that simulate platelet function in vitro’.)

Therapeutic versus prophylactic transfusion — By convention, most authors use the term “therapeutic transfusion” to refer both to transfusion of platelets to treat active bleeding and transfusion of platelets in preparation for an invasive procedure that could cause bleeding. The term “prophylactic transfusion” is used to refer to platelet transfusion given to prevent spontaneous bleeding.

We use prophylactic platelet transfusion to prevent spontaneous bleeding in most afebrile patients with platelet counts below 10,000/microL due to bone marrow suppression. We use higher thresholds (ie, 30,000/microL) in patients who are febrile or septic. Patients with acute promyelocytic leukemia (APL) have a coexisting coagulopathy, and we use a platelet transfusion threshold of 30,000 to 50,000/microLfor them. (See ‘Leukemia and chemotherapy’ below.)

Patients with platelet consumption disorders (eg, immune thrombocytopenia [ITP], disseminated intravascular coagulation) and platelet function disorders are typically transfused only for bleeding or, in some cases, invasive procedures. Platelets should not be withheld in bleeding patients with these conditions due to fear of “fueling the fire” of thrombus formation. (See ‘Immune thrombocytopenia (ITP)’ below and ‘TTP or HIT’ below and ‘Platelet function defects’ below.)

Given the need to balance the risk of spontaneous bleeding with the potential complications of unnecessary platelet transfusion, the decision of whether to transfuse platelets based upon a clinical event (ie, for active bleeding or invasive procedures) or at a particular threshold (ie, to prevent spontaneous bleeding) is challenging. Standard practice has evolved to transfusion of platelets at a threshold platelet count of 10,000 to 20,000/microL for most patients with severe hypoproliferative thrombocytopenia due to hematologic malignancies, cytotoxic chemotherapy, and hematopoietic cell transplant (HCT) [15]. However, the risks and benefits of reserving platelet transfusion for active bleeding episodes in these patients continue to be evaluated [7,16-19].

In a randomized trial, 400 patients with acute myeloid leukemia (AML; patients with APL were excluded) and patients undergoing autologous HCT for hematologic malignancies were assigned to receive platelet transfusions when morning platelet counts were ≤10,000/microL or only for active bleeding [20]. Patients transfused only for active bleeding received fewer platelet transfusions during the 14-day period after induction or consolidation chemotherapy (1.63 versus 2.44 per patient, a 33.5 percent reduction). However, among patients with AML who were transfused only for active bleeding, there were more episodes of major bleeding (six cerebral, four retinal, and one vaginal) and there were two fatal intracranial hemorrhages compared with four retinal hemorrhages among patients transfused for a platelet count ≤10,000/microL. Patients undergoing HCT also experienced more bleeding episodes when transfused only for active bleeding, but most of these were minor.

In another randomized trial, 600 patients with hematologic malignancies receiving chemotherapy, autologous, or allogeneic HCT were assigned to receive platelet transfusion for a platelet count ≤10,000/microL or only for active bleeding (the Trial of Prophylactic Platelets [TOPPS]) [21-23]. Compared with those who received prophylactic transfusions, patients transfused only for active bleeding received fewer platelet transfusions during the 30-day period after randomization, but had a higher incidence of major bleeding (50 versus 43 percent) and a shorter time to first bleed (1.2 versus 1.7 days) [24]. There were no differences in the duration of hospitalization, and no deaths due to bleeding. In a predefined subgroup analysis, patients undergoing autologous HCT had similar rates of major bleeding whether they were transfused for a platelet count≤10,000/microL or only for active bleeding (45 and 47 percent).

The findings from these trials support continued use of prophylactic transfusion for patients with hematologic malignancies and HCT until further data become available. Although the findings suggest that reserving platelet transfusion for active bleeding may be safe for some adults undergoing autologous HCT, such a strategy requires intensive monitoring and the ability to perform immediate imaging for suspected CNS or ocular bleeding. We do not recommend reserving platelet transfusion for active bleeding in patients with HCT outside of highly specialized centers with the ability to support this level of vigilance.

SPECIFIC CLINICAL SCENARIOS — There are several common clinical scenarios that raise the questions of whether to transfuse patients prophylactically to prevent bleeding, and, if prophylactic transfusion is used, of what platelet count is the best threshold for transfusion.

Leukemia and chemotherapy — Patients with leukemia, hematopoietic cell transplant (HCT), or those being treated with cytotoxic chemotherapy have a suppressed bone marrow that cannot produce adequate platelets. We use prophylactic transfusion in these settings. The thresholds suggested below apply to patients with thrombocytopenia who are afebrile and without active infection. If fever or sepsis is present, higher thresholds may be needed.

Acute myeloid leukemia (AML) – Patients with AML can have suppressed bone marrow from AML, chemotherapy, or HCT. We use standard dose prophylactic transfusion of these patients at a threshold platelet count of10,000/microL, and transfusion for any bleeding greater than petechial bleeding. (See ‘Dose’ below.)

This approach is in line with the 2001 American Society for Clinical Oncology (ASCO) guidelines (table 1) and a practice guideline from the AABB [25]. It is supported by randomized trials comparing prophylactic (ie, threshold-based) and therapeutic platelet transfusion, in which patients who did not receive prophylactic transfusion had more severe bleeding [20,24,26]. (See ‘Therapeutic versus prophylactic transfusion’ above and “Overview of the complications of acute myeloid leukemia”, section on ‘Bleeding’.)

