ENGAGE- 501: phase II study of entinostat (SNDX-275) in relapsed and refractory Hodgkin lymphoma

Fermented Wheat Germ Protein with Histone Deacetylase Inhibitor AR42 Demonstrates Enhanced Cytotoxicity against Lymphoma Cells In Vitro and In Vivo

Current treatments for lymphoma are plagued by substantial toxicity and the inability to overcome drug resistance, leading to eventual relapse and rationalizing the development of novel, less toxic therapeutics and drug combinations. Histone deacetylase inhibitors (HDACis) are a broad class of epigenetic modulators that have been studied in multiple tumor types, including lymphoma. Currently, HDACis are FDA-approved for treating relapsed T-cell lymphomas and multiple myeloma, with ongoing trials in other lymphomas and solid tumors. As single agents, HDACis frequently elicit toxic side effects and have limited efficacy; therefore, many current treatment strategies focus on combinations to boost efficacy while attempting to minimize toxicity. Fermented wheat germ extract (FWGE) is a complementary agent that has shown efficacy in several malignancies, including lymphoma. Here, we utilize a more potent FWGE derivative, known as fermented wheat germ protein (FWGP), in combination with the HDACi AR42, to assess for enhanced activity. We report increased in vitro killing, cell cycle arrest, and in vivo efficacy for this combination compared to each agent alone with minimal toxicity, suggesting a potentially new, minimally toxic treatment modality for lymphoma.

Efficacy of HDAC Inhibitors in Driving Peroxisomal β-Oxidation and Immune Responses in Human Macrophages: Implications for Neuroinflammatory Disorders

Elevated levels of saturated very long-chain fatty acids (VLCFAs) in cell membranes and secreted lipoparticles have been associated with neurotoxicity and, therefore, require tight regulation. Excessive VLCFAs are imported into peroxisomes for degradation by β-oxidation. Impaired VLCFA catabolism due to primary or secondary peroxisomal alterations is featured in neurodegenerative and neuroinflammatory disorders such as X-linked adrenoleukodystrophy and multiple sclerosis (MS). Here, we identified that healthy human macrophages upregulate the peroxisomal genes involved in β-oxidation during myelin phagocytosis and pro-inflammatory activation, and that this response is impaired in peripheral macrophages and phagocytes in brain white matter lesions in MS patients. The pharmacological targeting of VLCFA metabolism and peroxisomes in innate immune cells could be favorable in the context of neuroinflammation and neurodegeneration. We previously identified the epigenetic histone deacetylase (HDAC) inhibitors entinostat and vorinostat to enhance VLCFA degradation and pro-regenerative macrophage polarization. However, adverse side effects currently limit their use in chronic neuroinflammation. Here, we focused on tefinostat, a monocyte/macrophage-selective HDAC inhibitor that has shown reduced toxicity in clinical trials. By using a gene expression analysis, peroxisomal β-oxidation assay, and live imaging of primary human macrophages, we assessed the efficacy of tefinostat in modulating VLCFA metabolism, phagocytosis, chemotaxis, and immune function. Our results revealed the significant stimulation of VLCFA degradation with the upregulation of genes involved in peroxisomal β-oxidation and interference with immune cell recruitment; however, tefinostat was less potent than the class I HDAC-selective inhibitor entinostat in promoting a regenerative macrophage phenotype. Further research is needed to fully explore the potential of class I HDAC inhibition and downstream targets in the context of neuroinflammation.

Advances in Hodgkin's lymphoma pharmacotherapy: a focus on histone deacetylase inhibitors

INTRODUCTION

Classical Hodgkin lymphomas (cHL) usually have excellent cure rates. Yet, for patients with refractory or relapsed cHL, prognosis deteriorates as the disease becomes resistant to subsequent lines of therapies: autologous stem cell transplantation, brentuximab vedotin, and checkpoint inhibitors. Immune escape and drug resistance are hallmarks of Hodgkin Reed Sternberg cell survival, prompting the need for additional therapeutic strategies. Histone modification-based combination is an effective clinical strategy.

AREAS COVERED

In this review, we discuss the different histone deacetylase (HDAC) inhibitor molecules that have been developed and studied in cancer therapy with a focus on cHL. We review their preclinical and clinical activities both as single agents and in combination studies. Literature search was conducted in PubMed, Google Scholar, and ClinicalTrials.gov databases, using search terms 'Hodgkin lymphoma,' 'histone deacetylase inhibitor', and variations on such (e.g. 'HDAC' and individual drug names) in combination using operators 'AND,' 'OR,' and 'NOT' according to Boolean logic.

EXPERT OPINION

HDAC inhibitors alone will not be sufficient for the treatment of R/RcHL, but given their disease control capacity, synergistic interaction with currently approved drugs, and ability to overcome drug resistance, particularly PD-1 inhibitors, we believe that HDACinhibitors will eventually become incorporated into the treatment armamentarium of cHL.

