A phase I study of romidepsin, gemcitabine, dexamethasone and cisplatin combination therapy in the treatment of peripheral T-cell and diffuse large B-cell lymphoma; the Canadian cancer trials group LY.15 study†

HDAC inhibitors: Promising agents for leukemia treatment

The essential role of epigenetic modification in the pathogenesis of a series of cancers have gradually been recognized. Histone deacetylase (HDACs), as well-known epigenetic modulators, are responsible for DNA repair, cell proliferation, differentiation, apoptosis and angiogenesis. Studies have shown that aberrant expression of HDACs is found in many cancer types. Thus, inhibition of HDACs has provided a promising therapeutic approach alternative for these patients. Since HDAC inhibitor (HDACi) vorinostat was first approved by the Food and Drug Administration (FDA) for treating cutaneous T-cell lymphoma (CTCL) in 2006, the combination of HDAC inhibitors with other molecules such as chemotherapeutic drugs has drawn much attention in current cancer treatment, especially in hematological malignancies therapy. Up to now, there have been more than twenty HDAC inhibitors investigated in clinic trials with five approvals being achieved. Indeed, Histone deacetylase inhibitors promote or enhance several different anticancer mechanisms and therefore are in evidence as potential antileukemia agents. In this review, we will focus on possible mechanisms by how HDAC inhibitors exert therapeutic benefit and their clinical utility in leukemia.

Update on histone deacetylase inhibitors in peripheral T-cell lymphoma (PTCL)

Peripheral T-cell lymphomas (PTCLs) are a group of highly aggressive malignancies with generally poor prognoses, and the first-line chemotherapy of PTCL has limited efficacy. Currently, several novel targeted agents, including histone deacetylase inhibitors (HDACis), have been investigated to improve the therapeutic outcome of PTCLs. Several HDACis, such as romidepsin, belinostat, and chidamide, have demonstrated favorable clinical efficacy and safety in PTCLs. More novel HDACis and new combination therapies are undergoing preclinical or clinical trials. Mutation analysis based on next-generation sequencing may advance our understanding of the correlation between epigenetic mutation profiles and relevant targeted therapies. Multitargeted HDACis and HDACi-based prodrugs hold promising futures and offer further directions for drug design.

Efficacy and safety of histone deacetylase inhibitors in peripheral T-cell lymphoma: a systematic review and meta-analysis on prospective clinical trials

Background

The overall survival of peripheral T-cell lymphoma (PTCL) is dismal. Histone deacetylase (HDAC) inhibitors have exhibited promising treatment outcomes for PTCL patients. Therefore, this work aims to systematically evaluate the treatment outcome and safety profile of HDAC inhibitor-based treatment for untreated and relapsed/refractory (R/R) PTCL patients.

Methods

The prospective clinical trials of HDAC inhibitors for the treatment of PTCL were searched on the Web of Science, PubMed, Embase, ClinicalTrials.gov, and Cochrane Library database. The pooled overall response rate, complete response (CR) rate, and partial response rate were measured. The risk of adverse events was evaluated. Moreover, the subgroup analysis was utilized to assess the efficacy among different HDAC inhibitors and efficacy in different PTCL subtypes.

Results

For untreated PTCL, 502 patients in seven studies were involved, and the pooled CR rate was 44% (95% CI, 39-48%). For R/R PTCL patients, there were 16 studies included, and the CR rate was 14% (95% CI, 11-16%). The HDAC inhibitor-based combination therapy exhibited better efficacy when compared with HDAC inhibitor monotherapy for R/R PTCL patients (P = 0.02). In addition, the pooled CR rate was 17% (95% CI, 13-22%), 10% (95% CI, 5-15%), and 10% (95% CI, 5-15%) in the romidepsin, belinostat, and chidamide monotherapy subgroups, respectively. In the R/R angioimmunoblastic T-cell lymphoma subgroup, the pooled ORR was 44% (95% CI, 35-53%), higher than other subtypes. A total of 18 studies were involved in the safety assessment of treatment-related adverse events. Thrombocytopenia and nausea were the most common hematological and non-hematological adverse events, respectively.