Acute promyelocytic leukemia (APL) – Patients with APL differ from other patients with AML because they often have an associated coagulopathy that puts them at high risk for disseminated intravascular coagulation and bleeding. We prophylactically transfuse these patients at a platelet count of 30,000 to50,000/microL, and treat any sign of bleeding, especially central nervous system bleeding, with immediate platelet transfusion. (See “Clinical manifestations, pathologic features, and diagnosis of acute promyelocytic leukemia in adults”, section on ‘Disseminated intravascular coagulation’ and“Initial treatment of acute promyelocytic leukemia in adults”, section on ‘Control of coagulopathy’.)

Acute lymphoblastic leukemia (ALL) – Patients with ALL have thrombocytopenia from bone marrow suppression. In addition, these patients are often treated with L-asparaginase, which causes severe hypofibrinogenemia. However, the risk of life-threatening bleeding is low. As an example, in over 2500 children with ALL, only two intracranial hemorrhages occurred, and they were associated with hyperleukocytosis in one case and intracerebral fungal infection in the other [9]. We transfuse adults with ALL at a threshold platelet count of 10,000/microL. The use of platelet transfusion in children with ALL is discussed separately. (See “Overview of the treatment of acute lymphoblastic leukemia in children and adolescents”, section on ‘Bleeding’.)

Chemotherapy for solid tumors – Cancer chemotherapy often makes patients thrombocytopenic from bone marrow suppression. Randomized trials of platelet transfusion threshold in this population have not been performed. Observational studies support a prophylactic platelet transfusion threshold of 10,000/microL[26]. A threshold of 20,000/microL may be appropriate for patients with necrotic tumors. These recommendations are generally consistent with the ASCO 2001 Guidelines (table 1) [26].

Hematopoietic cell transplant (HCT) – Chemotherapy and radiation therapy administered as part of the conditioning regimen for HCT can be highly bone marrow suppressive, depending on the doses used. We use standard dose prophylactic transfusion of these patients at a threshold platelet count of10,000/microL, and therapeutic transfusion for any bleeding greater than petechial bleeding. (See “Hematopoietic support after hematopoietic cell transplantation”, section on ‘Platelet transfusion’.)

Aplastic anemia – Patients with aplastic anemia do not have a malignancy, but they may have severe thrombocytopenia, and they may be candidates for HCT. Issues related to platelet transfusion in these patients are discussed separately. (See “Treatment of aplastic anemia in adults”.)

Prophylactic platelet transfusion for a platelet count ≤10,000/microL in hospitalized patients with thrombocytopenia from therapy-induced bone marrow suppression is consistent with a practice guideline from the AABB [25].

Immune thrombocytopenia (ITP) — Individuals with immune thrombocytopenia produce anti-platelet antibodies that destroy circulating platelets and megakaryocytes in the bone marrow. Circulating platelets in patients with ITP tend to be highly functional, and platelet counts tend to be well above 30,000/microL. Bleeding is rare even in patients with severe thrombocytopenia (ie, platelet count <30,000/microL). (See “Immune thrombocytopenia (ITP) in adults: Clinical manifestations and diagnosis”, section on ‘Pathogenesis’.)

Our general approach to platelet transfusion in patients with ITP is to transfuse for bleeding rather than at a specific platelet count. (See “Immune thrombocytopenia (ITP) in adults: Initial treatment and prognosis”, section on ‘Indications for treatment’.)

TTP or HIT — Thrombotic thrombocytopenic purpura (TTP) and heparin-induced thrombocytopenia (HIT) are disorders in which platelet consumption causes thrombocytopenia and an increased risk of bleeding; but the underlying platelet activation in these conditions also increases the risk of thrombosis.

Platelet transfusions can be helpful or even life-saving in patients with these conditions who are bleeding and/or have anticipated bleeding due to a required invasive procedure (eg, placement of a central venous catheter), and platelet transfusion should not be withheld from a bleeding patient due to concerns that platelet transfusion will exacerbate thrombotic risk. However, platelet transfusions may cause a slightly increased risk of thrombosis in patients with these conditions; thus, we do not use prophylactic platelet transfusions routinely in patients with TTP or HIT in the absence of bleeding or a required invasive procedure.

Support for this approach comes from a large retrospective review of hospitalized patients with TTP and HIT, in which platelet transfusion was associated with a very slight increased risk of arterial thrombosis but not venous thromboembolism [27]. In contrast, the review found that patients with immune thrombocytopenia (ITP) had no increased risk of arterial or venous thrombosis with platelet transfusion. Of note, this was a retrospective study in which sicker patients were more likely to have received platelets, and the temporal relationships between platelet transfusions and thromboses were not assessed.

TTP – Of 10,624 patients with TTP in the large review mentioned above, approximately 10 percent received a platelet transfusion [27]. Arterial thrombosis occurred in 1.8 percent of patients who received platelets, versus 0.4 percent of patients who did not (absolute increase, 1.4 percent; adjusted odds ratio [OR], 5.8; 95% CI, 1.3-26.6). The rate of venous thrombosis was not different in those who received platelets and those who did not (adjusted OR 1.1; 95% CI 0.5-2.2).

