Swaminathan Padmanabhan Iyer

Highly Active Combination of BRD4 Antagonist and Histone Deacetylase Inhibitor against Human Acute Myelogenous Leukemia Cells

The bromodomain and extra-terminal (BET) protein family members, including BRD4, bind to acetylated lysines on histones and regulate the expression of important oncogenes, for example, c-MYC and BCL2. Here, we demonstrate the sensitizing effects of the histone hyperacetylation-inducing pan–histone deacetylase (HDAC) inhibitor panobinostat on human acute myelogenous leukemia (AML) blast progenitor cells (BPC) to the BET protein antagonist JQ1. Treatment with JQ1, but not its inactive enantiomer (R-JQ1), was highly lethal against AML BPCs expressing mutant NPM1c+ with or without coexpression of FLT3-ITD or AML expressing mixed lineage leukemia fusion oncoprotein. JQ1 treatment reduced binding of BRD4 and RNA polymerase II to the DNA of c-MYC and BCL2 and reduced their levels in the AML cells. Cotreatment with JQ1 and the HDAC inhibitor panobinostat synergistically induced apoptosis of the AML BPCs, but not of normal CD34+ hematopoietic progenitor cells. This was associated with greater attenuation of c-MYC and BCL2, while increasing p21, BIM, and cleaved PARP levels in the AML BPCs. Cotreatment with JQ1 and panobinostat significantly improved the survival of the NOD/SCID mice engrafted with OCI-AML3 or MOLM13 cells (P < 0.01). These findings highlight cotreatment with a BRD4 antagonist and an HDAC inhibitor as a potentially efficacious therapy of AML. Mol Cancer Ther; 13(5); 1142–54. ©2014 AACR.

BET Protein Antagonist JQ1 Is Synergistically Lethal with FLT3 Tyrosine Kinase Inhibitor (TKI) and Overcomes Resistance to FLT3-TKI in AML Cells Expressing FLT-ITD

Recently, treatment with bromodomain and extraterminal protein antagonist (BA) such as JQ1 has been shown to inhibit growth and induce apoptosis of human acute myelogenous leukemia (AML) cells, including those expressing FLT3-ITD. Here, we demonstrate that cotreatment with JQ1 and the FLT3 tyrosine kinase inhibitor (TKI) ponatinib or AC220 synergistically induce apoptosis of cultured and primary CD34+ human AML blast progenitor cells (BPC) expressing FLT3-ITD. Concomitantly, as compared with each agent alone, cotreatment with JQ1 and the FLT3-TKI caused greater attenuation of c-MYC, BCL2, and CDK4/6. Simultaneously, cotreatment with JQ1 and the FLT3-TKI increased the levels of p21, BIM, and cleaved PARP, as well as mediated marked attenuation of p-STAT5, p-AKT, and p-ERK1/2 levels in AML BPCs. Conversely, cotreatment with JQ1 and FLT3-TKI was significantly less active against CD34+ normal bone marrow progenitor cells. Knockdown of BRD4 by short hairpin RNA also sensitized AML cells to FLT3-TKI. JQ1 treatment induced apoptosis of mouse Ba/F3 cells ectopically expressing FLT3-ITD with or without FLT3-TKI–resistant mutations F691L and D835V. Compared with the parental human AML FLT3-ITD–expressing MOLM13, MOLM13-TKIR cells resistant to AC220 were markedly more sensitive to JQ1-induced apoptosis. Furthermore, cotreatment with JQ1 and the pan-histone deacetylase inhibitor (HDI) panobinostat synergistically induced apoptosis of FLT3-TKI–resistant MOLM13-TKIR and MV4-11-TKIR cells. Collectively, these findings support the rationale for determining the in vivo activity of combined therapy with BA and FLT3-TKI against human AML cells expressing FLT3-ITD or with BA and HDI against AML cells resistant to FLT3-TKI. Mol Cancer Ther; 13(10); 2315–27. ©2014 AACR.

Pre-clinical efficacy of combined therapy with novel β-catenin antagonist BC2059 and histone deacetylase inhibitor against AML cells

The canonical wingless-type MMTV integration site (WNT)-β-catenin pathway is essential for self-renewal, growth and survival of acute myeloid leukemia (AML) stem/blast progenitor cells (BPCs). Deregulated WNT signaling inhibits degradation of β-catenin, causing increased nuclear translocation and co-factor activity of β-catenin with the transcriptional regulator T-cell factor (TCF) 4/lymphoid enhancer factor 1 in AML BPCs. Here, we determined the pre-clinical anti-AML activity of the anthraquinone oxime-analog BC2059 (BC), known to attenuate β-catenin levels. BC treatment disrupted the binding of β-catenin with the scaffold protein transducin β-like 1 and proteasomal degradation and decline in the nuclear levels of β-catenin. This was associated with reduced transcriptional activity of TCF4 and expression of its target genes, cyclin D1, c-MYC and survivin. BC treatment dose-dependently induced apoptosis of cultured and primary AML BPCs. Treatment with BC also significantly improved the median survival of immune-depleted mice engrafted with either cultured or primary AML BPCs, exhibiting nuclear expression of β-catenin. Co-treatment with the pan-histone deacetylase inhibitor panobinostat and BC synergistically induced apoptosis of cultured and primary AML BPCs, including those expressing FLT3-ITD, as well as further significantly improved the survival of immune-depleted mice engrafted with primary AML BPCs. These findings underscore the promising pre-clinical activity and warrant further testing of BC against human AML, especially those expressing FLT3-ITD.