Conclusion

This meta-analysis demonstrated that HDAC inhibitors were effective treatment options for untreated and R/R PTCL patients. The combination of HDAC inhibitor and chemotherapy exhibited superior efficacy to HDAC inhibitor monotherapy in the R/R PTCL setting. Additionally, HDAC inhibitor-based therapy had higher efficacy in angioimmunoblastic T-cell lymphoma patients than that in other subtypes.

Molecular mechanistic pathways underlying the anticancer therapeutic efficiency of romidepsin

Romidepsin, also known as NSC630176, FR901228, FK-228, FR-901228, depsipeptide, or Istodax®, is a natural molecule produced by the Chromobacterium violaceum bacterium that has been approved for its anti-cancer effect. This compound is a selective histone deacetylase (HDAC) inhibitor, which modifies histones and epigenetic pathways. An imbalance between HDAC and histone acetyltransferase can lead to the down-regulation of regulatory genes, resulting in tumorigenesis. Inhibition of HDACs by romidepsin indirectly contributes to the anticancer therapeutic effect by causing the accumulation of acetylated histones, restoring normal gene expression in cancer cells, and promoting alternative pathways, including the immune response, p53/p21 signaling cascades, cleaved caspases, poly (ADP-ribose) polymerase (PARP), and other events. Secondary pathways mediate the therapeutic action of romidepsin by disrupting the endoplasmic reticulum and proteasome and/or aggresome, arresting the cell cycle, inducing intrinsic and extrinsic apoptosis, inhibiting angiogenesis, and modifying the tumor microenvironment. This review aimed to highlight the specific molecular mechanisms responsible for HDAC inhibition by romidepsin. A more detailed understanding of these mechanisms can significantly improve the understanding of cancer cell disorders and pave the way for new therapeutic approaches using targeted therapy.

Impact of Histone Modifications and Their Therapeutic Targeting in Hematological Malignancies

Hematologic malignancies are a large and heterogeneous group of neoplasms characterized by complex pathogenetic mechanisms. The abnormal regulation of epigenetic mechanisms and specifically, histone modifications, has been demonstrated to play a central role in hematological cancer pathogenesis and progression. A variety of epigenetic enzymes that affect the state of histones have been detected as deregulated, being either over- or underexpressed, which induces changes in chromatin compaction and, subsequently, affects gene expression. Recent advances in the field of epigenetics have revealed novel therapeutic targets, with many epigenetic drugs being investigated in clinical trials. The present review focuses on the biological impact of histone modifications in the pathogenesis of hematologic malignancies, describing a wide range of therapeutic agents that have been discovered to target these alterations and are currently under investigation in clinical trials.

Epigenetic Aberrations and Targets in Peripheral T-Cell Lymphoma

Peripheral T cell lymphomas (PTCL) comprise a diverse group of aggressive T-cell and NK-cell lymphomas with many subtypes sharing same treatment algorithms despite having different pathobiology and responses to treatment. The molecular advances made in discovery of genetic mutations that disrupt epigenetic modulation in some subtypes of PTCL such as angioimmunoblastic T cell lymphoma and PTCL-not otherwise specified (NOS) may explain the poor outcomes and unsatisfactory responses to frontline line CHOP and CHOP-like therapy seen in this group of lymphomas. In this article, we address the main genetic mutations such as IDH2, TET2 and DNMT3A seen in PTCL and that disrupt the epigenetic modulation pathways, focusing on acetylation, deacetylation and methylation. Since therapeutic agents that target the disrupted epigenetic modulation pathways in PTCL may change treatment landscape in the near future, we will highlight the ones approved for treatment of refractory and/or relapsed PTCL and also the pivotal regimens being evaluated in clinical trials for treatment of frontline and refractory relapsed disease. We stress the importance of determining whether there is an association between the discussed genetic mutations and responses to the highlighted therapeutic agents such that treatments could be better tailored in patients with this kind of lymphoma with unmet needs.