In contrast, a systematic review of patients with TTP who received platelet transfusions, which included retrospective data for 358 patients and prospective data for 54 patients, did not find clear evidence that platelet transfusions were associated with adverse outcomes [28].

HIT – Of 6332 patients with HIT in the large review mentioned above, approximately 7 percent received a platelet transfusion [27]. Arterial thrombosis occurred in 6.9 percent of patients who received platelets, versus 3.1 percent of patients who did not (absolute increase, 3.8 percent; adjusted OR, 3.4; 95% CI, 1.2-9.5). The rate of venous thrombosis was not different in those who received platelets and those who did not (adjusted OR 0.8; 95% CI 0.4-1.7).

In a series of four patients with HIT who received platelet transfusions, two of three with active bleeding had cessation of bleeding following platelet transfusion, and no thromboses occurred; a literature review was not able to identify any complications clearly attributable to platelet transfusion [29].

Management of TTP and HIT is discussed in detail separately. (See “Acquired TTP: Initial treatment” and “Management of heparin-induced thrombocytopenia”.)

Liver disease and DIC — Patients with liver disease and DIC have a complex mixture of procoagulant and anticoagulant defects along with thrombocytopenia, and therefore they are at risk for thrombosis and bleeding. There is no evidence to support the administration of platelets in these patients if they are not bleeding. However, platelet transfusion is justified in patients who have serious bleeding, are at high risk for bleeding (eg, after surgery), or require invasive procedures. (See “Clinical features, diagnosis, and treatment of disseminated intravascular coagulation in adults”, section on ‘Prevention/treatment of bleeding’ and “Hemostatic abnormalities in patients with liver disease”, section on ‘Bleeding’.)

Platelet function defects — Platelet function defects can be inherited or acquired, and may be associated with thrombocytopenia or a normal platelet count. Platelet transfusion in these settings is typically reserved for bleeding.

Inherited diseases Platelet function is impaired in Wiskott-Aldrich syndrome, Glanzmann thrombasthenia, and Bernard-Soulier syndrome. Bleeding in patients with these conditions is treated with platelet transfusion, along with other hemostatic agents discussed below. (See “Congenital and acquired disorders of platelet function”, section on ‘Inherited disorders of platelet function’ and‘Alternatives to platelet transfusion’ below.)

Acquired conditions – Uremia, diabetes mellitus, myeloproliferative disorders, and other medical conditions can impair platelet function. Bleeding risk can be reduced by treating the underlying condition. Platelet transfusion is typically reserved for major bleeding in these conditions. (See “Congenital and acquired disorders of platelet function”, section on ‘Acquired platelet functional disorders’.)

Patients who are febrile or septic can have impaired platelet function. We transfuse these patients for bleeding. We also use a higher threshold for when fever or sepsis coexist with thrombocytopenia (eg, in patients with leukemia). (See ‘Leukemia and chemotherapy’ above.)

Antiplatelet agentsAspirin, nonsteroidal antiinflammatory drugs (NSAIDs),dipyridamole, ADP receptor (P2Y12) inhibitors (eg, clopidogrel, ticlopidine), andGPIIb/IIIa antagonists (eg, abciximab, eptifibatide) are used to prevent thrombosis by interfering with normal platelet function. The antiplatelet effects of these agents are weakest with aspirin and more potent with the P2Y12inhibitors. (See “Platelet biology”, section on ‘Drugs with antiplatelet actions’.)

Typically, the approach to treating mild bleeding in a patient taking an antiplatelet agent is to discontinue the drug, assuming a favorable risk-benefit ratio. Although data are limited, platelet transfusion appears to be the best option in patients taking antiplatelet agents who experience severe bleeding [30].

Patients taking these agents may also require urgent surgical procedures (eg, coronary artery bypass grafting, neurosurgical interventions, and others). The role of platelet transfusion in this setting is not well defined. Some clinicians give prophylactic platelet transfusions to patients taking antiplatelet drugs who require major surgery, while other clinicians use platelet transfusion only to treat excessive surgical bleeding [30,31]. These cases can be complex, and we favor an individualized approach based on the complete clinical picture.

Other medications – Other medications may impair platelet function. As an example, the Bruton’s tyrosine kinase (BTK) inhibitor ibrutinib inhibits platelet aggregation by interfering with activation signals. The role of platelet transfusion in patients with ibrutinab-associated bleeding despite a sufficient platelet count is unknown, and decisions are individualized according to the platelet count and the severity and site of bleeding.

Massive blood loss — Patients with massive blood loss from surgery or trauma are transfused with red blood cells (RBC), resulting in partial replacement of the blood volume with a product lacking platelets and clotting factors. In this setting, we transfuse RBC, fresh frozen plasma (FFP), and random donor platelet units in a 1:1:1 ratio. As an example, a patient transfused with six units of RBC would also receive six units of pooled platelets or one apheresis unit (both of which provide approximately 5 x 1011 platelets) and six units of FFP. (See “Initial evaluation and management of shock in adult trauma”, section on ‘Transfusion of blood products’.).

Cardiopulmonary bypass — Patients who undergo prolonged cardiopulmonary bypass can have thrombocytopenia and impaired platelet function. The use of platelet transfusion in the cardiopulmonary bypass setting is discussed separately. (See“Congenital and acquired disorders of platelet function”, section on ‘Cardiopulmonary bypass’ and “Early noncardiac complications of coronary artery bypass graft surgery”, section on ‘Bleeding’.)

