A Multi-center Phase I Trial of Ipilimumab in Patients with Myelodysplastic Syndromes following Hypomethylating Agent Failure

Beyond HMAs: Novel Targets and Therapeutic Approaches

Myelodysplastic syndromes/neoplasms (MDS) constitute a heterogeneous group of clonal hematopoietic disorders with extremely variable clinical features and outcomes. Management of MDS is largely based on risk stratification of patients into either lower-risk or higher-risk categories using the International Prognostic Scoring System-Revised and, more recently, on the Molecular International Prognostic Scoring System. Lower-risk MDS is often managed with the goal of ameliorating cytopenias and improving quality of life, while higher-risk MDS is treated with therapies aimed at extending survival and delaying progression to acute myeloid leukemia (AML). Therapeutic strategies in lower-risk MDS patients may consist of erythropoiesis stimulating agents, luspatercept, and lenalidomide for selected patients. Furthermore, imetelstat has recently been added to the FDA-approved therapeutic armamentarium for lower-risk MDS. In higher-risk MDS, monotherapy with hypomethylating agents continues to be the standard of care. While several novel hypomethylating agent combinations have and are being studied in large randomized phase 3 clinical trials, including the combination of azacitidine and venetoclax, no combination to date have improved overall survival to azacitidine monotherapy. Moreover, biomarker-directed therapies as well as immonotherapeutic approaches are currently being evaluated in early phase trials. Despite recent advancements, the lack of therapeutic agents, particularly after the failure of first line therapy in higher risk MDS, continues to be a major hurdle in the management of MDS. In this review, we discuss the current treatment landscape of MDS and provide an overview of novel agents currently in clinical development that have the potential to alter our current treatment paradigms.

Targeted therapies for myelodysplastic syndromes/neoplasms (MDS): current landscape and future directions

INTRODUCTION

Myelodysplastic syndromes/neoplasms (MDS) are a heterogeneous group of hematologic malignancies that are stratified into high-risk (HR-MDS) and low-risk (LR-MDS) categories. Until recently, LR-MDS has been typically managed by supportive measures and erythropoiesis-stimulating agents (ESAs); whereas management of HR-MDS typically included hypomethylating agents and allogeneic hematopoietic stem cell transplant. However, the limited rates and durations of response observed with these interventions prompted the search for targeted therapies to improve the outcomes among patients with MDS.

AREAS COVERED

Here, we review the current landscape of targeted therapies in MDS. These include pyruvate kinase and hypoxia-inducible factor (HIF) activators; TGF-beta, telomerase, BCL2 and isocitrate dehydrogenase (IDH) inhibitors; as well as novel approaches targeting inflammation, pyroptosis, immune evasion, and RNA splicing machinery.

EXPERT OPINION

This review highlights the progress and challenges in MDS treatment. Despite some promising results, many therapies remain in early development or have faced setbacks, emphasizing the need for a more comprehensive understanding of the disease's pathobiology. Continued research into targeted therapies, homogenous clinical trial designs, as well as increased incorporation of molecular prognostic tools and artificial intelligence into trial design are essential for developing effective treatments for MDS and improving patient outcomes.

The immunobiology of myelodysplastic neoplasms: a mini-review

This mini review summarizes the immunobiology of myelodysplastic syndromes, specifically focusing on the interactions between immune cells, cytokines, and dysplastic cells within the tumor microenvironment in the bone marrow. We elucidate in detail how immune dysregulation and evasion influence the initiation and progression of myelodysplastic syndromes, as well as resistance to therapy and progression to AML. In addition, we highlight a range of therapeutic strategies, including the most recent breakthroughs and experimental therapies for treating MDS. Finally, we address the existing knowledge gaps in the understanding of the immunobiology of MDS and propose future research directions, promising advancements toward enhancing clinical outcomes and survival for patients with MDS.

BATF is a major driver of NK cell epigenetic reprogramming and dysfunction in AML

Myelodysplastic syndrome and acute myeloid leukemia (AML) belong to a continuous disease spectrum of myeloid malignancies with poor prognosis in the relapsed/refractory setting necessitating novel therapies. Natural killer (NK) cells from patients with myeloid malignancies display global dysfunction with impaired killing capacity, altered metabolism, and an exhausted phenotype at the single-cell transcriptomic and proteomic levels. In this study, we identified that this dysfunction was mediated through a cross-talk between NK cells and myeloid blasts necessitating cell-cell contact. NK cell dysfunction could be prevented by targeting the αvβ-integrin/TGF-β/SMAD pathway but, once established, was persistent because of profound epigenetic reprogramming. We identified BATF as a core transcription factor and the main mediator of this NK cell dysfunction in AML. Mechanistically, we found that BATF was directly regulated and induced by SMAD2/3 and, in turn, bound to key genes related to NK cell exhaustion, such as HAVCR2, LAG3, TIGIT, and CTLA4. BATF deletion enhanced NK cell function against AML in vitro and in vivo. Collectively, our findings reveal a previously unidentified mechanism of NK immune evasion in AML manifested by epigenetic rewiring and inactivation of NK cells by myeloid blasts. This work highlights the importance of using healthy allogeneic NK cells as an adoptive cell therapy to treat patients with myeloid malignancies combined with strategies aimed at preventing the dysfunction by targeting the TGF-β pathway or BATF.

Inflammation as a driver of hematological malignancies

Hematopoiesis is a tightly regulated process that produces all adult blood cells and immune cells from multipotent hematopoietic stem cells (HSCs). HSCs usually remain quiescent, and in the presence of external stimuli like infection or inflammation, they undergo division and differentiation as a compensatory mechanism. Normal hematopoiesis is impacted by systemic inflammation, which causes HSCs to transition from quiescence to emergency myelopoiesis. At the molecular level, inflammatory cytokine signaling molecules such as tumor necrosis factor (TNF), interferons, interleukins, and toll-like receptors can all cause HSCs to multiply directly. These cytokines actively encourage HSC activation, proliferation, and differentiation during inflammation, which results in the generation and activation of immune cells required to combat acute injury. The bone marrow niche provides numerous soluble and stromal cell signals, which are essential for maintaining normal homeostasis and output of the bone marrow cells. Inflammatory signals also impact this bone marrow microenvironment called the HSC niche to regulate the inflammatory-induced hematopoiesis. Continuous pro-inflammatory cytokine and chemokine activation can have detrimental effects on the hematopoietic system, which can lead to cancer development, HSC depletion, and bone marrow failure. Reactive oxygen species (ROS), which damage DNA and ultimately lead to the transformation of HSCs into cancerous cells, are produced due to chronic inflammation. The biological elements of the HSC niche produce pro-inflammatory cytokines that cause clonal growth and the development of leukemic stem cells (LSCs) in hematological malignancies. The processes underlying how inflammation affects hematological malignancies are still not fully understood. In this review, we emphasize the effects of inflammation on normal hematopoiesis, the part it plays in the development and progression of hematological malignancies, and potential therapeutic applications for targeting these pathways for therapy in hematological malignancies.

