CAR T cell trogocytosis and cooperative killing regulate tumour antigen escape

Overcoming extracellular vesicle-mediated fratricide improves CAR T cell treatment against solid tumors

The efficacy of chimeric antigen receptor (CAR) T cells against solid tumors is limited. The molecular mechanisms underlying CAR T cell resistance are yet to be elucidated and new strategies need to be developed to improve treatment outcomes. Here we report that solid tumors respond to CAR T cells by upregulating the secretion of small extracellular vesicles carrying tumor antigens, which are horizontally transferred to CAR T cells, leading to antigen recognition and CAR T cell fratricide. Engineered CAR T cells armored with Serpin B9, a major granzyme B inhibitor, show decreased fratricide and increased vitality, tumor infiltration, and antitumor activity in female mice. Moreover, Serpin B9-armored CAR T cells show higher efficacy than parental CAR T cells in treating solid tumors when combined with the anti-programmed death 1 antibody. Our study demonstrates a mechanism that limits CAR T cell function and suggests an improved strategy in tumor treatment.

Revolutionising Cancer Immunotherapy: Advancements and Prospects in Non-Viral CAR-NK Cell Engineering

The recent advancements in cancer immunotherapy have spotlighted the potential of natural killer (NK) cells, particularly chimeric antigen receptor (CAR)-transduced NK cells. These cells, pivotal in innate immunity, offer a rapid and potent response against cancer cells and pathogens without the need for prior sensitization or recognition of peptide antigens. Although NK cell genetic modification is evolving, the viral transduction method continues to be inefficient and fraught with risks, often resulting in cytotoxic outcomes and the possibility of insertional mutagenesis. Consequently, there has been a surge in the development of non-viral transfection technologies to overcome these challenges in NK cell engineering. Non-viral approaches for CAR-NK cell generation are becoming increasingly essential. Cutting-edge techniques such as trogocytosis, electroporation, lipid nanoparticle (LNP) delivery, clustered regularly interspaced short palindromic repeats-associated protein 9 (CRISPR-Cas9) gene editing and transposons not only enhance the efficiency and safety of CAR-NK cell engineering but also open new avenues for novel therapeutic possibilities. Additionally, the infusion of technologies already successful in CAR T-cell therapy into the CAR-NK paradigm holds immense potential for further advancements. In this review, we present an overview of the potential of NK cells in cancer immunotherapies, as well as non-viral transfection technologies for engineering NK cells.

TNF/TNFR Superfamily Members in Costimulation of T Cell Responses-Revisited

Prosurvival tumor necrosis factor receptor (TNFR) superfamily (TNFRSF) members on T cells, including 4-1BB, CD27, GITR, and OX40, support T cell accumulation during clonal expansion, contributing to T cell memory. During viral infection, tumor necrosis factor superfamily (TNFSF) members on inflammatory monocyte-derived antigen-presenting cells (APCs) provide a postpriming signal (signal 4) for T cell accumulation, particularly in the tissues. Patients with loss-of-function mutations in TNFR/TNFSF members reveal a critical role for 4-1BB and CD27 in CD8 T cell control of Epstein-Barr virus and other childhood infections and of OX40 in CD4 T cell responses. Here, on the 20th anniversary of a previous Annual Review of Immunology article about TNFRSF signaling in T cells, we discuss the effects of endogenous TNFRSF signals in T cells upon recognition of TNFSF members on APCs; the role of TNFRSF members, including TNFR2, on regulatory T cells; and recent advances in the incorporation of TNFRSF signaling in T cells into immunotherapeutic strategies for cancer.

