Agents For Hematologic Malignancies Research Articles

Targeting epigenetic regulation for cancer therapy using small molecule inhibitors.

Cancer cells display pervasive changes in DNA methylation, disrupted patterns of histone posttranslational modification, chromatin composition or organization and regulatory element activities that alter normal programs of gene expression. It is becoming increasingly clear that disturbances in the epigenome are hallmarks of cancer, which are targetable and represent attractive starting points for drug creation. Remarkable progress has been made in the past decades in discovering and developing epigenetic-based small molecule inhibitors. Recently, epigenetic-targeted agents in hematologic malignancies and solid tumors have been identified and these agents are either in current clinical trials or approved for treatment. However, epigenetic drug applications face many challenges, including low selectivity, poor bioavailability, instability and acquired drug resistance. New multidisciplinary approaches are being designed to overcome these limitations, e.g., applications of machine learning, drug repurposing, high throughput virtual screening technologies, to identify selective compounds with improved stability and better bioavailability. We provide an overview of the key proteins that mediate epigenetic regulation that encompass histone and DNA modifications and discuss effector proteins that affect the organization of chromatin structure and function as well as presently available inhibitors as potential drugs. Current anticancer small-molecule inhibitors targeting epigenetic modified enzymes that have been approved by therapeutic regulatory authorities across the world are highlighted. Many of these are in different stages of clinical evaluation. We also assess emerging strategies for combinatorial approaches of epigenetic drugs with immunotherapy, standard chemotherapy or other classes of agents and advances in the design of novel epigenetic therapies.

Polyphenols: Chemoprevention and therapeutic potentials in hematological malignancies.

Polyphenols are one of the largest plant-derived natural product and they play an important role in plants' defense as well as in human health and disease. A number of them are pleiotropic molecules and have been shown to regulate signaling pathways, immune response and cell growth and proliferation which all play a role in cancer development. Hematological malignancies on the other hand, are cancers of the blood. While current therapies are efficacious, they are usually expensive and with unwanted side effects. Thus, the search for newer less toxic agents. Polyphenols have been reported to possess antineoplastic properties which include cell cycle arrest, and apoptosis via multiple mechanisms. They also have immunomodulatory activities where they enhance T cell activation and suppress regulatory T cells. They carry out these actions through such pathways as PI3K/Akt/mTOR and the kynurenine. They can also reverse cancer resistance to chemotherapy agents. In this review, i look at some of the molecular mechanism of action of polyphenols and their potential roles as therapeutic agents in hematological malignancies. Here i discuss their anti-proliferative and anti-neoplastic activities especially their abilities modulate signaling pathways as well as immune response in hematological malignancies. I also looked at clinical studies done mainly in the last 10-15 years on various polyphenol combination and how they enhance synergism. I recommend that further preclinical and clinical studies be carried out to ensure safety and efficacy before polyphenol therapies be officially moved to the clinics.

Plant-derived natural compounds as promising anticancer agents in hematological malignancies

The latest treatments have improved outcomes for patients with hematological malignancies, but relapse, treatment resistance and particularly side effects still remain as common limitations of these treatments. Given the disadvantages of the existing conventional therapeutic methods, developing more effective drugs with less toxicity and side effects is of paramount importance. Medicinal herbs have historically proven their worth as a pool of potential therapeutic agents for leukemia and lymphoma, and today they still represent a rich source for the recognition of new drug leads. The role of the positive synergistic effects of plant-derived natural products and common chemotherapeutic drugs is also considered as one of the rational reasons for paying attention to the medicinal plants in recent chemoprevention and chemotherapeutic investigations. Noteworthy, targeted delivery of plant-derived natural products via the incorporation of nanoparticles or antibodies would be a major step to improve their bioavailability and then to increase their therapeutic effects. In this study, we reviewed plant-derived agents approved and/or under investigation for hematological malignancies.

Abstract 2764: Safety and efficacy of CAR T and TCR therapies in solid tumors: A systematic review and meta-analysis, including a comparison with five phase II trials in hematologic malignancies used for the first FDA approvals of these agents

