Deleting DNMT3A in CAR T cells prevents exhaustion and enhances antitumor activity

Characterization of the aryl hydrocarbon receptor as a potential candidate to improve cancer T cell therapies

The efficacy of T-cell-based cancer therapies can be limited by the tumor microenvironment which can lead to T cell dysfunction. Multiple studies, particularly in murine models, have demonstrated the capacity of the aryl hydrocarbon receptor (AHR) to negatively regulate antitumor T cell functions. AHR is a cytoplasmic receptor and transcription factor that was originally identified as a xenobiotic sensor, but has since been shown to play a significant role in the gene regulation of various immune cells, including T cells. Given the insights from murine studies, AHR emerges as a promising candidate to invalidate for optimizing T cell-based cancer therapies. However, the controversial role of AHR in human T cells underscores the need for a more comprehensive characterization of AHR expressing T cells. This study aims to investigate the regulatory mechanisms of AHR in human T cell biology to better understand its impact on reducing antitumor immune responses. Here, we knocked-out AHR in human T cells using CRISPR-Cas9 technology to characterize AHR's function in an in vitro chronic stimulation model. Engineered T cells exhibited enhanced effector- and memory-like profiles and expressed reduced amount of CD39 and TIGIT. AHR knockout enhanced human CAR-T cells' functionality and persistence upon tumor chronic stimulation. Collectively, these results highlight the role of AHR in human CAR-T cells efficiency.

New insights on potency assays from recent advances and discoveries in CAR T-cell therapy

This review explores recent advances in the characteristics and manufacturing of CAR T-cell products. Traditional potency assays have been designed based on well-established CAR T-cell functionalities. However, the advent of innovative tools and methodologies has revealed a broader spectrum of important CAR T-cell characteristics that correlate with function. Furthermore, as manufacturing strategies continue to evolve, conventional potency assays may no longer fully capture the complexity of these products. Therefore, it is essential to examine these emerging characteristics and manufacturing approaches and consider the development of tailored potency assays to ensure products are fully characterized.

Evolving CAR T-Cell Therapy to Overcome the Barriers in Treating Pediatric Central Nervous System Tumors

SIGNIFICANCE

CNS tumors are the leading cause of cancer-related death in children, highlighting the dire need for new treatment strategies. CAR T cells represent a unique approach, distinct from the cytotoxic chemotherapies and small-molecule inhibitors that have dominated the clinical trial space for decades. Phase I CAR T-cell trials have shown feasibility and possible efficacy against pediatric CNS tumors; however, many challenges must be overcome if these therapeutics are going to be beneficial to most affected children. Although rapid translational development and early-phase trials have quickly evolved our understanding, the pediatric CNS CAR T-cell community now yearns for critical assessments and open dialogue about overcoming the remaining obstacles ahead.

The mechanisms and countermeasures for CAR-T cell expansion and persistence deficiency

Chimeric antigen receptor (CAR) T cell therapy has emerged as a groundbreaking treatment for hematological malignancies, particularly B-cell malignancies. However, its high risk of relapse and low efficacy in malignancies such as chronic lymphocytic leukemia (CLL) and acute myeloid leukemia (AML) have limited its clinical utility. The expansion, infiltration and persistence of CAR-T cells are key determinants of their efficacy. It has been recognized that limited expansion and lack of persistence are major contributors to non-remission and early relapse, highlighting the need to elucidate their mechanisms and countermeasures. In this review, we described features of CAR-T cell expansion and persistence in various hematogenic malignancies and solid tumors. Then, current knowledge on the mechanisms underlying deficiency in CAR-T cell expansion and persistence is presented, focusing on the intrinsic deficiency of CAR-T cells as well as their interaction with the systemic and local immune environment. Finally, we summarize approaches to enhance CAR-T cell expansion and persistence by improving CAR-T cell quality and overcoming the immunosuppressive environment.

From Multi-Omics to Visualization and Beyond: Bridging Micro and Macro Insights in CAR-T Cell Therapy

Chimeric antigen receptor T (CAR-T) cell therapies, a cornerstone of immunotherapy, have demonstrated remarkable efficacy in treating hematological malignancies and have more recently expanded into applications for solid tumors and autoimmune diseases. Emerging multidimensional profiling technologies offer promising solutions for enhancing CAR-T efficacy, overcoming resistance, and facilitating the development of novel CAR-T constructs. The integration of genomics, epigenomics, transcriptomics, proteomics, metabolomics, and microbiomics enables a comprehensive understanding of the intrinsic mechanisms underlying CAR-T therapy, while single-cell and spatial omics significantly improve data resolution and analytical depth. Coupled with advances in biomedical engineering, visualization technologies form the foundation for omics data generation by bridging microscopic and macroscopic scales and enabling dynamic, 3D in vivo monitoring of CAR-T behavior. Artificial intelligence (AI) further supports this framework by enabling the analysis of complex, high-dimensional datasets. This review highlights recent advances in the integration of multidimensional omics within CAR-T therapy and explores cutting-edge developments in visualization technologies and AI applications. The full convergence of multi-omics, visualization tools, and AI is poised to deliver transformative insights into the mechanisms governing CAR-T cell therapy.

Strategies to overcome tumour relapse caused by antigen escape after CAR T therapy

Chimeric antigen receptor (CAR) T cell therapy has revolutionized the treatment of B cell and plasma cell malignancies, and numerous promising targets against solid tumours are being explored. Despite their initial therapeutic success in hematological cancers, relapse occurs in a significant fraction of patients, highlighting the need for further innovations in advancing CAR T cell therapy. Tumour antigen heterogeneity and acquired tumour resistance leading to antigen escape (antigen loss/downregulation) have emerged as a crucial factor contributing to immune escape and CAR T cell resistance, particularly in the case of solid tumours with only limited success achieved to date. In this review, we discuss mechanisms of tumour relapse in CAR T cell therapy and the promising strategies that are under development to overcome multiple resistance mechanisms, thereby reducing outgrowth of antigen escape variants. Specifically, we emphasize the importance of designing clinical translational strategies to enhance CAR T cell crosstalk with host immune cells, eliciting endogenous antitumour immune responses through antigen/epitope spreading, which offers a genuine solution to the limitations of targeting tumour antigen heterogeneity in solid tumours with monospecific T cell therapies.

Epigenetic landscapes drive CAR-T cell kinetics and fate decisions: Bridging persistence and resistance

Chimeric antigen receptor-T (CAR-T) cell therapy has revolutionized the treatment paradigm for B-cell malignancies and holds promise for solid tumor immunotherapy. However, CAR-T-cell therapy still faces many challenges, especially primary and secondary resistance. Some mechanisms of resistance, including CAR-T-cell dysfunction, an inhibitory tumor microenvironment, and tumor-intrinsic resistance, have been identified in previous studies. As insights into CAR-T-cell biology have increased, the role of epigenetic reprogramming in influencing the clinical effectiveness of CAR-T cells has become increasingly recognized. An increasing number of direct and indirect epigenetic targeting methods are being developed in combination with CAR-T-cell therapy. In this review, we emphasize the broad pharmacological links between epigenetic therapies and CAR-T-cell therapy, not only within CAR-T cells but also involving tumors and the tumor microenvironment. To elucidate the mechanisms through which epigenetic therapies promote CAR-T-cell therapy, we provide a comprehensive overview of the epigenetic basis of CAR-T-cell kinetics and differentiation, tumor-intrinsic factors and the microenvironment. We also describe some epigenetic strategies that have implications for CAR-T-cell therapy in the present and future. Because targeting epigenetics can have pleiotropic effects, developing more selective and less toxic targeting strategies and determining the optimal administration strategy in clinical trials are the focus of the next phase of research. In summary, we highlight the possible mechanisms and clinical potential of epigenetic regulation in CAR-T-cell therapy.