The epigenetic regulation of the germinal center response

In response to T-cell-dependent antigens, antigen-experienced B cells migrate to the center of the B-cell follicle to seed the germinal center (GC) response after cognate interactions with CD4⁺ T cells. These GC B cells eventually mature into memory and long-lived antibody-secreting plasma cells, thus generating long-lived humoral immunity. Within GC, B cells undergo somatic hypermutation of their B cell receptors (BCR) and positive selection for the emergence of high-affinity antigen-specific B-cell clones. However, this process may be dangerous, as the accumulation of aberrant mutations could result in malignant transformation of GC B cells or give rise to autoreactive B cell clones that can cause autoimmunity. Because of this, better understanding of GC development provides diagnostic and therapeutic clues to the underlying pathologic process. A productive GC response is orchestrated by multiple mechanisms. An emerging important regulator of GC reaction is epigenetic modulation, which has key transcriptional regulatory properties. In this review, we summarize the current knowledge on the biology of epigenetic mechanisms in the regulation of GC reaction and outline its importance in identification of immunotherapy decision making.

Use of ifosfamide, carboplatin and etoposide in combination with brentuximab vedotin or romidepsin based on CD30 positivity in relapsed/refractory peripheral T-cell lymphoma

BACKGROUND

Relapsed/refractory peripheral T-cell lymphoma (R/R PTCL) has a poor prognosis. Romidepsin (Ro) and brentuximab vedotin (Bv), combined with ifosfamide, carboplatin, and etoposide (ICE) has not been significantly studied in PTCL.

AIM

We report outcomes of Bv-ICE in CD30 (+) and Ro-ICE in CD30 (-) R/R PTCL treated in "Blinded for peer review" Cancer Center.

METHODS AND RESULTS

We retrospectively identified R/R PTCL patients treated with BV-ICE or romidepsin-ICE from May 2016 to September 2019. Out of 13 R/R PTCL patients, 6 were treated with Bv-ICE and 7 with Ro-ICE. Bv-ICE had an overall response rate (ORR) of 66.7%, with all the patients achieving a complete response. ORR was 71.4% for Ro-ICE with 57.1% of patients achieving a complete response. Two patients treated with Bv-ICE and three treated with Ro-ICE received transplantation.

CONCLUSION

In our experience, treatment with Bv-ICE and Ro-ICE based on CD30 positivity is feasible and effective to treat patients with R/R PTCL.

Histone Modifications and Their Targeting in Lymphoid Malignancies

In a wide range of lymphoid neoplasms, the process of malignant transformation is associated with somatic mutations in B cells that affect the epigenetic machinery. Consequential alterations in histone modifications contribute to disease-specific changes in the transcriptional program. Affected genes commonly play important roles in cell cycle regulation, apoptosis-inducing signal transduction, and DNA damage response, thus facilitating the emergence of malignant traits that impair immune surveillance and favor the emergence of different B-cell lymphoma subtypes. In the last two decades, the field has made a major effort to develop therapies that target these epigenetic alterations. In this review, we discuss which epigenetic alterations occur in B-cell non-Hodgkin lymphoma. Furthermore, we aim to present in a close to comprehensive manner the current state-of-the-art in the preclinical and clinical development of epigenetic drugs. We focus on therapeutic strategies interfering with histone methylation and acetylation as these are most advanced in being deployed from the bench-to-bedside and have the greatest potential to improve the prognosis of lymphoma patients.

Efficacy and Treatment-Related Adverse Events of Romidepsin in PTCL Clinical Studies: A Systematic Review and Meta-Analysis

Background: Peripheral T-cell lymphoma (PTCL) is an extensive class of biologically and clinically heterogeneous diseases with dismal outcomes. The histone deacetylase inhibitor (HDACi) romidepsin was approved for relapsed and refractory (R/R-PTCL) in 2011. This meta-analysis was performed to assess the efficacy and safety of romidepsin in PTCL.

Methods: We searched for articles on the HDAC inhibitor romidepsin in the treatment of PTCL in Embase, Web of Science, and PubMed. The methodology is further detailed in PROSPERO (CRD42020213651, CRD42020213553). The 2-year overall survival (OS), 2-year progression-free survival (PFS), and their corresponding to 95% confidence intervals (CIs) were measured. Besides, corresponding 95% CIs were pooled for the complete response (CR), partial response (PR), duration of response (DoR), and risk of adverse events (AEs).