HEXIM1 induction is mechanistically involved in mediating anti-AML activity of BET protein bromodomain antagonist.

HEXIM1 induction is mechanistically involved in mediating anti-AML activity of BET protein bromodomain antagonist

Phase 1/1B trial of the heat shock protein 90 inhibitor NVP-AUY922 as monotherapy or in combination with bortezomib in patients with relapsed or refractory multiple myeloma

NVP‐AUY922 (AUY; Luminespib) with or without bortezomib showed preclinical activity against multiple myeloma (MM) cells. This phase 1/1B study assessed NVP‐AUY922 alone and with bortezomib in patients with relapsed or refractory MM.

Romidepsin induces durable responses in patients with relapsed or refractory angioimmunoblastic T-cell lymphoma.

Peripheral T‐cell lymphoma (PTCL) is a heterogeneous group of mature, post‐thymic, T‐ and natural killer‐cell non‐Hodgkin lymphomas (NHL)— nearly all subtypes are associated with a poor prognosis. Regardless of subtype, patients with PTCL typically receive induction chemotherapy (commonly CHOP[cyclophosphamide+doxorubicin+vincristine+prednisone]) as first‐line treatment. Except for anaplastic lymphoma kinase– positive anaplastic large cell lymphoma, outcomes are generally poor and many responding patients rapidly relapse. Achievement of durable responses in patientswith relapsed/refractory PTCL is difficult, and there arefewtreatmentoptions. Angioimmunoblastic T‐cell lymphoma (AITL) is a common subtype of PTCL (16% of diagnoses in the USA, 18% in Asia and 29% in Europe). The 5‐year overall survival (OS) in patients with AITL is reported to be just 32%, and AITL is characterised by generalised lymphadenopathy, extranodal involvement, hypergammaglobulinemia, and advanced stage at presentation. Immune dysregulation commonly results in infections, which are a frequent cause of death in patients with AITL. Romidepsin is a structurally unique, potent, bicyclic class I selective histone deacetylase inhibitor approved for the treatment of all subtypes of relapsed/refractory PTCL. In the pivotal phase 2 trial conducted in patients with relapsed/refractory PTCL, romidepsin treatment resulted in durable responses with manageable toxicity. The objective response rate (ORR) was 25% (33/130), including 15% confirmed/unconfirmed complete responses (CR/CRu), and the median duration of response (DOR) was 28 months. Patient baseline characteristics (including PTCL subtype) or prior treatments did not significantly affect response rates. The most frequent romidepsin‐related adverse events (AEs) were gastrointestinal and asthenic conditions, which were primarily grade 1/2 and rarely resulted in drug discontinuation. Here, we report updated data from the pivotal phase 2 study focused on patients with AITL. In the overall study, eligible patients had PTCL (measurable disease by International Working Group [IWG] criteria 14 and/or measurable cutaneous disease) relapsed/refractory to ≥1 therapy, Eastern Cooperative Oncology Group performance status of zero to two and adequate bone marrow and organ function at enrollment. Patients with significant cardiac abnormalities were

Romidepsin for the Treatment of Peripheral T-Cell Lymphoma

UNLABELLED Peripheral T-cell lymphoma (PTCL) is a heterogeneous group of non-Hodgkin lymphomas associated with poor prognosis in most subtypes. Diagnosis of this rare disease by expert hematopathologists improves accuracy of subtyping, and referral to academic or specialty centers is recommended. Many patients, however, will receive treatment in the community, and knowledge of approved agents is key to optimizing therapeutic approaches for all patients. There is no current standard of care for patients with PTCL and no approved therapies for first-line treatment. Although many patients initially respond to induction chemotherapy, responses are often brief, and many patients relapse or become treatment refractory. For patients with relapsed or refractory PTCL, achievement of durable responses is challenging, and there are few treatment options. Romidepsin is a histone deacetylase inhibitor approved by the U.S. Food and Drug Administration for the treatment of patients with cutaneous T-cell lymphoma who have received one prior systemic therapy or more and patients with PTCL who have received one prior therapy or more. Approval of romidepsin for PTCL was based on a pivotal phase II study of patients with relapsed or refractory PTCL (n = 131) that demonstrated an objective response rate of 25% including 15% with complete response; responses lasted a median of >2 years. Long-term responses to romidepsin were achieved in patients regardless of baseline characteristics, including subtype, heavy pretreatment, response to prior therapy, or advanced disease. Common adverse events included hematologic abnormalities, gastrointestinal or asthenic conditions, and infections; romidepsin was not correlated with clinically meaningful QT prolongation or electrocardiogram abnormalities. IMPLICATIONS FOR PRACTICE Due to the rarity, severity, and heterogeneous nature of peripheral T-cell lymphoma (PTCL), diagnosis by expert hematopathologists is preferred, and referral to specialty centers is recommended. Many patients, however, will receive treatment in the community, and community oncologists play a key role in the recognition and treatment of PTCL. Knowledge of approved agents is key for optimizing therapeutic approaches. This review provides an overview of PTCL and an in-depth examination of romidepsin, a histone deacetylase inhibitor approved for the treatment of relapsed or refractory PTCL, and highlights difficulties of diagnosis and optimization of treatment modalities for patients with PTCL.