Abstract Background: Adoptive cellular therapies (ACT) have met with significant success in hematologic malignancies. The number of ACT trials in solid tumors has been increasing, however data are limited on the overall safety and efficacy of ACT in this population. We aimed to conduct a systematic review and meta-analysis looking specifically at TCR and CAR-T in solid tumors and rates of cytokine release syndrome (CRS) and immune effector cell-associated neurotoxicity syndrome (ICANS) relative to the current approved agents in hematologic malignancies. Methods: We conducted a systematic review of published studies/abstracts from January 2015 up to and including July 2021, selecting those that included ≥ 5 patients. Endpoints included rates and differences in CRS and ICANS. Response rates were evaluated. Statistical tests in the pooled data included χ2 and multivariable logistic regression. Results: This meta-analysis included a total of 1,250 patients [566 patients with solid tumors who had received ACT in phase I, II or I/II clinical trials; a comparison was made with five phase 2 clinical trials in hematologic malignancies used for the first FDA approvals of these agents (JULIET, ZUMA-1, ZUMA-2, TRANSCEND and KARMMA), encompassing 684 heme malignant patients]. Rates of CRS of any grade, CRS ≥ grade 3, ICANS of any grade, and ICANS ≥ grade 3 in solid tumors were 33.0%, 3.8%, 2.3% and 2.1%, respectively. Fever, hypotension, and hypoxia were experienced by 37.4%, 18.5%, and 8.5% of solid tumor patients, respectively. CRS, ICANS, fever and hypoxia in solid tumor patients did not differ by whether the ACT received was TCR or CAR T. Objective response (ORR = CR + PR) in patients with solid tumors was higher with TCR compared with CAR-T [odds ratio (OR) = 3.1, P=0.001] and with NY-ESO-1 than other targets (OR=2.0, P=0.031). Compared to hematologic patients treated with ACT, solid tumor patients treated with adoptive cellular therapies were significantly less likely to experience CRS of any grade (62.4% vs. 33.0%, P<0.001), CRS ≥ grade 3 (7.3% vs. 3.8%, P=0.043), fever (50.3% vs. 37.4%, P=0.001), hypoxia (34.1% vs. 8.5%, P<0.001) or hypotension (29.5% vs. 18.5%, P=0.006), ICANS of any grade (29.7% vs. 2.3%, P<0.001), or ICANS ≥ grade 3 (13.9% vs. 2.1%, P<0.001). However, objective response (20.1% vs. 75.4%, P<0.001) and clinical benefit (CBR = CR + PR + SD) (62.6% vs. 90.9%, P<0.001) rates for ACT were lower in patients with solid tumors than in patients with hematologic malignancies. Conclusions: CRS and ICANs were less prevalent in solid tumor cellular therapies. Based on this analysis, T-cell therapies in solid tumors are relatively safe, but further studies with larger populations and longer follow up are needed to address the role of these treatments in cancer. Citation Format: Mirella Nardo, Ji Y. Son, Goldy G. George, David S. Hong. Safety and efficacy of CAR T and TCR therapies in solid tumors: A systematic review and meta-analysis, including a comparison with five phase II trials in hematologic malignancies used for the first FDA approvals of these agents [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 2764.

The use of hypomethylating agents in hematologic malignancies: treatment preferences and results.

Aim:The objective of this article was to compare the efficiency of azacitidine (AZA) and decitabine (DAC) in patients with myelodysplastic syndrome (MDS) and acute myeloid leukemia (AML) who are not suitable for high-dose chemotherapy.Materials and methods:MDS and AML patients who were treated with hypomethylating agents (HMAs) between January 2005 and 2020 were evaluated retrospectively.Results:No statistically significant difference was found between the patients who received AZA or DAC in AML patients. In MDS group, the rate of patients who achieved remission was statistically significantly higher in patients who received DAC (p = 0.032).Conclusion:The advantage in terms of response for MDS and no survival difference between AZA and DAC for AML and MDS patients will be an important contribution to the literature.

Abstract 4439: BR101801 triggers anti-tumor immunity and enhances efficacy of immune checkpoint antibodies in syngeneic model