Epigenetic targets in B- and T-cell lymphomas: latest developments

Non-Hodgkin's lymphomas (NHLs) comprise a diverse group of diseases, either of mature B-cell or of T-cell derivation, characterized by heterogeneous molecular features and clinical manifestations. While most of the patients are responsive to standard chemotherapy, immunotherapy, radiation and/or stem cell transplantation, relapsed and/or refractory cases still have a dismal outcome. Deep sequencing analysis have pointed out that epigenetic dysregulations, including mutations in epigenetic enzymes, such as chromatin modifiers and DNA methyltransferases (DNMTs), are prevalent in both B- cell and T-cell lymphomas. Accordingly, over the past decade, a large number of epigenetic-modifying agents have been developed and introduced into the clinical management of these entities, and a few specific inhibitors have already been approved for clinical use. Here we summarize the main epigenetic alterations described in B- and T-NHL, that further supported the clinical development of a selected set of epidrugs in determined diseases, including inhibitors of DNMTs, histone deacetylases (HDACs), and extra-terminal domain proteins (bromodomain and extra-terminal motif; BETs). Finally, we highlight the most promising future directions of research in this area, explaining how bioinformatics approaches can help to identify new epigenetic targets in B- and T-cell lymphoid neoplasms.

New molecular targets in Hodgkin and Reed-Sternberg cells

Recent discoveries shed light on molecular mechanisms responsible for classical Hodgkin lymphoma (HL) development and progression, along with features of Hodgkin - Reed and Sternberg cells (HRS). Here, we summarize current knowledge on characteristic molecular alterations in HL, as well as existing targeted therapies and potential novel treatments for this disease. We discuss the importance of cluster of differentiation molecule 30 (CD30) and the programmed cell death-1 protein (PD-1) and ligands (PD-L1/2), and other molecules involved in immune modulation in HL. We highlight emerging evidence indicating that the altered function of SWI/SNF-type chromatin remodeling complexes, PRC2, and other epigenetic modifiers, contribute to variations in chromatin status, which are typical for HL. We postulate that despite of the existence of plentiful molecular data, the understanding of HL development remains incomplete. We therefore propose research directions involving analysis of reverse signaling in the PD-1/PD-L1 mechanism, chromatin remodeling, and epigenetics-related alterations, in order to identify HL features at the molecular level. Such attempts may lead to the identification of new molecular targets, and thus will likely substantially contribute to the future development of more effective targeted therapies.

Class I HDAC inhibitor entinostat synergizes with PLK1 inhibitors in MYC-amplified medulloblastoma cells

PURPOSE

We and others have demonstrated that MYC-amplified medulloblastoma (MB) cells are susceptible to class I histone deacetylase inhibitor (HDACi) treatment. However, single drug treatment with HDACi has shown limited clinical efficacy. We hypothesized that addition of a second compound acting synergistically with HDACi may enhance efficacy.

METHODS

We used a gene expression dataset to identify PLK1 as a second target in MB cells and validated the relevance of PLK1 in MB. We measured cell metabolic activity, viability, and cycle progression in MB cells after treatment with PLK1-specific inhibitors (PLK1i). Chou-Talalay synergy calculations were used to determine the nature of class I HDACi entinostat and PLK1i interaction which was validated. Finally, the clinical potential of the combination was assessed in the in vivo experiment.

RESULTS

MYC-amplified tumor cells are highly sensitive towards treatment with ATP-competitive PLK1i as a monotherapy. Entinostat and PLK1i in combination act synergistically in MYC-driven MB cells, exerting cytotoxic effects at clinically relevant concentrations. The downstream effect is exerted via MYC-related pathways, pointing out the potential of MYC amplification as a clinically feasible predictive biomarker for patient selection. While entinostat significantly extended survival of mice implanted with orthotopic MYC-amplified MB PDX, there was no evidence of the improvement of survival when treating the animals with the combination.

CONCLUSION

The combination of entinostat and PLK1i showed synergistic interaction in vitro, but not in vivo. Therefore, further screening of blood-brain barrier penetrating PLK1i is warranted to determine the true potential of the combination as no on-target activity was observed after PLK1i volasertib treatment in vivo.

Targeting Class I Histone Deacetylases in Human Uterine Leiomyosarcoma

Uterine leiomyosarcoma (uLMS) is the most frequent subtype of uterine sarcoma that presents a poor prognosis, high rates of recurrence, and metastasis. Currently, the molecular mechanism of the origin and development of uLMS is unknown. Class I histone deacetylases (including HDAC1, 2, 3, and 8) are one of the major classes of the HDAC family and catalyze the removal of acetyl groups from lysine residues in histones and cellular proteins. Class I HDACs exhibit distinct cellular and subcellular expression patterns and are involved in many biological processes and diseases through diverse signaling pathways. However, the link between class I HDACs and uLMS is still being determined. In this study, we assessed the expression panel of Class I HDACs in uLMS and characterized the role and mechanism of class I HDACs in the pathogenesis of uLMS. Immunohistochemistry analysis revealed that HDAC1, 2, and 3 are aberrantly upregulated in uLMS tissues compared to adjacent myometrium. Immunoblot analysis demonstrated that the expression levels of HDAC 1, 2, and 3 exhibited a graded increase from normal and benign to malignant uterine tumor cells. Furthermore, inhibition of HDACs with Class I HDACs inhibitor (Tucidinostat) decreased the uLMS proliferation in a dose-dependent manner. Notably, gene set enrichment analysis of differentially expressed genes (DEGs) revealed that inhibition of HDACs with Tucidinostat altered several critical pathways. Moreover, multiple epigenetic analyses suggested that Tucidinostat may alter the transcriptome via reprogramming the oncogenic epigenome and inducing the changes in microRNA-target interaction in uLMS cells. In the parallel study, we also determined the effect of DL-sulforaphane on the uLMS. Our study demonstrated the relevance of class I HDACs proteins in the pathogenesis of malignant uLMS. Further understanding the role and mechanism of HDACs in uLMS may provide a promising and novel strategy for treating patients with this aggressive uterine cancer.