Beyond the horizon: emerging therapeutic approaches in myelodysplastic neoplasms

Management of myelodysplastic neoplasms (MDS) requires a personalized approach, with a focus on improving quality of life and extending lifespan. The International Prognostic Scoring System-Revised and the molecular International Prognostic Scoring System are key tools for risk stratification and management of MDS. They provide a framework for predicting survival and the risk of transformation to acute myeloid leukemia. However, a major challenge in MDS management remains the limited therapeutic options available, especially after the failure of first-line therapies. In lower-risk MDS, the failure of erythropoietin-stimulating agents often leaves few alternatives, although in higher-risk MDS, the prognosis after hypomethylating agent failure is dismal. This highlights the urgent need for novel, more personalized therapeutic approaches. In this review, we discuss emerging novel therapeutic approaches in the treatment of MDS. Several new therapeutic targets are currently being evaluated, offering hope for improved management of MDS in the future.

PD-1H/VISTA mediates immune evasion in acute myeloid leukemia

Acute myeloid leukemia (AML) presents a pressing medical need in that it is largely resistant to standard chemotherapy as well as modern therapeutics, such as targeted therapy and immunotherapy, including anti-programmed cell death protein (anti-PD) therapy. We demonstrate that programmed death-1 homolog (PD-1H), an immune coinhibitory molecule, is highly expressed in blasts from the bone marrow of AML patients, while normal myeloid cell subsets and T cells express PD-1H. In studies employing syngeneic and humanized AML mouse models, overexpression of PD-1H promoted the growth of AML cells, mainly by evading T cell-mediated immune responses. Importantly, ablation of AML cell-surface PD-1H by antibody blockade or genetic knockout significantly inhibited AML progression by promoting T cell activity. In addition, the genetic deletion of PD-1H from host normal myeloid cells inhibited AML progression, and the combination of PD-1H blockade with anti-PD therapy conferred a synergistic antileukemia effect. Our findings provide the basis for PD-1H as a potential therapeutic target for treating human AML.

Phase to phase: Navigating drug combinations with hypomethylating agents in higher-risk MDS trials for optimal outcomes

Recent developments in high-risk Myelodysplastic Neoplasms (HR MDS) treatment are confronted with challenges in study design due to evolving drug combinations with Hypomethylating Agents (HMAs). The shift from the International Prognostic Scoring System (IPSS) to its molecular revision (IPSS-M) has notably influenced research and clinical practice. Introducing concepts like the MDS/AML overlap complicate classifications and including chronic myelomonocytic leukemia (CMML) in MDS studies introduces another layer of complexity. The International Consortium for MDS emphasizes aligning HR MDS criteria with the 2022 ELN criteria for AML. Differences in advancements between AML and MDS treatments and hematological toxicity in HR MDS underline the importance of detailed trial designs. Effective therapeutic strategies require accurate reporting of adverse events, highlighting the need for clarity in criteria like the Common Terminology Criteria for Adverse Events (CTCAE). We provide an overview on negative clinical trials in HR MDS, analyze possible reasons and explore possibilities to optimize future clinical trials in this challenging patient population.

Immune checkpoint blockade in hematological malignancies: current state and future potential

Malignant cells are known to evade immune surveillance by engaging immune checkpoints which are negative regulators of the immune system. By restoring the T-lymphocyte mediated anti-tumor effect, immune checkpoint inhibitors (ICI) have revolutionized the treatment of solid tumors but have met rather modest success in hematological malignancies. Currently, the only FDA approved indications for ICI therapy are in classic hodgkin lymphoma and primary mediastinal B cell lymphoma. Multiple clinical trials have assessed ICI therapy alone and in combination with standard of care treatments in other lymphomas, plasma cell neoplasms and myeloid neoplasms but were noted to have limited efficacy. These trials mostly focused on PD-1/PDL-1 and CTLA-4 inhibitors. Recently, there has been an effort to target other T-lymphocyte checkpoints like LAG-3, TIM-3, TIGIT along with improving strategies of PD-1/PDL-1 and CTLA-4 inhibition. Drugs targeting the macrophage checkpoint, CD47, are also being tested. Long term safety and efficacy data from these ongoing studies are eagerly awaited. In this comprehensive review, we discuss the mechanism of immune checkpoint inhibitors, the key takeaways from the reported results of completed and ongoing studies of these therapies in the context of hematological malignancies.

Efficacy and Safety of Immune Checkpoint Inhibitors in Hematologic Malignancies

The emergence of immune checkpoint inhibitors (ICIs) has led to a dramatic paradigm shift within the landscape of cancer treatment, igniting significant interest in their potential application in treating hematologic malignancies. This comprehensive review critically has examined the existing body of literature to shed light on the evolving understanding of the efficacy and safety of ICIs, both as a single agent and in combination regimens in hematologic malignancies. Across distinct lymphoma subtypes, the observed treatment responses exhibit diversity, and conflicts. Notably, Hodgkin lymphoma and certain non-Hodgkin lymphomas such as primary mediastinal B-cell lymphoma, emerge as remarkable cases, showing encouraging response rates and outcomes. However, the efficacy of ICIs reveals variations among subtypes such as chronic lymphocytic leukemia and multiple myeloma. Combination therapies consistently demonstrated superior outcomes compared to monotherapy in several malignancies. While the potential benefits of ICIs in hematologic malignancies are evident, the safety profile warrants careful consideration. Immune-related and other adverse events, though generally tolerable and manageable, highlight the necessity of meticulous monitoring and appropriate intervention. The discussions prompted by these findings underscore the need for tailored treatment approaches, driven by disease subtype, patient characteristics, and potential biomarkers. Moreover, the emerging realm of combination therapies involving immune checkpoint inhibitors holds promise for enhanced treatment outcomes, and ongoing research endeavors aim to unravel the optimal strategies.

A multicenter phase Ib trial of the histone deacetylase inhibitor entinostat in combination with pembrolizumab in patients with myelodysplastic syndromes/neoplasms or acute myeloid leukemia refractory to hypomethylating agents

Patients with myelodysplastic syndromes/neoplasms (MDS) or acute myeloid leukemia (AML) with hypomethylating agent failure have a poor prognosis. Myeloid-derived suppressor cells (MDSCs) can contribute to MDS progression and mediate resistance to anti-PD1 therapy. As histone deacetylase inhibitors (HDACi) decrease MDSCs in preclinical models, we conducted an investigator-initiated, NCI-Cancer Therapy Evaluation Program-sponsored, multicenter, dose escalation, and expansion phase Ib trial (NCT02936752) of the HDACi entinostat and the anti-PD1 antibody pembrolizumab. Twenty-eight patients (25 MDS and 3 AML) were enrolled. During dose escalation (n=13 patients), there was one dose-limiting toxicity (DLT) on dose level (DL) 1 (G5 pneumonia/bronchoalveolar hemorrhage) and two DLTs at DL 2 (G3 pharyngeal mucositis and G3 anorexia). Per the 3 + 3 dose escalation design, DL 1 (entinostat 8 mg PO days 1 and 15 + pembrolizumab 200 mg IV day 1 every 21 days) was expanded and another 15 patients were enrolled. Hematologic adverse events (AEs) were common. The most common non-hematologic ≥G3 AEs were infection (32%), hypoxia/respiratory failure (11%), and dyspnea (11%). There were no protocol-defined responses among the 28 patients enrolled. Two patients achieved a marrow complete remission (mCR). Using a systems immunology approach with mass cytometry and machine learning analysis, mCR patients had increased classical monocytes and macrophages but there was no significant change of MDSCs. In conclusion, combining entinostat with pembrolizumab in patients with advanced MDS and AML was associated with limited clinical efficacy and substantial toxicity. Absence of an effect on MDSCs could be a potential explanation for the limited efficacy of this combination. ClinicalTrial.gov Identifier: NCT02936752.