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Better Cancer Medication

Larry H. Bernstein, MD, FCAP, Curator

LPBI

A Better Class of Cancer Drugs
http://www.technologynetworks.com/medchem/news.aspx?ID=183124
An SDSU chemist has developed a technique to identify potential cancer drugs that are less likely to produce side effects.
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.

Inroads Against Leukaemia
http://www.technologynetworks.com/medchem/news.aspx?ID=183594
Potential for halting disease in molecule isolated from sea sponges.
A molecule isolated from sea sponges and later synthesized in the lab can halt the growth of cancerous cells and could open the door to a new treatment for leukemia, according to a team of Harvard researchers and other collaborators led by Matthew Shair, a professor of chemistry and chemical biology.

“Once we learned this molecule, named cortistatin A, was very potent and selective in terms of inhibiting the growth of AML [acute myeloid leukemia] cells, we tested it in mouse models of AML and found that it was as efficacious as any other molecule we had seen, without having deleterious effects,” Shair said. “This suggests we have identified a promising new therapeutic approach.”

It’s one that could be available to test in patients relatively soon.

“We synthesized cortistatin A and we are working to develop novel therapeutics based on it by optimizing its drug-like properties,” Shair said. “Given the dearth of effective treatments for AML, we recognize the importance of advancing it toward clinical trials as quickly as possible.”

The drug-development process generally takes years, but Shair’s lab is very close to having what is known as a development candidate that could be taken into late-stage preclinical development and then clinical trials. An industrial partner will be needed to push the technology along that path and toward regulatory approval. Harvard’s Office of Technology Development (OTD) is engaged in advanced discussions to that end.

The molecule works, Shair explained, by inhibiting a pair of nearly identical kinases, called CDK8 and CDK19, that his research indicates play a key role in the growth of AML cells.

The kinases operate as part of a poorly understood, massive structure in the nucleus of cells called the mediator complex, which acts as a bridge between transcription factors and transcriptional machinery. Inhibiting these two specific kinases, Shair and colleagues found, doesn’t shut down all transcription, but instead has gene-specific effects.

“We treated AML cells with cortistatin A and measured the effects on gene expression,” Shair said. “One of the first surprises was that it’s affecting a very small number of genes — we thought it might be in the thousands, but it’s in the low hundreds.”

When Shair, Henry Pelish, a senior research associate in chemistry and chemical biology, and then-Ph.D. student Brian Liau looked closely at which genes were affected, they discovered many were associated with DNA regulatory elements known as “super-enhancers.”

“Humans have about 220 different types of cells in their body — they all have the same genome, but they have to form things like skin and bone and liver cells,” Shair explained. “In all cells, there are a relatively small number of DNA regulatory elements, called super-enhancers. These super-enhancers drive high expression of genes, many of which dictate cellular identity. A big part of cancer is a situation where that identity is lost, and the cells become poorly differentiated and are stuck in an almost stem-cell-like state.”

While a few potential cancer treatments have attacked the disease by down-regulating such cellular identity genes, Shair and colleagues were surprised to find that their molecule actually turned up the activity of those genes in AML cells.

“Before this paper, the thought was that cancer is ramping these genes up, keeping the cells in a hyper-proliferative state and affecting cell growth in that way,” Shair said. “But our molecule is saying that’s one part of the story, and in addition cancer is keeping the dosage of these genes in a narrow range. If it’s too low, the cells die. If they are pushed too high, as with cortistatin A, they return to their normal identity and stop growing.”

Shair’s lab became interested in the molecule several years ago, shortly after it was first isolated and described by other researchers. Early studies suggested it appeared to inhibit just a handful of kinases.

“We tested approximately 400 kinases, and found that it inhibits only CDK8 and CDK19 in cells, which makes it among the most selective kinase inhibitors identified to date,” Shair said. “Having compounds that precisely hit a specific target, like cortistatin A, can help reduce side effects and increase efficacy. In a way, it shatters a dogma because we thought it wasn’t possible for a molecule to be this selective and bind in a site common to all 500 human kinases, but this molecule does it, and it does it because of its 3-D structure. What’s interesting is that most kinase-inhibitor drugs do not have this type of 3-D structure. Nature is telling us that one way to achieve this level of specificity is to make molecules more like cortistatin A.”

Shair’s team successfully synthesized the molecule, which helped them study how it worked and why it affected the growth of a very specific type of cell. Later on, with funding and drug-development expertise provided by Harvard’s Blavatnik Biomedical Accelerator, Shair’s lab created a range of new molecules that may be better suited to clinical application.

“It’s a complex process to make [cortistatin A] — 32 chemical steps,” said Shair. “But we have been able to find less complex structures that act just like the natural compound, with better drug-like properties, and they can be made on a large scale and in about half as many steps.”

“Over the course of several years, we have watched this research progress from an intriguing discovery to a highly promising development candidate,” said Isaac Kohlberg, senior associate provost and chief technology development officer. “The latest results are a real testament to Matt’s ingenuity and dedication to addressing a very tough disease.”

While there is still much work to be done — in particular, to better understand how CDK8 and CDK19 regulate gene expression — the early results have been dramatic.