Results: Eleven studies containing 388 patients were incorporated into the quantitative synthesis, of which R/R-PTCL patients were the dominant portion, accounting for 94.3% (366/388). For all studies, the CR rate was 20% (95% CI, 13–27%, random effects model), and the PR rate was 18% (95% CI, 12–25%, random effects model). The 2-year OS was 48% (95% CI, 38–59%, fixed effects model), and the 2-year PFS was 17% (95% CI, 13–21%, fixed effects model). There were no significant differences between romidepsin monotherapy and romidepsin plus additional drugs. Hematological toxicities, such as lymphopenia and granulocytopenia, remained the most continually happening grade 3 or higher AEs, accounting for 46 and 28%, respectively. None of the studies reported any drug-related mortality.

Conclusions: Considering that most of the included patients had R/R-PTCL, the addition of romidepsin significantly enhance the efficacy. And AEs were tolerable as the grade 3/4 AEs in romidepsin monotherapy was 7% (95% CI, 6–8%). It is imperative to further expand the first-line application of romidepsin and carry out personalized therapy based on epigenomics, which will improve the survival of PTCL patients.

Systematic Review Registration:https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42020213651 and https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42020213553.

Resistance to platinum-based cancer drugs: a special focus on epigenetic mechanisms

Chemoresistance is a significant clinical challenge, limiting the drug response in cancer. Several mechanisms associated with drug resistance have been characterized, and the role of epigenetics in generating resistance to platinum-based drugs has been clarified. Epigenetic mechanisms such as DNA methylation, histone modification, long noncoding RNA, and microRNA affect the expression of genes implicated in absorption, distribution, metabolism and excretion (ADME) of drugs, and other non-ADME genes that encode enzymes involved in the processes of cell proliferation, DNA repair, apoptosis and signal transduction key in the development of chemoresistance in cancer, specifically in platinum-based drugs. This review summarizes current discoveries in epigenetic regulation implicated in platinum drug resistance in cancer and the main clinical trials based on epigenetic therapy, evaluating their potential synergy with platinum-based drugs.

How to Sequence Therapies in Peripheral T Cell Lymphoma

OPINION STATEMENT

Peripheral T cell lymphoma (PTCL) represents a heterogeneous group of rare lymphoproliferative disorders. Historically, there has been a lack of pathobiological understanding of PTCL. With the exception of ALK-positive anaplastic large cell lymphoma, patients with PTCL have less favorable outcomes, with most patients relapsing shortly after conventional anthracycline-containing multi-agent chemotherapy. The standard management approach for PTCL involves induction therapy followed by autologous stem cell transplantation. Patients with relapsed/refractory PTCL have dismal outcomes and limited treatment options despite the available novel agents, therefore remaining a critical unmet need. By virtue of advancement in cancer biology over the recent years, the treatment landscape of PTCL has gradually evolved from conventional chemotherapy based on solely morphological diagnosis toward more individualized therapies by integrating molecular attributes of PTCL to the traditional treatment paradigm. We are at the edge of witnessing a paradigm shift in PTCL management.

Recent developments of HDAC inhibitors: Emerging indications and novel molecules

The histone deacetylase (HDAC) enzymes, a class of epigenetic regulators, are historically well established as attractive therapeutic targets. During investigation of trends within clinical trials, we have identified a high number of clinical trials involving HDAC inhibitors, prompting us to further evaluate the current status of this class of therapeutic agents. In total, we have identified 32 agents with HDAC-inhibiting properties, of which 29 were found to interact with the HDAC enzymes as their primary therapeutic target. In this review, we provide an overview of the clinical drug development highlighting the recent advances and provide analysis of specific trials and, where applicable, chemical structures. We found haematologic neoplasms continue to represent the majority of clinical indications for this class of drugs; however, it is clear that there is an ongoing trend towards diversification. Therapies for non-oncology indications including HIV infection, muscular dystrophies, inflammatory diseases as well as neurodegenerative diseases such as Alzheimer's disease, frontotemporal dementia and Friedreich's ataxia are achieving promising clinical progress. Combinatory regimens are proving to be useful to improve responsiveness among FDA-approved agents; however, it often results in increased treatment-related toxicities. This analysis suggests that the indication field is broadening through a high number of clinical trials while several fields of preclinical development are also promising.