Abstract Introduction: BR101801 received U.S. FDA approval of Phase Ia/Ib clinical trial as an anti-cancer drug candidate. PI3K γ / δ and DNA-PK inhibitory potency of BR101801 exerts anti-cancer efficacy as a target anticancer agent in hematologic malignancies. Recent studies have reported anti-cancer immunity by use of PI3K-δ inhibitor (Idelalisib), PI3K-γ inhibitor (IPI-549) and DNA-PK inhibitor (NU7441). Considering triple inhibitory activity of the BR101801. First, we investigated the anti-cancer efficacy of monotherapy by BR101801 in syngeneic model. Second, synergistic efficacy was confirmed through the combination of BR101801 with anti-PD1 or anti-PDL1, which are known as anti-tumor immunotherapeutics. Finally, immune cell response by BR101801 in human PBMC was tested. Overall, This study aims to demonstrate efficacy of the BR101801 as a potent immunocancer drug. Methods: The enzymatic potency of the PI3K isotype and DNA-PK was analyzed by Eurofin. Proliferation of 4T1(breast cancer) and CT26(colon cancer) cells following a 4 h treatment with the indicated BR101801, WST-8 staining after 72 h culture. Mice bearing syngeneic 4T1 or CT-26 cell lines were treated with vehicle, BR101801, anti-PD1, anti-PD1 + BR101801, anti-PDL1, anti-PDL1 + BR101801. Tumor volumes were measured by caliper. Tregs and CD8+ T cells were quantified by flow cytometry from mice bearing spleen. In addition, CD3 + cells were isolated from human PBMCs and stimulated with CD3/CD28 and analyzed for immunofluorescence by FACS for expression of PD-1, TIM3, LAG3 and TIGIT in Tregs and CD8. Results: In vitro selectivity and target potency of BR101801 on different PI3K subtypes including DNA-PK were studied in cell-free system. The biochemical IC50 values of BR101801 for PI3K-α, -β, -γ, -δ and DNA-PK were 106 nM, 171 nM, 15 nM, 2 nM and 6 nM. 50% growth inhibition in 4T1 and CT26 cell lines was measured above 10 uM. BR101801 showed tumor inhibitor efficacy in 4T1 and CT26 syngeneic models. In 4T1 or CT-26 bearing mouse spleens, Tregs decreased and CD8 + T cells increased. Strong anti-tumor efficacy was observed with about 70% reduction in tumor growth when using BR101801 with anti-PD1 or anti-PDL1 in 4T1 and CT26 syngeneic models. Finally, Tregs decreased and anticancer effects were increased by decreasing the expression of PD1, LAG3, TIM3 and TIGIT of CD8+ T cells. Conclusions: The immunosuppressive effect of BR101801 changing the tumor microenvironment was verified without cancer cells. It is demonstrated that anticancer immunity by decreasing Tregs and increasing CD8. Anti-tumor immunity was enhanced by decreasing the expression of PD1, TIM3, LAG3 and TIGIT in CD8 + cells. In this study, In addition to monotherapy of BR101801, It's synergistic effects with PD-1 or PDL1 have been proposed. This data supports the evidence that it is applicable not only to blood cancer but also to various cancer patients. Citation Format: Seungho Wang, Mi kwon Son, Bo Ram Lee, Byeongwook Jeon, Soo Jung Kim, Eunhui Yang, Min Park, Joo Han Lee, Jayhyuk Myung. BR101801 triggers anti-tumor immunity and enhances efficacy of immune checkpoint antibodies in syngeneic model [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 4439.

Cancer types applicable to efficacy assessment using real-world data analyzed from PMDA-approved data.

e19272 Background: Clinical development of anti-cancer agents has been accelerated due to emergence of new therapies. Although randomized comparative trials are the gold standard for the evaluation of clinical utility, it is often impossible to conduct such trials. At ASCO 2019, 89 real-world data (RWD) studies were presented. These studies highlighted the increasing awareness of the value of RWD. We here investigated for which cancer types RWD could be applicable to efficacy assessment based on the previous reviews of Pharmaceuticals and Medical Devices Agency, Japan (PMDA). Methods: Review reports and Summaries of submitted documents publicly available on the website of PMDA and research articles of trials included in the new drug applications of anti-cancer agents approved in Japan between 2006 and 2019 were reviewed. Results: Among 209 anticancer-agents approved for a new indication based on clinical trial (CT) data, 42 agents and 167 agents were approved based on results of single-arm CTs and those of comparative trials, respectively. The numbers of agents for hematological malignancies and solid tumors were nearly same. Among agents approved based on single-arm CT results, most of them (85.7%) were designated for orphan drug (OD), and 1/3 of them were specified for a biomarker (BM), such as ALK fusion gene in non-small cell lung cancer (35.7%). Among 42 single-arm CT-based approvals, a threshold for efficacy endpoint was set at least in one pivotal trial in 30 items based on the following references: (i) results of CTs for the same population (11), (ii) no standard therapy (10), (iii) clinical trial plans of other agents for the same population (7), (iv) others such as values defined by the investigators’ discretion (14). Regardless of BM, only 1/4 had a pre-defined threshold for efficacy evaluation in the pivotal trial based on the results of CTs for the same population. Among 15 BM-related agents, most of them (93.3%) had been designated for OD. Meanwhile, among the agents without biomarker and OD, the setting was (ii) or (iv). Conclusions: RWD could be applicable for efficacy evaluation of BM-related agents with OD designation, agents for BM-unrelated tumor types with no established standard treatment, and agents for those in which drug development has not been advanced enough to set a threshold for efficacy evaluation.

The Other Side of CAR T-Cell Therapy: Cytokine Release Syndrome, Neurologic Toxicity, and Financial Burden.

Immune effector cells, including T cells and natural killer cells, which are genetically engineered to express a chimeric antigen receptor (CAR), constitute a powerful new class of therapeutic agents to treat patients with hematologic malignancies. Several CAR T-cell trials have shown impressive remission rates in patients with relapsed/refractory hematologic cancers. Although the clinical responses of these agents in hematologic malignancies have been very encouraging, they have also produced substantial morbidity and occasionally mortality resulting from toxicity. With more experience and collaboration, hopefully the toxicities and the costs will come down, increasing the availability of CAR T cells to patients in need.

