Azacitidine and Durvalumab in First-line Treatment of Elderly Patients With Acute Myeloid Leukemia

The opportunities and challenges of using PD-1/PD-L1 inhibitors for leukemia treatment

Leukemia poses a significant clinical challenge due to its swift onset, rapid progression, and treatment-related complications. Tumor immune evasion, facilitated by immune checkpoints like programmed death receptor 1/programmed death receptor ligand 1 (PD-1/PD-L1), plays a critical role in leukemia pathogenesis and progression. In this review, we summarized the research progress and therapeutic potential of PD-L1 in leukemia, focusing on targeted therapy and immunotherapy. Recent clinical trials have demonstrated promising outcomes with PD-L1 inhibitors, highlighting their role in enhancing treatment efficacy. This review discusses the implications of PD-L1 expression levels on treatment response and long-term survival rates in leukemia patients. Furthermore, we address the challenges and opportunities in immunotherapy, emphasizing the need for personalized approaches and combination therapies to optimize PD-L1 inhibition in leukemia management. Future research prospects include exploring novel treatment strategies and addressing immune-related adverse events to improve clinical outcomes in leukemia. Overall, this review provides valuable insights into the role of PD-L1 in leukemia and its potential as a therapeutic target in the evolving landscape of leukemia treatment.

Integrated genetic, epigenetic, and immune landscape of TP53 mutant AML and higher risk MDS treated with azacitidine

Background

TP53 mutations are associated with an adverse prognosis in acute myeloid leukemia (AML) and higher-risk myelodysplastic syndromes (HR-MDS). However, the integrated genetic, epigenetic, and immunologic landscape of TP53-mutated AML/HR-MDS is not well defined.

Objectives

To define the genetic, epigenetic, and immunologic landscape of TP53-mutant and TP53 wild-type AML and HR-MDS patients.

Design

Post hoc analysis of TP53-mutant and TP53 wild-type patients treated on the randomized FUSION trial with azacitidine ± the anti-PD-L1 antibody durvalumab.

Methods

We performed extensive molecular, epigenetic, and immunologic assays on a well-annotated clinical trial dataset of 61 patients with TP53-mutated disease (37 AML, 24 MDS) and 144 TP53 wild-type (89 AML, 55 MDS) patients, all of whom received azacitidine-based therapy. A 38 gene-targeted myeloid mutation analysis from screening bone marrow (BM) was performed. DNA methylation arrays, immunophenotyping and immune checkpoint expression by flow cytometry, and gene expression profiles by bulk RNA sequencing were assessed at baseline and serially during the trial.

Results

Global DNA methylation from peripheral blood was independent of TP53 mutation and allelic status. AZA therapy led to a statistically significant decrease in global DNA methylation scores independent of TP53 mutation status. In BM from TP53-mutant patients, we found both a higher T-cell population and upregulation of inhibitory immune checkpoint proteins such as PD-L1 compared to TP53 wild-type. RNA sequencing analyses revealed higher expression of the myeloid immune checkpoint gene LILRB3 in TP53-mutant samples suggesting a novel therapeutic target.

Conclusion

This integrated analysis of the genetic, epigenetic, and immunophenotypic landscape of TP53 mutant AML/HR-MDS suggests that differences in the immune landscape resulting in an immunosuppressive microenvironment rather than epigenetic differences contribute to the poor prognosis of TP53-mutant AML/HR-MDS with mono- or multihit TP53 mutation status.

Trial registration

FUSION trial (NCT02775903).

Single-cell genomics-based immune and disease monitoring in blood malignancies

Achieving long-term disease control using therapeutic immunomodulation is a long-standing concept with a strong tradition in blood malignancies. Besides allogeneic hematopoietic stem cell transplantation that continues to provide potentially curative treatment for otherwise challenging diagnoses, recent years have seen impressive progress in immunotherapies for leukemias and lymphomas with immune checkpoint blockade, bispecific monoclonal antibodies, and CAR T cell therapies. Despite their success, non-response, relapse, and immune toxicities remain frequent, thus prioritizing the elucidation of the underlying mechanisms and identifying predictive biomarkers. The increasing availability of single-cell genomic tools now provides a system's immunology view to resolve the molecular and cellular mechanisms of immunotherapies at unprecedented resolution. Here, we review recent studies that leverage these technological advancements for tracking immune responses, the emergence of immune resistance, and toxicities. As single-cell immune monitoring tools evolve and become more accessible, we expect their wide adoption for routine clinical applications to catalyze more precise therapeutic steering of personal immune responses.

Therapeutic targeting of DNA methylation alterations in cancer

DNA methylation is a critical component of gene regulation and plays an important role in the development of cancer. Hypermethylation of tumor suppressor genes and silencing of DNA repair pathways facilitate uncontrolled cell growth and synergize with oncogenic mutations to perpetuate cancer phenotypes. Additionally, aberrant DNA methylation hinders immune responses crucial for antitumor immunity. Thus, inhibiting dysregulated DNA methylation is a promising cancer therapy. Pharmacologic inhibition of DNA methylation reactivates silenced tumor suppressors and bolster immune responses through induction of viral mimicry. Now, with the advent of immunotherapies and discovery of the immune-modulatory effects of DNA methylation inhibitors, there is great interest in understanding how targeting DNA methylation in combination with other therapies can enhance antitumor immunity. Here, we describe the role of aberrant DNA methylation in cancer and mechanisms by which it promotes tumorigenesis and modulates immune responses. Finally, we review the initial discoveries and ongoing efforts to target DNA methylation as a cancer therapeutic.