The development and potent antitumor efficacy of CD44/CD133 dual-targeting IL7Rα-armored CAR-T cells against glioblastoma

Tumor heterogeneity and an immunosuppressive microenvironment pose significant challenges for immunotherapy against solid tumors, particularly glioblastoma multiforme (GBM). Recent studies have highlighted the crucial role of glioma stem cells (GSCs) in tumor recurrence and therapeutic resistance. In this context, we developed a tandem chimeric antigen receptor (CAR)-T cell targeting CD44 and CD133 (PROM1), containing a truncated IL-7 receptor alpha intracellular domain (Δ7R) between the CD28 costimulatory receptor and the CD3ζ signaling chain (Tanζ-T28-Δ7R). Our target identification and validation were carried out using GSCs, samples from GBM patients, and the corresponding sequencing data. The antitumor efficacy of CAR-T cells was evaluated in patient-derived GSCs, intracranial xenograft models, patient-derived xenograft models, and glioblastoma organoids (GBOs). Single-cell RNA sequencing and mass cytometry were used to determine the immune phenotypes of CAR-T cells. We showed that locoregionally administered Tanζ-T28-Δ7R CAR-T cells induced long-term tumor regression with the desired safety outcomes. Patient-derived autologous Tanζ-T28-Δ7R CAR-T cells showed robust antitumor activity against GBOs. Our pre-clinical data has demonstrated the translational potential of Tanζ-T28-Δ7R CAR-T cell against GBM.

Engineering Mice to Study Human Immunity

Humanized mice, which carry a human hematopoietic and immune system, have greatly advanced our understanding of human immune responses and immunological diseases. These mice are created via the transplantation of human hematopoietic stem and progenitor cells into immunocompromised murine hosts further engineered to support human hematopoiesis and immune cell growth. This article explores genetic modifications in mice that enhance xeno-tolerance, promote human hematopoiesis and immunity, and enable xenotransplantation of human tissues with resident immune cells. We also discuss genetic editing of the human immune system, provide examples of how humanized mice with humanized organs model diseases for mechanistic studies, and highlight the roles of these models in advancing knowledge of organ biology, immune responses to pathogens, and preclinical drugs tested for cancer treatment. The integration of multi-omics and state-of-the art approaches with humanized mouse models is crucial for bridging existing human data with causality and promises to significantly advance mechanistic studies.

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.

Programmable macromolecule delivery via engineered trogocytosis

Trogocytosis, the transfer of plasma membrane fragments during cell-cell contact, offers potential for macromolecular delivery but is limited by uncertain fate of trogocytosed molecules, constraints to membrane cargo, and unclear generalizability. Here, we demonstrate that donor cells engineered with designed receptors specific to intrinsic ligands can transfer proteins to recipient cells through direct contact. We identified key principles for enhancing contact-mediated transfer and subsequent functionalization of transferred macromolecules, including receptor design, pH-responsive membrane fusion, inducible cargo localization, release, and subcellular translocation. Exploiting these findings, we developed TRANSFER, a versatile delivery system that integrates logic gate-based control to sense multiple ligand inputs and deliver diverse functional cargos for genome editing and targeted cell ablation across cell types. The study establishes trogocytosis as a novel, programmable framework for cell-based macromolecular delivery.

Advances in CAR optimization strategies based on CD28

Chimeric antigen receptor (CAR)-T cell therapy, which utilizes genetic engineering techniques to modify T-cells to achieve specific targeting of cancer cells, has made significant breakthroughs in cancer treatment in recent years. All marketed CAR-T products are second-generation CAR-T cells containing co-stimulatory structural domains, and co-stimulatory molecules are critical for CAR-T cell activation and function. Although CD28-based co-stimulatory molecules have demonstrated potent cytotoxicity in the clinical application of CAR-T cells, they still suffer from high post-treatment relapse rates, poor efficacy durability, and accompanying severe adverse reactions. In recent years, researchers have achieved specific results in enhancing the anti-tumor function of CD28 by mutating its signaling motifs, combining the co-stimulatory structural domains, and modifying other CAR components besides co-stimulation. This paper reviewed the characteristics and roles of CD28 in CAR-T cell-mediated anti-tumor signaling and activation. We explored potential strategies to enhance CAR-T cell efficacy and reduce side effects by optimizing CD28 motifs and CAR structures, aiming to provide a theoretical basis for further clinical CAR-T cell therapy development.

