Bhavana Bhatnagar

Decitabine priming enhances the antileukemic effects of exportin 1 (XPO1) selective inhibitor selinexor in acute myeloid leukemia

The prognosis of acute myeloid leukemia (AML) is poor, highlighting the need for novel treatments. Hypomethylating agents, including decitabine are used to treat elderly AML patients with relative success. Targeting nuclear export receptor (exportin 1 [XPO1]) is a novel approach to restore tumor suppressor (TS) function in AML. Here, we show that sequential treatment of AML blasts with decitabine followed by selinexor (XPO1 inhibitor) enhances the antileukemic effects of selinexor. These effects could be mediated by the re-expression of a subset of TSs (CDKN1A and FOXO3A) that are epigenetically silenced via DNA methylation, and cytoplasmic-nuclear trafficking is regulated by XPO1. We observed a significant upregulation of CDKN1A and FOXO3A in decitabine- versus control-treated cells. Sequential treatment of decitabine followed by selinexor in an MV4-11 xenograft model significantly improved survival compared with selinexor alone. On the basis of these preclinical results, a phase 1 clinical trial of decitabine followed by selinexor in elderly patients with AML has been initiated.

Persistence of DNMT3A R882 mutations during remission does not adversely affect outcomes of patients with acute myeloid leukaemia

Somatic mutation of the DNMT3A gene at the arginine R882 site is common in acute myeloid leukaemia (AML). The prognostic significance of DNMT3A R882 mutation clearance, using traditional diagnostic next generation sequencing (NGS) methods, during complete remission (CR) in AML patients is controversial. We examined the impact of clearing DNMT3A R882 mutations at diagnosis to the detectable threshold of ˂3% during CR on outcome in 56 adult AML patients. Mutational remission, defined as clearance of pre‐treatment DNMT3A R882 and all other AML‐associated mutations to a variant allele frequency ˂3%, occurred in 14 patients whereas persistent DNMT3A R882 mutations were observed in 42 patients. There were no significant differences in disease‐free or overall survival between patients with and without DNMT3A R882 mutation clearance. Patients with persistent DNMT3A R882 who cleared all other AML mutations and did not acquire new mutations (n = 30), trended towards longer disease‐free survival (1·6 vs. 0·6 years, P = 0·06) than patients with persistence of DNMT3A R882, in addition to other mutations or acquisition of new AML‐associated mutations, such as those in TET2, JAK2, ASXL1 and TP53 (n = 12). These data demonstrate that DNMT3A R882 mutations, as assessed by traditional NGS methods, persist in the majority of AML patients in CR.

XPO1 Inhibition using Selinexor Synergizes with Chemotherapy in Acute Myeloid Leukemia by Targeting DNA Repair and Restoring Topoisomerase IIα to the Nucleus.

Purpose: Selinexor, a selective inhibitor of XPO1, is currently being tested as single agent in clinical trials in acute myeloid leukemia (AML). However, considering the molecular complexity of AML, it is unlikely that AML can be cured with monotherapy. Therefore, we asked whether adding already established effective drugs such as topoisomerase (Topo) II inhibitors to selinexor will enhance its anti-leukemic effects in AML. Experimental Design: The efficacy of combinatorial drug treatment using Topo II inhibitors (idarubicin, daunorubicin, mitoxantrone, etoposide) and selinexor was evaluated in established cellular and animal models of AML. Results: Concomitant treatment with selinexor and Topo II inhibitors resulted in therapeutic synergy in AML cell lines and patient samples. Using a xenograft MV4-11 AML mouse model, we show that treatment with selinexor and idarubicin significantly prolongs survival of leukemic mice compared with each single therapy. Conclusions: Aberrant nuclear export and cytoplasmic localization of Topo IIα has been identified as one of the mechanisms leading to drug resistance in cancer. Here, we show that in a subset of patients with AML that express cytoplasmic Topo IIα, selinexor treatment results in nuclear retention of Topo IIα protein, resulting in increased sensitivity to idarubicin. Selinexor treatment of AML cells resulted in a c-MYC–dependent reduction of DNA damage repair genes (Rad51 and Chk1) mRNA and protein expression and subsequent inhibition of homologous recombination repair and increased sensitivity to Topo II inhibitors. The preclinical data reported here support further clinical studies using selinexor and Topo II inhibitors in combination to treat AML. Clin Cancer Res; 22(24); 6142–52. ©2016 AACR.

