benzofurans and Leukemia--Lymphocytic--Chronic--B-Cell

Histone deacetylase inhibitors are members of a class of epigenetic drugs that have proven activity in T-cell malignancies, but little is known about their efficacy in B-cell lymphomas. Abexinostat is an orally available hydroxamate-containing histone deacetylase inhibitor that differs from approved inhibitors; its unique pharmacokinetic profile and oral dosing schedule, twice daily four hours apart, allows for continuous exposure at concentrations required to efficiently kill tumor cells. In this phase II study, patients with relapsed/refractory non-Hodgkin lymphoma or chronic lymphocytic leukemia received oral abexinostat at 80 mg BID for 14 days of a 21-day cycle and continued until progressive disease or unacceptable toxicity. A total of 100 patients with B-cell malignancies and T-cell lymphomas were enrolled between October 2011 and July 2014. All patients received at least one dose of study drug. Primary reasons for discontinuation included progressive disease (56%) and adverse events (25%). Grade 3 or over adverse events and any serious adverse events were reported in 88% and 73% of patients, respectively. The most frequently reported grade 3 or over treatment-emergent related adverse events were thrombocytopenia (80%), neutropenia (27%), and anemia (12%). Among the 87 patients evaluable for efficacy, overall response rate was 28% (complete response 5%), with highest responses observed in patients with follicular lymphoma (overall response rate 56%), T-cell lymphoma (overall response rate 40%), and diffuse large B-cell lymphoma (overall response rate 31%). Further investigation of the safety and efficacy of abexinostat in follicular lymphoma, T-cell lymphoma, and diffuse large B-cell lymphoma implementing a less dose-intense week-on-week-off schedule is warranted. (

Topics: Adult; Aged; Aged, 80 and over; Benzofurans; Diarrhea; Disease-Free Survival; Drug Administration Schedule; Female; Histone Deacetylase Inhibitors; Humans; Hydroxamic Acids; Leukemia, Lymphocytic, Chronic, B-Cell; Lymphoma, Non-Hodgkin; Male; Middle Aged; Remission Induction; Thrombocytopenia; Treatment Outcome

Background We determined the safety, pharmacokinetics, pharmacodynamics, and antitumour activity of abexinostat in B-cell lymphoma or chronic lymphocytic leukaemia. Patients and methods Thirty-five patients received oral abexinostat 30, 45, or 60 mg/m(2) bid in a 3 + 3 design in three 21-day schedules: 14 days on treatment in schedule 1 (D1-14); 10 days in schedule 2 (D1-5 and D8-12); and 12 days in schedule 3 (D1-4, D8-11, and D15-18). Safety, tumour response, plasma concentration, and histone H3 acetylation were measured. Results Two dose-limiting toxicities occurred in each schedule (one grade 3 febrile neutropenia; five grade 4 thrombocytopenia) at 60 mg/m(2) bid (maximal tolerated dose). The recommended dose was 45 mg/m(2) bid; schedule 1 was considered optimal. Non-haematological drug-related toxicities included grade 1 or 2 diarrhoea (43%), nausea (23%), and vomiting (11%); haematological toxicities included thrombocytopenia (31% grade 3, and 26% grade 4), which remained manageable and reversible on withdrawal. Of 29 evaluable patients, there were 2 complete and 6 partial responses; median duration of response was 14.6 months (range 3-16.5 months) (1 cycle is equivalent to 0.75 months). There was no evidence for nonlinear pharmacokinetics. There was a correlation between dose and histone acetylation. Conclusion Abexinostat has manageable toxicity and induced some durable complete and partial responses in B-cell lymphoma or chronic lymphocytic leukaemia. Our results suggest most favourable responses in patients with follicular lymphoma, though further research would be needed to confirm this finding.