“This is the kind of thing you do science for,” Shair said, “the idea that once every 10 or 20 years you might find something this interesting, that sheds new light on important, difficult problems. This gives us an opportunity to generate a new understanding of cancer and also develop new therapeutics to treat it. We’re very excited and curious to see where it goes.”

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Treatment of Acute Leukemias

Author and Curator: Larry H. Bernstein, MD, FCAP

2.4.4 Treatment of Acute Leukemias

Treatment of Acute Lymphoblastic Leukemia

Ching-Hon Pu, and William E. Evans
N Engl J Med Jan 12, 2006; 354:166-178
http://dx.doi.org:/10.1056/NEJMra052603

Although the overall cure rate of acute lymphoblastic leukemia (ALL) in children is about 80 percent, affected adults fare less well. This review considers recent advances in the treatment of ALL, emphasizing issues that need to be addressed if treatment outcome is to improve further.

Acute Lymphoblastic Leukemia

Ching-Hon Pui, Mary V. Relling, and James R. Downing
N Engl J Med Apr 8, 2004; 350:1535-1548
http://dx.doi.org:/10.1056/NEJMra023001

This comprehensive survey emphasizes how recent advances in the knowledge of molecular mechanisms involved in acute lymphoblastic leukemia have influenced diagnosis, prognosis, and treatment.

Gene-Expression Patterns in Drug-Resistant Acute Lymphoblastic Leukemia Cells and Response to Treatment

Amy Holleman, Meyling H. Cheok, Monique L. den Boer, et al.
N Engl J Med 2004; 351:533-42

Childhood acute lymphoblastic leukemia (ALL) is curable with chemotherapy in approximately 80 percent of patients. However, the cause of treatment failure in the remaining 20 percent of patients is largely unknown.

Methods We tested leukemia cells from 173 children for sensitivity in vitro to prednisolone, vincristine, asparaginase, and daunorubicin. The cells were then subjected to an assessment of gene expression with the use of 14,500 probe sets to identify differentially expressed genes in drug-sensitive and drug-resistant ALL. Gene-expression patterns that differed according to sensitivity or resistance to the four drugs were compared with treatment outcome in the original 173 patients and an independent cohort of 98 children treated with the same drugs at another institution.

Results We identified sets of differentially expressed genes in B-lineage ALL that were sensitive or resistant to prednisolone (33 genes), vincristine (40 genes), asparaginase (35 genes), or daunorubicin (20 genes). A combined gene-expression score of resistance to the four drugs, as compared with sensitivity to the four, was significantly and independently related to treatment outcome in a multivariate analysis (hazard ratio for relapse, 3.0; P=0.027). Results were confirmed in an independent population of patients treated with the same medications (hazard ratio for relapse, 11.85; P=0.019). Of the 124 genes identified, 121 have not previously been associated with resistance to the four drugs we tested.

Conclusions  Differential expression of a relatively small number of genes is associated with drug resistance and treatment outcome in childhood ALL.

Leukemias Treatment & Management

Author: Lihteh Wu, MD; Chief Editor: Hampton Roy Sr
http://emedicine.medscape.com/article/1201870-treatment

The treatment of leukemia is in constant flux, evolving and changing rapidly over the past few years. Most treatment protocols use systemic chemotherapy with or without radiotherapy. The basic strategy is to eliminate all detectable disease by using cytotoxic agents. To attain this goal, 3 phases are typically used, as follows: remission induction phase, consolidation phase, and maintenance therapy phase.

Chemotherapeutic agents are chosen that interfere with cell division. Tumor cells usually divide more rapidly than host cells, making them more vulnerable to the effects of chemotherapy. Primary treatment will be under the direction of a medical oncologist, radiation oncologist, and primary care physician. Although a general treatment plan will be outlined, the ophthalmologist does not prescribe or manage such treatment.

  • The initial treatment of ALL uses various combinations of vincristine, prednisone, and L-asparaginase until a complete remission is obtained.
  • Maintenance therapy with mercaptopurine is continued for 2-3 years following remission.
  • Use of intrathecal methotrexate with or without cranial irradiation to cover the CNS varies from facility to facility.
  • Daunorubicin, cytarabine, and thioguanine currently are used to obtain induction and remission of AML.
  • Maintenance therapy for 8 months may lengthen remission. Once relapse has occurred, AML generally is curable only by bone marrow transplantation.
  • Presently, treatment of CLL is palliative.
  • CML is characterized by a leukocytosis greater than 100,000 cells. Emergent treatment with leukopheresis sometimes is necessary when leukostastic complications are present. Otherwise, busulfan or hydroxyurea may control WBC counts. During the chronic phase, treatment is palliative.
  • When CML converts to the blastic phase, approximately one third of cases behave as ALL and respond to treatment with vincristine and prednisone. The remaining two thirds resemble AML but respond poorly to AML therapy.
  • Allogeneic bone marrow transplant is the only curative therapy for CML. However, it carries a high early mortality rate.
  • Leukemic retinopathy usually is not treated directly. As the hematological parameters normalize with systemic treatment, many of the ophthalmic signs resolve. There are reports that leukopheresis for hyperviscosity also may alleviate intraocular manifestations.
  • When definite intraocular leukemic infiltrates fail to respond to systemic chemotherapy, direct radiation therapy is recommended.
  • Relapse, manifested by anterior segment involvement, should be treated by radiation. In certain cases, subconjunctival chemotherapeutic agents have been injected.
  • Optic nerve head infiltration in patients with ALL is an emergency and requires prompt radiation therapy to try to salvage some vision.

