Emerging epigenetic-modulating therapies in lymphoma

Despite considerable advances in the treatment of lymphoma, the prognosis of patients with relapsed and/or refractory disease continues to be poor; thus, a continued need exists for the development of novel approaches and therapies. Epigenetic dysregulation might drive and/or promote tumorigenesis in various types of malignancies and is prevalent in both B cell and T cell lymphomas. Over the past decade, a large number of epigenetic-modifying agents have been developed and introduced into the clinical management of patients with haematological malignancies. In this Review, we provide a concise overview of the most promising epigenetic therapies for the treatment of lymphomas, including inhibitors of histone deacetylases (HDACs), DNA methyltransferases (DNMTs), enhancer of zeste homologue 2 (EZH2), bromodomain and extra-terminal domain proteins (BETs), protein arginine N-methyltransferases (PRMTs) and isocitrate dehydrogenases (IDHs), and highlight the most promising future directions of research in this area.

The discovery and development of romidepsin for the treatment of T-cell lymphoma

INTRODUCTION

Romidepsin is a potent and selective inhibitor of histone deacetylases (HDCAi). It is also the only bicyclic inhibitor to undergo clinical assessment and is considered a promising drug for the treatment of T-cell lymphomas. The cellular action of romidepsin results in enhanced histone acetylation, as well as the acetylation of other nuclear or cytoplasmic proteins, influencing cell cycle, apoptosis, and angiogenesis. In phase II studies involving patients with relapsed or refractory of cutaneous T-cell lymphoma (CTCL) and peripheral T-cell lymphoma (PTCL), romidepsin produced overall response rates (ORR) of 34-35% and 25-38%, with complete response (CR) rates of 6% and 15-18%, respectively. Areas covered: This review summarizes the development of romidepsin, the mechanisms behind its antineoplastic action and its pharmacology. It also covers its pharmacokinetic and pharmacodynamic properties, as well as the preclinical and clinical data on its activity in T-cell lymphoma. Expert opinion: Since there are only few effective therapies available for T-cell lymphomas, romidepsin is a valuable option for relapsed/refractory patients with both CTCL and PTCL. It's also generally well tolerated, and gives potentially durable responses for patients with advanced and symptomatic disease. Combinations of romidepsin with other antineoplastic agents may also further improve drug response and outcomes in T-cell lymphoma.

Targeting histone deacetylases in T-cell lymphoma

Histone deacetylase inhibitors (HDACi) are epigenetic modifiers with single-agent activity in patients with cutaneous and peripheral T-cell lymphoma (CTCL, PTCL). The mechanisms for this preferential activity remain unclear, and although some would term this as 'class effect,' there are differences in efficacy and safety, likely a result of the varying chemical structures/classes, histone and non-histone targets, potencies, and clinical dosing for each. Three HDACi have single-agent approval in relapsed/refractory TCL in the United States: romidepsin in CTCL and PTCL, vorinostat in CTCL, and belinostat in PTCL. Although comparison of these agents is difficult due to differences in patient populations, through this review we aimed to provide a detailed overview of the clinical data for HDACi in TCL and their use in clinical practice. Despite early concerns, data demonstrate the cardiac safety of HDACi, while highlighting the need to maintain electrolytes in the normal range and monitor QT interval when initially co-administering antiemetics or other drugs that prolong QT. To further improve response rates and durability of responses, HDACi are under clinical investigation in combination with chemotherapy regimens and various novel agents.

Use of class I histone deacetylase inhibitor romidepsin in combination regimens

Histone deacetylase (HDAC) inhibitors are epigenetic-modifying agents that have shown promise as anticancer therapies. Several HDAC inhibitors have been approved by the US Food and Drug Administration (FDA) as single-agent therapies to treat T-cell lymphoma. The synergistic combination of HDAC inhibitors with other anticancer agents has the potential to constitute treatment regimens with enhanced efficacy. Romidepsin is a structurally unique, potent, bicyclic class 1 selective HDAC inhibitor approved by the FDA for the treatment of patients with peripheral T-cell lymphoma who have had at least 1 prior therapy and patients with cutaneous T-cell lymphoma who have had at least 1 prior systemic therapy. Here, we review data that support the use of romidepsin in combination with other anticancer agents for the treatment of various malignancies. Promising results have emerged from early clinical studies, supporting the potential for romidepsin combination regimens to constitute safe and effective treatments for cancer.