The emerging role of histone deacetylase 1 in allergic diseases

Histone deacetylase 1 (HDAC1) is a unique member of the classes I HDACs and helps to regulate acute and chronic adaptation to environmental stimuli such as allergen, stress. Allergic diseases are complex diseases resulting from the effect of multiple genetic and interacting foreign substances. Epigenetics play an important role in both pathological and immunomodulatory conditions of allergic diseases. To be consistent with this role, recent evidence strongly suggests that histone deacetylase 1 (HDAC1) plays a critical role in allergic response. HDAC1 expression is stimulated by allergen and attributes to increase T helper 2 (Th2) cytokine levels, decrease Th1/Th17 cells and anti-inflammatory cytokine Interleukin-10 (IL-10), and TWIK-related potassium channel-1 (Trek-1) expression. This review focuses on the contribution of HDAC1 and the regulatory role in characterizing allergic endotypes with common molecular pathways and understanding allergic multimorbidity relationships, as well as addressing their potential as therapeutic targets for these conditions.

Leveraging modeling and simulation to optimize the therapeutic window for epigenetic modifier drugs

Dysregulated epigenetic processes can lead to altered gene expression and give rise to malignant transformation and tumorigenesis. Epigenetic drugs aim to revert the phenotype of cancer cells to normally functioning cells, and are developed and applied to treat both hematological and solid cancers. Despite this promising therapeutic avenue, the successful development of epigenetic modulators has been challenging. We argue that besides identifying the right responder patient population, the selection of an optimized dosing regimen is equally important. For the majority of epigenetic modulators, hematological adverse effects such as thrombocytopenia, anemia or neutropenia are frequently observed and may limit their therapeutic potential. Therefore, one of the key challenges is to identify a dosing regimen that maximizes drug efficacy and minimizes toxicity. This requires a good understanding of the quantitative relationship between the administered dose, the drug exposure and the magnitude and duration of drug response related to safety and efficacy. With case examples, we highlight how modeling and simulation has been successfully applied to address those questions. As an outlook, we suggest the combination of efficacy and safety prediction models that capture the quantitative, mechanistic relationships governing the balance between their safety and efficacy dynamics. A stepwise approach for its implementation is presented. Utilizing in silico explorations, the impact of dosing regimen on the therapeutic window can be explored. This will serve as a basis to select the most promising dosing regimen that maximizes efficacy while minimizing adverse effects and to increase the probability of success for the given epigenetic drug.

The Status and Prospects of Epigenetics in the Treatment of Lymphoma

The regulation of gene transcription by epigenetic modifications is closely related to many important life processes and is a hot research topic in the post-genomic era. Since the emergence of international epigenetic research in the 1990s, scientists have identified a variety of chromatin-modifying enzymes and recognition factors, and have systematically investigated their three-dimensional structures, substrate specificity, and mechanisms of enzyme activity regulation. Studies of the human tumor genome have revealed the close association of epigenetic factors with various malignancies, and we have focused more on mutations in epigenetically related regulatory enzymes and regulatory recognition factors in lymphomas. A number of studies have shown that epigenetic alterations are indeed widespread in the development and progression of lymphoma and understanding these mechanisms can help guide clinical efforts. In contrast to chemotherapy which induces cytotoxicity, epigenetic therapy has the potential to affect multiple cellular processes simultaneously, by reprogramming cells to achieve a therapeutic effect in lymphoma. Epigenetic monotherapy has shown promising results in previous clinical trials, and several epigenetic agents have been approved for use in the treatment of lymphoma. In addition, epigenetic therapies in combination with chemotherapy and/or immunotherapy have been used in various clinical trials. In this review, we present several important epigenetic modalities of regulation associated with lymphoma, summarize the corresponding epigenetic drugs in lymphoma, and look at the future of epigenetic therapies in lymphoma.