Bispecific Antibodies in the Treatment of Hematologic Malignancies.

Monoclonal antibody therapies are an important approach for the treatment of hematologic malignancies, but typically show low single‐agent activity. Bispecific antibodies, however, redirect immune cells to the tumor for subsequent lysis, and preclinical and accruing clinical data support single‐agent efficacy of these agents in hematologic malignancies, presaging an exciting era in the development of novel bispecific formats. This review discusses recent developments in this area, highlighting the challenges in delivering effective immunotherapies for patients.

Molecular pathogenesis of myelodysplastic syndromes with deletion 5q.

The molecular pathogenesis of deletion 5q (del(5q)) myelodysplastic syndrome (MDS) has recently been realized as a result of major advances in our understanding of the mechanisms responsible for clinical phenotype. Identification of commonly deleted genes such as RPS14, miRNA-145, HSPA9, CD78, and CSNK1a1 have elucidated the precise biological changes responsible for the anemia, leukopenia, and thrombocytosis that characterizes del(5q) MDS and highlighted the importance of allelic haploinsufficiency in the hematological phenotype. Recent elegant investigations have also identified a critical role of innate immune signaling in del(5q) pathogenesis. TP53 and Wnt/β-catenin pathways have also been found to be involved in clonal expansion and progression of the disease as well as resistance and poor outcomes to available therapy. Understanding the molecular pathogenesis of the disease has provided a critical foundation in identifying the biological targets of lenalidomide in del(5q) MDS, which has led to the development of novel therapeutic agents in hematologic malignancies as well as potential alternative targets to exploit in patients who have failed lenalidomide treatment.

Implementation of a hepatitis B screening process prior to CD20 therapy treatment in an oncology practice.

287 Background: Reactivation of hepatitis B virus (HBV) during or after chemotherapy is a serious complication of cancer treatment. Guidelines suggest hepatitis B testing prior to the initiation of CD20 based therapies. Black box warnings mandate clinicians screen patients for HBV before starting immunosuppressive therapy due to the risk of hepatitis B reactivation. We conducted a workflow implementation change at our infusion center sites to improve hepatitis B serological testing in patients receiving CD20 agents at our cancer center. Methods: For baseline evaluation, patients at The University of Arizona Cancer Center who were treated with CD20 agents between the years 2013 to April 2014 were retrospectively evaluated for HBV serology results prior to the initiation of first treatment. We implemented a pharmacy and nursing workflow process regarding chemotherapy orders and lab testing through the integrated EMR technology. Presence of Hepatitis B Surface Antigen (HBsAg) and Hepatitis B Core Antibody (HBcAb) were considered complete; absence of all 2 was ‘not done’ with remaining being incomplete. We focused on improving our screening process during our analysis post-intervention from April 2014 to November 2017. Results: In our baseline study, 35% (n = 17) out of 48 patients had been tested for hepatitis B for hematologic malignancies. Post-implementation yielded 89 patients with 63 lymphoma patients, and 11 leukemia and 15 other hematological-associated diagnosis. Ninety one percent (n = 81) had been tested post-implementation for Hepatitis B labs prior to starting CD20 treatment. No Hepatitis B reactivation was identified in either study arms. Conclusions: Prior to implementation less than 35% of our patients were tested and our implementation process more than doubled our testing percentages to 91%. This process allows for an integrated workflow between pharmacy and nursing to mitigate required lab testing for CD20 agents in hematologic malignancies. The utilization of this workflow process is now being implemented with other CD20 agents for non-oncologic diagnosis.

Abstract 44: CG′806, a first-in-class FLT3/BTK inhibitor, exhibits potent activity against AML patient samples with mutant or wild type FLT3, as well as other hematologic malignancy subtypes