Advances in strategies to improve the immunotherapeutic efficacy of chimeric antigen receptor-T cell therapy for lymphoma

Chimeric antigen receptor-T (CAR-T) cell therapy is a precise immunotherapy for lymphoma. However, its long-term efficacy faces many challenges related to tumor cell heterogeneity, interference from immunosuppressive microenvironments, CAR-T cell exhaustion, and unmanageable adverse events. Diverse modifications have been introduced into conventional CAR-T cells to overcome these obstacles; examples include addition of recognition sites to prevent immune escape, coupling of cytokine domains to enhance killing ability, blocking of immune checkpoint signals to resist tumor microenvironments, and inclusion of suicide systems or safety switches to improve safety and flexibility. With increasing understanding of the importance of metabolism and epigenetics in cancer and cytotherapy, glycolysis, methylation, and acetylation have become crucial CAR-T cell therapeutic targets. Universal and in situ CAR-T cells are also expected to be used in clinical applications, thus providing hope to patients with relapsed/refractory lymphomas.

Natural killer cells' functional impairment drives the immune escape of pre-malignant clones in early-stage myelodysplastic syndromes

Dissecting the preneoplastic disease states' biological mechanisms that precede tumorigenesis can lead to interventions that can slow down disease progression and/or mitigate disease-related comorbidities. Myelodysplastic syndromes (MDS) cannot be cured by currently available pharmacological therapies, which fail to eradicate aberrant hematopoietic stem cells (HSCs), most of which are mutated by the time of diagnosis. Here, we sought to elucidate how MDS HSCs evade immune surveillance and expand in patients with clonal cytopenias of undetermined significance (CCUS), the pre-malignant stage of MDS. We used multi-omic single-cell approaches and functional in vitro studies to show that immune escape at disease initiation is mainly mediated by mutant, dysfunctional natural killer (NK) cells with impaired cytotoxic capability against cancer cells. Preclinical in vivo studies demonstrated that injecting NK cells from healthy donors efficiently depleted CCUS mutant cells while allowing normal cells to regenerate hematopoiesis. Our findings suggest that early intervention with adoptive cell therapy can prevent or delay the development of MDS.

Immunotherapy in chronic lymphocytic leukemia: advances and challenges

Chronic lymphocytic leukemia (CLL) is characterized as a clonal proliferation of mature B lymphocytes with distinct immunophenotypic traits, predominantly affecting the middle-aged and elderly population. This condition is marked by an accumulation of lymphocytes within the peripheral blood, bone marrow, spleen, and lymph nodes. The associated immune dysregulation predisposes CLL patients to a higher risk of secondary malignancies and infections, which significantly contribute to morbidity and mortality rates. The advent of immunotherapy has revolutionized the prognosis of CLL, advancing treatment modalities and offering substantial benefits to patient outcomes. This review endeavors to synthesize and scrutinize the efficacy, merits, and limitations of the current immunotherapeutic strategies for CLL. The aim is to inform the selection of optimal treatment regimens tailored to individual patient needs. Furthermore, the review juxtaposes various therapeutic combinations to elucidate the comparative advantages of each approach, with the ultimate objective of enhancing patient prognosis and quality of life.

Prior chemotherapy deteriorates T-cell quality for CAR T-cell therapy in B-cell non-Hodgkin's lymphoma

BACKGROUND

Chimeric antigen receptor (CAR) T-cell therapy depends on T cells that are genetically modified to recognize and attack cancer cells. Their effectiveness thus hinges on the functionality of a patient's own T cells. Since CAR T-cell therapy is currently only approved for advanced cancers after at least one line of chemotherapy, we evaluated the potential negative effects of prior exposure to chemotherapy on T-cell functionality.

METHODS

We studied T cells of two B-cell non-Hodgkin's lymphoma patient cohorts, one collected before treatment (pre-therapy) and the other after one or more (median 3) lines of chemotherapy (post-therapy). Leveraging advanced multiparameter flow cytometry, single-cell RNA sequencing (scRNA-seq), whole-genome DNA methylation arrays and in vitro functionality testing of generated CAR T cells, we compared patient samples in their suitability for effective CAR T-cell therapy.

RESULTS

We discovered significant modifications in T-cell subsets and their transcriptional profiles secondary to chemotherapy exposure. Our analysis revealed a discernible shift towards phenotypically more differentiated T cells and an upregulation of markers indicative of T-cell exhaustion. Additionally, scRNA-seq and DNA methylation analyses revealed gene expression and epigenetic changes associated with diminished functionality in post-therapy T cells. Cytotoxicity assays demonstrated superior killing efficacy of CAR T cells derived from treatment-naïve patients compared with those with chemotherapy history.

CONCLUSIONS

These findings corroborate that employing T cells collected prior to frontline chemotherapy could enhance the effectiveness of CAR T-cell therapy and improve patient outcomes.

Current landscape of vector safety and genotoxicity after hematopoietic stem or immune cell gene therapy

Malignant transformation of gene modified haematopoietic stem cells caused anxiety following adverse events in early clinical trials using gamma-retroviral vectors (γRV) to correct haematopoietic stem cells (HSC) in monogenic immune disorders. Adoption of HIV-derived lentiviral vectors (LV) with SIN (self-inactivating) configurations greatly reduced risks and subsequently hundreds of patients have been dosed with HSC gene therapy for blood, immune and metabolic conditions. Nevertheless, as experience builds, it's now well recognised that vector integration can drive clonal expansions and these may carry long term safety risks. Documented cases of haematological malignancy after SIN-LV gene therapy have recently emerged, in particular where heterologous retroviral promoters were employed and there are concerns around certain insulator elements and other possible contributors to clonal expansions. Similarly, tens of thousands of subjects have now received engineered T cell products, and longstanding dogma that mature T cells cannot be transformed is being questioned, with reports of a small number of malignant transformation events and wider concerns around secondary malignancies in some groups of patients. We summarize current clinical information and revisit genotoxicity risks following ex-vivo gene modification of HSC and T cells.

Molecular Mechanisms Governing CD8 T Cell Differentiation and Checkpoint Inhibitor Response in Cancer

CD8 T cells play a critical role in antitumor immunity. However, over time, they often become dysfunctional or exhausted and ultimately fail to control tumor growth. To effectively harness CD8 T cells for cancer immunotherapy, a detailed understanding of the mechanisms that govern their differentiation and function is crucial. This review summarizes our current knowledge of the molecular pathways that regulate CD8 T cell heterogeneity and function in chronic infection and cancer and outlines how T cells respond to therapeutic checkpoint blockade. We explore how T cell-intrinsic and -extrinsic factors influence CD8 T cell differentiation, fate choices, and functional states and ultimately dictate their response to therapy. Identifying cells that orchestrate long-term antitumor immunity and understanding the mechanisms that govern their development and persistence are critical steps toward improving cancer immunotherapy.

Two chemotherapeutic agents expand stem-like CD62L+CD8+ T cells in antitumor immune responses

Introduction

Recent findings reveal that the precursors of exhausted CD8+ T (CD8+ Tpex) cells possess stem-like signatures in tumor immunity, which originate from tumor draining lymph node (TdLN)-derived tumor-specific memory (CD8+ TTSM) cells. Both of these T subsets can be collectively referred to as stem-like CD8+ T cells, which demonstrate robust self-renewal ability and can proliferate and differentiate into transitory effector-like exhausted T cells (Texint). There are reports that chemotherapeutic drugs can promote the antitumor immune responses of patients by increasing the number of CD8+ T cells; however, whether chemotherapeutic drugs increase these two stem-like CD8+ T cells remain further exploration.

