Phase 1 study of the histone deacetylase inhibitor entinostat plus clofarabine for poor-risk Philadelphia chromosome-negative (newly diagnosed older adults or adults with relapsed refractory disease) acute lymphoblastic leukemia or biphenotypic leukemia

Mechanisms of HDACs in cancer development

Histone deacetylases (HDACs) are a class of epigenetic regulators that play pivotal roles in key biological processes such as cell proliferation, differentiation, metabolism, and immune regulation. Based on this, HDAC inhibitors (HDACis), as novel epigenetic-targeted therapeutic agents, have demonstrated significant antitumor potential by inducing cell cycle arrest, activating apoptosis, and modulating the immune microenvironment. Current research is focused on developing highly selective HDAC isoform inhibitors and combination therapy strategies tailored to molecular subtypes, aiming to overcome off-target effects and resistance issues associated with traditional broad-spectrum inhibitors. This review systematically elaborates on the multidimensional regulatory networks of HDACs in tumor malignancy and assesses the clinical translation progress of next-generation HDACis and their prospects in precision medicine, providing a theoretical framework and strategic reference for the development of epigenetic-targeted antitumor drugs.

Antibody-Based and Other Novel Agents in Adult B-Cell Acute Lymphoblastic Leukemia

Despite notable progress in managing B-cell acute lymphoblastic leukemia (B-ALL) over recent decades, particularly in pediatric cohorts where the 5-year overall survival (OS) reaches 90%, outcomes for the 10-15% with relapsed and refractory disease remain unfavorable. This disparity is further accentuated in adults, where individuals over the age of 40 years undergoing aggressive multiagent chemotherapy continue to have lower survival rates. While the adoption of pediatric-inspired treatment protocols has enhanced complete remission (CR) rates among younger adults, 20-30% of these patients experience relapse, resulting in a subsequent 5-year OS rate of 40-50%. For relapsed B-ALL in adults, there is no universally accepted standard salvage therapy, and the median OS is short. The cornerstone of B-ALL treatment continues to be the utilization of combined cytotoxic chemotherapy regimens to maximize early and durable disease control. In this manuscript, we go beyond the multiagent chemotherapy medications developed prior to the 1980s and focus on the incorporation of antibody-based therapy for B-ALL with an eye on existing and upcoming approved indications for blinatumomab, inotuzumab ozogamicin, other monoclonal antibodies, and chimeric antigen receptor (CAR) T cell products in frontline and relapsed/refractory settings. In addition, we discuss emerging investigational therapies that harness the therapeutic vulnerabilities of the disease through targeting apoptosis, modifying epigenetics, and inhibiting the mTOR pathway.

Epigenetics-targeted drugs: current paradigms and future challenges

Epigenetics governs a chromatin state regulatory system through five key mechanisms: DNA modification, histone modification, RNA modification, chromatin remodeling, and non-coding RNA regulation. These mechanisms and their associated enzymes convey genetic information independently of DNA base sequences, playing essential roles in organismal development and homeostasis. Conversely, disruptions in epigenetic landscapes critically influence the pathogenesis of various human diseases. This understanding has laid a robust theoretical groundwork for developing drugs that target epigenetics-modifying enzymes in pathological conditions. Over the past two decades, a growing array of small molecule drugs targeting epigenetic enzymes such as DNA methyltransferase, histone deacetylase, isocitrate dehydrogenase, and enhancer of zeste homolog 2, have been thoroughly investigated and implemented as therapeutic options, particularly in oncology. Additionally, numerous epigenetics-targeted drugs are undergoing clinical trials, offering promising prospects for clinical benefits. This review delineates the roles of epigenetics in physiological and pathological contexts and underscores pioneering studies on the discovery and clinical implementation of epigenetics-targeted drugs. These include inhibitors, agonists, degraders, and multitarget agents, aiming to identify practical challenges and promising avenues for future research. Ultimately, this review aims to deepen the understanding of epigenetics-oriented therapeutic strategies and their further application in clinical settings.