Abstract The Fms-like receptor tyrosine kinase 3 (FLT3) is expressed in approximately 90% of acute myeloid leukemia (AML), almost all B-lineage acute lymphoblastic leukemia (B-ALL), and some other hematologic malignancy subtype patients. Approximately one third of AML patients harbor constitutive activating internal tandem duplication in FLT3 (FLT3-ITD), which is associated with very poor prognosis. These observations have made FLT3 an attractive drug target. As more potent FLT3 inhibitors are developed, additional acquired point mutations have been identified, commonly at activation loop residue D835 and “gatekeeper” residue F691, which are related to drug resistance and relapse. CG′806, a first-in-class small molecule multikinase inhibitor against FLT3 and Bruton's tyrosine kinase (BTK), is under development as a next-generation agent for the treatment of FLT3-driven AML. Work from our collaborative laboratories has demonstrated that CG′806 retains full activity against Ba/F3 cells housing FLT3-ITD and/or point mutations, including D835G, D835Y, D835H, and F691L (abstract submitted to 2017 AACR Hematologic Malignancy Meeting). Herein we evaluated the potency of CG′806 on various hematologic malignancy cell lines and patient primary bone marrow specimens. Primary patient mononuclear cells were derived from 172 patients diagnosed with AML (n=82), myelodysplastic syndrome/myeloproliferative neoplasms (MDS/MPN, n=15), ALL (n=17), and chronic lymphocytic leukemia (CLL, n=58). Sensitivity to CG′806 was evaluated across a range of concentrations after 72-hour treatment. IC50s were calculated as a measure of drug sensitivity and compared to nonproprietary competitive agents in AML and CLL, including the bromodomain inhibitors OTX-015 and JQ-1 and the FLT3 inhibitor quizartinib. The inhibitory effect of CG′806 on FLT3 signaling was evaluated in MV4-11 cells by Western blotting. Across the four general subtypes of hematologic malignancies in the dataset, there is broad sensitivity to CG′806 with 59% (48/82) AML, 29% (5/17) ALL, 53% (8/15) MDS/MPN, and 40% (23/58) CLL cases exhibiting an IC50 of less than 0.1 μM. CG′806 demonstrated median IC50s of 0.07 μM and 0.22 μM against primary AML and CLL cells, respectively. FLT3 mutational status is known for 38 of the tested AML patient samples. Among those, the FLT3-ITD+ AML samples tended to have enhanced sensitivity to CG′806 (median IC50 = 0.02 μM, n=8) as compared to the FLT3-WT samples (median IC50 = 0.12 μM, n=30). CG′806 also exerted potent picomolar to low nanomolar IC50 antiproliferative activity against human AML, B-ALL, mantle cell lymphoma, Burkitt's lymphoma, and diffuse large B-cell lymphoma cell lines. As compared to the FLT3 inhibitor quizartinib, CG′806 at a concentration of 500 pM completely inhibited phosphorylation of FLT3 and STAT5 in MV4-11 cells upon 1 hour treatment, whereas quizartinib only partially inhibited their phosphorylation. CG′806 exhibits broad and potent activity against AML patient samples, as well as other hematologic malignancy subtypes. The median IC50 data for CG′806 indicates greater potency relative to the tested nonproprietary agents across AML and CLL. Preliminary analyses reveal a trend of greater sensitivity to CG′806 in FLT3 mutant AML cases compared with FLT3 wild type; however, ongoing accrual of additional patient samples will be required to sufficiently power a statistical association of CG'806 sensitivity with FLT3 mutational status. In summary, preclinical analyses of CG′806 against primary hematologic malignancy patient samples and cultured cell lines show evidence of broad drug activity in AML and other disease subtypes and support further development of this agent for hematologic malignancies. Citation Format: Stephen E. Kurtz, Beth Wilmot, Shannon McWeeney, Avanish Vellanki, Andrea Local, Khalid Benbatoul, Peter Folger, Susan Sheng, Hongying Zhang, Stephen B. Howell, William G. Rice, Brian J. Druker, Jeffrey W. Tyner. CG′806, a first-in-class FLT3/BTK inhibitor, exhibits potent activity against AML patient samples with mutant or wild type FLT3, as well as other hematologic malignancy subtypes [abstract]. In: Proceedings of the Second AACR Conference on Hematologic Malignancies: Translating Discoveries to Novel Therapies; May 6-9, 2017; Boston, MA. Philadelphia (PA): AACR; Clin Cancer Res 2017;23(24_Suppl):Abstract nr 44.

Beyond Anthracyclines: Preemptive Management of Cardiovascular Toxicity in the Era of Targeted Agents for Hematologic Malignancies.

Advances in drug discovery have led to the use of effective targeted agents in the treatment of hematologic malignancies. Drugs such as proteasome inhibitors in multiple myeloma and tyrosine kinase inhibitors in chronic myeloid leukemia and non-Hodgkin lymphoma have changed the face of treatment of hematologic malignancies. There are several reports of cardiovascular adverse events related to these newer agents. Both "on-target" and "off-target" effects of these agents can cause organ-specific toxicity. The need for long-term administration for most of these agents requires continued monitoring of toxicity. Moreover, the patient population is older, often over 50years of age, making them more susceptible to cardiovascular side effects. Additional factors such as prior exposure to anthracyclines often add to this toxicity. In light of their success and widespread use, it is important to recognize and manage the unique side effect profile of targeted agents used in hematologic malignancies. In this article, we review the current data for the incidence of cardiovascular side effects of targeted agents in hematologic malignancies and discuss a preemptive approach towards managing these toxicities.