Utility of 18fluoro-deoxyglucose positron emission tomography for prognosis and response assessments in a phase 2 study of romidepsin in patients with relapsed or refractory peripheral T-cell lymphoma

This study examined the utility of PET scans for assessing prognosis and response to treatment in patients with relapsed/refractory PTCL receiving romidepsin. For patients with stable disease or partial response by conventional criteria, PET status better differentiated durability of response than conventional response category. Routine PET use may aid in treatment planning in patients with PTCL.

Asia-Pacific Hematology Consortium Report on approach to multiple myeloma. Survey results from the 6th International Hematologic Malignancies Conference: Bridging the Gap 2015, Beijing, China

Abstract The Asia-Pacific Hematology Consortium (APHCON), in partnership with MDRingTM, a mobile global physician education network, has initiated a detailed longitudinal study of physician knowledge and practice preferences in the Asia-Pacific sphere. The first dataset comes from a series of surveys answered by delegates at the APHCON Bridging The Gap (BTG) conference in Beijing in January, 2015. In this report we present our findings regarding diagnosis and treatment of multiple myeloma (MM). We aim to create a conduit for physicians in this region to share their experiences with the rest of the world, to identify areas of consensus and best practices, and to highlight opportunities for improvement in communication, education and patient care.

Abstract 2960: Flavopiridol-mediated multiple modulatory effects synergistically increase sensitivity to TRAIL-induced cell death in human leukemia cells.

Proceedings: AACR 104th Annual Meeting 2013; Apr 6-10, 2013; Washington, DC Previously, we described the antileukemic synergistic interactions between the cyclin-dependent kinase inhibitor flavopiridol (F) and TRAIL in multiple cell lines representing a broad spectrum of human leukemia. With the introduction of new hybrid regimens for flavopiridol-based therapies and advances in the clinical development of TRAIL/TRAIL agonists, a renewed interest in this therapeutic concept has emerged. In an attempt to identify key mechanistic signaling networks, human U937 leukemia cells were treated simultaneously with F (SelleckChem, Houston TX) and TRAIL (Alexis, Enzo, Farmingdale, NY) and analyzed for signaling events associated to cell death induction. We found a dramatic F-mediated shift from cytoprotective NF-kB, AKT and ERK pathways to pro-cell death ceramide and JNK signals. Functional studies using both pharmacological inhibitors and genetically modified cells revealed the functional relevance of these signals. Furthermore, F-mediated transcriptional modifications played key roles in determining and regulating the cross-talk between anti- and pro-cell death pathways. Co-exposure to F resulted in transcriptional down-regulation of genes involved in the regulation of pro-apoptotic JNK including XIAP, Gadd45β and phosphatases DUSP1, -10 and -11. In addition, F induced a significant reduction of multiple anti-apoptotic genes/proteins directly implicated in the pro-apoptotic cascades including (Mcl-1, XIAP, Bcl-2, Bcl-xL, c-Flip, cIAP2/3), and cell cycle modulators (cyclin D1, -E1/E2, CDKs 1,7,9,13,17, p15, p57, p21). However, although in many cases similar changes were observed in F- and TRAIL/F-treated cells, additional factors may have to exist that lead to the potent synergistic interactions observed with the drug combination. In fact, by using clonogenic assays (long term effects), we observed that while TRAIL or F-treated cells were able to recover after treatment, that was not the case in TRAIL/F-exposed cells (% clonogenic survival: T= 82, F=47, TF= 1.4). Time-course analysis by flow cytometry of cell surface localized TRAIL Death Receptors DR4 and DR5 showed that in the presence of F, either alone or in combination with TRAIL, the membrane levels of both receptors were significantly increased during the first 2-6h of treatment. Together, these findings indicate that combined exposure of human acute leukemia cells to TRAIL/FP results in an early mobilization of TRAIL death receptors (DR4, DR5) to the cell surface, effect that is temporally associated with activation of anti-apoptotic ERK, AKT and NF-kB signals; however, activation of DR4/5-mediated apoptotic pathway is later potentiated by a shift toward pro-cell death JNK/ceramide signals that, in association to F-mediated transcriptional effects, results in a dramatic increase in the sensitivity to TRAIL in otherwise TRAIL-resistant human leukemia cells. Citation Format: Swaminathan P. Iyer, Jaime Mejia, Adriana E. Rosato, Steven Grant, Roberto R. Rosato. Flavopiridol-mediated multiple modulatory effects synergistically increase sensitivity to TRAIL-induced cell death in human leukemia cells. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 2960. doi:10.1158/1538-7445.AM2013-2960