Synthesis, Molecular Docking and Biological Characterization of Pyrazine Linked 2-Aminobenzamides as New Class I Selective Histone Deacetylase (HDAC) Inhibitors with Anti-Leukemic Activity

Class I histone deacetylases (HDACs) are key regulators of cell proliferation and they are frequently dysregulated in cancer cells. We report here the synthesis of a novel series of class-I selective HDAC inhibitors (HDACi) containing a 2-aminobenzamide moiety as a zinc-binding group connected with a central (piperazin-1-yl)pyrazine or (piperazin-1-yl)pyrimidine moiety. Some of the compounds were additionally substituted with an aromatic capping group. Compounds were tested in vitro against human HDAC1, 2, 3, and 8 enzymes and compared to reference class I HDACi (Entinostat (MS-275), Mocetinostat, CI994 and RGFP-966). The most promising compounds were found to be highly selective against HDAC1, 2 and 3 over the remaining HDAC subtypes from other classes. Molecular docking studies and MD simulations were performed to rationalize the in vitro data and to deduce a complete structure activity relationship (SAR) analysis of this novel series of class-I HDACi. The most potent compounds, including 19f, which blocks HDAC1, HDAC2, and HDAC3, as well as the selective HDAC1/HDAC2 inhibitors 21a and 29b, were selected for further cellular testing against human acute myeloid leukemia (AML) and erythroleukemic cancer (HEL) cells, taking into consideration their low toxicity against human embryonic HEK293 cells. We found that 19f is superior to the clinically tested class-I HDACi Entinostat (MS-275). Thus, 19f is a new and specific HDACi with the potential to eliminate blood cancer cells of various origins.

Dissecting Histone Deacetylase 3 in Multiple Disease Conditions: Selective Inhibition as a Promising Therapeutic Strategy

The acetylation of histone and non-histone proteins has been implicated in several disease states. Modulation of such epigenetic modifications has therefore made histone deacetylases (HDACs) important drug targets. HDAC3, among various class I HDACs, has been signified as a potentially validated target in multiple diseases, namely, cancer, neurodegenerative diseases, diabetes, obesity, cardiovascular disorders, autoimmune diseases, inflammatory diseases, parasitic infections, and HIV. However, only a handful of HDAC3-selective inhibitors have been reported in spite of continuous efforts in design and development of HDAC3-selective inhibitors. In this Perspective, the roles of HDAC3 in various diseases as well as numerous potent and HDAC3-selective inhibitors have been discussed in detail. It will surely open up a new vista in the discovery of newer, more effective, and more selective HDAC3 inhibitors.

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.

The application of histone deacetylases inhibitors in glioblastoma

The epigenetic abnormality is generally accepted as the key to cancer initiation. Epigenetics that ensure the somatic inheritance of differentiated state is defined as a crucial factor influencing malignant phenotype without altering genotype. Histone modification is one such alteration playing an essential role in tumor formation, progression, and resistance to treatment. Notably, changes in histone acetylation have been strongly linked to gene expression, cell cycle, and carcinogenesis. The balance of two types of enzyme, histone acetyltransferases (HATs) and histone deacetylases (HDACs), determines the stage of histone acetylation and then the architecture of chromatin. Changes in chromatin structure result in transcriptional dysregulation of genes that are involved in cell-cycle progression, differentiation, apoptosis, and so on. Recently, HDAC inhibitors (HDACis) are identified as novel agents to keep this balance, leading to numerous researches on it for more effective strategies against cancers, including glioblastoma (GBM). This review elaborated influences on gene expression and tumorigenesis by acetylation and the antitumor mechanism of HDACis. Besdes, we outlined the preclinical and clinical advancement of HDACis in GBM as monotherapies and combination therapies.

Safety and Efficacy of Brentuximab Vedotin in the Treatment of Classic Hodgkin Lymphoma

Classical Hodgkin lymphoma (cHL) is a B-cell-derived lymphoid malignancy with the most favorable prognosis among various adult malignancies. However, once it becomes refractory disease to chemotherapy or relapses after high-dose chemotherapy (HDC) with autologous stem cell transplantation (ASCT), it is difficult to manage with conventional cytotoxic chemotherapy. The introduction of brentuximab vedotin (BV) has changed the treatment landscape of cHL in the past decade. Several studies demonstrated high efficacy of BV monotherapy in heavily treated patients with cHL relapsed or refractory after HDC/ASCT. Recent studies also reported high efficacy of concurrent or sequential combination of BV and chemotherapy in patients with transplant-eligible relapsed/refractory cHL at the second-line setting. In addition, a randomized phase III trial ECHELON-1 reported a positive result of BV in combination with AVD (doxorubicin, vinblastine, and dacarbazine) in patients with newly diagnosed advanced-stage cHL. In this review, we summarize available data of BV for cHL and discuss the current and future role of BV in the management of cHL.

Searching the Link for Better Therapeutic Combination: The Case of Tumor Cells Migration Pattern and Modality of Immunosuppression Induction at the Metastatic Site

Cancer is a disease characterized by its high morbidity and mortality, mainly due to its metastatic ability. Metastasis is a multi-step process beginning with detachment of tumor cells from the primary tumor and leading ultimately to the establishment of a new tumoral site. This cascade includes intravascular migration of tumor cells either individually or collectively and the expansion of cancer cells at metastatic sites that is dependent on certain conditions such as an immunosuppressive environment. In this paper, blockers of tumor cell migration and suppressors of immunotolerance at metastatic sites are reviewed as an illustration of early and later phases intervention, respectively. A combination of these two therapeutics will be advocated based on the proposition of correlation between the pattern of tumor cell migration and the mechanism of immunotolerance induction. By extension, the ''delayed complementarity'' will be introduced as an approach to formulate new anticancer drug combinations.