Immune Checkpoint Inhibitors and Cardiotoxicity: A Comparative Meta-Analysis of Observational Studies and Randomized Controlled Trials

BACKGROUND

Immune checkpoint inhibitors (ICIs) have uncommon associations with cardiotoxicity, yet these cardiotoxic effects are associated with high mortality. An accurate assessment of risk for cardiotoxicity is essential for clinical decision-making, but data from randomized controlled trials often differ from real-world observational studies.

METHODS AND RESULTS

A systematic search of PubMed, Embase, Cochrane Library, and Scopus was performed, including phase II and III randomized controlled trials (RCTs) and observational studies (OSs) reporting myocarditis or pericardial disease, myocardial infarction, or stroke with an immunotherapy. Odds ratios (ORs) were used to pool results between ICIs and other cancer therapy in RCTs and OSs. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses guideline was followed. In total, 54 RCTs (N=38 264) and 24 OSs (N=12 561 455) were included. In RCTs, ICI use resulted in higher risk of myocarditis (OR, 3.55 [95% CI, 2.10-5.98]), pericardial disease (OR, 2.73 [95% CI, 1.57-4.77]), and myocardial infarction (OR, 1.83 [95% CI, 1.03-3.25]), compared with non-ICI (placebo or chemotherapy). In OSs, ICI use was not associated with myocarditis, pericardial disease, or myocardial infarction compared with controls; however, combination ICIs demonstrated higher risk of myocarditis compared with single ICI use (OR, 3.07 [95% CI, 1.28-7.39]). Stroke risk was not increased with use of ICIs in RCTs.

CONCLUSIONS

We demonstrated increased risk of ICI myocarditis, pericardial disease, and myocardial infarction in RCTs but not OSs. Results of this study suggest there are differences between ICI cardiotoxicity risk, possibly suggesting differences in diagnoses and management, in clinical trials versus the OSs.

Single-Cell CD4 and CD8 T-Cell Secretome Profiling Reveals Temporal and Niche Differences in Acute Myeloid Leukemia Following Immune Checkpoint Blockade Therapy

Acute myeloid leukemia (AML) is a heterogeneous malignancy of the blood primarily treated with intensive chemotherapy. The allogeneic T-cell antileukemic activity via donor lymphocyte infusions and stem cell transplantation suggests a potential role for checkpoint blockade therapy in AML. While clinical trials employing these treatments have fallen short of expected results, a deeper exploration into the functional states of T cells in AML could bridge this knowledge gap. In this study, we analyzed the polyfunctional activity of T cells in a cohort of patients with relapsed/refractory (RelRef) AML treated on the clinical trial (ClinicalTrials.gov identifier: NCT02397720) of combination therapy using azacitidine and nivolumab (Aza/Nivo). We utilized the single-cell polyfunctional multiplexed immune assay IsoPlexis to evaluate the CD4 and CD8 T cells in peripheral blood and bone marrow samples collected before and after immunotherapy. This revealed at a pseudobulk level that the CD4 T cells exhibited higher functional activity post-immunotherapy (post-IO), suggesting that CD4-directed therapies may play a role in RelRef AML. Additional single-cell analysis revealed significant differences in baseline polyfunctionality in bone marrows of responders as compared with nonresponders for both CD4 and CD8 T cells. Overall, this study highlights the impact of polyfunctional assessment in understanding CD4 and CD8 dynamics in contexts of therapy in AML.

SIGNIFICANCE

We found T-cell polyfunctionality differs between local and systemic microenvironments. Enhanced variability in proteomic profiles of bone marrow CD4 T cells post-IO suggests their pivotal role in AML treatment response. Single-cell analysis identified novel CD4 and CD8 T-cell functional groups linked to immunotherapy response within the bone marrow.

Unmet Horizons: Assessing the Challenges in the Treatment of TP53-Mutated Acute Myeloid Leukemia

Acute myeloid leukemia (AML) remains a challenging hematologic malignancy. The presence of TP53 mutations in AML poses a therapeutic challenge, considering that standard treatments face significant setbacks in achieving meaningful responses. There is a pressing need for the development of innovative treatment modalities to overcome resistance to conventional treatments attributable to the unique biology of TP53-mutated (TP53mut) AML. This review underscores the role of TP53 mutations in AML, examines the current landscape of treatment options, and highlights novel therapeutic approaches, including targeted therapies, combination regimens, and emerging immunotherapies, as well as agents being explored in preclinical studies according to their potential to address the unique hurdles posed by TP53mut AML.

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.

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.

Immunotherapies of acute myeloid leukemia: Rationale, clinical evidence and perspective

Acute myeloid leukemia (AML) is a prevalent hematological malignancy that exhibits a wide array of molecular abnormalities. Although traditional treatment modalities such as chemotherapy and allogeneic stem cell transplantation (HSCT) have become standard therapeutic approaches, a considerable number of patients continue to face relapse and encounter a bleak prognosis. The emergence of immune escape, immunosuppression, minimal residual disease (MRD), and other contributing factors collectively contribute to this challenge. Recent research has increasingly highlighted the notable distinctions between AML tumor microenvironments and those of healthy individuals. In order to investigate the potential therapeutic mechanisms, this study examines the intricate transformations occurring between leukemic cells and their surrounding cells within the tumor microenvironment (TME) of AML. This review classifies immunotherapies into four distinct categories: cancer vaccines, immune checkpoint inhibitors (ICIs), antibody-based immunotherapies, and adoptive T-cell therapies. The results of numerous clinical trials strongly indicate that the identification of optimal combinations of novel agents, either in conjunction with each other or with chemotherapy, represents a crucial advancement in this field. In this review, we aim to explore the current and emerging immunotherapeutic methodologies applicable to AML patients, identify promising targets, and emphasize the crucial requirement to augment patient outcomes. The application of these strategies presents substantial therapeutic prospects within the realm of precision medicine for AML, encompassing the potential to ameliorate patient outcomes.

