6LBA Phase 1 first-in-human study of the enhancer of zeste-homolog 2 (EZH2) histone methyl transferase inhibitor E7438 as a single agent in patients with advanced solid tumors or B cell lymphoma

YY1 Upregulates Checkpoint Receptors and Downregulates Type I Cytokines in Exhausted, Chronically Stimulated Human T Cells

T cells infiltrate affected organs in chronic infections and malignancy, but they may fail to eradicate virus-infected cells or tumor because of exhaustion. This report describes a Yin Yang-1 (YY1)-centered mechanism for diverse components that have been correlated with exhaustion. Utilizing an in vitro reconstruction of chronic T cell activation, YY1 is shown to positively regulate the checkpoint receptors PD1, Lag3, and Tim3 and to negatively regulate the type I cytokines interleukin-2 (IL-2) (in collaboration with Ezh2 histone methyltransferase) and interferon gamma (IFN-?). Other tests suggest that IL-2 failure drives a large component of cytotoxic functional decline rather than solely checkpoint receptor-ligand interactions that have been the focus of current anti-exhaustion therapies. Clinical evaluations confirm elevated YY1 and Ezh2 in melanoma tumor-infiltrating lymphocytes and in PD1+ T cells in patients with HIV. Exhaustion is revealed to be an active process as the culmination of repetitive two-signal stimulation in a feedback loop via CD3/CD28?p38MAPK/JNK?YY1? exhaustion.

CARM1-expressing ovarian cancer depends on the histone methyltransferase EZH2 activity

CARM1 is an arginine methyltransferase that asymmetrically dimethylates protein substrates on arginine residues. CARM1 is often overexpressed in human cancers. However, clinically applicable cancer therapeutic strategies based on CARM1 expression remain to be explored. Here, we report that EZH2 inhibition is effective in CARM1-expressing epithelial ovarian cancer. Inhibition of EZH2 activity using a clinically applicable small molecule inhibitor significantly suppresses the growth of CARM1-expressing, but not CARM1-deficient, ovarian tumors in two xenograft models and improves the survival of mice bearing CARM1-expressing ovarian tumors. The observed selectivity correlates with reactivation of EZH2 target tumor suppressor genes in a CARM1-dependent manner. Mechanistically, CARM1 promotes EZH2-mediated silencing of EZH2/BAF155 target tumor suppressor genes by methylating BAF155, which leads to the displacement of BAF155 by EZH2. Together, these results indicate that pharmacological inhibition of EZH2 represents a novel therapeutic strategy for CARM1-expressing cancers.

Safety, tolerability, and preliminary activity of CUDC-907, a first-in-class, oral, dual inhibitor of HDAC and PI3K, in patients with relapsed or refractory lymphoma or multiple myeloma: an open-label, dose-escalation, phase 1 trial

BACKGROUND

Treatment options for patients with relapsed or refractory lymphoma and multiple myeloma are limited. CUDC-907 is an oral, first-in-class, small molecule that is designed to inhibit both histone deacetylase (HDAC) and PI3K enzymes, which are members of common oncogenic pathways in haematological malignancies. We aimed to assess overall safety and preliminary activity in this dose-escalation study of CUDC-907 monotherapy in patients with relapsed or refractory lymphoma and multiple myeloma.

METHODS

This open-label, first-in-man, phase 1 trial recruited adult patients (aged ≥18 years) with lymphoma or multiple myeloma who were refractory to or had relapsed after two or more previous regimens, from four US cancer centres. CUDC-907 was orally administered in a standard 3 + 3 dose-escalation design at four different dosing schedules, to which participants were sequentially assigned as follows: once daily, intermittently (twice or three times weekly; simultaneous enrolment), and daily for 5 days followed by a 2-day break (5/2), in 21-day cycles. Dosing started at 30 mg for the once-daily schedule and 60 mg for other schedules, escalating in 30 mg increments. Patients continued to receive CUDC-907 until disease progression or until other treatment discontinuation criteria were met. The primary objective was to determine the maximum tolerated dose (MTD) and recommended phase 2 dose, assessed in patients who received at least 66% of cycle 1 doses without modification and those who had a dose-limiting toxicity (DLT) in cycle 1 irrespective of dose modification. We assessed safety in all patients who received at least one dose of study drug. This ongoing trial is registered at ClinicalTrials.gov, number NCT01742988.