Optimizing outcomes in relapsed/refractory Hodgkin lymphoma: a review of current and forthcoming therapeutic strategies

The outcome of patients with relapsed/refractory classical Hodgkin lymphoma (rr-cHL) has improved considerably in recent years owing to the approval of highly active novel agents such as brentuximab vedotin and Programmed Death-1 (PD-1) inhibitors. Although no randomized trials have been conducted to provide formal proof, it is almost undisputable that the survival of these patients has been prolonged. As autologous stem-cell transplantation (SCT) remains the standard of care for second-line therapy of most patients with rr-cHL, optimization of second-line regimens with the use of brentuximab vedotin, or, in the future, checkpoint inhibitors, is promising to increase both the eligibility rate for transplant and the final outcome. The need for subsequent therapy, and especially allogeneic SCT, can be reduced with brentuximab vedotin consolidation for 1 year, while pembrolizumab is also being tested in this setting. Several other drug categories appear to be active in rr-cHL, but their development has been delayed by the appearance of brentuximab vedotin, nivolumab and pembrolizumab, which have dominated the field of rr-cHL treatment in the last 5 years. Combinations of active drugs in chemo-free approaches may further increase efficacy and hopefully reduce toxicity in rr-cHL, but are still under development.

Targeting epigenetic regulators in the treatment of T-cell lymphoma

Introduction: T-cell lymphomas represent a broad group of malignant T-cell neoplasms with marked molecular, clinical, and biologic heterogeneity. Survival rates after conventional chemotherapy regimens are poor for most subtypes and new therapies are needed. Rapidly expanding knowledge in the field of epigenomics and the development of an increasing number of epigenetic-modifying agents have created new opportunities for epigenetic therapies for patients with this complex group of diseases.Areas covered: The present review summarizes current knowledge on epigenetic alterations in T-cell lymphomas, availability, and mechanisms of action of epigenetic-modifying agents, results of clinical trials of epigenetic therapies in T-cell lymphomas, status of FDA approval, and biomarker approaches to guide therapy. Promising future directions are discussed.Expert opinion: Mutations in epigenetic-modifying genes are among the most common genetic alterations in T-cell lymphomas, highlighting the potential for epigenetic therapies to improve management of this group of diseases. Single-agent efficacy is well documented, leading to FDA approval for several indications, but overall response rates and durability of responses remain modest. Critical next steps for the field include optimizing combination therapies that incorporate epigenetic-modifying agents and developing predictive biomarkers that help guide patient and drug selection.

Drug screening approach combines epigenetic sensitization with immunochemotherapy in cancer

BACKGROUND

The epigenome plays a key role in cancer heterogeneity and drug resistance. Hence, a number of epigenetic inhibitors have been developed and tested in cancers. The major focus of most studies so far has been on the cytotoxic effect of these compounds, and only few have investigated the ability to revert the resistant phenotype in cancer cells. Hence, there is a need for a systematic methodology to unravel the mechanisms behind epigenetic sensitization.

RESULTS

We have developed a high-throughput protocol to screen non-simultaneous drug combinations, and used it to investigate the reprogramming potential of epigenetic inhibitors. We demonstrated the effectiveness of our protocol by screening 60 epigenetic compounds on diffuse large B-cell lymphoma (DLBCL) cells. We identified several histone deacetylase (HDAC) and histone methyltransferase (HMT) inhibitors that acted synergistically with doxorubicin and rituximab. These two classes of epigenetic inhibitors achieved sensitization by disrupting DNA repair, cell cycle, and apoptotic signaling. The data used to perform these analyses are easily browsable through our Results Explorer. Additionally, we showed that these inhibitors achieve sensitization at lower doses than those required to induce cytotoxicity.

CONCLUSIONS

Our drug screening approach provides a systematic framework to test non-simultaneous drug combinations. This methodology identified HDAC and HMT inhibitors as successful sensitizing compounds in treatment-resistant DLBCL. Further investigation into the mechanisms behind successful epigenetic sensitization highlighted DNA repair, cell cycle, and apoptosis as the most dysregulated pathways. Altogether, our method adds supporting evidence in the use of epigenetic inhibitors as sensitizing agents in clinical settings.