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.

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.

[Synergistic effect of azacitidine with homoharringtonine by activating the c-MYC/DDIT3/PUMA axis in acute myeloid leukemia]

Objective: This study aimed to explore the synergistic effect and underlying mechanism of azacitidine (AZA) in combination with homoharringtonine (HHT) in acute myeloid leukemia (AML) . Methods: The synergistic effects of AZA and HHT were examined by cell proliferation, apoptosis, and colony formation assays. The synergistic effects were calculated using the combination index (CI) , and the underlying mechanisms were explored using RNA sequencing, pathway inhibitors, and gene knockdown approaches. Results: Compared with the single-drug controls, AZA and HHT combination significantly induced cell proliferation arrest and showed a synergistic effect with CI < 0.9 in AML cells. In the combination group versus the single-drug controls, colony formation was significantly decreased, whereas apoptosis was significantly increased in U937 (P<0.001) and MV4-11 (P<0.001) cells. AZA and HHT combination activated the integrated stress response (ISR) signaling pathway and induced DDIT3-PUMA-dependent apoptosis in cells. Furthermore, it remarkably downregulated the expression of c-MYC. The combination also activated c-MYC/DDIT3/PUMA-mediated ISR signaling to induce synergy on apoptosis. The synergy of AZA+HHT on apoptosis was induced by activating c-MYC/DDIT3/PUMA-mediated ISR signaling. Conclusion: The combination of AZA and HHT exerts synergistic anti-AML effects by inhibiting cellular proliferation and promoting apoptosis through activation of the ISR signaling pathway via the c-MYC/DDIT3/PUMA axis.

Novel immunotherapies in the treatment of AML: is there hope?

The success of allogeneic stem cell transplantation has demonstrated the potential for immunotherapy to treat acute myeloid leukemia (AML). Although alternative T-cell-based immunotherapies have shown efficacy, they also pose the risk of on-target off-leukemia hematotoxicity. So far, adoptive autologous or allogeneic chimeric antigen receptor (CAR) T/natural killer cell therapy is almost exclusively employed as a bridge-to-transplant strategy in the context of clinical trials. For now, clinical trials predominantly target lineage-restricted antigens, but emerging approaches focus on leukemia-associated/specific intracellular target antigens, including dual and split targeting strategies. Adapter CAR T cells and T-cell-recruiting bispecific antibodies offer transient exposure with enhanced safety and multitargeting potential against antigen-escape variants. However, these have yet to demonstrate sustained responses and should be used earlier to treat low leukemia burden, preferably if measurable residual disease is present. To address immune dysregulation and enhance T-cell fitness, novel CAR T and bispecific designs, along with combinatorial strategies, might prove essential. Furthermore, genetic associations with inflammatory bone marrow signatures suggest the need for tailored platforms in defined AML subtypes. The eagerly anticipated results of trials investigating magrolimab, an anti-CD47 antibody targeting the "do not eat me" signal in p53-mutated AML, should shed further light on the potential of these evolving immunotherapeutic approaches.

Targeting the epigenome to reinvigorate T cells for cancer immunotherapy

Cancer immunotherapy using immune-checkpoint inhibitors (ICIs) has revolutionized the field of cancer treatment; however, ICI efficacy is constrained by progressive dysfunction of CD8+ tumor-infiltrating lymphocytes (TILs), which is termed T cell exhaustion. This process is driven by diverse extrinsic factors across heterogeneous tumor immune microenvironment (TIME). Simultaneously, tumorigenesis entails robust reshaping of the epigenetic landscape, potentially instigating T cell exhaustion. In this review, we summarize the epigenetic mechanisms governing tumor microenvironmental cues leading to T cell exhaustion, and discuss therapeutic potential of targeting epigenetic regulators for immunotherapies. Finally, we outline conceptual and technical advances in developing potential treatment paradigms involving immunostimulatory agents and epigenetic therapies.

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 in Acute Myeloid Leukemia: A Literature Review of Emerging Strategies

In the last twenty years, we have witnessed a paradigm shift in the treatment and prognosis of acute myeloid leukemia (AML), thanks to the introduction of new efficient drugs or approaches to refine old therapies, such as Gemtuzumab Ozogamicin, CPX 3-5-1, hypomethylating agents, and Venetoclax, the optimization of conditioning regimens in allogeneic hematopoietic stem cell transplantation and the improvement of supportive care. However, the long-term survival of non-M3 and non-core binding factor-AML is still dismal. For this reason, the expectations for the recently developed immunotherapies, such as antibody-based therapy, checkpoint inhibitors, and chimeric antigen receptor strategies, successfully tested in other hematologic malignancies, were very high. The inherent characteristics of AML blasts hampered the development of these treatments, and the path of immunotherapy in AML has been bumpy. Herein, we provide a detailed review of potential antigenic targets, available data from pre-clinical and clinical trials, and future directions of immunotherapies in AML.

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.