Methods

Tpex cell-associated subpopulations in human colorectal tumors were analyzed by using single-cell sequencing data. CT26 and B16 tumor models of wild type and Eomes conditional knockout mice were constructed, and the changes of TTSM, Tpex and Tex subsets in mice were dissected by flow cytometry after treatment with decitabine (DAC), doxorubicin (DOX) and 5-Fluorouracil (5-FU).

Results

In this study, we demonstrated that DAC and 5-FU expanded CD8+ TTSM cells in TdLNs. At the same time, we validated that DAC and 5-FU substantially promoted the expansion of CD62L+CD8+ Tpex cells and subsequently increased effector function of CX3CR1+ CD8+ Texint cells. In addition, the conditional knockout of transcription factor Eomes in CD8+ T cells partially eliminated DAC-amplified CD62L+ CD8+ Tpex cells, but had no effect on such CD8+ T subset expanded by 5-FU.

Conclusion

The present study demonstrated that both DAC and 5-FU promoted the differentiation of stem-like CD8+ TTSM cells in TdLNs and significantly enhanced the differentiation and expansion of stem-like CD62L+ CD8+ Tpex and CX3CR1+ Texint cells in tumor microenvironment. The knockout of Eomes partially influenced the role of DAC in promoting the differentiation and expansion of stem-like CD8+ T cells.

T cell-based cancer immunotherapy: opportunities and challenges

T cells play a central role in the cancer immunity cycle. The therapeutic outcomes of T cell-based intervention strategies are determined by multiple factors at various stages of the cycle. Here, we summarize and discuss recent advances in T cell immunotherapy and potential barriers to it within the framework of the cancer immunity cycle, including T-cell recognition of tumor antigens for activation, T cell trafficking and infiltration into tumors, and killing of target cells. Moreover, we discuss the key factors influencing T cell differentiation and functionality, including TCR stimulation, costimulatory signals, cytokines, metabolic reprogramming, and mechanistic forces. We also highlight the key transcription factors dictating T cell differentiation and discuss how metabolic circuits and specific metabolites shape the epigenetic program of tumor-infiltrating T cells. We conclude that a better understanding of T cell fate decision will help design novel strategies to overcome the barriers to effective cancer immunity.

Harnessing the potential of gene-editing technology to overcome the current bottlenecks of CAR-T cell therapy in T-cell malignancies

T-cell malignancies (TCMs) include a diverse spectrum of hematologic cancers marked by complex biology and aggressive nature. Treating TCMs remains a critical unmet need in oncology with poor response to standard therapies. Chimeric antigen receptor (CAR)-T cell therapy is one of the most successful types of immunotherapy that has revolutionized cancer treatment, as evidenced by various approved products for CD19 B-cell malignancies and multiple myeloma. Nonetheless, due to some unique hurdles, such as the risk of CAR-T cell fratricide, product contamination with malignant cells, and severe T-cell aplasia, the translation of this treatment approach to TCMs has not been particularly successful. Moreover, irrespective of the type of treated cancer, CAR-T cell therapy can also present some complexities and potential side effects, such as cumbersome and costly manufacturing processes, impaired in vivo function, cytokine release syndrome (CRS), neurotoxicity, and leukemic transformation of CAR-T cells. Recent groundbreaking advances in gene-editing technology and the evolution of precise gene-editing tools such as the CRISPR/Cas9 system and its derivatives have opened a new way to overcoming the mentioned bottlenecks and paving the way for CAR-T cell therapy in TCMs. This review sheds light on how gene editing is being incorporated into CAR-T cell therapy to address current hurdles, enhance therapeutic efficacy, and improve the safety profile of CAR-T cell therapy in TCMs. Ongoing/conducted clinical trials are also discussed to provide a comprehensive view of the evolving landscape of genome-edited CAR-T cell therapy for TCMs.

Immunometabolite L-2-HG promotes epigenetic modification of exhausted T cells and improves antitumor immunity

This study aimed to explore the potential correlation between the metabolic intermediate L-2-hydroxyglutarate (L-2-HG) and T cell exhaustion, as well as the underlying mechanisms involved. In this study, we investigated the presence of exhausted T (Tex) cells in patients under certain conditions: HIV infection, chronic leukemia, and hepatocellular carcinoma. To gain insights into the epigenetic signatures and transcriptome changes in Tex cells, we employed a combination of RNA-seq and ATAC-seq analyses. To evaluate the impact of L-2-HG on mitochondrial function, differentiation, and antitumor capacity of Tex cells, we utilized in vitro cell culture experiments and animal tumor models. We observed mitochondrial depolarization and metabolic dysfunction in Tex cells, accompanied by a significant reduction in L-2-HG levels. Moreover, altered epigenetic characteristics were observed in Tex cells, including a substantial increase in H3K27me3 abundance. Culturing Tex cells with L-2-HG demonstrated improved mitochondrial metabolism, reduced H3K27me3 abundance, and enhanced memory T cell differentiation. In a mouse melanoma tumor model, L-2-HG-treated CD8+ T cells for adoptive therapy led to significantly reduced tumor volume and significantly enhanced effector function of T cells. The study revealed that L-2-HG acted as an immune metabolite through epigenetic modifications of Tex cells.

Chimeric antigen receptor-modified T-cell therapy: Recent updates and challenges in autoimmune diseases

Chimeric antigen receptor (CAR) T-cell therapy (CAR-T) has revolutionized the treatment of hematologic malignancies, demonstrating significant clinical efficacy and leading to US Food and Drug Administration approval of several CAR T-cell-based products. This success has prompted exploration of CAR-T in other disease areas, including autoimmune diseases (AIDs). CAR-T targeting B cells has been shown to provide clinical and biological improvements in patients with refractory AIDs. The aim of this review is to discuss promising strategies involving CAR-T in AIDs, such as those targeting B cells and T cells, and to explore new approaches targeting fibroblasts or plasmacytoid dendritic cells. Despite these advances, the application of CAR-T in AIDs faces several unique challenges. The quality and functionality of T cells in patients with AIDs may be compromised as a result of previous treatments and the underlying inflammatory state, affecting the generation and efficacy of CAR-T. In addition, achieving adequate tissue biodistribution and persistence of CAR T cells in affected tissues remains a major challenge. Finally, the high costs associated with T-cell production pose economic problems, particularly in the context of chronic diseases, which are far more numerous than the hematologic diseases for which CAR-Ts have been granted marketing authorization to date. If the indications for CAR-T increase significantly, production costs will have to drop drastically in order to obtain reliable economic models.

Significance of targeting DNMT3A mutations in AML

Acute myeloid leukemia (AML) is the most prevalent form of leukemia among adults, characterized by aggressive behavior and significant genetic diversity. Despite decades of reliance on conventional chemotherapy as the mainstay treatment, patients often struggle with achieving remission, experience rapid relapses, and have limited survival prospects. While intensified induction chemotherapy and allogeneic stem cell transplantation have enhanced patient outcomes, these benefits are largely confined to younger AML patients capable of tolerating intensive treatments. DNMT3A, a crucial enzyme responsible for establishing de novo DNA methylation, plays a pivotal role in maintaining the delicate balance between hematopoietic stem cell differentiation and self-renewal, thereby influencing gene expression programs through epigenetic regulation. DNMT3A mutations are the most frequently observed genetic abnormalities in AML, predominantly in older patients, occurring in approximately 20-30% of adult AML cases and over 30% of AML with a normal karyotype. Consequently, the molecular underpinnings and potential therapeutic targets of DNMT3A mutations in AML are currently being thoroughly investigated. This article provides a comprehensive summary and the latest insights into the structure and function of DNMT3A, examines the impact of DNMT3A mutations on the progression and prognosis of AML, and explores potential therapeutic approaches for AML patients harboring DNMT3A mutations.