Treatments and drugs

http://www.mayoclinic.org/diseases-conditions/leukemia/basics/
treatment/con-20024914

Common treatments used to fight leukemia include:

  • Chemotherapy. Chemotherapy is the major form of treatment for leukemia. This drug treatment uses chemicals to kill leukemia cells.

Depending on the type of leukemia you have, you may receive a single drug or a combination of drugs. These drugs may come in a pill form, or they may be injected directly into a vein.

  • Biological therapy. Biological therapy works by using treatments that help your immune system recognize and attack leukemia cells.
  • Targeted therapy. Targeted therapy uses drugs that attack specific vulnerabilities within your cancer cells.

For example, the drug imatinib (Gleevec) stops the action of a protein within the leukemia cells of people with chronic myelogenous leukemia. This can help control the disease.

  • Radiation therapy. Radiation therapy uses X-rays or other high-energy beams to damage leukemia cells and stop their growth. During radiation therapy, you lie on a table while a large machine moves around you, directing the radiation to precise points on your body.

You may receive radiation in one specific area of your body where there is a collection of leukemia cells, or you may receive radiation over your whole body. Radiation therapy may be used to prepare for a stem cell transplant.

  • Stem cell transplant. A stem cell transplant is a procedure to replace your diseased bone marrow with healthy bone marrow.

Before a stem cell transplant, you receive high doses of chemotherapy or radiation therapy to destroy your diseased bone marrow. Then you receive an infusion of blood-forming stem cells that help to rebuild your bone marrow.

You may receive stem cells from a donor, or in some cases you may be able to use your own stem cells. A stem cell transplant is very similar to a bone marrow transplant.

2.4.4.2 Acute Myeloid Leukemia

New treatment approaches in acute myeloid leukemia: review of recent clinical studies.

Norsworthy K1Luznik LGojo I.
Rev Recent Clin Trials. 2012 Aug; 7(3):224-37.
http://www.ncbi.nlm.nih.gov/pubmed/22540908

Standard chemotherapy can cure only a fraction (30-40%) of younger and very few older patients with acute myeloid leukemia (AML). While conventional allografting can extend the cure rates, its application remains limited mostly to younger patients and those in remission. Limited efficacy of current therapies and improved understanding of the disease biology provided a spur for clinical trials examining novel agents and therapeutic strategies in AML. Clinical studies with novel chemotherapeutics, antibodies, different signal transduction inhibitors, and epigenetic modulators demonstrated their clinical activity; however, it remains unclear how to successfully integrate novel agents either alone or in combination with chemotherapy into the overall therapeutic schema for AML. Further studies are needed to examine their role in relation to standard chemotherapy and their applicability to select patient populations based on recognition of unique disease and patient characteristics, including the development of predictive biomarkers of response. With increasing use of nonmyeloablative or reduced intensity conditioning and alternative graft sources such as haploidentical donors and cord blood transplants, the benefits of allografting may extend to a broader patient population, including older AML patients and those lacking a HLA-matched donor. We will review here recent clinical studies that examined novel pharmacologic and immunologic approaches to AML therapy.

Novel approaches to the treatment of acute myeloid leukemia.

Roboz GJ1
Hematology Am Soc Hematol Educ Program. 2011:43-50.
http://dx.doi.org:/10.1182/asheducation-2011.1.43.

Approximately 12 000 adults are diagnosed with acute myeloid leukemia (AML) in the United States annually, the majority of whom die from their disease. The mainstay of initial treatment, cytosine arabinoside (ara-C) combined with an anthracycline, was developed nearly 40 years ago and remains the worldwide standard of care. Advances in genomics technologies have identified AML as a genetically heterogeneous disease, and many patients can now be categorized into clinicopathologic subgroups on the basis of their underlying molecular genetic defects. It is hoped that enhanced specificity of diagnostic classification will result in more effective application of targeted agents and the ability to create individualized treatment strategies. This review describes the current treatment standards for induction, consolidation, and stem cell transplantation; special considerations in the management of older AML patients; novel agents; emerging data on the detection and management of minimal residual disease (MRD); and strategies to improve the design and implementation of AML clinical trials.

Age ≥ 60 years has consistently been identified as an independent adverse prognostic factor in AML, and there are very few long-term survivors in this age group.5 Poor outcomes in elderly AML patients have been attributed to both host- and disease-related factors, including medical comorbidities, physical frailty, increased incidence of antecedent myelodysplastic syndrome and myeloproliferative disorders, and higher frequency of adverse cytogenetics.28 Older patients with multiple poor-risk factors have a high probability of early death and little chance of long-term disease-free survival with standard chemotherapy. In a retrospective analysis of 998 older patients treated with intensive induction at the M.D. Anderson Cancer Center, multivariate analysis identified age ≥ 75 years, unfavorable karyotype, poor performance status, creatinine > 1.3 mg/dL, duration of antecedent hematologic disorder > 6 months, and treatment outside a laminar airflow room as adverse prognostic indicators.29 Patients with 3 or more of these factors had expected complete remission rates of < 20%, 8-week mortality > 50%, and 1-year survival < 10%. The Medical Research Council (MRC) identified cytogenetics, WBC count at diagnosis, age, and de novo versus secondary disease as critical factors influencing survival in > 2000 older patients with AML, but cautioned in their conclusions that less objective factors, such as clinical assessment of “fitness” for chemotherapy, may be equally important in making treatment decisions in this patient population.30 It is hoped that data from comprehensive geriatric assessments of functional status, cognition, mood, quality of life, and other measures obtained during ongoing cooperative group trials will improve our ability to predict how older patients will tolerate treatment.