STAT5 promotes PD-L1 expression by facilitating histone lactylation to drive immunosuppression in acute myeloid leukemia

Immunotherapy is a revolutionized therapeutic strategy for tumor treatment attributing to the rapid development of genomics and immunology, and immune checkpoint inhibitors have successfully achieved responses in numbers of tumor types, including hematopoietic malignancy. However, acute myeloid leukemia (AML) is a heterogeneous disease and there is still a lack of systematic demonstration to apply immunotherapy in AML based on PD-1/PD-L1 blockage. Thus, the identification of molecules that drive tumor immunosuppression and stratify patients according to the benefit from immune checkpoint inhibitors is urgently needed. Here, we reported that STAT5 was highly expressed in the AML cohort and activated the promoter of glycolytic genes to promote glycolysis in AML cells. As a result, the increased-lactate accumulation promoted E3BP nuclear translocation and facilitated histone lactylation, ultimately inducing PD-L1 transcription. Immune checkpoint inhibitor could block the interaction of PD-1/PD-L1 and reactive CD8+ T cells in the microenvironment when co-culture with STAT5 constitutively activated AML cells. Clinically, lactate accumulation in bone marrow was positively correlated with STAT5 as well as PD-L1 expression in newly diagnosed AML patients. Therefore, we have illustrated a STAT5-lactate-PD-L1 network in AML progression, which demonstrates that AML patients with STAT5 induced-exuberant glycolysis and lactate accumulation may be benefited from PD-1/PD-L-1-based immunotherapy.

TP53 Mutation in Acute Myeloid Leukemia: An Old Foe Revisited

INTRODUCTION

TP53 is the most commonly mutated gene in human cancers and was the first tumor suppressor gene to be discovered in the history of medical science. Mutations in the TP53 gene occur at various genetic locations and exhibit significant heterogeneity among patients. Mutations occurring primarily within the DNA-binding domain of TP53 result in the loss of the p53 protein's DNA-binding capability. However, a complex phenotypic landscape often combines gain-of-function, dominant negative, or altered specificity features. This complexity poses a significant challenge in developing an effective treatment strategy, which eradicates TP53-mutated cancer clones. This review summarizes the current understanding of TP53 mutations in AML and their implications. TP53 mutation in AML: In patients with acute myeloid leukemia (AML), six hotspot mutations (R175H, G245S, R248Q/W, R249S, R273H/S, and R282W) within the DNA-binding domain are common. TP53 mutations are frequently associated with a complex karyotype and subgroups of therapy-related or secondary AML. The presence of TP53 mutation is considered as a poor prognostic factor. TP53-mutated AML is even classified as a distinct subgroup of AML by itself, as TP53-mutated AML exhibits a significantly distinct landscape in terms of co-mutation and gene expression profiles compared with wildtype (WT)-TP53 AML.

CLINICAL IMPLICATIONS

To better predict the prognosis in cancer patients with different TP53 mutations, several predictive scoring systems have been proposed based on screening experiments, to assess the aggressiveness of TP53-mutated cancer cells. Among those scoring systems, a relative fitness score (RFS) could be applied to AML patients with TP53 mutations in terms of overall survival (OS) and event-free survival (EFS). The current standard treatment, which includes cytotoxic chemotherapy and allogeneic hematopoietic stem cell transplantation, is largely ineffective for patients with TP53-mutated AML. Consequently, most patients with TP53-mutated AML succumb to leukemia within several months, despite active anticancer treatment. Decitabine, a hypomethylating agent, is known to be relatively effective in patients with AML. Numerous trials are ongoing to investigate the effects of novel drugs combined with hypomethylating agents, TP53-targeting agents or immunologic agents.

CONCLUSIONS

Developing an effective treatment strategy for TP53-mutated AML through innovative and multidisciplinary research is an urgent task. Directly targeting mutated TP53 holds promise as an approach to combating TP53-mutated AML, and recent developments in immunologic agents for AML offer hope in this field.

Progress of research on PD-1/PD-L1 in leukemia

Leukemia cells prevent immune system from clearing tumor cells by inducing the immunosuppression of the bone marrow (BM) microenvironment. In recent years, further understanding of the BM microenvironment and immune landscape of leukemia has resulted in the introduction of several immunotherapies, including checkpoint inhibitors, T-cell engager, antibody drug conjugates, and cellular therapies in clinical trials. Among them, the programmed cell death protein 1 (PD-1)/programmed death-ligand 1 (PD-L1) axis is a significant checkpoint for controlling immune responses, the PD-1 receptor on tumor-infiltrating T cells is bound by PD-L1 on leukemia cells. Consequently, the activation of tumor reactive T cells is inhibited and their apoptosis is promoted, preventing the rejection of the tumor by immune system and thus resulting in the occurrence of immune tolerance. The PD-1/PD-L1 axis serves as a significant mechanism by which tumor cells evade immune surveillance, and PD-1/PD-L1 checkpoint inhibitors have been approved for the treatment of lymphomas and varieties of solid tumors. However, the development of drugs targeting PD-1/PD-L1 in leukemia remains in the clinical-trial stage. In this review, we tally up the basic research and clinical trials on PD-1/PD-L1 inhibitors in leukemia, as well as discuss the relevant toxicity and impacts of PD-1/PD-L1 on other immunotherapies such as hematopoietic stem cell transplantation, bi-specific T-cell engager, chimeric antigen receptor T-cell immunotherapy.