Dual-targeting CAR T cells for B-cell acute lymphoblastic leukemia and B-cell non-Hodgkin lymphoma

ABSTRACT

Relapse after CD19-directed chimeric antigen receptor (CAR) T-cell therapy remains a major challenge in B-cell acute lymphoblastic leukemia (ALL) and B-cell non-Hodgkin lymphoma (B-NHL). One of the main strategies to avoid CD19-negative relapse has been the development of dual CAR T cells targeting CD19 and an additional target, such as CD22 or CD20. Different methods have been used to achieve this, including coadministration of 2 products targeting 1 single antigen, cotransduction of autologous T cells, use of a bicistronic vector, or the development of bivalent CARs. Phase 1 and 2 trials across all manufacturing strategies have shown this to be a safe approach with equivalent remission rates and initial product expansion. CAR T-cell persistence remains a significant issue, with the majority of relapses being antigen-positive after CAR T-cell infusion. Further, despite adding a second antigen, antigen-negative relapses have not yet been eliminated. This review summarizes the state of the art with dual-targeting CAR T cells for B-cell ALL and B-NHL, the challenges encountered, and possible next steps to overcome them.

Characterization of Rationally Designed CRISPR/Cas9-Based DNA Methyltransferases with Distinct Methyltransferase and Gene Silencing Activities in Human Cell Lines and Primary Human T Cells

Nuclease-deactivated Cas (dCas) proteins can be used to recruit epigenetic effectors, and this class of epigenetic editing technologies has revolutionized the ability to synthetically control the mammalian epigenome and transcriptome. DNA methylation is one of the most important and well-characterized epigenetic modifications in mammals, and while many different forms of dCas-based DNA methyltransferases (dCas-DNMTs) have been developed for programmable DNA methylation, these tools are frequently poorly tolerated and/or lowly expressed in mammalian cell types. Further, the use of dCas-DNMTs has largely been restricted to cell lines, which limits mechanistic insights in karyotypically normal contexts and hampers translational utility in the longer term. Here, we extend previous insights into the rational design of the catalytic core of the mammalian DNMT3A methyltransferase and test three dCas9-DNMT3A/3L variants across different human cell lines and in primary donor-derived human T cells. We find that mutations within the catalytic core of DNMT3A stabilize the expression of dCas9-DNMT3A/3L fusion proteins in Jurkat T cells without sacrificing DNA methylation or gene-silencing performance. We also show that these rationally engineered mutations in DNMT3A alter DNA methylation profiles at loci targeted with dCas9-DNMT3A/3L in cell lines and donor-derived human T cells. Finally, we leverage the transcriptionally repressive effects of dCas9-DNMT3A/3L variants to functionally link the expression of a key immunomodulatory transcription factor to cytokine secretion in donor-derived T cells. Overall, our work expands the synthetic biology toolkit for epigenetic editing and provides a roadmap for the use of engineered dCas-based DNMTs in primary mammalian cell types.

Supercharging CAR-T cells through transcriptional and epigenetic armoring

Inspired by the remarkable success of CAR-T therapy in hematologic malignancies, research is increasingly focused on adapting this treatment for solid tumors. However, CAR-T efficacy remains limited due to its exhaustion and shortened persistence. Transcription factors and epigenetic modifications play pivotal roles in modulating T cell differentiation and functionality, which have been leveraged in numerous strategies to promote the formation of long-lasting memory cells with stem-like properties and supercharging CAR-T performance. This review highlights pivotal transcriptional factors, such as c-Jun and FOXO1, which enhance and sustain T cell effector function, diminishes exhaustion, and epigenetic regulators like TET2 and DNMT3A, whose knockout promotes memory T subsets formation. We explore their interconnections, downstream targets, biological impacts, and the potential application risks of certain candidates, providing a comprehensive theoretical framework for supercharging CAR-T therapies through transcriptional and epigenetic interventions.

Unleashing the potential of a low CpG Passer transposon for superior CAR-T cell therapy

Background

To date, the non-viral vector Chimeric Antigen Receptor (CAR) T cell preparation platform, exemplified by transposons, has demonstrated significant potential in tumor immunotherapy and yielded positive results in multiple clinical trials. Nonetheless, non-methylated CpG sequences within plasmid DNA can elicit an inflammatory response via Toll-like receptor 9 (TLR9) during CAR-T cell preparation, adversely affecting transgene expression. Additionally, de novo DNA methylation programs promote T cell exhaustion, which poses a significant limitation for CAR-T cell therapy applications.

Methods

High-throughput liquid protein chip and CBA analyses were utilized to determine the expression levels of inflammatory factors. Flow cytometry and luciferase reporter assays were employed for mutation screening. BALB/c mice and M-NSG mice were used to evaluate the inflammatory response and efficacy of LCG CAR-T in vivo, with TIL grouping detected via immunohistochemistry.

Results

In this study, we modified the newly discovered Passer (JL) transposon to construct a low-CpG content transposon for CAR-T cell (LCG CAR-T cell) preparation. In vitro experiments demonstrated that LCG CAR-T cells prepared using this new transposon exhibited stronger cytotoxicity. In animal models, LCG CAR-T cells significantly inhibited tumor growth and increased the populations of CD4+CAR-T cells and tumor-infiltrating lymphocytes. Furthermore, LCG CAR-T cells modulated pro-inflammatory cytokine release, thereby reducing in vivo inflammatory responses and surpassing the effects observed with unmodified CAR-T cells.

Conclusions

Collectively, our results demonstrate the high safety and efficacy of non-viral, low CpG Passer transposon CAR-T cells, offering new avenues for improving CAR-T cell efficacy while minimizing in vivo inflammation.

Metabolization of microbial postbiotic pentanoate drives anti-cancer CAR T cells

The microbiome is a complex host factor and key determinant of the outcome of antibody-based and cellular immunotherapy. Its postbiotics are a blend of soluble commensal byproducts that are released into the host environment and have been associated with the regulation of immune homeostasis, particularly through impacts on epigenetics and cell signaling. In this study, we show that the postbiotic pentanoate is metabolized to citrate within the TCA cycle via both the acetyl- and succinyl-CoA entry points, a feature uniquely enabled by the chemical structure of the C5 aliphatic chain. We identified ATP-citrate lyase as the crucial factor that redirects pentanoate-derived citrate from the succinyl-CoA route to the nucleus, thereby linking metabolic output and histone acetylation. This epigenetic-metabolic crosstalk mitigated T cell exhaustion and promoted naive-like differentiation in pentanoate-programmed chimeric antigen receptor (CAR) T cells. The predictive and therapeutic potential of pentanoate was corroborated in two independent patient cohorts and three syngeneic models of CAR T adoptive therapy. Our data demonstrate that postbiotics are integrated into mitochondrial metabolism and subsequently incorporated as epigenetic imprints. This bridge between microbial and mammalian interspecies communication can ultimately impact T cell differentiation and efficacy.

Electrical Stimulation Generates Induced Tumor-Suppressing Cells, Offering a Potential Option for Combatting Breast Cancer and Bone Metastasis

Treating advanced metastatic cancer, particularly with bone metastasis, remains a significant challenge. In previous studies, induced tumor-suppressing (iTS) cells were successfully generated through genetic, chemical, and mechanical interventions. This study investigates the potential of electrical stimulation to generate iTS cells. Using a custom electrical stimulator with platinum electrodes, mesenchymal stem cells (MSCs) and Jurkat T cells were stimulated under optimized conditions (50 mV/cm, 10-100 Hz, 1 h). Conditioned medium (CM) from electrically stimulated cells demonstrated tumor-suppressing capabilities, inhibiting tumor cell migration, 3D spheroid growth, and cancer tissue fragment viability. Additionally, the CM reduced osteoclast maturation while promoting osteoblast differentiation. Proteomic analysis revealed enrichment of tumor-suppressing proteins, including histone H4, in the CM. Functional studies identified Piezo1 as a key mediator, as its knockdown significantly impaired the tumor-suppressive effects. Mechanistically, the process was distinct from other methods, such as mechanical vibration, with SUN1 inhibition showing no effect on iTS cell generation by electrical stimulation. These findings demonstrate the efficacy of electrical stimulation in enhancing the antitumor capabilities of MSCs and T cells, offering a novel approach to cancer therapy. Further exploration of this strategy could provide valuable insights into developing new treatments for metastatic cancer.