Current treatment of acute myeloid leukemia.

Roboz GJ1.
Curr Opin Oncol. 2012 Nov; 24(6):711-9.
http://dx.doi.org:/10.1097/CCO.0b013e328358f62d.

The objectives of this review are to discuss standard and investigational nontransplant treatment strategies for acute myeloid leukemia (AML), excluding acute promyelocytic leukemia.

RECENT FINDINGS: Most adults with AML die from their disease. The standard treatment paradigm for AML is remission induction chemotherapy with an anthracycline/cytarabine combination, followed by either consolidation chemotherapy or allogeneic stem cell transplantation, depending on the patient’s ability to tolerate intensive treatment and the likelihood of cure with chemotherapy alone. Although this approach has changed little in the last three decades, increased understanding of the pathogenesis of AML and improvements in molecular genomic technologies are leading to novel drug targets and the development of personalized, risk-adapted treatment strategies. Recent findings related to prognostically relevant and potentially ‘druggable’ molecular targets are reviewed.

SUMMARY: At the present time, AML remains a devastating and mostly incurable disease, but the combination of optimized chemotherapeutics and molecularly targeted agents holds significant promise for the future.

Adult Acute Myeloid Leukemia Treatment (PDQ®)
http://www.cancer.gov/cancertopics/pdq/treatment/adultAML/healthprofessional/page9

About This PDQ Summary

This summary is reviewed regularly and updated as necessary by the PDQ Adult Treatment Editorial Board, which is editorially independent of the National Cancer Institute (NCI). The summary reflects an independent review of the literature and does not represent a policy statement of NCI or the National Institutes of Health (NIH).

Board members review recently published articles each month to determine whether an article should:

  • be discussed at a meeting,
  • be cited with text, or
  • replace or update an existing article that is already cited.

Treatment Option Overview for AML

Successful treatment of acute myeloid leukemia (AML) requires the control of bone marrow and systemic disease and specific treatment of central nervous system (CNS) disease, if present. The cornerstone of this strategy includes systemically administered combination chemotherapy. Because only 5% of patients with AML develop CNS disease, prophylactic treatment is not indicated.[13]

Treatment is divided into two phases: remission induction (to attain remission) and postremission (to maintain remission). Maintenance therapy for AML was previously administered for several years but is not included in most current treatment clinical trials in the United States, other than for acute promyelocytic leukemia. (Refer to the Adult Acute Myeloid Leukemia in Remission section of this summary for more information.) Other studies have used more intensive postremission therapy administered for a shorter duration of time after which treatment is discontinued.[4] Postremission therapy appears to be effective when given immediately after remission is achieved.[4]

Since myelosuppression is an anticipated consequence of both the leukemia and its treatment with chemotherapy, patients must be closely monitored during therapy. Facilities must be available for hematologic support with multiple blood fractions including platelet transfusions and for the treatment of related infectious complications.[5] Randomized trials have shown similar outcomes for patients who received prophylactic platelet transfusions at a level of 10,000/mm3 rather than 20,000/mm3.[6] The incidence of platelet alloimmunization was similar among groups randomly assigned to receive pooled platelet concentrates from random donors; filtered, pooled platelet concentrates from random donors; ultraviolet B-irradiated, pooled platelet concentrates from random donors; or filtered platelets obtained by apheresis from single random donors.[7] Colony-stimulating factors, for example, granulocyte colony–stimulating factor (G-CSF) and granulocyte-macrophage colony–stimulating factor (GM-CSF), have been studied in an effort to shorten the period of granulocytopenia associated with leukemia treatment.[8] If used, these agents are administered after completion of induction therapy. GM-CSF was shown to improve survival in a randomized trial of AML in patients aged 55 to 70 years (median survival was 10.6 months vs. 4.8 months). In this Eastern Cooperative Oncology Group (ECOG) (EST-1490) trial, patients were randomly assigned to receive GM-CSF or placebo following demonstration of leukemic clearance of the bone marrow;[9] however, GM-CSF did not show benefit in a separate similar randomized trial in patients older than 60 years.[10] In the latter study, clearance of the marrow was not required before initiating cytokine therapy. In a Southwest Oncology Group (NCT00023777) randomized trial of G-CSF given following induction therapy to patients older than 65 years, complete response was higher in patients who received G-CSF because of a decreased incidence of primary leukemic resistance. Growth factor administration did not impact on mortality or on survival.[11,12] Because the majority of randomized clinical trials have not shown an impact of growth factors on survival, their use is not routinely recommended in the remission induction setting.