The Association between Immune Checkpoint Proteins and Therapy Outcomes in Acute Myeloid Leukaemia Patients

The development of novel drugs with different mechanisms of action has dramatically changed the treatment landscape of AML patients in recent years. Considering a significant dysregulation of the immune system, inhibitors of immune checkpoint (ICI) proteins provide a substantial therapeutic option for those subjects. However, use of ICI in haematological malignancies remains very limited, in contrast to their wide use in solid tumours. Here, we analysed expression patterns of the most promising selected checkpoint-based therapeutic targets in AML patients. Peripheral blood of 72 untreated AML patients was used for flow cytometric analysis. Expression of PD-1, PD-L1, CTLA-4, and B7-H3 was assessed within CD4+ (Th) lymphocytes and CD33+ blast cells. Patients were stratified based on therapy outcome and cytogenetic molecular risk. AML non-responders (NR) showed a higher frequency of PD-1 in Th cells compared to those with complete remission (CR). Reduced blast cell level of CTLA-4 was another factor differentiating CR from NR subjects. Elevated levels of PD-1 were associated with a trend for poorer patients' survival. Additionally, prognosis for AML patients was worse in case of a higher frequency of B7-H3 in Th lymphocytes. In summary, we showed the significance of selected ICI as outcome predictors in AML management. Further, multicentre studies are required for validation of those data.

Immunotherapy for Acute Myeloid Leukemia: Current Trends, Challenges, and Strategies

BACKGROUND

In the past decade, there have been significant breakthroughs in immunotherapies for B-cell lymphoid malignancies and multiple myeloma, but progress has been much less for acute myeloid leukemia (AML). Nevertheless, challenge begets innovation and several therapeutic strategies are under investigation.

SUMMARY

In this review, we review the state of the art in AML immunotherapy including CD33- and CD123-targeted agents, immune checkpoint inhibition, and adoptive cell therapy strategies. We also share conceptual frameworks for approaching the growing catalog of investigational AML immunotherapies and propose future directions for the field.

KEY MESSAGES

Immunotherapies for AML face significant challenges but novel strategies are in development.

Immunotherapy in Acute Leukemias: Past Success Paves the Way for Future Progress

Immunotherapy as a cancer treatment modality has undergone recent widespread proliferation across all cancer types, especially amongst patients with solid tumors. However, the longest tenured immunotherapy approach to cancer is allogeneic stem cell transplantation (allo-SCT) for two hematologic malignancies: acute myeloid and acute lymphoid leukemia (AML and ALL, respectively). While allo-SCT remains a standard of care for eligible patients, recent advances/applications of monoclonal antibodies, immune checkpoint inhibitors, bispecific T-cell engagers (BiTEs), and CAR T-cell therapy are changing the treatment landscape for these acute leukemias by either direct to tumor immune targeting or through decreased toxicities that expand patient eligibility. Pre-clinical data and clinical trials have shown promising results for novel immunotherapies in acute leukemia, and multiple ongoing trials are investigating these novel approaches. While there have been promising results with these approaches, particularly in the relapsed/refractory setting, there remain challenges in optimizing the use of these therapies, such as managing cytokine release syndrome and other immune-related toxicities. Immunotherapy is a rapidly evolving field in the treatment of acute leukemia and has the potential to significantly impact the management of both AML and ALL. This review highlights the history of immunotherapy in the treatment of acute leukemias, the evolution of immunotherapy into more targeted approaches, the potential benefits and limitations of different immune targeting approaches, and ongoing research and development in the field.

TP53-Mutated Myelodysplasia and Acute Myeloid Leukemia

TP53-mutated myelodysplastic syndrome (MDS) and acute myeloid leukemia (AML) form a distinct and heterogeneous group of myeloid malignancies associated with poor outcomes. Studies carried out in the last years have in part elucidated the complex role played by TP53 mutations in the pathogenesis of these myeloid disorders and in the mechanisms of drug resistance. A consistent number of studies has shown that some molecular parameters, such as the presence of a single or multiple TP53 mutations, the presence of concomitant TP53 deletions, the association with co-occurring mutations, the clonal size of TP53 mutations, the involvement of a single (monoallelic) or of both TP53 alleles (biallelic) and the cytogenetic architecture of concomitant chromosome abnormalities are major determinants of outcomes of patients. The limited response of these patients to standard treatments, including induction chemotherapy, hypomethylating agents and venetoclax-based therapies and the discovery of an immune dysregulation have induced a shift to new emerging therapies, some of which being associated with promising efficacy. The main aim of these novel immune and nonimmune strategies consists in improving survival and in increasing the number of TP53-mutated MDS/AML patients in remission amenable to allogeneic stem cell transplantation.

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.

Immunotherapy for myelodysplastic syndrome and acute myeloid leukemia: where do we stand?

INTRODUCTION

Myelodysplastic syndrome (MDS) and acute myeloid leukemia (AML) are generally characterized by a poor prognosis with currently available therapies. Immunotherapies have already seen success in treating a variety of malignant disorders, and their role in managing myeloid cancers is evolving rapidly.

AREAS COVERED

This is a review of the immunotherapies tested in MDS and AML, including immune checkpoint inhibitors, bispecific antibodies, and cell therapies such as chimeric antigen receptor (CAR) T cell therapy, T cell receptor (TCR) engineered T cells, and natural killer (NK) cells, with a focus on clinical trials conducted to date and future directions.

EXPERT OPINION

Initial clinical trials exploring checkpoint inhibitors in MDS and AML have demonstrated high toxicity and disappointing efficacy. However, ongoing trials adding novel checkpoint inhibitors to standard therapy are more promising. Technological advances are improving the outlook for bispecific antibodies, and cellular therapies like adoptive NK cell infusion have favorable efficacy and tolerability in early trials. As our understanding of the immune microenvironment in MDS and AML improves, the role for immunotherapy in the treatment of these diseases will become clearer.