Advances in CAR T cell therapy: antigen selection, modifications, and current trials for solid tumors

Chimeric antigen receptor (CAR) T cell therapy has revolutionized the treatment of hematologic malignancies, achieving remarkable clinical success with FDA-approved therapies targeting CD19 and BCMA. However, the extension of these successes to solid tumors remains limited due to several intrinsic challenges, including antigen heterogeneity and immunosuppressive tumor microenvironments. In this review, we provide a comprehensive overview of recent advances in CAR T cell therapy aimed at overcoming these obstacles. We discuss the importance of antigen identification by emphasizing the identification of tumor-specific and tumor-associated antigens and the development of CAR T therapies targeting these antigens. Furthermore, we highlight key structural innovations, including cytokine-armored CARs, protease-regulated CARs, and CARs engineered with chemokine receptors, to enhance tumor infiltration and activity within the immunosuppressive microenvironment. Additionally, novel manufacturing approaches, such as the Sleeping Beauty transposon system, mRNA-based CAR transfection, and in vivo CAR T cell production, are discussed as scalable solution to improve the accessibility of CAR T cell therapies. Finally, we address critical therapeutic limitations, including cytokine release syndrome (CRS), immune effector cell-associated neurotoxicity syndrome (ICANS), and suboptimal persistence of CAR T cells. An examination of emerging strategies for countering these limitations reveals that CRISPR-Cas9-mediated genetic modifications and combination therapies utilizing checkpoint inhibitors can improve CAR T cell functionality and durability. By integrating insights from preclinical models, clinical trials, and innovative engineering approaches, this review addresses advances in CAR T cell therapies and their performance in solid tumors.

CAR-T Therapy Beyond B-Cell Hematological Malignancies

Despite the advances of CAR-T cells in certain hematological malignancies, mostly from B-cell derivations such as non-Hodgkin lymphomas, acute lymphoblastic leukemia and multiple myeloma, a significant portion of other hematological and non-hematological pathologies can benefit from this innovative treatment, as the results of clinical studies are demonstrating. The clinical application of CAR-T in the setting of acute T-lymphoid leukemia, acute myeloid leukemia, solid tumors, autoimmune diseases and infections has encountered limitations that are different from those of hematological B-cell diseases. To overcome these restrictions, strategies based on different molecular engineering platforms have been devised and will be illustrated below. The aim of this manuscript is to provide an overview of the CAR-T application in pathologies other than those currently treated, highlighting both the limits and results obtained with these settings.

Cancer epigenetic therapy: recent advances, challenges, and emerging opportunities

Epigenetic dysregulation is an important nexus in the development and maintenance of human cancers. This review provides an overview of how understanding epigenetic dysregulation in cancers has led to insights for novel cancer therapy development. Over the past two decades, significant strides have been made in drug discovery efforts targeting cancer epigenetic mechanisms, leading to successes in clinical development and approval of cancer epigenetic therapeutics. This article will discuss the current therapeutic rationale guiding the discovery and development of epigenetic therapeutics, key learnings from clinical experiences and new opportunities on the horizon.

Detection and Characterization of Clonal Hematopoiesis

Clonal hematopoiesis (CH) is the age-related expansion of hematopoietic stem cell clones resulting from the acquisition of somatic point mutations or mosaic chromosomal alterations (mCAs). It is linked to adverse systemic effects, including hematologic malignancies, cardiovascular diseases, metabolic disorders, as well as liver and kidney ailments, ultimately contributing to elevated overall mortality.Given its diverse biological and clinical implications, the identification of clonal hematopoiesis holds significance in various contexts. While traditionally centered on mutations associated with myeloid malignancies, stem/progenitor cell involvement has been documented for various lymphoid malignancies, including T-cell lymphoma, chronic lymphocytic leukemia (CLL), and follicular lymphoma (FL). Lymphoid CH (L-CH) involves a broader spectrum of genes and occurs at a lower prevalence, resulting in reduced mutation prevalences per gene. This characteristic poses challenges for efficient CH detection.The major strategies to identify CH are whole exome sequencing (WES), whole genome sequencing (WGS), or targeted sequencing. Targeted sequencing allows for much higher sequencing depth compared to WES and WGS because of the focus on genes known to be associated with CH and therefore allows detecting potential variants at low frequencies with high precision. Here, we describe an error-corrected targeted sequencing approach for detection of CH in bone marrow (BM) or peripheral blood (PB) samples, which we have successfully established and used in various cohorts. This protocol includes the process of DNA isolation from PB and BM samples, library preparation with molecular tags including quality control steps and computational analysis including variant filtering.

Optimising CAR T therapy for the treatment of solid tumors

INTRODUCTION

Adoptive immunotherapy using chimeric antigen receptor (CAR)-engineered T cells has proven transformative in the management of B cell and plasma cel derived malignancies. However, solid tumors have largely proven to be resistant to this therapeutic modality. Challenges include the paucity of safe target antigens, heterogeneity of target expression within the tumor, difficulty in delivery of CAR T cells to the site of disease, poor penetration within solid tumor deposits and inability to circumvent the array of immunosuppressive and biophysical barriers imposed by the solid tumor microenvironment.

AREAS COVERED

Literature was reviewed on the PubMed database, excluding occasional papers which were not available as open access publications or through other means.

EXPERT OPINION

Here, we have surveyed the large body of technological advances that have been made in the quest to bridge the gap toward successful deployment of CAR T cells for the treatment of solid tumors. These encompass the development of more sophisticated targeting strategies to engage solid tumor cells safely and comprehensively, improved drug delivery solutions, design of novel CAR architectures that achieve improved functional persistence and which resist physical, chemical and biological hurdles present in tumor deposits. Prospects for combination therapies that incorporate CAR T cells are also considered.

Clinical trials, challenges, and changes in TCR-based therapeutics for hematologic malignancies

INTRODUCTION

T cells engineered to express antigen-specific T cell receptors (TCR; TCR-T) are a promising class of immunotherapeutic for patients with hematologic malignancies. Like chimeric antigen receptor-engineered T cells (CAR-T), TCR-T are cell products with defined specificity and composition. Unlike CAR-T, TCR-T can recognize targets arising both from intracellular and cell surface proteins and leverage the sensitivity of natural TCR signaling machinery. A growing number of TCR-T targeting various antigens in different hematologic malignancies are in early-phase clinical trials, and more are in preclinical development.

AREAS COVERED

This review covers results from early-phase TCR-T clinical trials for hematologic malignancies. Challenges in the field are reviewed, including identifying optimal targets, engaging CD4+ help for CD8+ T cells, and overcoming tumor-induced suppression; recent innovations to overcome these challenges are also highlighted.

EXPERT OPINION

In the future, TCR-T's promise for hematologic malignancies will be borne out in later-phase clinical trials and approvals for clinical use. Improved antigen discovery methods will help build the toolbox of targets needed for broadly applicable TCR-T. Rationally designed TCR-T modifications including incorporation of accessory receptors and gene editing will enhance TCR-T function. New hybrid receptors combining features of TCR and CAR will enter the clinic.