Harnessing autologous immune effector mechanisms in acute myeloid leukemia: 2023 update of trials and tribulations

Numerous recent advances have been made in therapeutic approaches toward acute myeloid leukemia (AML). Since 2017, we have seen eleven novel Food & Drug Administration (FDA)-approved medications for AML, all of which extend beyond the classical cytarabine-based cytostatic chemotherapy. In the recent two decades, the role of immune surveillance in AML has been intensively investigated. The power of one's own innate and adaptive immunity has been harnessed pharmacologically toward the goal of clearance of AML cells. Specifically, pre-clinical studies have shown great promise for antibodies that disinhibit T cells and macrophages by blocking checkpoint receptors within the immunologic synapse, thereby resulting in the elimination of AML cells. Anti-CD33 CAR-T therapies and anti-CD3/CD123 bispecific antibodies have also exhibited encouraging results in pre-clinical and early clinical studies. However, despite these translational efforts, we currently have no immune-based therapies for AML on the market, with the exception of gemtuzumab ozogamicin. In this focused review, we discuss molecular target validation and the most relevant clinical updates for immune-based experimental therapeutics including anti-CD47 monoclonal antibodies, CAR-T therapies, and bispecific T cell engagers. We highlight barriers to the clinical translation of these therapies in AML, and we propose solutions to optimize the manufacturing and delivery of the most novel immune-based therapies in the pipeline.

Immunotherapy with Monoclonal Antibodies for Acute Myeloid Leukemia: A Work in Progress

In the last few years, molecularly targeted agents and immune-based treatments (ITs) have significantly changed the landscape of anti-cancer therapy. Indeed, ITs have been proven to be very effective when used against metastatic solid tumors, for which outcomes are extremely poor when using standard approaches. Such a scenario has only been partially reproduced in hematologic malignancies. In the context of acute myeloid leukemia (AML), as innovative drugs are eagerly awaited in the relapsed/refractory setting, different ITs have been explored, but the results are still unsatisfactory. In this work, we will discuss the most important clinical studies to date that adopt ITs in AML, providing the basis to understand how this approach, although still in its infancy, may represent a promising therapeutic tool for the future treatment of AML patients.

A Personalized Cancer Vaccine that Induces Synergistic Innate and Adaptive Immune Responses

To demonstrate potent efficacy, a cancer vaccine needs to activate both innate and adaptive immune cells. Personalized cancer vaccine strategies often require the identification of patient-specific neoantigens; however, the clonal and mutational heterogeneity of cancer cells presents inherent challenges. Here, extracellular nanovesicles derived from alpha-galactosylceramide-conjugated autologous acute myeloid leukemia (AML) cells (ECNV-αGC) are presented as a personalized therapeutic vaccine that activates both innate and adaptive immune responses, bypassing the need to identify patient-specific neoantigens. ECNV-αGC vaccination directly engages with and activates both invariant natural killer T (iNKT) cells and leukemia-specific CD8+ T cells in mice with AML, thereby promoting long-term anti-leukemic immune memory. ECNV-αGC sufficiently serves as an antigen-presenting platform that can directly activate antigen-specific CD8+ T cells even in the absence of dendritic cells, thereby demonstrating a multifaceted cellular mechanism of immune activation. Moreover, ECNV-αGC vaccination results in a significantly lower AML burden and higher percentage of leukemia-free survivors among cytarabine-treated hosts with AML. Human AML-derived ECNV-αGCs activate iNKT cells in both healthy individuals and patients with AML regardless of responsiveness to conventional therapies. Together, autologous AML-derived ECNV-αGCs may be a promising personalized therapeutic vaccine that efficiently establishes AML-specific long-term immunity without requiring the identification of neoantigens.

Current landscape of translational and clinical research in myelodysplastic syndromes/neoplasms (MDS): Proceedings from the 1st International Workshop on MDS (iwMDS) Of the International Consortium for MDS (icMDS)

Biological events that contribute to the pathogenesis of myelodysplastic syndromes/neoplasms (MDS) are becoming increasingly characterized and are being translated into rationally designed therapeutic strategies. Herein, we provide updates from the first International Workshop on MDS (iwMDS) of the International Consortium for MDS (icMDS) detailing recent advances in understanding the genetic landscape of MDS, including germline predisposition, epigenetic and immune dysregulation, the complexities of clonal hematopoiesis progression to MDS, as well as novel animal models of the disease. Connected to this progress is the development of novel therapies targeting specific molecular alterations, the innate immune system, and immune checkpoint inhibitors. While some of these agents have entered clinical trials (e.g., splicing modulators, IRAK1/4 inhibitors, anti-CD47 and anti-TIM3 antibodies, and cellular therapies), none have been approved for MDS. Additional preclinical and clinical work is needed to develop a truly individualized approach to the care of MDS patients.

An Overview of Targeted Therapies in Acute Myeloid Leukemia

Acute myeloid leukemia (AML) is the most aggressive adult leukemia, characterized by clonal differentiation arrest of progenitor or precursor hematopoietic cells. Intense preclinical and clinical research has led to regulatory approval of several targeted therapeutics, administered either as single agents or as combination therapies. However, the majority of patients still face a poor prognosis and disease relapse frequently occurs due to selection of therapy-resistant clones. Hence, more effective novel therapies, most likely as innovative, rational combination therapies, are urgently needed. Chromosomal aberrations, gene mutations, and epigenetic alterations drive AML pathogenesis but concurrently provide vulnerabilities to specifically target leukemic cells. Other molecules, either aberrantly active and/or overexpressed in leukemic stem cells, may also be leveraged for therapeutic benefit. This concise review of targeted therapies for AML treatment, which are either approved or are being actively investigated in clinical trials or recent preclinical studies, provides a flavor of the direction of travel, but also highlights the current challenges in AML treatment.

Immunologic Predictors for Clinical Responses during Immune Checkpoint Blockade in Patients with Myelodysplastic Syndromes

PURPOSE

The aim of this study is to determine immune-related biomarkers to predict effective antitumor immunity in myelodysplastic syndrome (MDS) during immunotherapy (IMT, αCTLA-4, and/or αPD-1 antibodies) and/or hypomethylating agent (HMA).

EXPERIMENTAL DESIGN

Peripheral blood samples from 55 patients with MDS were assessed for immune subsets, T-cell receptor (TCR) repertoire, mutations in 295 acute myeloid leukemia (AML)/MDS-related genes, and immune-related gene expression profiling before and after the first treatment.

RESULTS

Clinical responders treated with IMT ± HMA but not HMA alone showed a significant expansion of central memory (CM) CD8+ T cells, diverse TCRβ repertoire pretreatment with increased clonality and emergence of novel clones after the initial treatment, and a higher mutation burden pretreatment with subsequent reduction posttreatment. Autophagy, TGFβ, and Th1 differentiation pathways were the most downregulated in nonresponders after treatment, while upregulated in responders. Finally, CTLA-4 but not PD-1 blockade attributed to favorable changes in immune landscape.

CONCLUSIONS

Analysis of tumor-immune landscape in MDS during immunotherapy provides clinical response biomarkers.