CD26lowPD-1+ CD8 T cells are terminally exhausted and associated with leukemia progression in acute myeloid leukemia

Acute myeloid leukemia (AML) is a devastating blood cancer with poor prognosis. Novel effective treatment is an urgent unmet need. Immunotherapy targeting T cell exhaustion by blocking inhibitory pathways, such as PD-1, is promising in cancer treatment. However, results from clinical studies applying PD-1 blockade to AML patients are largely disappointing. AML is highly heterogeneous. Identification of additional immune regulatory pathways and defining predictive biomarkers for treatment response are crucial to optimize the strategy. CD26 is a marker of T cell activation and involved in multiple immune processes. Here, we performed comprehensive phenotypic and functional analyses on the blood samples collected from AML patients and discovered that CD26^lowPD-1⁺ CD8 T cells were associated with AML progression. Specifically, the percentage of this cell fraction was significantly higher in patients with newly diagnosed AML compared to that in patients achieved completed remission or healthy controls. Our subsequent studies on CD26^lowPD-1⁺ CD8 T cells from AML patients at initial diagnosis demonstrated that this cell population highly expressed inhibitory receptors and displayed impaired cytokine production, indicating an exhaustion status. Importantly, CD26^lowPD-1⁺ CD8 T cells carried features of terminal exhaustion, manifested by higher frequency of T_EMRA differentiation, increased expression of transcription factors that are observed in terminally exhausted T cells, and high level of intracellular expression of granzyme B and perforin. Our findings suggest a prognostic and predictive value of CD26 in AML, providing pivotal information to optimize the immunotherapy for this devastating cancer.

Novel Investigational Agents and Pathways That May Influence the Future Management of Acute Myeloid Leukemia

Acute Myeloid leukemia (AML) is a clinically heterogeneous disease with a 5-year overall survival of 32% between 2012 to 2018. The above number severely dwindles with age and adverse risk of disease, presenting opportunities for new drug development and is an area of dire unmet need. Basic science and clinical investigators across the world have been working on many new and old molecule formulations and combination strategies to improve outcomes in this disease. In this review, we discuss select promising novel agents in various stages of clinical development for patients with AML.

Single-center phase 2 study of PD-1 inhibitor combined with DNA hypomethylation agent + CAG regimen in patients with relapsed/refractory acute myeloid leukemia

Anti-PD-1 monotherapy had limited clinical efficacy in relapsed/refractory (r/r) AML patients with higher PD-1 and PD-L1 expression. Hence, we investigated the efficacy and safety of PD-1 inhibitor with DNA hypomethylating agent (HMA) + CAG regimen in patients who had failed prior AML therapy. In this phase 2, single-arm study, r/r AML patients received azacitidine or decitabine plus CAG regimen with tislelizumab. Primary endpoints were efficacy (objective response rate [ORR]) and safety. Secondary endpoints included overall survival (OS), event-free survival (EFS) and duration of response (DOR). Statistical analyses were performed using Stata 14.0 and SPSS 20.0 software where P < 0.05 denoted significance. Twenty-seven patients were enrolled patients and completed 1 cycle, and 14 (51.9%) and 4 (14.8%) patients completed 2 and 3 cycles, respectively. ORR was 63% (14: complete remission [CR]/CR with incomplete hematologic recovery [CRi], 3: partial remission (PR), 10: no response [NR]). Median OS (mOS) and EFS were 9.7 and 9.2 months, respectively. With a median follow-up of 8.2 months (1.1-26.9), the mOS was not reached in responders (CR/CRi/PR) while it was 2.4 months (0.0-5.4) in nonresponders (P = 0.002). Grade 2-3 immune-related adverse events (irAEs) were observed in 4 (14.8%) patients and 3 nonresponders died of lung infection after treatment. Tislelizumab + HMA + CAG regimen showed improved outcomes in r/r AML patients with lower pretherapy leukemia burden. irAEs were mild and low-grade and higher pretherapy bone marrow CD4⁺ CD127⁺ PD-1⁺ T cells might serve as a predictor of treatment response.ClinicalTrials.gov identifier NCT04541277.

Mechanisms of response and resistance to combined decitabine and ipilimumab for advanced myeloid disease

The challenge of eradicating leukemia in patients with acute myelogenous leukemia (AML) after initial cytoreduction has motivated modern efforts to combine synergistic active modalities including immunotherapy. Recently, the ETCTN/CTEP 10026 study tested the combination of the DNA methyltransferase inhibitor decitabine together with the immune checkpoint inhibitor ipilimumab for AML/myelodysplastic syndrome (MDS) either after allogeneic hematopoietic stem cell transplantation (HSCT) or in the HSCT-naïve setting. Integrative transcriptome-based analysis of 304 961 individual marrow-infiltrating cells for 18 of 48 subjects treated on study revealed the strong association of response with a high baseline ratio of T to AML cells. Clinical responses were predominantly driven by decitabine-induced cytoreduction. Evidence of immune activation was only apparent after ipilimumab exposure, which altered CD4+ T-cell gene expression, in line with ongoing T-cell differentiation and increased frequency of marrow-infiltrating regulatory T cells. For post-HSCT samples, relapse could be attributed to insufficient clearing of malignant clones in progenitor cell populations. In contrast to AML/MDS bone marrow, the transcriptomes of leukemia cutis samples from patients with durable remission after ipilimumab monotherapy showed evidence of increased infiltration with antigen-experienced resident memory T cells and higher expression of CTLA-4 and FOXP3. Altogether, activity of combined decitabine and ipilimumab is impacted by cellular expression states within the microenvironmental niche of leukemic cells. The inadequate elimination of leukemic progenitors mandates urgent development of novel approaches for targeting these cell populations to generate long-lasting responses. This trial was registered at www.clinicaltrials.gov as #NCT02890329.