Therapeutic advantage of combinatorial chimeric antigen receptor T cell and chemotherapies

Chimeric antigen receptor (CAR) T cell therapies have transformed outcomes for many patients with hematological malignancies. However, some patients do not respond to CAR T cell treatment, and adapting CAR T cells for treatment of solid and brain tumors has been met with many challenges, including a hostile tumor microenvironment and poor CAR T cell persistence. Thus, it is unlikely that CAR T cell therapy alone will be sufficient for consistent, complete tumor clearance across patients with cancer. Combinatorial therapies of CAR T cells and chemotherapeutics are a promising approach for overcoming this because chemotherapeutics could augment CAR T cells for improved antitumor activity or work in tandem with CAR T cells to clear tumors. Herein, we review efforts toward achieving successful CAR T cell and chemical drug combination therapies. We focus on combination therapies with approved chemotherapeutics because these will be more easily translated to the clinic but also review nonapproved chemotherapeutics and drug screens designed to reveal promising new CAR T cell and chemical drug combinations. Overall, this review highlights the promise of CAR T cell and chemotherapy combinations with a specific focus on how combinatorial therapy overcomes challenges faced by either monotherapy and supports the potential of this therapeutic strategy to improve outcomes for patients with cancer. SIGNIFICANCE STATEMENT: Improving currently available CAR T cell products via combinatorial therapy with chemotherapeutics has the potential to drastically expand the types of cancers and number of patients that could benefit from these therapies when neither alone has been sufficient to achieve tumor clearance. Herein, we provide a thorough review of the current efforts toward studying CAR T and chemotherapy combinatorial therapies and offer perspectives on optimal ways to identify new and effective combinations moving forward.

Correlative studies reveal factors contributing to successful CAR-T cell therapies in cancer

Cellular and targeted immunotherapies have revolutionized cancer treatments in the last several decades. Successful cellular therapies require both effective and durable cytotoxic activity from the immune cells as well as an accessible and susceptible response from targeted cancer cells. Correlative studies from clinical trials as well as real-world data from FDA-approved therapies have revealed invaluable insights about immune cell factors and cancer cell factors that impact rates of response and relapse to cellular therapies. This review focuses on the flagship cellular therapy of engineered chimeric antigen receptor T-cells (CAR-T cells). Within the CAR-T cell compartment, we discuss discoveries about T-cell phenotype, transcriptome, epigenetics, cytokine signaling, and metabolism that inform the cell manufacturing process to produce the most effective and durable CAR-T cells. Within the cancer cell compartment, we discuss mechanisms of resistance and relapse caused by mutations, alternative splicing, post-transcriptional modifications, and cellular reprogramming. Continued correlative and mechanistic studies are required to help us further optimize cellular therapies in a variety of malignancies.

Inflammation in myelodysplastic syndrome pathogenesis

Inflammation is a key driver of the progression of preleukemic myeloid conditions, such as clonal hematopoiesis of indeterminate potential (CHIP) and clonal cytopenia of undetermined significance (CCUS), to myelodysplastic syndromes (MDS). Inflammation is a critical mediator in the complex interplay of the genetic, epigenetic, and microenvironmental factors contributing to clonal evolution. Under inflammatory conditions, somatic mutations in TET2, DNMT3A, and ASXL1, the most frequently mutated genes in CHIP and CCUS, induce a competitive advantage to hematopoietic stem and progenitor cells, which leads to their clonal expansion in the bone marrow. Chronic inflammation also drives metabolic reprogramming and immune system deregulation, further promoting the expansion of malignant clones. This review underscores the urgent need to fully elucidate the role of inflammation in MDS initiation and highlights the potential of the therapeutical targeting of inflammatory pathways as an early intervention in MDS.

Targeting epigenetic mechanisms of resistance to chemotherapy in gliomas

Glioma, an aggressive type of brain tumors of glial origin is highly heterogeneous, posing significant treatment challenges due to its intrinsic resistance to conventional therapeutic schemes. It is characterized by an interplay between epigenetic and genetic alterations in key signaling pathways which further endorse their resistance potential. Aberrant DNA methylation patterns, histone modifications and non-coding RNAs may alter the expression of genes associated with drug response and cell survival, induce gene silencing or deregulate key pathways contributing to glioma resistance. There is evidence that epigenetic plasticity enables glioma cells to adapt dynamically to therapeutic schemes and allow the formation of drug-resistant subpopulations. Furthermore, the tumor microenvironment adds an extra input on epigenetic regulation, increasing the complexity of resistance mechanisms. Herein, we discuss epigenetic changes conferring to drug resistance mechanisms in gliomas in order to delineate novel therapeutic targets and potential approaches that will enable personalized treatment.

Epigenetics behind CD8+ T cell activation and exhaustion

CD8+ T cells play a critical role in specific immunity. In recent years, cell therapy has been emerging rapidly. The specific cytotoxic capabilities of these cells enable them to precisely identify and kill cells presenting specific antigens. This has demonstrated promise in the treatment of autoimmune diseases and cancers, with wide-ranging applications and value. However, in some diseases, such as tumors and chronic infections, T cells may adopt an exhausted phenotype, resulting in a loss of cytotoxicity and limiting their further application. Epigenetics plays a significant role in the differentiation and regulation of gene expression in cells. There is extensive evidence indicating that epigenetic remodeling plays an important role in T cell exhaustion. Therefore, further understanding its role in CD8+ T cell function can provide insights into the programmatic regulation of CD8+ T cells from a genetic perspective and overcome these diseases. We attempted to describe the relationship between the activation, function, and exhaustion mechanisms of CD8+ T cells, as well as epigenetics. This understanding makes it possible for us to address the aforementioned issues.

Leveraging CRISPR gene editing technology to optimize the efficacy, safety and accessibility of CAR T-cell therapy

Chimeric Antigen Receptor (CAR)-T-cell therapy has revolutionized cancer immune therapy. However, challenges remain including increasing efficacy, reducing adverse events and increasing accessibility. Use of Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR) technology can effectively perform various functions such as precise integration, multi-gene editing, and genome-wide functional regulation. Additionally, CRISPR screening using large-scale guide RNA (gRNA) genetic perturbation provides an unbiased approach to understanding mechanisms underlying anti-cancer efficacy of CAR T-cells. Several emerging CRISPR tools with high specificity, controllability and efficiency are useful to modify CAR T-cells and identify new targets. In this review we summarize potential uses of the CRISPR system to improve results of CAR T-cells therapy including optimizing efficacy and safety and, developing universal CAR T-cells. We discuss challenges facing CRISPR gene editing and propose solutions highlighting future research directions in CAR T-cell therapy.

Optimizing Adoptive Cell Therapy for Solid Tumors via Epigenetic Regulation of T-cell Destiny

Adoptive cell therapy (ACT) emerged as a promising approach for cancer treatment, yet its application in solid tumors faced challenges such as inadequate tumor infiltration and cellular dysfunction. Histone acetylation is reported to play a crucial role in restoring T-cell function within tumor tissues. Building upon previous research, a novel strategy involving the co-loading of two drugs, G3C12 and vorinostat (SAHA), into PLGA microspheres to form G3C12+SAHA@PLGA is developed for intratumoral injection. The G3C12 peptide enhances adoptive T-cell recruitment to the tumor site by modulating the binding state of IFN-γ. While SAHA, a histone deacetylase inhibitor, promotes memory phenotypes of infiltrating T-cells and prevents their transition to an exhausted state. This synergistic approach effectively augmentes the efficacy of ACT in the "cold" tumor model (4T1) or the "hot" tumor model (CT26). These findings highlight the potential of combining epigenetic regulation with recruitment signaling as a means to enhance the therapeutic impact of ACT in treating solid tumors.