Topics: Adult; Aged; Aged, 80 and over; Antineoplastic Combined Chemotherapy Protocols; Benzofurans; Dose-Response Relationship, Drug; Drug Administration Schedule; Female; Histone Deacetylase Inhibitors; Hodgkin Disease; Humans; Hydroxamic Acids; Leukemia, Lymphocytic, Chronic, B-Cell; Lymphoma, Non-Hodgkin; Lymphoproliferative Disorders; Male; Maximum Tolerated Dose; Middle Aged

Signaling via the B-cell receptor (BCR) is a key driver and therapeutic target in chronic lymphocytic leukemia (CLL). BCR stimulation of CLL cells induces expression of eIF4A, an initiation factor important for translation of multiple oncoproteins, and reduces expression of PDCD4, a natural inhibitor of eIF4A, suggesting that eIF4A may be a critical nexus controlling protein expression downstream of the BCR in these cells. We, therefore, investigated the effect of eIF4A inhibitors (eIF4Ai) on BCR-induced responses. We demonstrated that eIF4Ai (silvestrol and rocaglamide A) reduced anti-IgM-induced global mRNA translation in CLL cells and also inhibited accumulation of MYC and MCL1, key drivers of proliferation and survival, respectively, without effects on upstream signaling responses (ERK1/2 and AKT phosphorylation). Analysis of normal naïve and non-switched memory B cells, likely counterparts of the two main subsets of CLL, demonstrated that basal RNA translation was higher in memory B cells, but was similarly increased and susceptible to eIF4Ai-mediated inhibition in both. We probed the fate of MYC mRNA in eIF4Ai-treated CLL cells and found that eIF4Ai caused a profound accumulation of MYC mRNA in anti-IgM treated cells. This was mediated by MYC mRNA stabilization and was not observed for MCL1 mRNA. Following drug wash-out, MYC mRNA levels declined but without substantial MYC protein accumulation, indicating that stabilized MYC mRNA remained blocked from translation. In conclusion, BCR-induced regulation of eIF4A may be a critical signal-dependent nexus for therapeutic attack in CLL and other B-cell malignancies, especially those dependent on MYC and/or MCL1.

Topics: Antibodies, Anti-Idiotypic; Benzofurans; Cells, Cultured; Eukaryotic Initiation Factor-4A; Humans; Leukemia, Lymphocytic, Chronic, B-Cell; Leukocytes, Mononuclear; Myeloid Cell Leukemia Sequence 1 Protein; Protein Biosynthesis; Proto-Oncogene Proteins c-myc; Receptors, Antigen, B-Cell; RNA Stability; RNA, Messenger; Signal Transduction; Triterpenes

Microtubule targeting agents, such as vinblastine, are usually thought to arrest cells in mitosis and subsequently induce apoptosis. However, they can also cause rapid induction of apoptosis in a cell-cycle phase independent manner. BNC105 is a novel vascular and microtubule disrupting drug that also induces apoptosis rapidly but with markedly increased potency compared to vinca alkaloids and combretastatin A4. BNC105 binds to the colchicine-binding site on tubulin resulting in activation of c-Jun N-terminal kinase (JNK), phosphorylation of ATF2, and induction of ATF3 and Noxa leading to acute apoptosis in chronic lymphocytic leukemia (CLL) cells. Apoptosis induced by BNC105 is dependent upon both JNK activation and Noxa induction. Normal leukocytes and one CLL sample also exhibited JNK activation but not Noxa induction and were resistant to BNC105. This study emphasizes the importance of Noxa and JNK for induction of apoptosis in CLL cells by microtubule targeting drugs, and highlights the potential of BNC105 as a potent therapeutic to treat haematopoietic malignancies.

Topics: Anisoles; Apoptosis; Benzofurans; Cell Line, Tumor; Humans; JNK Mitogen-Activated Protein Kinases; Leukemia, Lymphocytic, Chronic, B-Cell; MAP Kinase Signaling System; Microtubules; Stilbenes; Transfection; Tubulin Modulators; Vinblastine