Evolution of Therapeutic Benefit Measurement Criteria in Myelodysplastic Syndromes/Neoplasms

ABSTRACT

Myelodysplastic syndromes/neoplasms (MDS) are heterogeneous, clonal myeloid neoplasms characterized by ineffective hematopoiesis, progressive cytopenias, and an increased risk of progression to acute myeloid leukemia. The diversity in disease severity, morphology, and genetic landscape challenges not only novel drug development but also therapeutic response assessment. The MDS International Working Group (IWG) response criteria were first published in the year 2000 focusing on measures of blast burden reduction and hematologic recovery. Despite revision of the IWG criteria in 2006, correlation between IWG-defined responses and patient-focused outcomes, including long-term benefits, remains limited and has potentially contributed to failures of several phase III clinical trials. Several IWG 2006 criteria also lacked clear definitions leading to problems in practical applications and interobserver and intraobserver consistency of response reporting. Although the 2018 revision addressed lower-risk MDS, the most recent update in 2023 redefined responses for higher-risk MDS and has set out to provide clear definitions to enhance consistency while focusing on clinically meaningful outcomes and patient-centered responses. In this review, we analyze the evolution of the MDS response criteria, limitations, and areas of improvement.

Therapeutic approaches for the management of higher risk myelodysplastic syndromes

The heterogeneous nature of myelodysplastic syndromes (MDS) demands a risk-adapted therapeutic approach, and higher risk MDS, characterized by an increased risk of transformation into acute myeloid leukemia and inferior survival, is typically defined based on an integrated assessment of cytopenias, bone marrow blast percentage, and cytogenetic findings using the revised International Prognostic Scoring System. Incorporating mutational data could further refine the risk assessment and identify those with higher-than-expected disease risk. The principal therapeutic goal in this disease subset is to modify the natural history and prolong survival. Allogeneic stem cell transplant, the only potentially curative treatment, should be offered to eligible patients. Hypomethylating agents are the only approved treatment with unsatisfactory response rates and duration, and patients who failed prior hypomethylating agents unfortunately have dismal outcomes with urgent need of novel therapeutic agents. In this review, we provide the therapeutic landscape in higher risk MDS based on the current evidence and discuss the investigational treatment options under development.

Novel immune directed therapies in myelodysplastic syndromes and acute myeloid leukemia

PURPOSE OF REVIEW

Therapies that target the immune system are increasingly used across oncology, including in hematologic malignancies such as myelodysplastic syndromes (MDS) and acute myeloid leukemia (AML). While allogeneic transplant has been a key therapy in these cancers, new approaches that target the immune system are being explored including immune checkpoint therapies, antibody-drug conjugates, and cellular therapies.

RECENT FINDINGS

This review outlines updates in the preclinical rationale for immune directed therapies in MDS and AML, as well as recent clinical trials exploring these therapies. This manuscript summarizes the development of therapies targeting T cell immunoglobulin and mucin domain-containing protein 3 (TIM-3) and CD47, which are being evaluated in late phase studies in MDS and AML. It also reviews the landscape of other immune based therapies including antibody-drug conjugates, chimeric antigen receptor-T cells, bispecific antibodies, and tumor vaccines.

SUMMARY

The treatment landscape in MDS and AML is rapidly changing; with a goal of improving the quality and duration of responses, a number of immune based therapies are under investigation. This review outlines recent advances with these therapies as well as some of the challenges that remain to incorporate them into leukemia care.

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.

High Co-Expression of PDCD1/TIGIT/CD47/KIR3DL2 in Bone Marrow Is Associated with Poor Prognosis for Patients with Myelodysplastic Syndrome

Cellular immune disorder is a common characteristic of myelodysplastic syndrome (MDS). Abnormal natural killer (NK) cell function has been reported in MDS patients, and this is closely related to disease progression and poor prognosis. However, little is known about the association between the abnormal immune checkpoint (IC) that results in abnormal immune NK cell function and the prognosis of MDS. In this study, RNA-sequencing data from 80 patients in the GSE114922 dataset and bone marrow (BM) samples from 46 patients with MDS in our clinical center were used for overall survival (OS) analysis and validation. We found that the NK cell-related IC genes PDCD1, TIGIT, CD47, and KIR3DL2 had higher expression and correlated with poor OS for MDS patients. High expression of PDCD1 or TIGIT was significantly associated with poor OS for MDS patients younger than 60 years of age. Moreover, co-expression of PDCD1 and TIGIT had the greatest contribution to OS prediction. Interestingly, PDCD1, TIGIT, CD47, and KIR3DL2 and risk stratification based on the Revised International Prognostic Scoring System were used to construct a nomogram model, which could visually predict the 1-, 2-, and 3-year survival rates of MDS patients. In summary, high expression of IC receptors in the BM of MDS patients was associated with poor OS. The co-expression patterns of PDCD1, TIGIT, CD47, and KIR3DL2 might provide novel insights into designing combined targeted therapies for MDS.

Advances in myelodysplastic syndromes: promising novel agents and combination strategies

INTRODUCTION

Myelodysplastic syndromes (MDS) are heterogeneous group of clonal hematopoietic stem cell neoplasms that have limited approved treatment options. Multiple novel agents are currently being tested in a clinical trial setting. From a therapeutic perspective, MDS is generally divided into lower-risk and higher-risk disease. In this review, we summarize some of the most prominent novel agents currently in development.

AREAS COVERED

This review focuses on select clinical trials in both lower- and higher-risk MDS, elucidating the mechanisms of action and rationale for drug combinations and summarizing early safety and efficacy data using novel agents in MDS.

EXPERT OPINION

Advances in understanding the innate immune system, telomere biology, as well as genomic drivers of the disease have led to the development of multiple novel agents that are currently in late stages of clinical development in MDS. Imetelstat is being tested in lower-risk disease and the phase III clinical trial recently completed accrual. Magrolimab, sabatolimab, and venetoclax in addition to novel oral hypomethylating agents (HMA) are being investigated in higher-risk MDS. These advances will hopefully bring better treatment options to patients and lead to a shift in the treatment paradigm. Post HMA therapy remains an area of dire unmet need.

SOHO State of the Art and Next Questions: Treatment of Higher-Risk Myelodysplastic Syndromes

Higher-risk myelodysplastic syndromes (MDS) carry a dismal prognosis with rapid disease progression, disease-related complications that impact quality of life, high risk of transformation to acute myeloid leukemia (AML), and poor long-term survival. Higher-risk disease is determined by a number of factors including the depth and type of cytopenias, percentage of myeloblasts occupying the bone marrow, cytogenetic abnormalities, and increasingly also by the presence of higher-risk molecular alterations. In addition to disease characteristics, a patient's performance status and degree of co-morbidity strongly influence treatment decisions and clinical outcomes. A critical first step in the management of patients with higher-risk MDS is evaluating eligibility for allogeneic hematopoietic stem cell transplant (HCT), which currently remains the only curative therapy, and is available to an ever-increasing number of patients. Outside of stem cell transplant, treatment with hypomethylating agent chemotherapy, azacitidine or decitabine, remains the cornerstone of therapy with improvements in overall survival and reduced transformation to AML; however, these approaches are palliative in nature and outcomes remain very poor overall. With a deepening understanding of disease pathophysiology has come a burgeoning array of novel targeted therapies that are currently in pre-clinical and early phase clinical trials offering hope for new treatment options for this malignancy.