Molecularly targeted therapies for relapsed and refractory peripheral T-cell lymphomas

The advent of molecularly targeted agents for patients with peripheral T-cell lymphomas (PTCL) has begun to change the therapeutic landscape in these diseases, especially for patients with relapsed or refractory disease. These agents, grounded in targeting numerous pathways or alterations related to disease pathogenesis, have shown promise across many PTCL subhistologies. Aided by significant advances in experimental techniques related to molecular biology, epigenetics, and immunology, more recent studies have begun elucidating mediators of resistance, both intrinsic and acquired, to inform future therapeutic advances. Defining and targeting these escape mechanisms through rational combination approaches will likely be important to continue to build on these promising advances and further improve clinical outcomes for patients facing PTCL.

Advances in the pharmacotherapeutic options for primary nodal peripheral T-cell lymphoma

INTRODUCTION

Peripheral T cell lymphomas (PTCL) are a group of heterogenous hematologic malignancies derived from post-thymic T lymphocytes and mature NK cells. Conventional chemotherapy does not guarantee a good outcome.

AREAS COVERED

The article summarizes recent investigational therapies and their mechanism of action, as well as the pharmacological properties, clinical activity, and toxicity of new agents in the treatment of primary nodal PTCLs. The review scrutinized papers included in the MEDLINE (PubMed) database between 2010 and October 2020. These were supplemented with a manual search of conference proceedings from the previous five years of the American Society of Hematology, European Hematology Association, and American Society of Clinical Oncology. Further relevant publications were obtained by reviewing the references from the chosen articles.

EXPERT OPINION

PTCLs have proved difficult to treat and investigate because of their rarity. Studies of aggressive lymphoma, including a small proportion of T-cell lymphomas, found that any benefit from intensified traditional chemotherapy in patients with PTCL is accompanied by increased toxicity. However, the management of PTCL is beginning to change dramatically, thanks to the use of more sophisticated agents targeting the mechanisms of disease development.

Small Molecules Targeting HATs, HDACs, and BRDs in Cancer Therapy

Evidence for research over the past decade shows that epigenetic regulation mechanisms run through the development and prognosis of tumors. Therefore, small molecular compounds targeting epigenetic regulation have become a research hotspot in the development of cancer therapeutic drugs. According to the obvious abnormality of histone acetylation when tumors occur, it suggests that histone acetylation modification plays an important role in the process of tumorigenesis. Currently, as a new potential anti-cancer therapeutic drugs, many active small molecules that target histone acetylation regulatory enzymes or proteins such as histone deacetylases (HDACs), histone acetyltransferase (HATs) and bromodomains (BRDs) have been developed to restore abnormal histone acetylation levels to normal. In this review, we will focus on summarizing the changes of histone acetylation levels during tumorigenesis, as well as the possible pharmacological mechanisms of small molecules that target histone acetylation in cancer treatment.

Role of HDACs in normal and malignant hematopoiesis

Normal hematopoiesis requires the accurate orchestration of lineage-specific patterns of gene expression at each stage of development, and epigenetic regulators play a vital role. Disordered epigenetic regulation has emerged as a key mechanism contributing to hematological malignancies. Histone deacetylases (HDACs) are a series of key transcriptional cofactors that regulate gene expression by deacetylation of lysine residues on histone and nonhistone proteins. In normal hematopoiesis, HDACs are widely involved in the development of various lineages. Their functions involve stemness maintenance, lineage commitment determination, cell differentiation and proliferation, etc. Deregulation of HDACs by abnormal expression or activity and oncogenic HDAC-containing transcriptional complexes are involved in hematological malignancies. Currently, HDAC family members are attractive targets for drug design, and a variety of HDAC-based combination strategies have been developed for the treatment of hematological malignancies. Drug resistance and limited therapeutic efficacy are key issues that hinder the clinical applications of HDAC inhibitors (HDACis). In this review, we summarize the current knowledge of how HDACs and HDAC-containing complexes function in normal hematopoiesis and highlight the etiology of HDACs in hematological malignancies. Moreover, the implication and drug resistance of HDACis are also discussed. This review presents an overview of the physiology and pathology of HDACs in the blood system.

Brentuximab vedotin in the treatment of CD30+ PTCL

In this timely Blood Spotlight, Barta et al summarize for the practicing hematologist the strengths and limitations of current data on brentuximab vedotin–based treatment in peripheral T-cell lymphoma (PTCL).