Bruton's tyrosine kinase (BTK) is a critical mediator of survival in B-cell neoplasms. Although BTK inhibitors have transformed therapy in chronic lymphocytic leukemia (CLL), patients with high-risk genetics are at risk for relapse and have a poor prognosis. Identification of novel therapeutic strategies for this group of patients is an urgent unmet clinical need, and therapies that target BTK via alternative mechanisms may fill this niche. Herein, we identify a set of microRNAs (miRs) that target BTK in primary CLL cells and show that the histone deacetylase (HDAC) repressor complex is recruited to these miR promoters to silence their expression. Targeting the HDACs by using either RNA interference against HDAC1 in CLL or a small molecule inhibitor (HDACi) in CLL and mantle cell lymphoma restored the expression of the BTK-targeting miRs with loss of BTK protein and downstream signaling and consequent cell death. We have also made the novel and clinically relevant discovery that inhibition of HDAC induces the BTK-targeting miRs in ibrutinib-sensitive and resistant CLL to effectively reduce both wild-type and C481S-mutant BTK. This finding identifies a novel strategy that may be promising as a therapeutic modality to eliminate the C481S-mutant BTK clone that drives resistance to ibrutinib and provides the rationale for a combination strategy that includes ibrutinib to dually target BTK to suppress its prosurvival signaling.

Topics: Adenine; Agammaglobulinaemia Tyrosine Kinase; Animals; Benzofurans; Cell Survival; Clone Cells; Drug Resistance, Neoplasm; Drug Synergism; Epigenesis, Genetic; Gene Expression Profiling; Gene Silencing; Histone Deacetylase Inhibitors; Humans; Hydroxamic Acids; Leukemia, Lymphocytic, Chronic, B-Cell; Mice, Inbred C57BL; MicroRNAs; Molecular Targeted Therapy; Mutant Proteins; Neoplasm Proteins; Piperidines; Promoter Regions, Genetic; Protein-Tyrosine Kinases; Pyrazoles; Pyrimidines; RNA Interference; Signal Transduction; Up-Regulation

Trans-resveratrol, its dimer epsilon-viniferin and two preparations of vineatrol (a grape-derived polyphenol fraction isolated from vine-shots extracts) were compared for their effects on the proliferation and survival of normal and leukemic human lymphocytes. The two different batches of vineatrol (vineatrol 10 and 25%) was obtained by HPLC fractionation and contained 10 and 25% trans-resveratrol, respectively. The different polyphenols were added to cultures of leukemic cells from chronic B cell malignancies (B-cell chronic lymphocytic leukemia, B-CLL or hairy cell leukemia, HCL) or normal peripheral blood-derived mononuclear cells (PBMC) as a control. The different polyphenols displayed anti-proliferative effect on the leukemic cells, as estimated by the observed inhibition of tritiated thymidine uptake and the reduction of cell recovery. Vineatrol 10% was the most potent whereas vineatrol 25% and resveratrol displayed comparable activity, epsilon-viniferin only exhibiting slight effets. The same order of potency was observed for their capacity to induce apoptosis in leukemic B cells. In contrast, the survival of normal peripheral blood mononuclear cells (PBMC) was little affected in the presence of these polyphenolic compounds and higher concentrations were required in order to elicit cell death. Polyphenol-driven apoptosis in chronic leukemic B cells was shown to correlate with an activation of caspase 3, a drop in the mitochondrial transmembrane potential, a reduction in the expression of the anti-apoptotic protein bcl-2, as well as a reduction in the expression of the inducible nitric oxide synthase (iNOS). Our data therefore indicate that vine-shoots may be a convenient and natural source of material for the purification of resveratrol and other polyphenolic compounds of putative therapeutic interest.

Topics: Antineoplastic Agents, Phytogenic; Apoptosis; B-Lymphocytes; Benzofurans; Caspase 3; Caspases; Cell Division; Flavonoids; Humans; Intracellular Membranes; Leukemia, Lymphocytic, Chronic, B-Cell; Leukocytes, Mononuclear; Membrane Potentials; Mitochondria; Nitric Oxide Synthase; Nitric Oxide Synthase Type II; Phenols; Plant Extracts; Polymers; Polyphenols; Proto-Oncogene Proteins c-bcl-2; Resveratrol; Stilbenes; Vitis