Immune dysfunction signatures predict outcomes and define checkpoint blockade-unresponsive microenvironments in acute myeloid leukemia

BackgroundImmune exhaustion and senescence are dominant dysfunctional states of effector T cells and major hurdles for the success of cancer immunotherapy. In the current study, we characterized how acute myeloid leukemia (AML) promotes the generation of senescent-like CD8+ T cells and whether they have prognostic relevance.METHODSWe analyzed NanoString, bulk RNA-Seq and single-cell RNA-Seq data from independent clinical cohorts comprising 1,896 patients treated with chemotherapy and/or immune checkpoint blockade (ICB).ResultsWe show that senescent-like bone marrow CD8+ T cells were impaired in killing autologous AML blasts and that their proportion negatively correlated with overall survival (OS). We defined what we believe to be new immune effector dysfunction (IED) signatures using 2 gene expression profiling platforms and reported that IED scores correlated with adverse-risk molecular lesions, stemness, and poor outcomes; these scores were a more powerful predictor of OS than 2017-ELN risk or leukemia stem cell (LSC17) scores. IED expression signatures also identified an ICB-unresponsive tumor microenvironment and predicted significantly shorter OS.ConclusionThe IED scores provided improved AML-risk stratification and could facilitate the delivery of personalized immunotherapies to patients who are most likely to benefit.TRIAL REGISTRATIONClinicalTrials.gov; NCT02845297.FUNDINGJohn and Lucille van Geest Foundation, Nottingham Trent University's Health & Wellbeing Strategic Research Theme, NIH/NCI P01CA225618, Genentech-imCORE ML40354, Qatar National Research Fund (NPRP8-2297-3-494).

The yin-yang of immunity: Immune dysregulation in myelodysplastic syndrome with different risk stratification

Myelodysplastic syndrome (MDS) is a heterogeneous group of myeloid clonal diseases with diverse clinical courses, and immune dysregulation plays an important role in the pathogenesis of MDS. However, immune dysregulation is complex and heterogeneous in the development of MDS. Lower-risk MDS (LR-MDS) is mainly characterized by immune hyperfunction and increased apoptosis, and the immunosuppressive therapy shows a good response. Instead, higher-risk MDS (HR-MDS) is characterized by immune suppression and immune escape, and the immune activation therapy may improve the survival of HR-MDS. Furthermore, the immune dysregulation of some MDS changes dynamically which is characterized by the coexistence and mutual transformation of immune hyperfunction and immune suppression. Taken together, the authors think that the immune dysregulation in MDS with different risk stratification can be summarized by an advanced philosophical thought “Yin-Yang theory” in ancient China, meaning that the opposing forces may actually be interdependent and interconvertible. Clarifying the mechanism of immune dysregulation in MDS with different risk stratification can provide the new basis for diagnosis and clinical treatment. This review focuses on the manifestations and roles of immune dysregulation in the different risk MDS, and summarizes the latest progress of immunotherapy in MDS.

Treatment of myelodysplastic syndromes in the era of precision medicine and immunomodulatory drugs: a focus on higher-risk disease

Myelodysplastic syndromes (MDS) are a heterogeneous clonal disease of myeloid neoplasms characterized by ineffective hematopoiesis, variable degree of cytopenias, and an increased risk of progression to acute myeloid leukemia (AML). Molecular and genetic characterization of MDS has led to a better understanding of the disease pathophysiology and is leading to the development of novel therapies. Targeted and immune therapies have shown promising results in different hematologic malignancies. However, their potential use in MDS is yet to be fully defined. Here, we review the most recent advances in therapeutic approaches in MDS, focusing on higher-risk disease. Allogeneic hematopoietic cell transplantation is beyond the scope of this article.

Tumor-specific T cell-mediated upregulation of PD-L1 in myelodysplastic syndrome cells does not affect T-cell killing

The PD-1:PD-L1 axis is a binary interaction that delivers inhibitory signals to T cells, impeding both immune surveillance and response to immunotherapy. Here we analyzed a phenomenon whereby tumor-specific T cells induce PD-L1 upregulation in autologous MDS cells in short-term culture, through a mechanism that is cell-contact-independent and partially IFNγ-dependent. After investigating a panel of small-molecule inhibitors, we determined that PD-L1 upregulation was attributed to the PKR-like ER kinase (PERK) branch of the unfolded protein response. Interestingly, we found that the cytotoxic capacity of tumor-specific T cells was not impaired by the expression of PD-L1 on MDS target cells. These results highlight a little appreciated aspect of PD-1:PD-L1 regulation in hematologic cancers and indicate that this phenomenon, while likely to hinder autochthonous immune surveillance, may not be an obstacle to immunotherapies such as personalized adoptive T-cell therapy.

Immune Checkpoint Inhibition in Acute Myeloid Leukemia and Myelodysplastic Syndromes

Immune checkpoint inhibitors (ICIs) have revolutionized the treatment of many solid tumors, with limited progress made in the area of myeloid malignancies. The low mutational burden of acute myeloid leukemia (AML) is one potential reason behind the lack of activity of T-cell harnessing ICIs, particularly CTLA-4 and PD-1 inhibitors. Innate immune checkpoints play a critical role in the immune escape of AML and myelodysplastic syndromes (MDS). The CD47 targeting agent, magrolimab, has shown promising activity when combined with azacitidine in early phase trials conducted in AML and higher-risk MDS, especially among patients harboring a TP53 mutation. Similarly, sabatolimab (an anti-TIM-3 monoclonal antibody) plus hypomethylating agents have shown durable responses in higher-risk MDS and AML in early clinical trials. Randomized trials are currently ongoing to confirm the efficacy of these agents. In this review, we will present the current progress and future directions of immune checkpoint inhibition in AML and MDS.

New Frontiers in Monoclonal Antibodies for the Targeted Therapy of Acute Myeloid Leukemia and Myelodysplastic Syndromes

Acute myeloid leukemia (AML) and myelodysplastic syndromes (MDS) represent an unmet clinical need whose prognosis is still dismal. Alterations of immune response play a prominent role in AML/MDS pathogenesis, revealing novel options for immunotherapy. Among immune system regulators, CD47, immune checkpoints, and toll-like receptor 2 (TLR2) are major targets. Magrolimab antagonizes CD47, which is overexpressed by AML and MDS cells, thus inducing macrophage phagocytosis with clinical activity in AML/MDS. Sabatolimab, an inhibitor of T-cell immunoglobulin and mucin domain-containing protein 3 (TIM3), which disrupts its binding to galectin-9, has shown promising results in AML/MDS, enhancing the effector functions of lymphocytes and triggering tumor cell death. Several other surface molecules, namely CD33, CD123, CD45, and CD70, can be targeted with monoclonal antibodies (mAbs) that exert different mechanisms of action and include naked and conjugated antibodies, bispecific T-cell engagers, trispecific killer engagers, and fusion proteins linked to toxins. These novel mAbs are currently under investigation for use as monotherapy or in combination with hypomethylating agents, BCL2 inhibitors, and chemotherapy in various clinical trials at different phases of development. Here, we review the main molecular targets and modes of action of novel mAb-based immunotherapies, which can represent the future of AML and higher risk MDS treatment.