An Empirical Study of the Prescription Pattern of Drugs for Hematological Malignancies in Japan from 2010-2014.

The number of elderly patients with hematologic malignancies has been steadily increasing with the aging of society. However, little research has been conducted to evaluate the prescription status of drugs for such diseases in Japan. Therefore, the aims of this study were to identify the patient population currently being prescribed drugs for hematologic malignancies in Japan and the direction of drug development. To examine the prescription pattern of drugs for the treatment of hematological malignancies in Japan from 2010-2014, we used the IMS Japan Pharmaceutical Market database and the Japanese Society of Hematology Clinical Practice Guidelines, and for drug development status, we used ClinicalTrials.gov and the University Hospital Medical Information Network Clinical Trials Registry. We found a significant upward trend in prescriptions for molecular-targeted agents, which are typically prescribed over the long term, and a significant downward trend in chemotherapeutic agents, which are usually prescribed for the short term. We also found that recent drug development in hematological malignancies has focused on molecular-targeted agents. These results suggest that drug development should be directed toward anti-tumor agents in hematological malignancies that can help maintain and improve patients' QOL.

HMG-CoA reductase inhibitors as adjuvant treatment for hematologic malignancies: what is the current evidence?

Statins have been shown to possess properties that go beyond their lipid-lowering effects. These agents act on the mevalonate pathway and inhibit synthesis of cholesterol, geranylgeranyl pyrophosphate, and farnesyl pyrophosphate, which are necessary for posttranslational modification of the Rho, Rac, and Ras superfamily of proteins. Early phase studies have demonstrated that this modulation of cellular signaling can ultimately exert pro-apoptotic, anti-angiogenic, and immunomodulatory effects, and might even restore chemosensitivity in several hematologic cancers. Nonetheless, these promising preclinical results have not yet migrated from the bench to the bedside as their effectiveness as adjuvant agents in hematologic malignancies is currently uncertain. In the present review, we summarize the existing evidence stemming from preclinical and clinical studies pertaining to the use of statins as adjuvant therapies in hematologic malignancies, and discuss the new insights gained from the ongoing translational research.

Unique Apoptotic Effects Of Panobinostat and Marizomib In Acute Myeloid Leukemia and Bortezomib-Resistant Models

Panobinostat, a potent pan-histone deacetylase inhibitor (HDACi) is emerging as a valuable therapeutic option for cancer treatment. Compared with the FDA-approved vorinostat, it displays a more potent and broader spectrum of inhibitory activity (inhibiting all class I, II and IV HDACs) at clinically achievable concentrations. Combinatorial therapies with proteasome inhibitors (PI) have been recently evaluated.Marizomib, a second-generation irreversible PI, exhibits excellent pre-clinical activity against numerous hematologic malignancies. Indeed, published work from our laboratory has shown that marizomib is more effective than the FDA approved PI bortezomib in inhibiting the activity of the proteasome. Additionally, marizomib has been shown to induce higher caspase-8 and reactive oxygen species (ROS) dependent cell death than bortezomib, alone and in combination with HDACi in acute lymphoblastic leukemia (ALL) models.Despite progress in the treatment of acute myeloid leukemia (AML), 40% of patients die from disease recurrence or treatment toxicities; therefore, targeted approaches allowing for low drug doses are needed to increase clinical efficacy. The objectives of this study were to (1) determine if a panobinostat/PI regimen displayed synergy; (2) whether cell death by this combination triggers an unique profile of caspase activation; and (3) assess utility of this combination in a bortezomib refractory setting.Human-derived AML cell lines, ML-1 and AML3, were exposed to increasing concentrations of HDACi, (panobinostat or vorinostat), and PI (bortezomib or marizomib) alone and in combination. Panobinostat had an IC50 within the nanomolar range at 24 hours of treatment; in contrast, an IC50 was not achievable with vorinostat until after 48 hours of treatment. Marizomib was found to have a much lower IC50 and higher DNA fragmentation capacity than bortezomib. Calcusyn software was used to determine synergistic combinations. Synergistic cytotoxicity was observed with the combination treatment of panobinostat with both PIs. No synergy was observed with combinations involving vorinostat. Interestingly, the panobinostat + marizomib combination demonstrated earlier and higher ROS induction.To assess the differences in apoptotic mechanisms between these agents, caspase activities were measured. The combination of panobinostat + marizomib induced an earlier and 2.5x higher induction of caspase-3 activation than the combination of panobinostat + bortezomib. Caspase-8 and caspase-9 dependence, were evaluated using pre-treatment with specific caspase-8 (IETD-fmk) and caspase-9 (LEHD-fmk) inhibitors. Caspase-8 inhibition decreased the cytotoxicity of the panobinostat + marizomib combination compared to control, whereas no difference was observed on cells treated with panobinostat + bortezomib. Western blotting for cleaved caspase-8 corroborated these data. Caspase-9 inhibitors did not significantly protect against DNA fragmentation in any of the combinations. These AML results were consistent with our prior published work using ALL cells, highlighting a role for caspase-8 in sensitivity to synergistic combinations of HDACi and PI.Bortezomib resistance is an emerging problem in the treatment of hematological malignancies. Therefore, RPMI-8226vr10 (bortezomib-resistant multiple myeloma) cells were treated with equimolar doses of either of the HDACi; panobinostat was able to induce higher DNA fragmentation than vorinostat. When panobinostat was combined with either PI, the combination with marizomib caused higher DNA fragmentation than the bortezomib combination. Because caspase-2 has been implicated in panobinostat cytotoxicity in other systems, caspase-2 cleavage was assessed by western blotting assays. At 12 hours of treatment, panobinostat + marizomib caused stronger caspase-2 cleavage than the panobinostat + bortezomib combination, suggesting that marizomib may uniquely augment the caspase-2 activating capacity of panobinostat, providing insight into a potential mechanism of bortezomib resistance.Further experiments will focus on the molecular mechanisms of panobinostat and marizomib combinations and how efficacy could be further optimized. Overall, these data support the use of these novel anticancer agents in hematological malignancies. Disclosures:Orlowski:Genentech: Honoraria, Membership on an entity's Board of Directors or advisory committees; Array Biopharma: Honoraria, Membership on an entity's Board of Directors or advisory committees; Resverlogix: Research Funding; Onyx: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Millennium: The Takeda Oncology Company: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Bristol-Myers Squibb: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Merck: Membership on an entity's Board of Directors or advisory committees.