Myeloma cell-intrinsic ANXA1 elevation and T cell dysfunction contribute to BCMA-negative relapse after CAR-T therapy

Multiple myeloma (MM) relapse still occurs after a durable response to anti-B cell maturation antigen (BCMA) chimeric antigen receptor-engineered T (CAR-T) cell therapy with less-defined factors. Herein, we investigated a CAR-T-exposed MM patient who relapsed after 12 months of remission by single-cell transcriptome sequencing. The bone marrow CAR-T population at relapse exhibited exhaustion and proliferation attenuation. The recurrent myeloma cells were deficient in or weakly expressed TNFRSF17 (BCMA) but possessed an identical immunoglobulin clonality to the baseline tumor. Interestingly, combined with the transcriptome profile of the myeloma strains, MM cells with BCMA negativity featured high ANXA1 expression that was identified as an inferior prognostic indicator for MM patients. At a single-cell resolution, BCMA-negative myeloma could be present in the MM patients without CAR-T cell exposure and displayed an increased level of intrinsic ANXA1 transcripts. In vitro assays unveiled that Annexin A1 (ANXA1) elevation conferred growth capacity to BCMA-negative myeloma cells via AMPKα signaling activation and disturbed CAR-T cell fitness. Blockade of Annexin A1 reduced BCMA-negative myeloma cell proliferation. Murine models further demonstrated that Annexin A1 inhibition could effectively diminish BCMA-negative myeloma that escaped from CAR-T's attack. Together, our data identified ANXA1 as a potential target for BCMA-negative myeloma clearance. The ANXA1-targeting strategy might be helpful for CAR-T treatment optimization.

The costimulatory domain influences CD19 CAR-T cell resistance development in B-cell malignancies

CD19-CAR-T-cells emerge as a major therapeutic option for relapsed/refractory B-cell-derived malignancies, however approximately half of patients eventually relapse. To identify resistance-driving factors, we repeatedly exposed B-cell lymphoma/B-cell acute lymphoblastic leukemia to 4-1BB/CD28-based CD19-CAR-T-cells in vitro. Generated models revealed costimulatory domain-dependent differences in CD19 loss. While CD19-4-1BB-CAR-T-cells induced combination epitope/total CD19 protein loss, CD19-CD28-CAR-T-cells did not drive antigen-escape. Consistent with observations in patients relapsing after CD19-4-1BB-CAR-T-cells, we identified CD19 frameshift/missense mutations affecting residues critical for FMC63 epitope recognition. Mathematical simulations revealed that differences between CD19-4-1BB- and CD19-CD28-CAR-T-cells activity against low-antigen-expressing tumor contribute to heterogeneous therapeutic responses. By integrating in vitro and in silico data, we propose a biological scenario where CD19-4-1BB-CAR-T-cells fail to eliminate low-antigen tumor cells, fostering CAR-resistance. These findings offer mechanistic insight into the observed clinical differences between axi-cel (CD28-based) and tisa-cel (4-1BB-based)-treated B-cell lymphoma patients and advance our understanding on CAR-T resistance. Furthermore, we underscore the need for specific FMC63 epitope detection to deliver information on antigen levels accessible for CD19-CAR-T-cells.

Novel FRET-based Immunological Synapse Biosensor for the Prediction of Chimeric Antigen Receptor-T Cell Function

Chimeric antigen receptor (CAR)-T cell therapy has revolutionized cancer treatment. CARs are activated at the immunological synapse (IS) when their single-chain variable fragment (scFv) domain engages with an antigen, allowing them to directly eliminate cancer cells. Here, an innovative IS biosensor based on fluorescence resonance energy transfer (FRET) for the real-time assessment of CAR-IS architecture and signaling competence is presented. Using this biosensor, scFv variants for mesothelin-targeting CARs and identified as a novel scFv with enhanced CAR-T cell functionality despite its lower affinity than the original screened. The original CAR promoted internalization and trogocytosis, disrupting stable IS formation and impairing functionality are further observed. These findings emphasize the importance of enhancing IS quality rather than maximizing scFv affinity for superior CAR-T cell responses. Therefore, the FRET-based IS biosensor is a powerful tool for predicting CAR-T cell function, enabling the efficient engineering of next-generation CARs with enhanced antitumor potency.