Cancer Resistance to Immunotherapy: Comprehensive Insights with Future Perspectives

Cancer immunotherapy is a type of treatment that harnesses the power of the immune systems of patients to target cancer cells with better precision compared to traditional chemotherapy. Several lines of treatment have been approved by the US Food and Drug Administration (FDA) and have led to remarkable success in the treatment of solid tumors, such as melanoma and small-cell lung cancer. These immunotherapies include checkpoint inhibitors, cytokines, and vaccines, while the chimeric antigen receptor (CAR) T-cell treatment has shown better responses in hematological malignancies. Despite these breakthrough achievements, the response to treatment has been variable among patients, and only a small percentage of cancer patients gained from this treatment, depending on the histological type of tumor and other host factors. Cancer cells develop mechanisms to avoid interacting with immune cells in these circumstances, which has an adverse effect on how effectively they react to therapy. These mechanisms arise either due to intrinsic factors within cancer cells or due other cells within the tumor microenvironment (TME). When this scenario is used in a therapeutic setting, the term “resistance to immunotherapy” is applied; “primary resistance” denotes a failure to respond to treatment from the start, and “secondary resistance” denotes a relapse following the initial response to immunotherapy. Here, we provide a thorough summary of the internal and external mechanisms underlying tumor resistance to immunotherapy. Furthermore, a variety of immunotherapies are briefly discussed, along with recent developments that have been employed to prevent relapses following treatment, with a focus on upcoming initiatives to improve the efficacy of immunotherapy for cancer patients.

TP53-altered higher-risk myelodysplastic syndromes/neoplasms and acute myeloid leukemia: a distinct genetic entity with unique unmet needs

Pathogenic alterations of TP53 are an independent poor prognostic factor in myelodysplastic syndromes (MDS) and acute myeloid leukemia (AML). Clinical course of TP53- altered myeloid neoplasms is dictated by genetic characteristics, such as TP53 allelic state and variant allele frequency (VAF), and not the blast count. Hence, it was recently proposed that MDS (with increased blasts) and AML with TP53 alterations may be best classified as a single molecular disease entity, TP53-mutated higher-risk (HR)-MDS/AML. TP53 mutations drive resistance to intensive chemotherapies and less intensive hypomethylating agents (HMA). Novel combinations incorporating BCL2 inhibitor venetoclax improve response rates for TP53-mutated subgroup, but the survival is not improved. Early clinical studies combining HMA with investigational agents demonstrated activity in TP53-mutated HR-MDS/AML, but updated results with larger samples, longer follow-up, or randomized trials were less impressive to date. Future research should focus on finding novel, potentially disease-modifying therapies to improve outcomes in patients with TP53-mutated HR-MDS/AML.

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.

Biological therapy in elderly patients with acute myeloid leukemia

INTRODUCTION

The introduction of target molecules and immunological therapies is changing the treatment landscape of acute myeloid leukemia (AML).

AREAS COVERED

We recapitulate the biological therapies that can be employed in the treatment of elderly patients with AML. Alongside small molecules inhibitors that target specific gene mutations, antibodies, tumor microenvironment modulators, and cellular therapies are being developed for the cure of the disease. Here, we report the biological activities, the efficacy and toxicities of humanized antibodies and antibody-drug conjugates that targets surface antigens as CD33 (gemtuzumab ozogamicine) or CD123 (pivekimab sunirine). We further explore mechanisms and effectiveness of medications that modify the microenvironment, such as glasdegib, or that harness the immune system against leukemia, such as CD47 antibody magrolimab, PD1/PDL1 inhibitors pembrolizumab and nivolumab, TIM3 inhibitor sabatolimab, T-cell and NK-cell engagers. Cellular therapies are considered, even if a large trial is still pending for the feasibility of the approach. In this scenario, a brief overview of the mechanism of action of target agents is provided, particularly with respect to their biological mechanisms.

EXPERT OPINION

Overall, this therapeutic armamentarium will constitute the basis for multimodal and personalized combinations that, in the idea of precision medicine, will enormously benefit elderly AML patients.

Targeting DNA Methylation in Leukemia, Myelodysplastic Syndrome, and Lymphoma: A Potential Diagnostic, Prognostic, and Therapeutic Tool

DNA methylation represents a crucial mechanism of epigenetic regulation in hematologic malignancies. The methylation process is controlled by specific DNA methyl transferases and other regulators, which are often affected by genetic alterations. Global hypomethylation and hypermethylation of tumor suppressor genes are associated with hematologic cancer development and progression. Several epi-drugs have been successfully implicated in the treatment of hematologic malignancies, including the hypomethylating agents (HMAs) decitabine and azacytidine. However, combinations with other treatment modalities and the discovery of new molecules are still the subject of research to increase sensitivity to anti-cancer therapies and improve patient outcomes. In this review, we summarized the main functions of DNA methylation regulators and genetic events leading to changes in methylation landscapes. We provide current knowledge about target genes with aberrant methylation levels in leukemias, myelodysplastic syndromes, and malignant lymphomas. Moreover, we provide an overview of the clinical trials, focused mainly on the combined therapy of HMAs with other treatments and its impact on adverse events, treatment efficacy, and survival rates among hematologic cancer patients. In the era of precision medicine, a transition from genes to their regulation opens up the possibility of an epigenetic-based approach as a diagnostic, prognostic, and therapeutic tool.