A phase II study on the role of gemcitabine plus romidepsin (GEMRO regimen) in the treatment of relapsed/refractory peripheral T-cell lymphoma patients

Background

There is no consensus regarding optimal treatment for peripheral T-cell lymphomas (PTCL), especially in relapsed or refractory cases, which have very poor prognosis and a dismal outcome, with 5-year overall survival of 30 %.

Methods

A multicenter prospective phase II trial was conducted to investigate the role of the combination of gemcitabine plus romidepsin (GEMRO regimen) in relapsed/refractory PTCL, looking for a potential synergistic effect of the two drugs. GEMRO regimen contemplates an induction with romidepsin plus gemcitabine for six 28-day cycles followed by maintenance with romidepsin for patients in at least partial remission. The primary endpoint was the overall response rate (ORR); secondary endpoints were survival, duration of response, and safety of the regimen.

Results

The ORR was 30 % (6/20) with 15 % (3) complete response (CR) rate. Two-year overall survival was 50 % and progression-free survival 11.2 %. Grade ≥3 adverse events were represented by thrombocytopenia (60 %), neutropenia (50 %), and anemia (20 %). Two patients are still in CR with median response duration of 18 months. The majority of non-hematological toxicities were mild and transient. No treatment-related death occurred and no toxicity led to treatment interruption.

Conclusions

GEMRO combination regimen shows efficacy data similar to those of single-agent romidepsin with additional hematologic toxicities. Synergy observed in preclinical phase did not turn into ability to improve clinical outcomes.

Trial registration

The trial was registered under EudraCT 2012-001404-38; ClinicalTrials.gov number, NCT01822886.

Romidepsin for the treatment of non-Hodgkin's lymphoma

INTRODUCTION

Patients with relapsed or refractory lymphoma remain a population with unmet medical needs. Histone deacetylase inhibitors (HDACIs) represent a novel class of anticancer drugs currently in development in several malignancies. Inhibition of HDACs leads to acetylation of histone and non-histone proteins, which in turn results in epigenetic modification of gene expression that leads to a plethora of effects, such as cell cycle arrest, apoptosis and inhibition of angiogenesis. Romidepsin is a novel HDACI that has demonstrated preclinical and clinical activity.

AREAS COVERED

This review discusses the different HDACs and epigenetic regulation with a particular focus on the preclinical and clinical development of romidepsin in lymphoma. The review of romidepsin includes: the mechanism of action, its synergistic interaction with novel agents, pivotal clinical trials that lead to its US FDA approval in cutaneous T-cell lymphoma and peripheral T-cell lymphoma as well as active combinations currently in clinical trials.

EXPERT OPINION

Romidepsin is a potent HDACI with clinical activity in T-cell lymphoma where novel agents and combinations are desperately needed. A deeper understanding of the molecular characteristics of this class of agents will allow the design of more potent drugs with improved toxicity profiles and future rational combinations that will expand the indication and benefit from these novel agents.

Novel treatments for T-cell lymphoma

T-cell lymphomas are a biologically and clinically diverse collection of diseases that collectively account for 10% to 15% of non-Hodgkin lymphomas. Unlike B-cell lymphomas, the response of T-cell lymphomas to standard anthracycline-containing chemotherapy regimens is suboptimal and the prognosis of patients is accordingly poor. To address these shortcomings, there has been a proliferation in biologic agents with novel mechanisms of action that target surface antigens, signaling pathways, or cellular processes. Given the large number of candidate molecules showing preclinical promise and the rarity of these diseases, drug development for peripheral T-cell lymphoma is challenging. We provide an overview of agents that have recently been approved for relapsed/refractory T-cell lymphoma and highlight efforts to introduce these agents into front-line treatment protocols in combination with chemotherapy. We discuss biologic doublets currently being evaluated as "chemotherapy-free" salvage regimens and highlight some of the most promising investigational agents in early clinical development.

Novel Pharmacotherapies for B-Cell Lymphomas and Leukemias

Novel pharmacotherapeutic agents were recently approved for treatment of low-grade B-cell neoplasms, and many other agents are under investigation. Several agents have demonstrated impressive activity in targeting malignant B-cell processes and specific pathways, all with the potential to expand our ability to effectively treat B-cell malignancies. The inhibitors of several cell regulatory proteins, including Bruton tyrosine kinase (Btk), phosphoinositide 3-kinase (PI3-K), B-cell lymphoma/leukemia-2 (Bcl-2), and histone deacetylases, as well as immunomodulatory agents are a few of the many pharmacotherapeutic agents under study. A comprehensive review and assessment is presented of the current pharmacotherapies under investigation targeting B-cell lymphomas and leukemias.