Mechanisms for resistance to BCMA-targeted immunotherapies in multiple myeloma

Multiple myeloma (MM) remains incurable and patients eventually face the relapse/refractory dilemma. B cell maturation antigen (BCMA)-targeted immunotherapeutic approaches have shown great effectiveness in patients with relapsed/refractory MM, mainly including chimeric antigen receptor T cells (CAR-T), bispecific T cell engagers (TCEs), and antibody-drug conjugates (ADCs). However, their impact on long-term survival remains to be determined. Nonetheless, resistance to these novel therapies is still inevitable, raising a challenge that we have never met in both laboratory research and clinical practice. In this scenario, the investigation aiming to enhance and prolong the anti-MM activity of BCMA-targeted therapies has been expanding rapidly. Despite considerable uncertainty in our understanding of the mechanisms for their resistance, they have mainly been attributed to antigen-dependency, T cell-driven factors, and (immune) tumor microenvironment. In this review, we summarize the current understanding of the mechanisms for resistance to BCMA-targeted immunotherapies and discuss potential strategies for overcoming it.

Anti-CD19 antibody cotreatment enhances serial killing activity of anti-CD19 CAR-T/-NK cells and reduces trogocytosis

ABSTRACT

Anti-CD19 chimeric antigen receptor (CAR)-engineered T and natural killer (NK) cell therapies have revolutionized the treatment of B-cell malignancies, but challenges including CD19 antigen loss greatly hinder their full therapeutic potential. Here, we revealed that cotreatment with anti-CD19 monoclonal antibody enhances antitumor activity of anti-CD19 CAR-T and -NK cells. Even though the treated antibody interferes with CD19 antigen binding of CAR, it significantly induces rapid detachment of anti-CD19 CAR effector cells from target cells, facilitating improved serial killing. This reduced interaction between CAR effector cells and target cells also leads to the alleviation of CAR-mediated trogocytosis. Interestingly, cotreatment with anti-CD19 antibody reveals time-dependent effects on the antitumor activity of anti-CD19 CAR-T cells, characterized by a reduction in early T cell activation followed by sustained high activity during prolonged exposure to target cells. This temporal modulation ultimately results in enhanced antitumor potency in vivo. These findings underscore the improved therapeutic efficacy achieved by combining anti-CD19 antibody with anti-CD19 CAR-T or -NK cells against B-cell malignancies.

Mechanisms of antigen-dependent resistance to chimeric antigen receptor (CAR)-T cell therapies

Cancer immunotherapy has reshaped the landscape of cancer treatment over the past decades. Genetic manipulation of T cells to express synthetic receptors, known as chimeric antigen receptors (CAR), has led to the creation of tremendous commercial and therapeutic success for the treatment of certain hematologic malignancies. However, since the engagement of CAR-T cells with their respective antigens is solely what triggers their cytotoxic reactions against target cells, the slightest changes to the availability and/or structure of the target antigen often result in the incapacitation of CAR-T cells to enforce tumoricidal responses. This results in the resistance of tumor cells to a particular CAR-T cell therapy that requires meticulous heeding to sustain remissions in cancer patients. In this review, we highlight the antigen-dependent resistance mechanisms by which tumor cells dodge being recognized and targeted by CAR-T cells. Moreover, since substituting the target antigen is the most potent strategy for overcoming antigen-dependent disease relapse, we tend to highlight the current status of some target antigens that might be considered suitable alternatives to the currently available antigens in various cancers. We also propose target antigens whose targeting might reduce the off-tumor adverse events of CAR-T cells in certain malignancies.