How I Manage Transplant Ineligible Patients with Myelodysplastic Neoplasms

Myelodysplastic neoplasms, formerly known as myelodysplastic syndromes (MDS), represent a group of clonal disorders characterized by a high degree of clinical and molecular heterogeneity, and an invariable tendency to progress to acute myeloid leukemia. MDS typically present in the elderly with cytopenias of different degrees and bone marrow dysplasia, the hallmarks of the disease. Allogeneic hematopoietic stem cell transplant is the sole curative approach to date. Nonetheless, given the disease’s demographics, only a minority of patients can benefit from this procedure. Currently used prognostic schemes such as the Revised International Prognostic Scoring System (R-IPSS), and most recently the molecular IPSS (IPSS-M), guide clinical management by dividing MDS into two big categories: lower- and higher-risk cases, based on a cut-off score of 3.5. The main clinical problem of the lower-risk group is represented by the management of cytopenias, whereas the prevention of secondary leukemia progression is the goal for the latter. Herein, we discuss the non-transplant treatment of MDS, focusing on current practice and available therapeutic options, while also presenting new investigational agents potentially entering the MDS therapeutic arsenal in the near future.

5-Azacytidine-Mediated Modulation of the Immune Microenvironment in Murine Acute Myeloid Leukemia

Cancer cells accumulate epigenetic modifications that allow escape from intrinsic and extrinsic surveillance mechanisms. In the case of acute myeloid leukemias (AML) and myelodysplastic syndromes, agents that disrupt chromatin structure, namely hypomethylating agents (HMAs), have shown tremendous promise as an alternate, milder treatment option for older, clinically non-fit patients. HMAs reprogram the epigenetic landscape in tumor cells through the reversal of DNA hypermethylation. Therapeutic effects resulting from these epigenetic changes are incredibly effective, sometimes resulting in complete remissions, but are frequently lost due to primary or acquired resistance. In this study, we describe syngeneic murine leukemias that are responsive to the HMA 5-azacytidine (5-Aza), as determined by augmented expression of a transduced luciferase reporter. We also found that 5-Aza treatment re-established immune-related transcript expression, suppressed leukemic burden and extended survival in leukemia-challenged mice. The effects of 5-Aza treatment were short-lived, and analysis of the immune microenvironment reveals possible mechanisms of resistance, such as simultaneous increase in immune checkpoint protein expression. This represents a model system that is highly responsive to HMAs and recapitulates major therapeutic outcomes observed in human leukemia (relapse) and may serve as a pre-clinical tool for studying acquired resistance and novel treatment combinations.

TP53-Mutated Myelodysplastic Syndrome and Acute Myeloid Leukemia: Biology, Current Therapy, and Future Directions

TP53-mutated myelodysplastic syndrome (MDS) and acute myeloid leukemia (AML) form a distinct group of myeloid disorders with dismal outcomes. TP53-mutated MDS and AML have lower response rates to either induction chemotherapy, hypomethylating agent-based regimens, or venetoclax-based therapies compared with non-TP53-mutated counterparts and a poor median overall survival of 5 to 10 months. Recent advances have identified novel pathogenic mechanisms in TP53-mutated myeloid malignancies, which have the potential to improve treatment strategies in this distinct clinical subgroup. In this review, we discuss recent insights into the biology of TP53-mutated MDS/AML, current treatments, and emerging therapies, including immunotherapeutic and nonimmune-based approaches for this entity.

SIGNIFICANCE

Emerging data on the impact of cytogenetic aberrations, TP53 allelic burden, immunobiology, and tumor microenvironment of TP53-mutated MDS and AML are further unraveling the complexity of this disease. An improved understanding of the functional consequences of TP53 mutations and immune dysregulation in TP53-mutated AML/MDS coupled with dismal outcomes has resulted in a shift from the use of cytotoxic and hypomethylating agent-based therapies to novel immune and nonimmune strategies for the treatment of this entity. It is hoped that these novel, rationally designed combinations will improve outcomes in this area of significant unmet need.

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).

A Focus on Intermediate-Risk Acute Myeloid Leukemia: Sub-Classification Updates and Therapeutic Challenges

Acute myeloid leukemia (AML) represents a heterogeneous group of hematopoietic neoplasms deriving from the abnormal proliferation of myeloid progenitors in the bone marrow. Patients with AML may have highly variable outcomes, which are generally dictated by individual clinical and genomic characteristics. As such, the European LeukemiaNet 2017 and 2022 guidelines categorize newly diagnosed AML into favorable-, intermediate-, and adverse-risk groups, based on their molecular and cytogenetic profiles. Nevertheless, the intermediate-risk category remains poorly defined, as many patients fall into this group as a result of their exclusion from the other two. Moreover, further genomic data with potential prognostic and therapeutic influences continue to emerge, though they are yet to be integrated into the diagnostic and prognostic models of AML. This review highlights the latest therapeutic advances and challenges that warrant refining the prognostic classification of intermediate-risk AML.

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.

Cellular and Molecular Biomarkers Predictive of Response to Immunotherapy in Acute Myeloid Leukemia

Immunotherapy has without question revolutionized the treatment of both hematologic and solid malignancies. Over the last several years novel strategies are being developed to incorporate these groundbreaking therapies into the care of patients with AML. Here we present an overview of the recent developments in immunotherapy for AML with a focus on biomarkers of response. Topics reviewed include antibody drug conjugates, BiTEs, DARTs, checkpoint inhibitors, and cellular therapy as well as the development of biomarkers predictive of response in each class.