Midostaurin, bortezomib and MEC in relapsed/refractory acute myeloid leukemia

Abstract Targeting aberrant tyrosine kinase activity may impact clinical outcome in acute myeloid leukemia (AML). We conducted a phase I study of the tyrosine kinase inhibitor midostaurin with bortezomib alone and in combination with chemotherapy in patients with AML. Patients on dose levels 1 and 2 (DL1 & 2) received midostaurin 50 mg bid and escalating doses of bortezomib (1 to 1.3 mg/m2). Patients on DL3 or higher received midostaurin and bortezomib following chemotherapy with mitoxantrone, etoposide, cytarabine (MEC). None of the patients enrolled to DL1 & 2 had dose-limiting toxicities (DLTs) or a clinical response. Among patients enrolled to DL3 or higher, DLTs were peripheral neuropathy, decrease in ejection fraction and diarrhea. A 56.5% CR rate and 82.5% overall response rate (CR + CR with incomplete neutrophil or platelet count recovery) were observed. The midostaurin/bortezomib/MEC combination is active in refractory/relapsed AML, but is associated with expected drug-related toxicities (NCT01174888).

p53−/− synergizes with enhanced NrasG12D signaling to transform megakaryocyte-erythroid progenitors in acute myeloid leukemia

Somatic mutations in TP53 and NRAS are associated with transformation of human chronic myeloid diseases to acute myeloid leukemia (AML). Here, we report that concurrent RAS pathway and TP53 mutations are identified in a subset of AML patients and confer an inferior overall survival. To further investigate the genetic interaction between p53 loss and endogenous NrasG12D/+ in AML, we generated conditional NrasG12D/+p53-/- mice. Consistent with the clinical data, recipient mice transplanted with NrasG12D/+p53-/- bone marrow cells rapidly develop a highly penetrant AML. We find that p53-/- cooperates with NrasG12D/+ to promote increased quiescence in megakaryocyte-erythroid progenitors (MEPs). NrasG12D/+p53-/- MEPs are transformed to self-renewing AML-initiating cells and are capable of inducing AML in serially transplanted recipients. RNA sequencing analysis revealed that transformed MEPs gain a partial hematopoietic stem cell signature and largely retain an MEP signature. Their distinct transcriptomes suggests a potential regulation by p53 loss. In addition, we show that during AML development, transformed MEPs acquire overexpression of oncogenic Nras, leading to hyperactivation of ERK1/2 signaling. Our results demonstrate that p53-/- synergizes with enhanced oncogenic Nras signaling to transform MEPs and drive AML development. This model may serve as a platform to test candidate therapeutics in this aggressive subset of AML.

The Use of Molecular Genetics to Refine Prognosis in Acute Myeloid Leukemia

The discovery and application of advanced molecular techniques, such as gene and microRNA expression profiling, whole genome and exome sequencing, proteomic analysis and methylation assays, have allowed for the identification of recurrent molecular abnormalities in acute myeloid leukemia (AML) that have revolutionized our understanding of the genetic landscape of the disease. These modalities have emerged as valuable tools that permit a more comprehensive and detailed molecular characterization of AML. Many of these molecular abnormalities have been shown to predict prognosis, particularly within the context of cytogenetically normal AML. This review will discuss the major techniques and platforms that have been used to identify novel recurrent gene mutations in AML and briefly describe how these discoveries have impacted on outcome prediction.

Clinical features and gene- and microRNA-expression patterns in adult acute leukemia patients with t(11;19)(q23;p13.1) and t(11;19)(q23;p13.3).

Clinical features and gene- and microRNA-expression patterns in adult acute leukemia patients with t(11;19)(q23;p13.1) and t(11;19)(q23;p13.3)

Long noncoding RNAs to predict survival in acute myeloid leukemia: a step toward personalized medicine?