Strategies to Overcome Antigen Heterogeneity in CAR-T Cell Therapy

Chimeric antigen receptor (CAR) gene-modified T-cell therapy has achieved significant success in the treatment of hematological malignancies. However, this therapy has not yet made breakthroughs in the treatment of solid tumors and still faces issues of resistance and relapse in hematological cancers. A major reason for these problems is the antigenic heterogeneity of tumor tissues. This review outlines the antigenic heterogeneity encountered in CAR-T cell therapy and the corresponding strategies to address it. These strategies include using combination therapy to increase the abundance of target antigens, optimizing the structure of CARs to enhance sensitivity to low-density antigens, developing multi-targeted CAR-T cells, and reprogramming the TME to activate endogenous immunity. These approaches offer new directions for overcoming tumor antigenic heterogeneity in CAR-T cell therapy.

Targeting HLA-E-overexpressing cancers with a NKG2A/C switch receptor

BACKGROUND

Human leukocyte antigen (HLA)-E is overexpressed by a large proportion of solid tumors, including malignant glioblastoma, and acts as a major checkpoint for NKG2A+ CD8+ T cells and natural killer (NK) cells in the tumor microenvironment and circulation. This axis operates alongside PD-L1 to inhibit effector responses by T and NK cells.

METHODS

We engineered a chimeric A/C switch receptor, combining the high HLA-E binding affinity of the NKG2A receptor ectodomain with the activating signaling of the NKG2C receptor endodomain. The cytotoxic function of A/C switch-transduced NK and T cells was evaluated against tumor cells with varying levels of HLA-E expression. In vivo efficacy was assessed using a xenograft model of glioblastoma.

FINDINGS

A/C switch-transduced NK and T cells exhibited superior and specific cytotoxicity against tumor cells with medium to high HLA-E expression. A/C switch-expressing human T cells demonstrated enhanced anti-tumor function in a glioblastoma xenograft model. The activity of the modified T cells was governed by an equilibrium between A/C switch levels and HLA-E expression, creating a therapeutic window to minimize on-target, off-tumor toxicities. Normal cells remained insensitive to A/C switch T cells, even after interferon (IFN)-γ pretreatment to induce HLA-E expression.

CONCLUSIONS

The A/C switch receptor effectively targets tumor cells expressing high levels of HLA-E, either alone or in combination with other engineered specificities, to overcome the suppressive NKG2A/HLA-E checkpoint. This approach offers a promising therapeutic strategy with a favorable safety profile for targeting HLA-E-overexpressing tumors.

FUNDING

This work was funded by The Research Council of Norway, the Norwegian Cancer Society, and the National Cancer Institute.

Target cell adhesion limits macrophage phagocytosis and promotes trogocytosis

Macrophage phagocytosis is an essential immune response that eliminates pathogens, antibody-opsonized cancer cells and debris. Macrophages can also trogocytose, or nibble, targets. Trogocytosis and phagocytosis are often activated by the same signal, including IgG antibodies. What makes a macrophage trogocytose instead of phagocytose is not clear. Using both CD47 antibodies and a Her2 Chimeric Antigen Receptor (CAR) to induce phagocytosis, we found that macrophages preferentially trogocytose adherent target cells instead of phagocytose in both 2D cell monolayers and 3D cancer spheroid models. Disrupting target cell integrin using an RGD peptide or through CRISPR-Cas9 knockout of the αV integrin subunit in target cells increased macrophage phagocytosis. Conversely, increasing cell adhesion by ectopically expressing E-Cadherin in Raji B cell targets reduced phagocytosis. Finally, we examined phagocytosis of mitotic cells, a naturally occurring example of cells with reduced adhesion. Arresting target cells in mitosis significantly increased phagocytosis. Together, our data show that target cell adhesion limits phagocytosis and promotes trogocytosis.