FINDINGS

Between Jan 23, 2013, and July 27, 2015, we enrolled 44 patients, of whom ten were sequentially assigned to CUDC-907 once-daily (MTD 60 mg), 12 to twice-weekly (MTD 150 mg), 15 to three-times-weekly (MTD 150 mg), and seven to the 5/2 dosing schedule (MTD 60 mg). 37 (84%) patients had discontinued study drug as a result of progressive disease or clinical signs of progressive disease at the data cutoff. Four DLTs occurred in three of 40 DLT-evaluable patients (diarrhoea and hyperglycaemia in one patient on 60 mg once daily, hyperglycaemia in one patient on 150 mg twice weekly, and diarrhoea in one patient on 150 mg three times weekly); no DLTs were reported in patients on the 5/2 schedule. Grade 3 or worse adverse events occurred in 19 (43%) of 44 patients, the most common of which were thrombocytopenia (in nine [20%] of 44 patients), neutropenia (three [7%]), and hyperglycaemia (three [7%]). 11 (25%) of 44 patients had serious adverse events, three of which were regarded as treatment related (epistaxis and the DLTs of diarrhoea and hyperglycaemia). Adverse events led to dose reductions in six (14%) patients and treatment discontinuation in seven (16%). Five (14%) of 37 response-evaluable patients achieved an objective response (two complete responses and three partial responses). All five responses occurred in the subgroup of patients with diffuse large B-cell lymphoma (DLBCL; n=9), and three occurred in those with transformed follicular lymphoma DLBCL (n=5). 21 (57%) of 37 response-evaluable patients had stable disease, including those with DLBCL, Hodgkin's lymphoma, and multiple myeloma. On the basis of these findings, we selected CUDC-907 60 mg on the 5/2 dosing schedule as the recommended phase 2 dose.

INTERPRETATION

The safety and tolerability profile of CUDC-907 and the promising preliminary evidence of response support continued development of CUDC-907 at the 60 mg 5/2 dosing schedule, alone and in combination with other therapies. A dose-expansion trial of this dose in patients with refractory and relapsed DLBCL in particular, is ongoing.

FUNDING

Curis, Inc, and the Leukemia and Lymphoma Society.

Advances in therapies for non-Hodgkin lymphoma in children

Pediatric patients with newly diagnosed, non-Hodgkin Lymphoma (NHL) have an excellent overall survival. However, therapy regimens are associated with acute toxicity and late effects. Furthermore, patients with relapsed or refractory disease have relatively few options with proven clinical benefit. Both histologic and molecular differences exist between adult and pediatric NHL preventing simple translation of adult NHL successes into improvements in pediatric NHL treatment. This review summarizes the introduction of targeted therapies into frontline treatments for patients with anaplastic large-cell lymphoma and CD20–positive tumors, with the goal of improving overall survival while limiting both short- and long-term toxicities. In addition, newer approaches that have limited data in children but may have a significant role in how we treat pediatric NHL in the future are reviewed, which include CD19 directed therapy, Notch inhibition, the tri-functional antibody, FBTA05, and EZH2 inhibition.

