The targeted histone deacetylase inhibitor tefinostat (CHR-2845) shows selective in vitro efficacy in monocytoid-lineage leukaemias

Target Cell Activation of a Structurally Novel NOD-Like Receptor Pyrin Domain-Containing Protein 3 Inhibitor NT-0796 Enhances Potency

The NOD-like receptor pyrin domain-containing protein 3 (NLRP3) inflammasome is a central regulator of innate immunity, essential for processing and release of interleukin-1β and pyroptotic cell death. As endogenous NLRP3 activating triggers are hallmarks of many human chronic inflammatory diseases, inhibition of NLRP3 has emerged as a therapeutic target. Here we identify NDT-19795 as a novel carboxylic acid-containing NLRP3 activation inhibitor in both human and mouse monocytes and macrophages. Remarkably, conversion of the carboxylate to an isopropyl-ester (NT-0796) greatly enhances NLRP3 inhibitory potency in human monocytes. This increase is attributed to the ester-containing pharmacophore being more cell-penetrant than the acid species and, once internalized, the ester being metabolized to NDT-19795 by carboxylesterase-1 (CES-1). Mouse macrophages do not express CES-1, and NT-0796 is ineffective in these cells. Mice also contain plasma esterase (Ces1c) activity which is absent in humans. To create a more human-like model, we generated a mouse line in which the genome was modified, removing Ces1c and replacing this segment of DNA with the human CES-1 gene driven by a mononuclear phagocyte-specific promoter. We show human CES-1 presence in monocytes/macrophages increases the ability of NT-0796 to inhibit NLRP3 activation both in vitro and in vivo. As NLRP3 is widely expressed by monocytes/macrophages, the co-existence of CES-1 in these same cells affords a unique opportunity to direct ester-containing NLRP3 inhibitors precisely to target cells of interest. Profiling NT-0796 in mice humanized with respect to CES-1 biology enables critical modeling of the pharmacokinetics and pharmacodynamics of this novel therapeutic candidate. SIGNIFICANCE STATEMENT: Inhibition of NLRP3 represents a desirable therapeutic strategy for the treatment of multiple human disorders. In this study pharmacological properties of a structurally-novel, ester-containing NLRP3 inhibitor NT-0796 are characterized. To study pharmacodynamics of NT-0796 in vivo, a mouse line was engineered possessing more human-like traits with respect to carboxylesterase biology. In the context of these hCES-1 mice, NT-0796 serves as a more effective inhibitor of NLRP3 activation than the corresponding acid, highlighting the full translational potential of the ester strategy.

Epigenetic regulation in hematopoiesis and its implications in the targeted therapy of hematologic malignancies

Hematologic malignancies are one of the most common cancers, and the incidence has been rising in recent decades. The clinical and molecular features of hematologic malignancies are highly heterogenous, and some hematologic malignancies are incurable, challenging the treatment, and prognosis of the patients. However, hematopoiesis and oncogenesis of hematologic malignancies are profoundly affected by epigenetic regulation. Studies have found that methylation-related mutations, abnormal methylation profiles of DNA, and abnormal histone deacetylase expression are recurrent in leukemia and lymphoma. Furthermore, the hypomethylating agents and histone deacetylase inhibitors are effective to treat acute myeloid leukemia and T-cell lymphomas, indicating that epigenetic regulation is indispensable to hematologic oncogenesis. Epigenetic regulation mainly includes DNA modifications, histone modifications, and noncoding RNA-mediated targeting, and regulates various DNA-based processes. This review presents the role of writers, readers, and erasers of DNA methylation and histone methylation, and acetylation in hematologic malignancies. In addition, this review provides the influence of microRNAs and long noncoding RNAs on hematologic malignancies. Furthermore, the implication of epigenetic regulation in targeted treatment is discussed. This review comprehensively presents the change and function of each epigenetic regulator in normal and oncogenic hematopoiesis and provides innovative epigenetic-targeted treatment in clinical practice.

Repurposing From Oncology to Cardiology: Low-Dose 5-Azacytidine Attenuates Pathological Cardiac Remodeling in Response to Pressure Overload Injury

INTRODUCTION

Recent evidence suggests that transcriptional reprogramming is involved in the pathogenesis of cardiac remodeling (cardiomyocyte hypertrophy and fibrosis) and the development of heart failure. 5-Azacytidine (5aza), an inhibitor of DNA methylation approved for hematological malignancies, has previously demonstrated beneficial effects on cardiac remodeling in hypertension. The aim of our work was to investigate whether pressure overload is associated with alterations in DNA methylation and if intervention with low-dose 5aza can attenuate the associated pathological changes.