CAR-T cell therapy in the treatment of relapsed or refractory primary central nervous system lymphoma: recent advances and challenges

Primary central nervous system lymphoma (PCNSL) is a rare and aggressive lymphoma that is isolated in the central nervous system (CNS) or vitreoretinal space. High-dose methotrexate (HD-MTX)-based immunochemotherapy is the frontline for its treatment, with a high early response rate. However, relapsed or refractory (R/R) patients present numerous difficulties and challenges in clinical treatment. Chimeric antigen receptor (CAR)-T cells offer a promising option for the treatment of hematologic malignancies, especially in the R/R B-cell lymphoma and multiple myeloma. Despite the exclusion of most PCNSL cases from pivotal CAR-T cell trials due to their specific tumor microenvironment (TME), available preclinical and clinical studies with small cohorts suggest an overall acceptable safety profile and remarkable anti-tumor effects. In this review, we will provide the development process of CAR-T cells and summarize the research progress, limitations, and future perspectives of CAR-T cell therapy in patients with R/R PCNSL.

Trogocytosis-mediated immune evasion in the tumor microenvironment

Trogocytosis is a dynamic cellular process characterized by the exchange of the plasma membrane and associated cytosol during cell-to-cell interactions. Unlike phagocytosis, this transfer maintains the surface localization of transferred membrane molecules. For example, CD4 T cells engaging with antigen-presenting cells undergo trogocytosis, which facilitates the transfer of antigen-loaded major histocompatibility complex (MHC) class II molecules from antigen-presenting cells to CD4 T cells. This transfer results in the formation of antigen-loaded MHC class II molecule-dressed CD4 T cells. These "dressed" CD4 T cells subsequently participate in antigen presentation to other CD4 T cells. Additionally, trogocytosis enables the acquisition of immune-regulatory molecules, such as CTLA-4 and Tim3, in recipient cells, thereby modulating their anti-tumor immunity. Concurrently, donor cells undergo plasma membrane loss, and substantial loss can trigger trogocytosis-mediated cell death, termed trogoptosis. This review aims to explore the trogocytosis-mediated transfer of immune regulatory molecules and their implications within the tumor microenvironment to elucidate the underlying mechanisms of immune evasion in cancers.

Harmonizing the symphony of chimeric antigen receptor T cell immunotherapy with the elegance of biomaterials

Chimeric antigen receptor T cell (CAR-T) immunotherapy has become a heated field of cancer research, demonstrating revolutionary efficacy in refractory and relapsed hematologic malignancies. However, CAR-T therapy has still encountered tough challenges, including complicated and lengthy manufacturing procedures, mediocre targeted delivery, limited therapeutic effect against solid tumors and difficulties in real-time in vivo monitoring. To overcome these limitations, various versatile biomaterials have been used in the above aspects and have improved CAR-T therapy impressively. This review mainly summarizes the latest research progress of biomaterials promoting CAR-T therapy in manufacturing, enhancing targeted delivery and tumor infiltration, and dramatic in vivo tracking to provide new insights and inspiration for clinical treatment.

CAR-engineered NK cells versus CAR T cells in treatment of glioblastoma; strength and flaws

Glioblastoma (GBM) is a highly aggressive primary brain tumor that carries a grim prognosis. Because of the dearth of treatment options available for treatment of GBM, Chimeric Antigen Receptor (CAR)-engineered T cell and Natural Killer (NK) therapy could provide alternative strategies to address the challenges in GBM treatment. In these approaches, CAR T and NK cells are engineered for cancer-specific immunotherapy by recognizing surface antigens independently of major histocompatibility complex (MHC) molecules. However, the efficacy of CAR T cells is hindered by GBM's downregulation of its targeted antigens. CAR NK cells face similar challenges, but, in contrast, they offer advantages as off-the-shelf allogeneic products, devoid of graft-versus-host disease (GVHD) risk as well as anti-cancer activity beyond CAR specificity, potentially reducing the risk of relapse or resistance. Despite CAR T cell therapies being extensively studied in clinical settings, the use of CAR-modified NK cells in GBM treatment remains largely in the preclinical stage. This review aims to discuss recent advancements in NK cell and CAR T cell therapies for GBM, including methods for introducing CARs into both NK cells and T cells, addressing manufacturing challenges, and providing evidence supporting the efficacy of these approaches from preclinical and early-phase clinical studies. The comprehensive evaluation of CAR-engineered NK cells and CAR T cells seeks to identify the optimal therapeutic approach for GBM, contributing to the development of effective immunotherapies for this devastating disease.