Antibody-based therapy for acute myeloid leukemia: a review of phase 2 and 3 trials

INTRODUCTION

Despite recent advances in the treatment of adult acute myeloid leukemia (AML), the clinical outcome of patients continues to be unsatisfactory especially among older patients, those with a high-risk profile, and in the relapsed/refractory setting. For this reason, recent clinical trials have explored novel therapeutic agents either used alone or in combination with intensive chemotherapy or low-intensity treatments.

AREAS COVERED

The current paper reviews the clinical development of monoclonal antibody-based therapies in AML, their current status and phases 2 and 3 prospective trials.

EXPERT OPINION

Monoclonal antibody-based therapies demonstrated efficacy and tolerability in several clinical trials, especially when used in combination either with '3+7' chemotherapy or with low-intensity treatments. Additional studies are needed to determine new antigens for antibody-based therapies that target leukemia stem cells and spare normal hematopoiesis. Phase 2 and 3 additional clinical trial data are needed to assess the promise of first trials, especially regarding chimeric antigen receptor T cells redirected against myeloid antigens and immune checkpoint inhibitor therapies.

Monoclonal antibodies used for the management of haematological disorders

INTRODUCTION

Monoclonal antibodies Ab (MoAb) are increasingly becoming part of therapeutic armamentarium for haematologists and haemato-oncologists. This review brings together commonly used antibodies in one place for brevity and novel understanding.

AREAS COVERED

Pubmed and Scopus databases were explored focusing on MoAb in clinical haematological practice. Emphasis was given to current review articles. The data base was searched from 1997 till present. 24 different antibodies, most of which are in use were discussed. Antibodies are used for diverse conditions i.e. malignant and benign haematological conditions, treatment at various phases of stem cell transplantation. These antibodies were used both alone or in combination with various chemotherapy, targeted small molecules or as immunoconjugates. Some of the side effect profiles of these antibodies were common and some were unique. Unusual infections or organ dysfunctions were noted. Improved function of antibodies by protein engineering is also advancing rapidly. Dosage, frequency and route of administration depended on the convenience and condition for which the antibody is used.

EXPERT OPINION

: MoAbs are increasingly used in haematology practice either alone or in combination with other types of therapy for improved out come in various haematological conditions.

Role of the bone marrow immune microenvironment in chronic myelomonocytic leukemia pathogenesis: novel mechanisms and insights into clonal propagation

Recent studies in chronic myelomonocytic leukemia (CMML) involving clonal dendritic cell (DC) aggregates and association with systemic immune dysregulation have highlighted novel and potentially targetable pathways of disease progression. CMML DC aggregates are populated by heterogeneous cell types such as CD123⁺ plasmacytoid dendritic cells (pDCs), CD11c + myeloid-derived DCs (mDCs), myeloid-derived suppressor cells (MDSCs), monocytes, and associate with an immune checkpoint called indoleamine 2,3-dioxygenase (IDO). Systemically, these IDO + DC aggregates are associated with immune tolerance marked by regulatory T cell expansion, likely mediated by aberrant DC-T cell interactions occurring within the bone marrow (BM) microenvironment. Somatic mutational events in CMML such as ASXL1 and NRAS mutations cooperate to induce T cell exhaustion and contribute toward disease progression to acute myeloid leukemia (AML). In this review, we explore the role of aging-induced alterations in the BM immune microenvironment, aberrant innate immune and proinflammatory signaling, and the adaptive immune system in CMML.

Translating recent advances in the pathogenesis of acute myeloid leukemia to the clinic

Despite FDA approval of nine new drugs for patients with acute myeloid leukemia (AML) in the United States over the last 4 years, AML remains a major area of unmet medical need among hematologic malignancies. In this review, we discuss the development of promising new molecular targeted approaches for AML, including menin inhibition, novel IDH1/2 inhibitors, and preclinical means to target TET2, ASXL1, and RNA splicing factor mutations. In addition, we review progress in immune targeting of AML through anti-CD47, anti-SIRPα, and anti-TIM-3 antibodies; bispecific and trispecific antibodies; and new cellular therapies in development for AML.

A Randomized Phase 2 Trial of Azacitidine ± Durvalumab as First-line Therapy for Higher-Risk Myelodysplastic Syndromes

This is the first reported randomized trial of immune checkpoint inhibitor therapy in HR-MDS.

Azacitidine combined with the PD-L1 inhibitor durvalumab was feasible but did not improve outcomes over azacitidine alone.

Azacitidine-mediated hypomethylation promotes tumor cell immune recognition but may increase the expression of inhibitory immune checkpoint molecules. We conducted the first randomized phase 2 study of azacitidine plus the immune checkpoint inhibitor durvalumab vs azacitidine monotherapy as first-line treatment for higher-risk myelodysplastic syndromes (HR-MDS). In all, 84 patients received 75 mg/m² subcutaneous azacitidine (days 1-7 every 4 weeks) combined with 1500 mg intravenous durvalumab on day 1 every 4 weeks (Arm A) for at least 6 cycles or 75 mg/m² subcutaneous azacitidine alone (days 1-7 every 4 weeks) for at least 6 cycles (Arm B). After a median follow-up of 15.25 months, 8 patients in Arm A and 6 in Arm B remained on treatment. Patients in Arm A received a median of 7.9 treatment cycles and those in Arm B received a median of 7.0 treatment cycles with 73.7% and 65.9%, respectively, completing ≥4 cycles. The overall response rate (primary end point) was 61.9% in Arm A (26 of 42) and 47.6% in Arm B (20 of 42; P = .18), and median overall survival was 11.6 months (95% confidence interval, 9.5 months to not evaluable) vs 16.7 months (95% confidence interval, 9.8-23.5 months; P = .74). Durvalumab-related adverse events (AEs) were reported by 71.1% of patients; azacitidine-related AEs were reported by 82% (Arm A) and 81% (Arm B). Grade 3 or 4 hematologic AEs were reported in 89.5% (Arm A) vs 68.3% (Arm B) of patients. Patients with TP53 mutations tended to have a worse response than patients without these mutations. Azacitidine increased programmed cell death ligand 1 (PD-L1 [CD274]) surface expression on bone marrow granulocytes and monocytes, but not blasts, in both arms. In summary, combining azacitidine with durvalumab in patients with HR-MDS was feasible but with more toxicities and without significant improvement in clinical outcomes over azacitidine alone. This trial was registered at www.clinicaltrials.gov as #NCT02775903.

Atezolizumab alone or in combination did not demonstrate a favorable risk-benefit profile in myelodysplastic syndrome

Safety and efficacy data demonstrated that atezolizumab alone or with azacitidine did not support a favorable risk-benefit profile in MDS.

The differential toxicity profile observed between patients with R/R and those with HMA-naïve MDS requires additional investigation.