CAR T-cells for pediatric solid tumors: where to go from here?

Despite the great success that chimeric antigen receptor (CAR) T-cells have had in patients with B-cell malignancies and multiple myeloma, they continue to have limited efficacy against most solid tumors. Especially in the pediatric population, pre- and post-treatment biopsies are rarely performed due to ethical reasons, and thus, our understanding is still very limited regarding the mechanisms in the tumor microenvironment by which tumor cells exclude effectors and attract immune-suppressive cells. Nevertheless, based on the principles that are known, current T-cell engineering has leveraged some of these processes and created more potent CAR T-cells. The recent discovery of new oncofetal antigens and progress made in CAR design have expanded the potential pool of candidate antigens for therapeutic development. The most promising approaches to enhance CAR T-cells are novel CAR gating strategies, creative ways of cytokine delivery to the TME without enhancing systemic toxicity, and hijacking the chemokine axis of tumors for migratory purposes. With these new modifications, the next step in the era of CAR T-cell development will be the clinical validation of these promising preclinical findings.

IL-2-inducible T cell kinase deficiency sustains chimeric antigen receptor T cell therapy against tumor cells

Despite the revolutionary achievements of chimeric antigen receptor (CAR) T cell therapy in treating cancers, especially leukemia, several key challenges still limit its therapeutic efficacy. Of particular relevance is the relapse of cancer in large part as a result of exhaustion and short persistence of CAR-T cells in vivo. IL-2-inducible T cell kinase (ITK) is a critical modulator of the strength of T cell receptor signaling, while its role in CAR signaling is unknown. By electroporation of CRISPR-associated protein 9 (Cas9) ribonucleoprotein (RNP) complex into CAR-T cells, we successfully deleted ITK in CD19-CAR-T cells with high efficiency. Bulk and single-cell RNA sequencing analyses revealed downregulation of exhaustion and upregulation of memory gene signatures in ITK-deficient CD19-CAR-T cells. Our results further demonstrated a significant reduction of T cell exhaustion and enhancement of T cell memory, with significant improvement of CAR-T cell expansion and persistence both in vitro and in vivo. Moreover, ITK-deficient CD19-CAR-T cells showed better control of tumor relapse. Our work provides a promising strategy of targeting ITK to develop sustainable CAR-T cell products for clinical use.

IL-18R supported CAR T cells targeting oncofetal tenascin C for the immunotherapy of pediatric sarcoma and brain tumors

BACKGROUND

Oncofetal splice variants of extracellular matrix (ECM) proteins present a unique group of target antigens for the immunotherapy of pediatric cancers. However, limited data is available if these splice variants can be targeted with T cells expressing chimeric antigen receptors (CARs).

METHODS

To determine the expression of the oncofetal version of tenascin C (TNC) encoding the C domain (C.TNC) in pediatric brain and solid tumors, we used quantitative reverse transcription PCR and immunohistochemistry. Genetically modified T cells were generated from human peripheral blood mononuclear cells and evaluated in vitro and in vivo.

RESULTS

We demonstrate that C.TNC is expressed on a protein level in pediatric tumors, including diffuse intrinsic pontine glioma, osteosarcoma, rhabdomyosarcoma, and Ewing sarcoma. We generate C.TNC-CAR T cells and establish that these recognize and kill C.TNC-positive tumor cells. However, their antitumor activity in vivo is limited. To improve the effector function of C.TNC-CAR T cells, we design a leucine zipper-based chimeric cytokine receptor that activates interleukin-18 signaling pathways (Zip18R). Expression of Zip18R in C.TNC-CAR T cells improves their ability to secrete cytokines and expand in repeat stimulation assays. C.TNC-CAR.Zip18R T cells also have significantly greater antitumor activity in vivo compared with unmodified C.TNC-CAR T cells.

CONCLUSIONS

Our study identifies the C domain of the ECM protein TNC as a promising CAR T-cell therapy for pediatric solid tumors and brain tumors. While we focus here on pediatric cancer, our work has relevance to a broad range of adult cancers that express C.TNC.

Degradation of IKZF1 prevents epigenetic progression of T cell exhaustion in an antigen-specific assay

In cancer, chronic antigen stimulation drives effector T cells to exhaustion, limiting the efficacy of T cell therapies. Recent studies have demonstrated that epigenetic rewiring governs the transition of T cells from effector to exhausted states and makes a subset of exhausted T cells non-responsive to PD1 checkpoint blockade. Here, we describe an antigen-specific assay for T cell exhaustion that generates T cells phenotypically and transcriptionally similar to those found in human tumors. We perform a screen of human epigenetic regulators, identifying IKZF1 as a driver of T cell exhaustion. We determine that the IKZF1 degrader iberdomide prevents exhaustion by blocking chromatin remodeling at T cell effector enhancers and preserving the binding of AP-1, NF-κB, and NFAT. Thus, our study uncovers a role for IKZF1 as a driver of T cell exhaustion through epigenetic modulation, providing a rationale for the use of iberdomide in solid tumors to prevent T cell exhaustion.

TET2 regulates early and late transitions in exhausted CD8+ T cell differentiation and limits CAR T cell function

CD8+ T cell exhaustion hampers control of cancer and chronic infections and limits chimeric antigen receptor (CAR) T cell efficacy. Targeting TET2 in CAR T cells provides therapeutic benefit; however, TET2's role in exhausted T cell (TEX) development is unclear. In chronic lymphocytic choriomeningitis virus (LCMV) infection, TET2 drove conversion from stem cell-like TEX progenitors toward terminally differentiated and effector (TEFF)-like TEX. TET2 also enforced a terminally differentiated state in the early bifurcation between TEFF and TEX, indicating broad roles for TET2 in acquisition of effector biology. To exploit the therapeutic potential of TET2, we developed clinically actionable TET2-targeted CAR T cells by disrupting TET2 via knock-in of a safety switch alongside CAR knock-in at the TRAC locus. TET2-targeted CAR T cells exhibited restrained terminal exhaustion in vitro and enhanced antitumor responses in vivo. Thus, TET2 regulates fate transitions in TEX differentiation and can be targeted with a safety mechanism in CAR T cells for improved tumor control.

Advancing CAR T-cell therapies: Preclinical insights and clinical translation for hematological malignancies

Chimeric antigen receptor (CAR) T-cell therapy has achieved significant success in achieving durable and potentially curative responses in patients with hematological malignancies. CARs are tailored fusion proteins that direct T cells to a specific antigen on tumor cells thereby eliciting a targeted immune response. The approval of several CD19-targeted CAR T-cell therapies has resulted in a notable surge in clinical trials involving CAR T cell therapies for hematological malignancies. Despite advancements in understanding response mechanisms, resistance patterns, and adverse events associated with CAR T-cell therapy, the translation of these insights into robust clinical efficacy has shown modest outcomes in both clinical trials and real-world scenarios. Therefore, the assessment of CAR T-cell functionality through rigorous preclinical studies plays a pivotal role in refining therapeutic strategies for clinical applications. This review provides an overview of the various in vitro and animal models used to assess the functionality of CAR T-cells. We discuss the findings from preclinical research involving approved CAR T-cell products, along with the implications derived from recent preclinical studies aiming to optimize the functionality of CAR T-cells. The review underscores the importance of robust preclinical evaluations and the need for models that accurately replicate human disease to bridge the gap between preclinical success and clinical efficacy.