Trogocytosis of chimeric antigen receptors between T cells is regulated by their transmembrane domains

Trogocytosis is an exchange of membrane-associated molecules between cells that can either halt or boost immune responses. However, the mechanism that regulates trogocytosis in T cells and its consequences are not yet clear. Here, we demonstrate that T cells can exchange chimeric antigen receptors (CARs) by trogocytosis, thereby arming recipient T cells with the capacity to respond to tumor antigens by up-regulating proteins associated with a cytotoxic response and killing of target cells. We demonstrate that although trogocytosis is dependent on cell-cell contact, the exchange of a specific cell membrane protein does not require a cognate binding partner on the surface of recipient cells. Instead, the probability that a protein is exchanged by trogocytosis is determined by its transmembrane domain. This finding opens new avenues for modulating this process in CAR-T cells.

GITRL enhances cytotoxicity and persistence of CAR-T cells in cancer therapy

Chimeric antigen receptor (CAR)-T cell therapy has achieved remarkable clinical success in treating hematological malignancies. However, its clinical efficacy in solid tumors is less satisfactory, partially due to poor in vivo expansion and the limited persistence of CAR-T cells. Here, we demonstrated that the overexpression of GITR ligand enhances the anti-tumor activity of CAR-T cells. Compared to prostate-specific membrane antigen-BB-Z (PSMA-BB-Z) CAR-T, PSMA-BB-Z-GITRL CAR-T cells have much more interferon (IFN)-γ, TNF-α, and interleukin (IL)-9 secretion, a higher proportion of central memory T (TCM) cells and T helper 9 (Th9) cells, less expression of exhaustion markers, and robust proliferation capacity. Consequently, PSMA-BB-Z-GITRL CAR-T cells exhibited more potent anti-tumor activity against established solid tumors in vivo than PSMA-BB-Z CAR-T cells. The results of the in vivo persistence experiment also indicated that PSMA-BB-Z-GITRL CAR-T cells exhibited much more retention in mouse blood, spleen, and tumor tissue than PSMA-BB-Z CAR-T cells 15 days after CAR-T cell therapy. In addition, PSMA-BB-Z-GITRL CAR-T cells produce higher levels of IFN-γ, TNF-α, and IL-9 in mouse blood, exhibiting a higher proportion of TCM cells and a lower proportion of Treg cells compared to PSMA-BB-Z CAR-T cells. Our results demonstrate that the overexpression of GITRL has important implications for improving CAR-T cell-based human solid tumor immunotherapy.

Leveraging Vector-Based Gene Disruptions to Enhance CAR T-Cell Effectiveness

Anti-CD19 chimeric antigen receptor (CAR) T-cell therapy represents a breakthrough in the treatment of relapsed and refractory B-cell malignancies, such as chronic lymphocytic leukemia (CLL), inducing long-term, sometimes curative, responses. However, fewer than 30% of CLL patients achieve such outcomes. It has been shown that a smaller subset of T cells capable of expansion and persistence is crucial for treatment effectiveness. Notably, a pre-existing mutation in the epigenetic regulator TET2, combined with CAR vector-induced disruption of the other intact allele, significantly enhanced the potency of the CAR-engineered T-cell clone in one CLL patient. This finding aligns with independent research, suggesting that the CAR gene's genomic insertion site influences tumor-targeting capability. Thus, it is plausible that vector-induced gene disruptions affect CAR T-cell function. This review synthesizes existing knowledge on vector integration into the host genome and its impact on clinical outcomes in CAR T-cell therapy patients. Our aim is to inform the development of improved therapies and enhance their overall efficacy.