We present primary results from the phase 1b GO29754 study evaluating the safety and tolerability of atezolizumab, a programmed death-ligand 1 inhibitor, alone and in combination with azacitidine, a hypomethylating agent (HMA), in patients with relapsed/refractory (R/R) or HMA-naïve myelodysplastic syndrome (MDS). Patients with R/R MDS received atezolizumab for 12 months (cohort A) or atezolizumab plus azacitidine for 6 cycles followed by atezolizumab as maintenance for 8 cycles (cohort B). Patients with HMA-naïve MDS received atezolizumab plus azacitidine until loss of clinical benefit (cohort C). Safety, activity, and exploratory end points were investigated. Forty-six patients were enrolled and received treatment (cohort A, n = 11; cohort B, n = 14; cohort C, n = 21). All patients experienced ≥1 adverse event (AE) on study, and all patients discontinued atezolizumab. In cohort A, 7 patients (63.6%) died, and no patients responded. In cohort B, 8 patients (57.1%) discontinued azacitidine, 11 (78.6%) died, and 2 (14.3%) responded. In cohort C, all 21 patients discontinued azacitidine, 13 died (61.9%), and 13 (61.9%) responded. The study was terminated by the sponsor before completion of recruitment because of the unexpected high early death rate in cohort C (6 [46.2%] of 13 deaths were due to AEs and occurred within the first 4 treatment cycles.). The high death rate and poor efficacy observed in this study do not support a favorable risk-benefit profile for atezolizumab as a single agent or in combination with azacitidine in R/R or HMA-naïve MDS. This trial was registered at www.clinicaltrials.gov as #NCT02508870.

Innate Immune Mechanisms and Immunotherapy of Myeloid Malignancies

Similar to other cancers, myeloid malignancies are thought to subvert the immune system during their development. This subversion occurs via both malignant cell-autonomous and non-autonomous mechanisms and involves manipulation of the innate and adaptive immune systems. Multiple strategies are being studied to rejuvenate, redirect, or re-enforce the immune system in order to fight off myeloid malignancies. So far, the most successful strategies include interferon treatment and antibody-based therapies, though chimeric antigen receptor (CAR) cells and immune checkpoint inhibitors are also promising therapies. In this review, we discuss the inherent immune mechanisms of defense against myeloid malignancies, currently-approved agents, and agents under investigation. Overall, we evaluate the efficacy and potential of immuno-oncology in the treatment of myeloid malignancies.

From Immune Dysregulations to Therapeutic Perspectives in Myelodysplastic Syndromes: A Review

The pathophysiology of myelodysplastic syndromes (MDSs) is complex and often includes immune dysregulation of both the innate and adaptive immune systems. Whereas clonal selection mainly involves smoldering inflammation, a cellular immunity dysfunction leads to increased apoptosis and blast proliferation. Addressing immune dysregulations in MDS is a recent concept that has allowed the identification of new therapeutic targets. Several approaches targeting the different actors of the immune system have therefore been developed. However, the results are very heterogeneous, indicating the need to improve our understanding of the disease and interactions between chronic inflammation, adaptive dysfunction, and somatic mutations. This review highlights current knowledge of the role of immune dysregulation in MDS pathophysiology and the field of new drugs.

Immune Therapies for Myelodysplastic Syndromes and Acute Myeloid Leukemia

Myelodysplastic syndromes (MDS) and acute myeloid leukemia (AML) are hematologic malignancies arising from the bone marrow. Despite recent advances in treating these diseases, patients with higher-risk MDS and AML continue to have a poor prognosis with limited survival. It has long been recognized that there is an immune component to the pathogenesis of MDS and AML, but until recently, immune therapies have played a limited role in treating these diseases. Immune suppressive therapy exhibits durable clinical responses in selected patients with MDS, but the question of which patients are most suitable for this treatment remains unclear. Over the past decade, there has been remarkable progress in identifying genomic features of MDS and AML, which has led to an improved discernment of the molecular pathogenesis of these diseases. An improved understanding of immune and inflammatory molecular mechanisms of MDS and AML have also recently revealed novel therapeutic targets. Emerging treatments for MDS and AML include monoclonal antibodies such as immune checkpoint inhibitors, bispecific T-cell-engaging antibodies, antibody drug conjugates, vaccine therapies, and cellular therapeutics including chimeric antigen receptor T-cells and NK cells. In this review, we provide an overview of the current understanding of immune dysregulation in MDS and AML and an update on novel immune therapies for these bone marrow malignancies.

Molecular Targeted Therapy and Immunotherapy for Myelodysplastic Syndrome

Myelodysplastic syndrome (MDS) is a heterogeneous, clonal hematological disorder characterized by ineffective hematopoiesis, cytopenia, morphologic dysplasia, and predisposition to acute myeloid leukemia (AML). Stem cell genomic instability, microenvironmental aberrations, and somatic mutations contribute to leukemic transformation. The hypomethylating agents (HMAs), azacitidine and decitabine are the standard of care for patients with higher-risk MDS. Although these agents induce responses in up to 40-60% of patients, primary or secondary drug resistance is relatively common. To improve the treatment outcome, combinational therapies comprising HMA with targeted therapy or immunotherapy are being evaluated and are under continuous development. This review provides a comprehensive update of the molecular pathogenesis and immune-dysregulations involved in MDS, mechanisms of resistance to HMA, and strategies to overcome HMA resistance.

Toxicity of Immune-Checkpoint Inhibitors in Hematological Malignancies

Immune checkpoint inhibitors (ICIs), especially those targeting the programmed-death 1 (PD-1) receptor and its ligands, have become indispensable agents in solid tumor anti-cancer therapy. Concerning hematological malignancies, only nivolumab and pembrolizumab have been approved for the treatment of relapsed and refractory classical Hodgkin lymphoma and primary mediastinal large B cell lymphoma to date. Nevertheless, clinical research in this field is very active. The mechanism of action of ICIs is based on unblocking the hindered immune system to recognize and eliminate cancer cells, but that also has its costs in the form of ICI-specific immune related adverse events (irAEs), which can affect any organ system and can even be lethal. In this article, we have reviewed all prospective blood cancer clinical trials investigating ICIs (both monotherapy and combination therapy) with available toxicity data with the purpose of determining the incidence of irAEs in this specific setting and to offer a brief insight into their management, as the use of immune checkpoint blockade is not so frequent in hemato-oncology.

Novel CAR T therapy is a ray of hope in the treatment of seriously ill AML patients

Acute myeloid leukemia (AML) is a serious, life-threatening, and hardly curable hematological malignancy that affects the myeloid cell progenies and challenges patients of all ages but mostly occurs in adults. Although several therapies are available including chemotherapy, allogeneic hematopoietic stem cell transplantation (alloHSCT), and receptor-antagonist drugs, the 5-year survival of patients is quietly disappointing, less than 30%. alloHSCT is the major curative approach for AML with promising results but the treatment has severe adverse effects such as graft-versus-host disease (GVHD). Therefore, as an alternative, more efficient and less harmful immunotherapy-based approaches such as the adoptive transferring T cell therapy are in development for the treatment of AML. As such, chimeric antigen receptor (CAR) T cells are engineered T cells which have been developed in recent years as a breakthrough in cancer therapy. Interestingly, CAR T cells are effective against both solid tumors and hematological cancers such as AML. Gradually, CAR T cell therapy found its way into cancer therapy and was widely used for the treatment of hematologic malignancies with successful results particularly with somewhat better results in hematological cancer in comparison to solid tumors. The AML is generally fatal, therapy-resistant, and sometimes refractory disease with a disappointing low survival rate and weak prognosis. The 5-year survival rate for AML is only about 30%. However, the survival rate seems to be age-dependent. Novel CAR T cell therapy is a light at the end of the tunnel. The CD19 is an important target antigen in AML and lymphoma and the CAR T cells are engineered to target the CD19. In addition, a lot of research goes on the discovery of novel target antigens with therapeutic efficacy and utilizable for generating CAR T cells against various types of cancers. In recent years, many pieces of research on screening and identification of novel AML antigen targets with the goal of generation of effective anti-cancer CAR T cells have led to new therapies with strong cytotoxicity against cancerous cells and impressive clinical outcomes. Also, more recently, an improved version of CAR T cells which were called modified or smartly reprogrammed CAR T cells has been designed with less unwelcome effects, less toxicity against normal cells, more safety, more specificity, longer persistence, and proliferation capability. The purpose of this review is to discuss and explain the most recent advances in CAR T cell-based therapies targeting AML antigens and review the results of preclinical and clinical trials. Moreover, we will criticize the clinical challenges, side effects, and the different strategies for CAR T cell therapy.