Abstract C243: Activity of BTK and HDAC inhibitors alone and in combination in a mouse model of non-small cell lung cancer.

Abstract Background: The effectiveness of two drugs, a Bruton's Tyrosine Kinase inhibitor (BTKi: ibrutinib, PCI-32765) and a histone deacetylase inhibitor (HDACi: abexinostat, PCI-24781), was tested on a mouse model for non-small lung cancer (NSCLC). The Grg1 mouse model is a transgenic mouse line that overexpresses the Groucho-related gene (Grg1; TLE1 in humans) and develops tumors that resemble human non-small cell lung cancer. The tumors initiate at 1 month of age, progress to bronchioalveolar carcinoma, and continue to invasive adenocarcinoma by 8 months. Both abexinostat and ibrutinib have shown promising activity as single agents in hematologic malignancies in the clinic. In this model, abexinostat was tested to determine if it was effective against the Grg1/HDAC function in lung tumor growth. Ibrutinib was tested to determine if this drug had activity in vivo in solid tumors, and if so further determine the mechanism of action. Lastly, it was of interest to determine if the combination of these agents with possibly different mechanism would be more or less active compared to the single agents. Methods: Mice were treated with the drugs or vehicle in two therapeutic settings: early intervention, starting at 2 months or late intervention starting at 5 months of age. In both cases, the drugs were administered for 4 weeks, 5 days per week. Following treatment, mice were sacrificed and visible tumors on the lung surface were counted using a dissecting microscope. In addition, the left lobe was used for histological analysis and the number of tumors in 5 um sections over two levels of 100 um was determined. Tumors in the sections were counted and tumor diameter was measured. Results: In the 3 month old cohort (Figure 1), the average number of surface visible tumors in untreated mice was 5.9 (n=10), BTKi-treated mice was 2.6 (n=8), HDACi-treated mice was 2.9 (n=9), and BTKi and HDACi-treated mice was 1.4 (n=11). In the serial sections the number of tumors in untreated mice was 5, BTKi-treated was 2, HDACi-treated was 3 and BTKi and HDACi-treated was 3 (n=4 for all groups). In the 6 month old cohort, the average number per mice of surface visible tumors in untreated mice was variable and ranged from 0 to 13 tumors. However the number of large tumors (over 1 mm) was higher for the untreated mice than the treated mice (untreated: 1.0; BTKi-treated: 0.2, HDACi-treated: 0.2, BTKi and HDACi treated: 0.2; n=5 for all groups). Pharmacodynamic analysis of the tumors showed histone acetylation in abexinostat-treated tumors, but did not reveal BTK expression or occupancy with a fluorescent-labeled probe. However, significant differences were observed in immune-cell infiltration in the large tumors. While the large control tumors exhibited areas of necrotic cell death, HDACi-treated tumors had larger areas of tumor cell death as well as apoptotic macrophages whereas BTKi-treated tumors had few or no infiltrating live or apoptotic macrophages. Conclusions: NSCLC tumors and others solid tumors that over-express Grg1 may respond to treatment with HDACi or BTKi by different mechanisms; the combination is more active than either agent alone. Interestingly, even solid tumors, such as lung cancer, may respond to immunomodulatory drugs such as BTK inhibitors by modulating infiltrating immune cells. Abexinostat and ibrutinib thus may have potential as a combination for treating solid tumors. Citation Information: Mol Cancer Ther 2013;12(11 Suppl):C243. Citation Format: Corrinne G. Lobe, Michael J. Allain, Wenyi Yang, Mint Sirisawad, Sriram Balasubramanian. Activity of BTK and HDAC inhibitors alone and in combination in a mouse model of non-small cell lung cancer. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2013 Oct 19-23; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2013;12(11 Suppl):Abstract nr C243.