Advances in therapies for non-Hodgkin lymphoma in children

Pediatric patients with newly diagnosed, non-Hodgkin Lymphoma (NHL) have an excellent overall survival. However, therapy regimens are associated with acute toxicity and late effects. Furthermore, patients with relapsed or refractory disease have relatively few options with proven clinical benefit. Both histologic and molecular differences exist between adult and pediatric NHL preventing simple translation of adult NHL successes into improvements in pediatric NHL treatment. This review summarizes the introduction of targeted therapies into frontline treatments for patients with anaplastic large-cell lymphoma and CD20–positive tumors, with the goal of improving overall survival while limiting both short- and long-term toxicities. In addition, newer approaches that have limited data in children but may have a significant role in how we treat pediatric NHL in the future are reviewed, which include CD19 directed therapy, Notch inhibition, the tri-functional antibody, FBTA05, and EZH2 inhibition.

Mutation spectra of histone methyltransferases with canonical SET domains and EZH2-targeted therapy

Germline mutations in canonical SET-methyltransferases have been identified in autism and intellectual disability syndromes and gain-of-function somatic alterations in EZH2, MLL3, NSD1, WHSC1 (NSD2) and WHSC1L1 (NSD3) in cancer. EZH2 interacts with AR, ERα, β-catenin, FOXP3, NF-κB, PRC2, REST and SNAI2, resulting in context-dependent transcriptional activation and repression. Pharmacological EZH2 inhibitors are currently in clinical trials for the treatment of B-cell lymphomas and solid tumors. EZH2 inhibitors might also be applicable in the treatment of SWI/SNF-mutant cancers, reflecting the reciprocal expression of and functional overlap between EZH2 and SMARCA4. Because of the risks for autoimmune diseases, cognitive impairment, cardiomyopathy and myelodysplastic syndrome, EZH2 inhibitors should be utilized for cancer treatment in patients receiving long-term surveillance but not for cancer chemoprevention.

H3K27 Demethylation at the Proviral Promoter Sensitizes Latent HIV to the Effects of Vorinostat in Ex Vivo Cultures of Resting CD4+ T Cells

Histone methyltransferase inhibitors (HMTis) and histone deacetylase inhibitors (HDACis) are reported to synergistically induce the expression of latent human immunodeficiency virus type 1 (HIV-1), but studies have largely been performed with cell lines. As specific and potent HMTis directed at EZH1 (enhancer of zeste 2 Polycomb repressive complex 2 subunit 1)/EZH2 are now in human testing, we wished to rigorously test such an inhibitor in a primary resting T-cell model of HIV latency. We found that GSK343, a potent and selective EZH2/EZH1 inhibitor, reduced trimethylation of histone 3 at lysine 27 (H3K27) of the HIV provirus in resting cells. Remarkably, this epigenetic change was not associated with increased proviral expression in latently infected resting cells. However, following the reduction in H3K27 at the HIV long terminal repeat (LTR), subsequent exposure to the HDACi suberoylanilide hydroxamic acid or vorinostat (VOR) resulted in increases in HIV gag RNA and HIV p24 antigen production that were up to 2.5-fold greater than those induced by VOR alone. Therefore, in primary resting CD4(+) T cells, true mechanistic synergy in the reversal of HIV latency may be achieved by the combination of HMTis and HDACis. Although other cellular effects of EZH2 inhibition may contribute to the sensitization of the HIV LTR to subsequent exposure to VOR, and to increase viral antigen production, this synergistic effect is directly associated with H3K27 demethylation at nucleosome 1 (Nuc-1). Based upon our findings, the combination of HMTis and HDACis should be considered for testing in animal models or clinical trials.

IMPORTANCE

Demethylation of H3K27 mediated by the histone methyltransferase inhibitor GSK343 in primary resting T cells is slow, occurring over 96 h, but by itself does not result in a significant upregulation of cell-associated HIV RNA expression or viral antigen production. However, following H3K27 demethylation, latent viral expression within infected primary resting CD4(+) T cells is synergistically increased upon exposure to the histone deacetylase inhibitor vorinostat. Demethylation at H3K27 sensitizes the HIV promoter to the effects of an HDACi and provides a proof-of-concept for the testing of combination epigenetic approaches to disrupt latent HIV infection, a necessary step toward the eradication of HIV infection.