RIG-I is an intracellular checkpoint that limits CD8+ T-cell antitumour immunity

Retinoic acid-inducible gene I (RIG-I) is a pattern recognition receptor involved in innate immunity, but its role in adaptive immunity, specifically in the context of CD8+ T-cell antitumour immunity, remains unclear. Here, we demonstrate that RIG-I is upregulated in tumour-infiltrating CD8+ T cells, where it functions as an intracellular checkpoint to negatively regulate CD8+ T-cell function and limit antitumour immunity. Mechanistically, the upregulation of RIG-I in CD8+ T cells is induced by activated T cells, and directly inhibits the AKT/glycolysis signalling pathway. In addition, knocking out RIG-I enhances the efficacy of adoptively transferred T cells against solid tumours, and inhibiting RIG-I enhances the response to PD-1 blockade. Overall, our study identifies RIG-I as an intracellular checkpoint and a potential target for alleviating inhibitory constraints on T cells in cancer immunotherapy, either alone or in combination with an immune checkpoint inhibitor.

Immune Checkpoint Inhibitor Therapy and Associations with Clonal Hematopoiesis

Cancer cohorts are now known to be associated with increased rates of clonal hematopoiesis (CH). We sort to characterize the hematopoietic compartment of patients with melanoma and non-small cell lung cancer (NSCLC) given our recent population level analysis reporting evolving rates of secondary leukemias. The advent of immune checkpoint blockade (ICB) has dramatically changed our understanding of cancer biology and has altered the standards of care for patients. However, the impact of ICB on hematopoietic myeloid clonal expansion remains to be determined. We studied if exposure to ICB therapy affects hematopoietic clonal architecture and if their evolution contributed to altered hematopoiesis. Blood samples from patients with melanoma and NSCLC (n = 142) demonstrated a high prevalence of CH. Serial samples (or post ICB exposure samples; n = 25) were evaluated in melanoma and NSCLC patients. Error-corrected sequencing of a targeted panel of genes recurrently mutated in CH was performed on peripheral blood genomic DNA. In serial sample analysis, we observed that mutations in DNMT3A and TET2 increased in size with longer ICB exposures in the melanoma cohort. We also noted that patients with larger size DNMT3A mutations with further post ICB clone size expansion had longer durations of ICB exposure. All serial samples in this cohort showed a statistically significant change in VAF from baseline. In the serial sample analysis of NSCLC patients, we observed similar epigenetic expansion, although not statistically significant. Our study generates a hypothesis for two important questions: (a) Can DNMT3A or TET2 CH serve as predictors of a response to ICB therapy and serve as a novel biomarker of response to ICB therapy? (b) As ICB-exposed patients continue to live longer, the myeloid clonal expansion may portend an increased risk for subsequent myeloid malignancy development. Until now, the selective pressure of ICB/T-cell activating therapies on hematopoietic stem cells were less known and we report preliminary evidence of clonal expansion in epigenetic modifier genes (also referred to as inflammatory CH genes).

[The mechanisms and salvage treatment strategies underlying positive relapse following CD19 CAR-T cell therapy in B-acute lymphoblastic leukemia]

Approximately 50% of patients suffering from relapsed/refractory B-acute lymphoblastic leukemia (R/R B-ALL), experience relapse within one year, with around 60% of these relapses being antigen-positive, despite the transformative impact of chimeric antigen receptor (CAR) T cell therapy. The mechanisms underlying relapse are primarily associated with tumor heterogeneity, CAR-T cell dysfunction, subopimal in vivo expansion and persistence, and an inhibitory immune microenvironment. This review aims to investigate salvage strategies designed to enhance outcomes for patients undergoing relapse or disease progression following the CAR-T cell therapy. These strategies include a second CAR-T cell infusion that targets either the same antigen or an alternative target, the administration of immune checkpoint inhibitors, and the utilization of novel targeted therapies including monoclonal antibodies, antibody-conjugated drugs and small molecule compounds aimed at mitigating CD19-positive relapse or overcoming CAR-T cell resistance. Nevertheless, achieving improved long-term survival for these patients continues be challenging.

Epigenetic regulators of clonal hematopoiesis control CD8 T cell stemness during immunotherapy

Epigenetic reinforcement of T cell exhaustion is known to be a major barrier limiting T cell responses during immunotherapy. However, the core epigenetic regulators restricting antitumor immunity during prolonged antigen exposure are not clear. We investigated three commonly mutated epigenetic regulators that promote clonal hematopoiesis to determine whether they affect T cell stemness and response to checkpoint blockade immunotherapy. CD8 T cells lacking Dnmt3a, Tet2, or Asxl1 preserved a progenitor-exhausted (Tpex) population for more than 1 year during chronic antigen exposure without undergoing malignant transformation. Asxl1 controlled the self-renewal capacity of T cells and reduced CD8 T cell differentiation through H2AK119 ubiquitination and epigenetic modification of the polycomb group-repressive deubiquitinase pathway. Asxl1-deficient T cells synergized with anti-PD-L1 immunotherapy to improve tumor control in experimental models and conferred a survival advantage to mutated T cells from treated patients.

The Epigenetic Hallmarks of Cancer

Cancer is a complex disease in which several molecular and cellular pathways converge to foster the tumoral phenotype. Notably, in the latest iteration of the cancer hallmarks, "nonmutational epigenetic reprogramming" was newly added. However, epigenetics, much like genetics, is a broad scientific area that deserves further attention due to its multiple roles in cancer initiation, progression, and adaptive nature. Herein, we present a detailed examination of the epigenetic hallmarks affected in human cancer, elucidating the pathways and genes involved, and dissecting the disrupted landscapes for DNA methylation, histone modifications, and chromatin architecture that define the disease. Significance: Cancer is a disease characterized by constant evolution, spanning from its initial premalignant stages to the advanced invasive and disseminated stages. It is a pathology that is able to adapt and survive amidst hostile cellular microenvironments and diverse treatments implemented by medical professionals. The more fixed setup of the genetic structure cannot fully provide transformed cells with the tools to survive but the rapid and plastic nature of epigenetic changes is ready for the task. This review summarizes the epigenetic hallmarks that define the ecological success of cancer cells in our bodies.

Decitabine consolidation after CD19/CD22 CAR-T therapy as a novel maintenance treatment significantly improves survival outcomes in relapsed/refractory B-ALL patients

OBJECTIVE

We aimed to evaluate the efficacy of decitabine consolidation after treatment with CD19/CD22 chimeric antigen receptor T-cell (CAR-T) for patients with relapsed/refractory B-cell acute lymphoblastic leukaemia (r/r B-ALL).

METHODS

We retrospectively analysed 48 patients with r/r B-ALL who received CD19/CD22 CAR-T therapy between September 2017 and May 2021. Sixteen patients received decitabine consolidation (20 mg/m2/day for 5 days at 3-month intervals) after CAR-T therapy (DAC group), while 32 patients did not receive decitabine consolidation (CON group). Overall survival (OS), leukaemia-free survival (LFS), and cumulative incidence of relapse (CIR) were evaluated in both groups. Time-to-event analysis was performed using the Kaplan-Meier method.

RESULTS

The median follow-up periods in the DAC and CON groups were 41.2 months and 28.6 months, respectively. The 4-year OS and 4-year LFS rates in both groups were 93.3 % and 64.3 % (P=0.029) and 87.5 % and 55.9 % (P=0.059), respectively. The 1-year CIR was 6.25 % and 28.6 %, respectively. Univariate and multivariate Cox regression analyses showed that decitabine consolidation after CAR-T therapy was significantly associated with superior OS (hazard ratio [HR]: 0.121, 95 % confidence interval [CI]: 0.015-0.947, P=0.044), and bridging to haematopoietic stem cell transplantation after CAR-T therapy was significantly associated with superior LFS (HR: 0.279, 95 %CI: 0.093-0.840, P=0.023).

CONCLUSIONS

Our study recommends decitabine consolidation after CD19/CD22 CAR-T therapy as a novel maintenance strategy to improve the survival outcomes of patients with r/r B-ALL.