Histone deacetylase inhibitors for leukemia treatment: current status and future directions

Leukemia remains a major therapeutic challenge in clinical oncology. Despite significant advancements in treatment modalities, leukemia remains a significant cause of morbidity and mortality worldwide, as the current conventional therapies are accompanied by life-limiting adverse effects and a high risk of disease relapse. Histone deacetylase inhibitors have emerged as a promising group of antineoplastic agents due to their ability to modulate gene expression epigenetically. In this review, we explore these agents, their mechanisms of action, pharmacokinetics, safety and clinical efficacy, monotherapy and combination therapy strategies, and clinical challenges associated with histone deacetylase inhibitors in leukemia treatment, along with the latest evidence and ongoing studies in the field. In addition, we discuss future directions to optimize the therapeutic potential of these agents.

Developing Targeted Therapies for T Cell Acute Lymphoblastic Leukemia/Lymphoma

PURPOSE OF REVIEW

Largely, treatment advances in relapsed and/or refractory acute lymphoblastic leukemia (ALL) have been made in B cell disease leaving T cell ALL reliant upon high-intensity chemotherapy. Recent advances in the understanding of the biology of T-ALL and the improvement in immunotherapies have led to new therapeutic pathways to target and exploit. Here, we review the more promising pathways that are able to be targeted and other therapeutic possibilities for T-ALL.

RECENT FINDINGS

Preclinical models and early-phase clinical trials have shown promising results in some case in the treatment of T-ALL. Targeting many different pathways could lead to the next advancement in the treatment of relapsed and/or refractory disease. Recent advances in cellular therapies have also shown promise in this space. When reviewing the literature as a whole, targeting important pathways and antigens likely will lead to the next advancement in T-ALL survival since intensifying chemotherapy.

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.

Topical histone deacetylase 1 inhibitor Entinostat ameliorates psoriasiform dermatitis through suppression of IL-17A response

BACKGROUND

Biologics against IL-17A, IL-23 and TNF-α achieve a great success in treating psoriasis. However, the majority of patients still have some residual lesions left and require combination therapy to reach complete clearance. Topical medicine is an optional choice but only has limited categories. Besides, drug resistance is very often. Thus, topical medicine targeting new signaling pathway is still in an urgent need in the biologics era.

OBJECTIVE

To investigate the role of topical Entinostat, a selective inhibitor of histone deacetylases 1 (HDAC1) that has been tested in clinic trials to treat solid tumors and hematological malignancies, in psoriasis therapy.

METHODS

Efficacious Entinostat were tested in a mouse imiquimod (IMQ)-induced psoriasiform dermatitis (PsD) model. An in vitro model consisting of human CD4 + T cell, murine T cells and NHEKs were used to screen Entinostat for inhibition of cutaneous inflammatory genes.

RESULTS

Topical application of Entinostat significantly improved psoriasiform inflammation in imiquimod-induced mice model with great reduction of IL-17A+ γδT cell infiltration in skin. Entinostat is powerful agent in inhibition of Th17 cell generation and the expression of psoriasis-related inflammatory mediators by primary keratinocytes upon CD4⁺ T cells stimulation.

CONCLUSION

Our findings suggest Entinostat is a promising topical medicine for psoriasis treatment.

Myeloid-derived suppressor cells: key immunosuppressive regulators and therapeutic targets in hematological malignancies

The immunosuppressive tumor microenvironment (TME) supports the development of tumors and limits tumor immunotherapy, including hematological malignancies. Hematological malignancies remain a major public health issue with high morbidity and mortality worldwide. As an important component of immunosuppressive regulators, the phenotypic characteristics and prognostic value of myeloid-derived suppressor cells (MDSCs) have received much attention. A variety of MDSC-targeting therapeutic approaches have produced encouraging outcomes. However, the use of various MDSC-targeted treatment strategies in hematologic malignancies is still difficult due to the heterogeneity of hematologic malignancies and the complexity of the immune system. In this review, we summarize the biological functions of MDSCs and further provide a summary of the phenotypes and suppressive mechanisms of MDSC populations expanded in various types of hematological malignancy contexts. Moreover, we discussed the clinical correlation between MDSCs and the diagnosis of malignant hematological disease, as well as the drugs targeting MDSCs, and focused on summarizing the therapeutic strategies in combination with other immunotherapies, such as various immune checkpoint inhibitors (ICIs), that are under active investigation. We highlight the new direction of targeting MDSCs to improve the therapeutic efficacy of tumors.