Mechanisms of activity of the TORC1 inhibitor everolimus in Waldenstrom macroglobulinemia.

The TORC1 inhibitor everolimus has previously shown significant activity as a single agent in hematologic malignancies, with reported responses of 30% to 70% in Waldenstrom macroglobulinemia. However, the specific mechanisms by which this class of mTOR inhibitors exerts anti-Waldenstrom macroglobulinemia activity have not been fully investigated. We therefore sought to dissect the mechanisms of everolimus-dependent modulation of Waldenstrom macroglobulinemia cell survival. We confirmed that everolimus targets mTOR in patients treated with everolimus and responding to therapy. We evaluated the effect of everolimus on proliferation and survival of primary Waldenstrom macroglobulinemia cells, as well as of other IgM-secreting lymphoma cell lines. Everolimus-dependent mechanisms of induced apoptosis and its effect on Waldenstrom macroglobulinemia cells in the context of bone marrow microenvironment have been also evaluated. miRNA-155 loss-of-function studies were conducted. Moreover, the combinatory effect of bortezomib and rituximab has been tested. We showed that everolimus targeted mTOR downstream signaling pathways, ex vivo, in patients responding to everolimus treatment. Everolimus induced toxicity in primary Waldenstrom macroglobulinemia cells, as well as in other IgM-secreting lymphoma cells, supported by cell-cycle arrest and caspase-dependent and -independent induction of apoptosis. Importantly, everolimus targeted Waldenstrom macroglobulinemia cells even in the context of bone marrow milieu, where it affected migration, adhesion, and angiogenesis. Everolimus-dependent anti-Waldenstrom macroglobulinemia activity was partially driven by miRNA-155. Moreover, everolimus synergized with bortezomib and rituximab in targeting Waldenstrom macroglobulinemia cells, as shown by synergistic inhibition of p65/ and p50/NF-κB activities. These findings provide a better understanding of the mechanisms that are responsible for everolimus-induced anti-Waldenstrom macroglobulinemia activity.

Clinical trials with anti-angiogenic agents in hematological malignancies

New blood vessel formation (angiogenesis) is not only essential for the growth of solid tumors but there is also emerging evidence that progression of hematological malignancies like multiple myeloma, acute leukemias, and myeloproliferative neoplasms, also depends on new blood vessel formation. Anti-angiogenic strategies have become an important therapeutic modality for solid tumors. Several anti-angiogenic agents targeting angiogenesis-related pathways like monoclonal antibodies, receptor tyrosine kinase inhibitors, immunomodulatory drugs, and proteasome inhibitors have been entered clinical trials or have been already approved for the treatment of hematological malignancies as well and in some instances these pathways have emerged as promising therapeutic targets. This review summarizes recent advances in the basic understanding of the role of angiogenesis in hematological malignancies and clinical trials with novel therapeutic approaches targeting angiogenesis.

Finding the place of histone deacetylase inhibitors in prostate cancer therapy

Histone deacetylase inhibitors (HDACIs) are showing promise as therapeutic agents for hematological malignancies and solid tumors. In the case of prostate cancer, HDACIs are effective at inhibiting proliferation and inducing apoptosis in a range of in vitro and in vivo experimental models. Recent studies have revealed that the actions of HDACIs in prostate cancer cells extend beyond regulation of histone acetylation and affect proteins involved in maintaining cellular homeostasis and tumor progression, including the androgen receptor, p21WAF1 and VEGF. The broad spectrum of HDACI targets has allowed rational design of combinations with other therapeutic agents to target multiple pathways involved in prostate cancer progression, including angiogenesis and androgen signaling. In particular, synergistic inhibition of prostate cancer cell growth has been demonstrated using HDACIs in combination with radio- and chemo-therapy, Apo2L/TRAIL, angiogenesis inhibitors, heat-shock protein 90 inhibitors and androgen receptor antagonists. This review examines the current understanding of the actions of HDACIs in prostate cancer cells, both in a laboratory and a clinical context and discusses the potential utility of combination strategies for the treatment of prostate cancer.