Class I HDAC inhibitors enhance YB-1 acetylation and oxidative stress to block sarcoma metastasis

Outcomes for metastatic Ewing sarcoma and osteosarcoma are dismal and have not changed for decades. Oxidative stress attenuates melanoma metastasis, and melanoma cells must reduce oxidative stress to metastasize. We explored this in sarcomas by screening for oxidative stress sensitizers, which identified the class I HDAC inhibitor MS-275 as enhancing vulnerability to reactive oxygen species (ROS) in sarcoma cells. Mechanistically, MS-275 inhibits YB-1 deacetylation, decreasing its binding to 5'-UTRs of NFE2L2 encoding the antioxidant factor NRF2, thereby reducing NFE2L2 translation and synthesis of NRF2 to increase cellular ROS. By global acetylomics, MS-275 promotes rapid acetylation of the YB-1 RNA-binding protein at lysine-81, blocking binding and translational activation of NFE2L2, as well as known YB-1 mRNA targets, HIF1A, and the stress granule nucleator, G3BP1. MS-275 dramatically reduces sarcoma metastasis in vivo, but an MS-275-resistant YB-1K81-to-alanine mutant restores metastatic capacity and NRF2, HIF1α, and G3BP1 synthesis in MS-275-treated mice. These studies describe a novel function for MS-275 through enhanced YB-1 acetylation, thus inhibiting YB-1 translational control of key cytoprotective factors and its pro-metastatic activity.

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.

NOD-like receptor signaling in inflammation-associated cancers: From functions to targeted therapies

BACKGROUND

Recently, many studies have reported that some botanicals and natural products were able to regulate NOD-like receptor signaling. NOD-like receptors (NLRs) have been established as crucial regulators in inflammation-associated tumorigenesis, angiogenesis, cancer cell stemness and chemoresistance. NLRs specifically sense pathogen-associated molecular patterns and respond by activating other signaling regulators, including Rip2 kinase, NF-κB, MAPK and ASC/caspase-1, leading to the secretion of various cytokines.

PURPOSE

The aim of this article is to review the molecular mechanisms of NOD-like receptor signaling in inflammation-associated cancers and the NLRs-targeted botanicals and synthetic small molecules in cancer intervention.

RESULTS

Aberrant activation of NLRs occurs in various cancers, orchestrating the tissue microenvironment and potentiating neoplastic risk. Blocking NLR inflammasome activation by botanicals or synthetic small molecules may be a valuable way to prevent cancer progression. Moreover, due to the roles of NLRs in regulating cytokine production, NLR signaling may be correlated with senescence-associated secretory phenotype.

CONCLUSION

In this review, we discuss how NLR signaling is involved in inflammation-associated cancers, and highlight the NLR-targeted botanicals and synthetic small molecules in cancer intervention.

Recent Advances in the Targeting of Epigenetic Regulators in B-Cell Non-Hodgkin Lymphoma

In the last 10 years, major advances have been made in the diagnosis and development of selective therapies for several blood cancers, including B-cell non-Hodgkin lymphoma (B-NHL), a heterogeneous group of malignancies arising from the mature B lymphocyte compartment. However, most of these entities remain incurable and current treatments are associated with variable efficacy, several adverse events, and frequent relapses. Thus, new diagnostic paradigms and novel therapeutic options are required to improve the prognosis of patients with B-NHL. With the recent deciphering of the mutational landscapes of B-cell disorders by high-throughput sequencing, it came out that different epigenetic deregulations might drive and/or promote B lymphomagenesis. Consistently, over the last decade, numerous epigenetic drugs (or epidrugs) have emerged in the clinical management of B-NHL patients. In this review, we will present an overview of the most relevant epidrugs tested and/or used so far for the treatment of different subtypes of B-NHL, from first-generation epigenetic therapies like histone acetyl transferases (HDACs) or DNA-methyl transferases (DNMTs) inhibitors to new agents showing selectivity for proteins that are mutated, translocated, and/or overexpressed in these diseases, including EZH2, BET, and PRMT. We will dissect the mechanisms of action of these epigenetic inhibitors, as well as the molecular processes underlying their lack of efficacy in refractory patients. This review will also provide a summary of the latest strategies being employed in preclinical and clinical settings, and will point out the most promising lines of investigation in the field.

Epigenetic Metalloenzymes

Epigenetics controls the expression of genes and is responsible for cellular phenotypes. The fundamental basis of these mechanisms involves in part the post-translational modifications (PTMs) of DNA and proteins, in particular, the nuclear histones. DNA can be methylated or demethylated on cytosine. Histones are marked by several modifications including acetylation and/or methylation, and of particular importance are the covalent modifications of lysine. There exists a balance between addition and removal of these PTMs, leading to three groups of enzymes involved in these processes: the writers adding marks, the erasers removing them, and the readers able to detect these marks and participating in the recruitment of transcription factors. The stimulation or the repression in the expression of genes is thus the result of a subtle equilibrium between all the possibilities coming from the combinations of these PTMs. Indeed, these mechanisms can be deregulated and then participate in the appearance, development and maintenance of various human diseases, including cancers, neurological and metabolic disorders. Some of the key players in epigenetics are metalloenzymes, belonging mostly to the group of erasers: the zinc-dependent histone deacetylases (HDACs), the iron-dependent lysine demethylases of the Jumonji family (JMJ or KDM) and for DNA the iron-dependent ten-eleven-translocation enzymes (TET) responsible for the oxidation of methylcytosine prior to the demethylation of DNA. This review presents these metalloenzymes, their importance in human disease and their inhibitors.