Management of the Older Patient with Myelodysplastic Syndrome

No two diagnoses of myelodysplastic syndrome are genuinely alike, owing to differing and dynamic mutational topography and epigenetic aberrancy. Consequently, no two patients with myelodysplastic syndrome are identical and disease-specific and patient-specific factors are considered in formulating the optimal treatment, which includes few that are disease modifying. Age itself should not be an absolute contraindication to therapy, including intensive therapy such as allogeneic hematopoietic stem cell transplantation, which is the only curative therapy. However, age associates with an increased prevalence of frailty and comorbidities that must be considered and may preclude a path to cure. Palliative therapies are the mainstay for many patients with myelodysplastic syndrome, which is a disease of older adults with the majority of patients diagnosed at age ≥ 75 years. The older patient requires heightened attention to end organ function/reserve and drug-drug interactions as well as insurance, income, cost, and socioeconomic and psychosocial issues that influence management. Many prior studies have included relatively younger populations or have not specifically performed high-quality subgroup analyses of older patients. In this review, we discuss the available standard-of-care therapies for myelodysplastic syndrome as they specifically relate to the older population and assess the emerging therapeutics that may further the pursuit for personalized treatment and improve both the outcomes and quality of life of the older patient with myelodysplastic syndrome.

TIM-3 restrains anti-tumour immunity by regulating inflammasome activation

T cell immunoglobulin and mucin-containing molecule 3 (TIM-3), first identified as a molecule expressed on interferon-γ producing T cells1, is emerging as an important immune-checkpoint molecule, with therapeutic blockade of TIM-3 being investigated in multiple human malignancies. Expression of TIM-3 on CD8+ T cells in the tumour microenvironment is considered a cardinal sign of T cell dysfunction; however, TIM-3 is also expressed on several other types of immune cell, confounding interpretation of results following blockade using anti-TIM-3 monoclonal antibodies. Here, using conditional knockouts of TIM-3 together with single-cell RNA sequencing, we demonstrate the singular importance of TIM-3 on dendritic cells (DCs), whereby loss of TIM-3 on DCs-but not on CD4+ or CD8+ T cells-promotes strong anti-tumour immunity. Loss of TIM-3 prevented DCs from expressing a regulatory program and facilitated the maintenance of CD8+ effector and stem-like T cells. Conditional deletion of TIM-3 in DCs led to increased accumulation of reactive oxygen species resulting in NLRP3 inflammasome activation. Inhibition of inflammasome activation, or downstream effector cytokines interleukin-1β (IL-1β) and IL-18, completely abrogated the protective anti-tumour immunity observed with TIM-3 deletion in DCs. Together, our findings reveal an important role for TIM-3 in regulating DC function and underscore the potential of TIM-3 blockade in promoting anti-tumour immunity by regulating inflammasome activation.

Optimizing NK Cell-Based Immunotherapy in Myeloid Leukemia: Abrogating an Immunosuppressive Microenvironment

Natural killer (NK) cells are prominent cytotoxic and cytokine-producing components of the innate immune system representing crucial effector cells in cancer immunotherapy. Presently, various NK cell-based immunotherapies have contributed to the substantial improvement in the reconstitution of NK cells against advanced-staged and high-risk AML. Various NK cell sources, including haploidentical NK cells, adaptive NK cells, umbilical cord blood NK cells, stem cell-derived NK cells, chimeric antigen receptor NK cells, cytokine-induced memory-like NK cells, and NK cell lines have been identified. Devising innovative approaches to improve the generation of therapeutic NK cells from the aforementioned sources is likely to enhance NK cell expansion and activation, stimulate ex vivo and in vivo persistence of NK cells and improve conventional treatment response of myeloid leukemia. The tumor-promoting properties of the tumor microenvironment and downmodulation of NK cellular metabolic activity in solid tumors and hematological malignancies constitute a significant impediment in enhancing the anti-tumor effects of NK cells. In this review, we discuss the current NK cell sources, highlight ongoing interventions in enhancing NK cell function, and outline novel strategies to circumvent immunosuppressive factors in the tumor microenvironment to improve the efficacy of NK cell-based immunotherapy and expand their future success in treating myeloid leukemia.

Chimeric CTLA4-CD28-CD3z T Cells Potentiate Antitumor Activity Against CD80/CD86-Positive B Cell Malignancies

The adoptive transfer of chimeric antigen receptor T (CAR T) cells have been recognized as a promising therapeutic strategy for the treatment of hematological malignancies; however, clinical success using CAR T cells for the treatment of solid tumors are still limited since the T-cell function is inhibited by negative signals in the microenvironment of solid tumors. CTLA4 is a well-known immune checkpoint molecule, thus we developed a novel CAR by converting this negative signal to positive signal. The CAR developed consists of the extracellular and transmembrane domains of CTLA4 and the cytoplasmic domains of CD28 and CD3z (CTLA4-CAR T). CTLA4-CAR T cells exhibited superior cytokine secreting activities and cytotoxic to tumor cells in vitro and in xenograft models. CTLA4-CAR T cells were found to accumulate in tumors and are toxic to myeloid-derived suppressor cells (MDSCs) without signs of severe GVHD and CRS in preclinical models. Thus, this chimeric CTLA4-CAR can enhance the antitumor activity of CAR T cells and shed light on the strategy of using armed CAR T cells to target the immunomodulatory tumor microenvironment.

Risk-Adapted, Individualized Treatment Strategies of Myelodysplastic Syndromes (MDS) and Chronic Myelomonocytic Leukemia (CMML)

Myelodysplastic syndrome (MDS) and chronic myelomonocytic leukemia (CMML) are two distinct blood cancers with a variable clinical symptom burden and risk of progression to acute myeloid leukemia. Management decisions should be guided by individual patient and disease characteristics and based on validated risk stratification tools. While supportive care with red blood cell transfusions, erythropoiesis-stimulating agents, and iron chelation remains the mainstay of therapy for lower-risk (LR)-MDS patients, luspatercept has recently been approved for transfusion-dependent anemic LR-MDS patients ending a decade without any new drug approvals for MDS. For higher-risk patients, allogeneic hematopoietic cell transplant (allo-HCT) remains the only curative therapy for both MDS and CMML but most patients are not eligible for allo-HCT. For those patients, the hypomethylating agents (HMA) azacitidine and decitabine remain standard of care with azacitidine being the only agent that has shown an overall survival benefit in randomized trials. Although early results from novel molecularly driven agents such as IDH1/2 inhibitors, venetoclax, magrolimab, and APR-246 for MDS as well as tagraxofusp, tipifarnib, and lenzilumab for CMML appear encouraging, confirmatory randomized trials must be completed to fully assess their safety and efficacy prior to routine clinical use. Herein, we review the current management of MDS and CMML and conclude with a critical appraisal of novel therapies and general trends in this field.