METHODS AND RESULTS

C57Bl6/J mice underwent surgical constriction of the aortic arch for 8 weeks. Mice began treatment 4 weeks post-surgery with either vehicle or 5aza (5 mg/kg). Cardiac structure and function was examined in vivo using echocardiography followed by post mortem histological assessment of hypertrophy and fibrosis. Global DNA methylation was examined by immunostaining for 5-methylcytosine (5MeC) and assessment of DNA methyltransferase expression. The results highlighted that pressure overload-induced pathological cardiac remodeling is associated with increased DNA methylation (elevated cardiac 5MeC positivity and Dnmt1 expression). Administration of 5aza attenuated pathological remodeling and diastolic dysfunction. These beneficial changes were mirrored by a treatment-related reduction in global 5MeC levels and expression of Dnmt1 and Dnmt3B in the heart.

CONCLUSION

DNA methylation plays an important role in the pathogenesis of pressure overload-induced cardiac remodeling. Therapeutic intervention with 5aza, at a dose 5 times lower than clinically given for oncology treatment, attenuated myocardial hypertrophy and fibrosis. Our work supports the rationale for its potential use in cardiac pathologies associated with aberrant cardiac wound healing.

HDAC Inhibitors in Acute Myeloid Leukemia

Acute myeloid leukemia (AML) is a hematological malignancy characterized by uncontrolled proliferation, differentiation arrest, and accumulation of immature myeloid progenitors. Although clinical advances in AML have been made, especially in young patients, long-term disease-free survival remains poor, making this disease an unmet therapeutic challenge. Epigenetic alterations and mutations in epigenetic regulators contribute to the pathogenesis of AML, supporting the rationale for the use of epigenetic drugs in patients with AML. While hypomethylating agents have already been approved in AML, the use of other epigenetic inhibitors, such as histone deacetylases (HDAC) inhibitors (HDACi), is under clinical development. HDACi such as Panobinostat, Vorinostat, and Tricostatin A have been shown to promote cell death, autophagy, apoptosis, or growth arrest in preclinical AML models, yet these inhibitors do not seem to be effective as monotherapies, but rather in combination with other drugs. In this review, we discuss the rationale for the use of different HDACi in patients with AML, the results of preclinical studies, and the results obtained in clinical trials. Although so far the results with HDACi in clinical trials in AML have been modest, there are some encouraging data from treatment with the HDACi Pracinostat in combination with DNA demethylating agents.

Targeting Histone Deacetylases in Myeloid Cells Inhibits Their Maturation and Inflammatory Function With Limited Effects on Atherosclerosis

Monocytes and macrophages are key drivers in the pathogenesis of inflammatory diseases. Epigenetic targets have been shown to control the transcriptional profile and phenotype of these cells. Since histone deacetylase protein inhibitors demonstrate profound anti-inflammatory activity, we wanted to test whether HDAC inhibition within monocytes and macrophages could be applied to suppress inflammation in vivo. ESM technology conjugates an esterase-sensitive motif (ESM) onto small molecules to allow targeting of cells that express carboxylesterase 1 (CES1), such as mononuclear myeloid cells. This study utilized an ESM-HDAC inhibitor to target monocytes and macrophages in mice in both an acute response model and an atherosclerosis model. We demonstrate that the molecule blocks the maturation of peritoneal macrophages and inhibits pro-inflammatory cytokine production in both models but to a lesser extent in the atherosclerosis model. Despite regulating the inflammatory response, ESM-HDAC528 did not significantly affect plaque size or phenotype, although histological classification of the plaques demonstrated a significant shift to a less severe phenotype. We hereby show that HDAC inhibition in myeloid cells impairs the maturation and activation of peritoneal macrophages but shows limited efficacy in a model of atherosclerosis.

Histone Deacetylase Inhibitors: A Prospect in Drug Discovery

Cancer is a provocative issue across the globe and treatment of uncontrolled cell growth follows a deep investigation in the field of drug discovery. Therefore, there is a crucial requirement for discovering an ingenious medicinally active agent that can amend idle drug targets. Increasing pragmatic evidence implies that histone deacetylases (HDACs) are trapped during cancer progression, which increases deacetylation and triggers changes in malignancy. They provide a ground-breaking scaffold and an attainable key for investigating chemical entity pertinent to HDAC biology as a therapeutic target in the drug discovery context. Due to gene expression, an impending requirement to prudently transfer cytotoxicity to cancerous cells, HDAC inhibitors may be developed as anticancer agents. The present review focuses on the basics of HDAC enzymes, their inhibitors, and therapeutic outcomes.

Treatment options for patients with myelodysplastic syndromes after hypomethylating agent failure

The treatment of patients with myelodysplastic syndromes (MDSs) has hinged primarily on supportive care (ie, blood transfusions, colony stimulating agents, iron chelation, etc.) and the US Food and Drug Administration-approved agents, including 5-azacytidine, deoxyazacytidine, and lenalidomide. For patients no longer benefitting from these agents, there is a paucity of effective therapies. The challenges at this time include our limited understanding of the mechanisms of resistance to these therapies and the variables employed to select next best therapies for patients based on: (1) their performance status and medical comorbidities; (2) the molecular feature(s) of their MDS; (3) the prior treatments they have received; and (4) the long-term goal(s)/possibilities for their future treatment (ie, transplant vs no transplant).