HDAC inhibitors as antifibrotic drugs in cardiac and pulmonary fibrosis

Fibrosis usually results from dysregulated wound repair and is characterized by excessive scar tissue. It is a complex process with unclear mechanisms. Accumulating evidence indicates that epigenetic alterations, including histone acetylation, play a pivotal role in this process. Histone acetylation is governed by histone acetyltransferases (HATs) and histone deacetylases (HDACs). HDACs are enzymes that remove the acetyl groups from both histone and nonhistone proteins. Aberrant HDAC activities are observed in fibrotic diseases, including cardiac and pulmonary fibrosis. HDAC inhibitors (HDACIs) are molecules that block HDAC functions. HDACIs have been studied extensively in a variety of tumors. Currently, there are four HDACIs approved by the US Food and Drug Administration for cancer treatment yet none for fibrotic diseases. Emerging evidence from in vitro and in vivo preclinical studies has presented beneficial effects of HDACIs in preventing or reversing fibrogenesis. In this review, we summarize the latest findings of the roles of HDACs in the pathogenesis of cardiac and pulmonary fibrosis and highlight the potential applications of HDACIs in these two fibrotic diseases.

Immune Checkpoint Inhibition in Classical Hodgkin Lymphoma: From Early Achievements towards New Perspectives

Immune checkpoint inhibition (ICI) became one of the major breakthroughs in cancer treatment over the past decade and entered into therapy within standard oncohematology practice. ICI has demonstrated impressive response rates as salvage therapy in relapsed/refractory (R/R) classical Hodgkin lymphoma (cHL) and is now being tested as an adjunction to chemotherapy in the frontline settings. CHL exquisite sensitivity to PD-1/PD-L1 axis inhibition relies on a particular biological background. By contrast, non-Hodgkin lymphomas (NHL) have demonstrated heterogeneous response rates using ICI. These observations highlight discrepancies between various types of lymphomas in terms of genetic alterations, immune microenvironment interactions, and disease phenotype. This review aims to focus on cHL immune escape mechanisms, focusing on cHL biological sensitivity to PD-1 blockade. We will summarize the available data issued from clinical trials on ICI in cHL and its safety profile. Going beyond the current use of monoclonal antibodies (mAb) targeting immune checkpoints in clinical practice, we will offer an overview of new combinatory therapeutic perspectives where cHL immunotherapy may be considered.

Epigenetic changes: An emerging potential pharmacological target in allergic rhinitis

The importance of epigenetics has increased due to identification of its role in the pathophysiology of a number of diseases including allergic rhinitis. Amongst the different epigenetic changes in allergic retinitis, deacetylation of histone proteins by histone deacetylase (HDACs), hypermethylation of DNA by DNA methyltransferases (DNMT) and alteration in post-transcriptional process by the changes in the levels of miRNA are widely studied. Studies conducted related to allergic rhinitis have shown the elevation in the levels of HDAC1, 3 and 11 in the nasal epithelia and HDAC inhibitors have shown effectiveness in decreasing the symptoms of rhinitis. Their beneficial effects are attributed to restoration of the expression of TWIK-related potassium channel-1, correction of cytokine profile along with normalization of Th1/Th2 imbalance. Another epigenetic change due to increase in DNMT activity may induce DNA hypermethylation in CpG sites in the airway epithelial cells and CD4⁺ T-cells. The reduction in DNA methylation decreases allergic symptoms and normalizes the over-reactive immune system. Mechanistically, allergens may promote the hypermethylation in the promoter region of IFN-γ gene in CD4⁺ T cells via activation of ERK pathway to decrease the expression of IFN-γ. In allergic rhinitis patients, there is also a downregulation of certain miRNAs including miR-135a, miR-146a, miR-181a, miR-155 and upregulation of miRNA19a. This review discusses the studies describing the epigenetic changes taking place in the host cells in response to allergen along with possible mechanisms.

Quantitative Chemotherapeutic Profiling of Gynecologic Cancer Cell Lines Using Approved Drugs and Bioactive Compounds

Heterogeneous response to chemotherapy is a major issue for the treatment of cancer. For most gynecologic cancers including ovarian, cervical, and placental, the list of available small molecule therapies is relatively small compared to options for other cancers. While overall cancer mortality rates have decreased in the United States as early diagnoses and cancer therapies have become more effective, ovarian cancer still has low survival rates due to the lack of effective treatment options, drug resistance, and late diagnosis. To understand chemotherapeutic diversity in gynecologic cancers, we have screened 7914 approved drugs and bioactive compounds in 11 gynecologic cancer cell lines to profile their chemotherapeutic sensitivity. We identified two HDAC inhibitors, mocetinostat and entinostat, as pan-gynecologic cancer suppressors with IC50 values within an order of magnitude of their human plasma concentrations. In addition, many active compounds identified, including the non-anticancer drugs and other compounds, diversely inhibited the growth of three gynecologic cancer cell groups and individual cancer cell lines. These newly identified compounds are valuable for further studies of new therapeutics development, synergistic drug combinations, and new target identification for gynecologic cancers. The results also provide a rationale for the personalized chemotherapeutic testing of anticancer drugs in treatment of gynecologic cancer.