Acute myeloid leukemia (AML) is a clinically, biologically, molecularly diverse and highly aggressive hematologic malignancy characterized by clonal expansion of immature myeloid precursors, or blasts, in the blood and bone marrow. Despite current treatments, the long-term overall survival (OS) rates are only approximately 40% for younger (<60 years) and approximately 10% for older (>60 years) AML patients [1]. One of the major goals in leukemia research is to fully characterize the genetics and molecular alterations in AML in order to: first, develop novel therapeutic strategies and, second, identify biomarkers for treatment response and outcome that will allow for optimal risk-based stratification for treatment. Over the past 20 years, there has been great progress in this area. Several studies have established that pretreatment cytogenetics provide significant information regarding prognosis and responsiveness to intensive standard chemotherapy [2] and are still considered, by many, to be the most important disease characteristic by which to risk-stratify AML patients. The systematic discovery of the landscape of recurrent mutations in AML has contributed greatly to the molecular characterization and outcome prediction of AML. However, using current cytogenetic and molecularly risk-stratified therapies, about 20–30% of AML patients never achieve complete response (CR), and over 50% of those who do achieve CR subsequently experience early disease relapse, typically within 2 or 3 years [3]. Thus, much work is still needed in this area. Approximately half of AML diagnoses are associated with a normal karyotype (i.e., cytogenetically normal AML [CNAML]) and highly variable disease outcomes [2]. The discovery and application of recurrent genetic mutations to current prognostic models in AML has not only provided a multidimensional understanding of disease biology [4] but has also allowed for refinement in determining overall prognosis, especially for patients with CN-AML [5,6]. Typically, these mutations lead either to activation of signal-transduction pathways resulting in proliferation or survival of malignant cells (e.g., FLT3-ITD and RAS mutations), or to impaired hematopoietic differentiation such as (e.g., CEBPA mutations and MLL-PTD). Furthermore, the presence of certain molecular abnormalities helps guide future therapeutic strategies, including the decision to pursue allogeneic transplant, tyrosine kinase inhibition or provide higher doses of chemotherapy. In addition to providing prognostic information and guiding treatment decisions, specific molecular mutations (NPM1) have been shown to be stable, useful biomarkers of persistent disease or impending relapse in Long noncoding RNAs to predict survival in acute myeloid leukemia: a step toward personalized medicine?

Polo-like kinase inhibitor volasertib marginally enhances the efficacy of the novel Fc-engineered anti-CD33 antibody BI 836858 in acute myeloid leukemia

Acute myeloid leukemia (AML) is the second most common type of leukemia in adults. Incidence of AML increases with age with a peak incidence at 67 years. Patients older than 60 years have an unfavorable prognosis due to resistance to conventional chemotherapy. Volasertib (BI 6727) is a cell-cycle regulator targeting polo-like kinase which has been evaluated in clinical trials in AML. We evaluated effects of volasertib in primary patient samples and NK cells. At equivalent doses, volasertib is cytotoxic to AML blasts but largely spares healthy NK cells. We then evaluated the effect of volasertib treatment in combination with BI 836858 on primary AML blast samples using antibody-dependent cellular cytotoxicity (ADCC) assays. Volasertib treatment of NK cells did not impair NK function as evidenced by comparable levels of BI 836858 mediated ADCC in both volasertib-treated and control-treated NK cells. In summary, volasertib is cytotoxic to AML blasts while sparing NK cell viability and function. Higher BI 836858 mediated ADCC was observed in patient samples pretreated with volasertib. These findings provide a strong rationale to test combination of BI 836858 and volasertib in AML.

Chronic Myeloid Leukemia, Version 1.2019, NCCN Clinical Practice Guidelines in Oncology

Chronic myeloid leukemia (CML) is defined by the presence of Philadelphia chromosome (Ph), resulting from a reciprocal translocation between chromosomes 9 and 22 [t(9;22] that gives rise to a BCR-ABL1 fusion gene. CML occurs in 3 different phases (chronic, accelerated, and blast phase) and is usually diagnosed in the chronic phase. Tyrosine kinase inhibitor (TKI) therapy is a highly effective first-line treatment option for all patients with newly diagnosed chronic phase CML (CP-CML). The selection TKI therapy should be based on the risk score, toxicity profile of TKI, patients age, ability to tolerate therapy, and the presence of comorbid conditions. This manuscript discusses the recommendations outlined in the NCCN Guidelines for the diagnosis and management of patients with CP-CML.