The administration of GM-CSF or other myeloid growth factors before and during induction therapy, to augment the effects of cytotoxic therapy through the recruitment of leukemic blasts into cell cycle (growth factor priming), has been an area of active clinical research. Evidence from randomized studies of GM-CSF priming have come to opposite conclusions. A randomized study of GM-CSF priming during conventional induction and postremission therapy showed no difference in outcomes between patients who received GM-CSF and those who did not receive growth factor priming.[13,14][Level of evidence: 1iiA] In contrast, a similar randomized placebo-controlled study of GM-CSF priming in patients with AML aged 55 to 75 years showed improved disease-free survival (DFS) in the group receiving GM-CSF (median DFS for patients who achieved complete remission was 23 months vs. 11 months; 2-year DFS was 48% vs. 21%), with a trend towards improvement in overall survival (2-year survival was 39% vs. 27%, = .082) for patients aged 55 to 64 years.[15][Level of evidence: 1iiDii]

References

  1. Kebriaei P, Champlin R, deLima M, et al.: Management of acute leukemias. In: DeVita VT Jr, Lawrence TS, Rosenberg SA: Cancer: Principles and Practice of Oncology. 9th ed. Philadelphia, Pa: Lippincott Williams & Wilkins, 2011, pp 1928-54.
  2. Wiernik PH: Diagnosis and treatment of acute nonlymphocytic leukemia. In: Wiernik PH, Canellos GP, Dutcher JP, et al., eds.: Neoplastic Diseases of the Blood. 3rd ed. New York, NY: Churchill Livingstone, 1996, pp 283-302.
  3. Morrison FS, Kopecky KJ, Head DR, et al.: Late intensification with POMP chemotherapy prolongs survival in acute myelogenous leukemia–results of a Southwest Oncology Group study of rubidazone versus adriamycin for remission induction, prophylactic intrathecal therapy, late intensification, and levamisole maintenance. Leukemia 6 (7): 708-14, 1992. [PUBMED Abstract]
  4. Cassileth PA, Lynch E, Hines JD, et al.: Varying intensity of postremission therapy in acute myeloid leukemia. Blood 79 (8): 1924-30, 1992. [PUBMED Abstract]
  5. Supportive Care. In: Wiernik PH, Canellos GP, Dutcher JP, et al., eds.: Neoplastic Diseases of the Blood. 3rd ed. New York, NY: Churchill Livingstone, 1996, pp 779-967.
  6. Rebulla P, Finazzi G, Marangoni F, et al.: The threshold for prophylactic platelet transfusions in adults with acute myeloid leukemia. Gruppo Italiano Malattie Ematologiche Maligne dell’Adulto. N Engl J Med 337 (26): 1870-5, 1997. [PUBMED Abstract]
  7. Leukocyte reduction and ultraviolet B irradiation of platelets to prevent alloimmunization and refractoriness to platelet transfusions. The Trial to Reduce Alloimmunization to Platelets Study Group. N Engl J Med 337 (26): 1861-9, 1997. [PUBMED Abstract]
  8. Geller RB: Use of cytokines in the treatment of acute myelocytic leukemia: a critical review. J Clin Oncol 14 (4): 1371-82, 1996. [PUBMED Abstract]
  9. Rowe JM, Andersen JW, Mazza JJ, et al.: A randomized placebo-controlled phase III study of granulocyte-macrophage colony-stimulating factor in adult patients (> 55 to 70 years of age) with acute myelogenous leukemia: a study of the Eastern Cooperative Oncology Group (E1490). Blood 86 (2): 457-62, 1995. [PUBMED Abstract]
  10. Stone RM, Berg DT, George SL, et al.: Granulocyte-macrophage colony-stimulating factor after initial chemotherapy for elderly patients with primary acute myelogenous leukemia. Cancer and Leukemia Group B. N Engl J Med 332 (25): 1671-7, 1995. [PUBMED Abstract]
  11. Dombret H, Chastang C, Fenaux P, et al.: A controlled study of recombinant human granulocyte colony-stimulating factor in elderly patients after treatment for acute myelogenous leukemia. AML Cooperative Study Group. N Engl J Med 332 (25): 1678-83, 1995. [PUBMED Abstract]
  12. Godwin JE, Kopecky KJ, Head DR, et al.: A double-blind placebo-controlled trial of granulocyte colony-stimulating factor in elderly patients with previously untreated acute myeloid leukemia: a Southwest oncology group study (9031). Blood 91 (10): 3607-15, 1998. [PUBMED Abstract]
  13. Buchner T, Hiddemann W, Wormann B, et al.: GM-CSF multiple course priming and long-term administration in newly diagnosed AML: hematologic and therapeutic effects. [Abstract] Blood 84 (10 Suppl 1): A-95, 27a, 1994.
  14. Löwenberg B, Boogaerts MA, Daenen SM, et al.: Value of different modalities of granulocyte-macrophage colony-stimulating factor applied during or after induction therapy of acute myeloid leukemia. J Clin Oncol 15 (12): 3496-506, 1997. [PUBMED Abstract]
  15. Witz F, Sadoun A, Perrin MC, et al.: A placebo-controlled study of recombinant human granulocyte-macrophage colony-stimulating factor administered during and after induction treatment for de novo acute myelogenous leukemia in elderly patients. Groupe Ouest Est Leucémies Aiguës Myéloblastiques (GOELAM). Blood 91 (8): 2722-30, 1998. [PUBMED Abstract]

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