Targeting cancer stem cells and their niche: perspectives for future therapeutic targets and strategies

A small subpopulation of cells within the bulk of tumors share features with somatic stem cells, in that, they are capable of self-renewal, they differentiate, and are highly resistant to conventional therapy. These cells have been referred to as cancer stem cells (CSCs). Recent reports support the central importance of a cancer stem cell-like niche that appears to help foster the generation and maintenance of CSCs. In response to signals provided by this microenvironment, CSCs express the tumorigenic characteristics that can drive tumor metastasis by the induction of epithelial-mesenchymal-transition (EMT) that in turn fosters the migration and recolonization of the cells as secondary tumors within metastatic niches. We summarize here recent advances in cancer stem cell research including the characterization of their genetic and epigenetic features, metabolic specialities, and crosstalk with aging-associated processes. Potential strategies for targeting CSCs, and their niche, by regulating CSCs plasticity, or therapeutic sensitivity is discussed. Finally, it is hoped that new strategies and related therapeutic approaches as outlined here may help prevent the formation of the metastatic niche, as well as counter tumor progression and metastatic growth.

SOHO State of the Art Updates and Next Questions: Hodgkin Lymphoma

Until recently, advances in classic Hodgkin lymphoma (HL) treatment primarily consisted of minor modifications of highly effective decades-old chemotherapy and radiation approaches. In early-stage disease, excellent outcomes have been reported with fewer cycles of chemotherapy, lower doses, smaller radiation fields and in some circumstances, radiation elimination. In advanced-stage disease, maintaining the dose intensity of standard chemotherapy regimens has resulted in modest improvements in outcomes. During the past decade, the use of early interim positron emission tomography (PET) scans to escalate or de-escalate treatment has been the subject of intense investigation with the goal of maximizing efficacy and minimizing toxicity. Important updates from recent PET-directed trials include; elimination of bleomycin in patients with advanced-stage HL and negative interim PET findings, the benefit of therapy escalation in patients with unfavorable early-stage HL and positive interim PET findings, and the minimal benefit of consolidative radiotherapy in patients with unfavorable early-stage HL and negative interim PET findings. A more nuanced approach to consolidative radiotherapy is required for patients with favorable early-stage disease based on age, disease sites, secondary cancer risk, and cardiovascular disease. Brentuximab vedotin and nivolumab/pembrolizumab have provided promising new options with surprisingly high response rates and modest toxicity for patients with relapsed HL whose disease does not respond to standard treatments. Incorporating these agents into earlier therapy is an area of active investigation for all stages of HL. Although the overall prognosis for HL patients has seen incremental improvement, efforts to optimize treatment with more effective and less toxic approaches continue.

Antiproliferative effects of TSA, PXD‑101 and MS‑275 in A2780 and MCF7 cells: Acetylated histone H4 and acetylated tubulin as markers for HDACi potency and selectivity

Inhibition of histone deacetylase enzymes (HDACs) has been well documented as an attractive target for the development of chemotherapeutic drugs. The present study investigated the effects of two prototype hydroxamic acid HDAC inhibitors, namely Trichostatin A (TSA) and Belinostat (PXD-101) and the benzamide Entinostat (MS-275) in A2780 ovarian carcinoma and MCF7 breast adenocarcinoma cells. The three HDACi inhibited the proliferation of A2780 and MCF7 cells at comparable levels, below the µM range. Enzyme inhibition assays in a cell-free system showed that TSA was the most potent inhibitor of total HDAC enzyme activity followed by PXD-101 and MS-275. Incubation of A2780 and MCF7 cells with the hydroxamates TSA and PXD-101 for 24 h resulted in a dramatic increase of acetylated tubulin induction (up to 30-fold for TSA). In contrast to acetylated tubulin, western blot analysis and flow cytometry indicated that the induction of acetylated histone H4 was considerably smaller. The benzamide MS-275 exhibited nearly a 2-fold induction of acetylated histone H4 and an even smaller induction of acetylated tubulin in A2780 and MCF7 cells. Taken together, these data suggest that although the three HDACi were equipotent in inhibiting proliferation of MCF7 and A2780 cells, only the benzamide MS-275 did not induce acetylated tubulin expression, a marker of class IIb HDACs.

Epigenetics in cancer stem cells

Compelling evidence have demonstrated that bulk tumors can arise from a unique subset of cells commonly termed "cancer stem cells" that has been proposed to be a strong driving force of tumorigenesis and a key mechanism of therapeutic resistance. Recent advances in epigenomics have illuminated key mechanisms by which epigenetic regulation contribute to cancer progression. In this review, we present a discussion of how deregulation of various epigenetic pathways can contribute to cancer initiation and tumorigenesis, particularly with respect to maintenance and survival of cancer stem cells. This information, together with several promising clinical and preclinical trials of epigenetic modulating drugs, offer new possibilities for targeting cancer stem cells as well as improving cancer therapy overall.