Levental K, Leen AM, Mamonkin M, Carisey A, Varadarajan N, Hegde M, Joseph SK, Levental I, Mukherjee M, Ahmed N. Molecular dynamics at immune synapse lipid rafts influence the cytolytic behavior of CAR T cells

Chimeric antigen receptor T cells (CART) targeting CD19 through CD28.ζ signaling induce rapid lysis of leukemic blasts, contrasting with persistent tumor control exhibited by 4-1BB.ζ-CART. We reasoned that molecular dynamics at the CART immune synapse (CARIS) could explain differences in their tumor rejection kinetics. We observed that CD28.ζ-CART engaged in brief highly lethal CARIS and mastered serial killing, whereas 4-1BB.ζ-CART formed lengthy CARIS and relied on robust expansion and cooperative killing. We analyzed CARIS membrane lipid rafts (mLRs) and found that, upon tumor engagement, CD28.ζ-CAR molecules rapidly but transiently translocated into mLRs, mobilizing the microtubular organizing center and lytic granules to the CARIS. This enabled fast CART recovery and sensitivity to low target site density. In contrast, gradual accumulation of 4-1BB.ζ-CAR and LFA-1 molecules at mLRs built mechanically tonic CARIS mediating chronic Fas ligand-based killing. The differences in CD28.ζ- and 4-1BB.ζ-CARIS dynamics explain the distinct cytolytic behavior of CART and can guide engineering of more adaptive effective cellular products.

CAR-T cell therapy: developments, challenges and expanded applications from cancer to autoimmunity

Chimeric Antigen Receptor (CAR)-T cell therapy has rapidly emerged as a groundbreaking approach in cancer treatment, particularly for hematologic malignancies. However, the application of CAR-T cell therapy in solid tumors remains challenging. This review summarized the development of CAR-T technologies, emphasized the challenges and solutions in CAR-T cell therapy for solid tumors. Also, key innovations were discussed including specialized CAR-T, combination therapies and the novel use of CAR-Treg, CAR-NK and CAR-M cells. Besides, CAR-based cell therapy have extended its reach beyond oncology to autoimmune disorders. We reviewed preclinical experiments and clinical trials involving CAR-T, Car-Treg and CAAR-T cell therapies in various autoimmune diseases. By highlighting these cutting-edge developments, this review underscores the transformative potential of CAR technologies in clinical practice.

CAR T-cell therapy combined with autologous hematopoietic cell transplantation in patients with refractory/relapsed Burkitt Lymphoma

Burkitt lymphoma (BL) is a highly aggressive type of non-Hodgkin lymphomas that have a high likelihood of relapse and are highly refractory to initial treatment. While high-intensity chemotherapy has improved the outcomes, many adult patients still experience treatment failure, and effective salvage therapies are limited. This study retrospectively analyzed the outcomes of 21 relapsed or refractory (R/R) adult BL patients treated with chimeric antigen receptor T-cell (CAR-T) therapy, combined or not with hematopoietic cell transplantation (HCT), across four Chinese hospitals. Patients were grouped based on treatment strategies: autologous HCT followed by CAR T-cell therapy (auto-HCT+CART group, n = 8), and CAR T-cell therapy alone (CART group, n = 13). The auto-HCT+CART group demonstrated superior outcomes, with an overall response rate (ORR) of 87.5 % and significantly higher 1-year overall survival (OS) and progression-free survival (PFS) rates compared to the CART group (p = 0.014 and p = 0.045, respectively). These findings suggest that combining auto-HCT with CAR-T therapy may enhance long-term disease control in R/R BL patients. These encouraging results highlight the need for further prospective studies to validate our data.

Preclinical development of three novel CARs targeting CD79b for the treatment of non-Hodgkin's lymphoma and characterization of the loss of the target antigen

BACKGROUND

Infusion of T cells modified with a chimeric antigen receptor (CAR) targeting CD19 has achieved exceptional responses in patients with non-Hodgkin's lymphoma (NHL), which led to the approval of CAR targeting CD19 (CART19) (Axi-cel and Liso-cel) as second line of treatment for adult patients with relapsed/refractory NHL. Unfortunately, 60% of patients still relapse after CART19 due to either a loss of expression of the target antigen (CD19) in the tumor cell, observed in 27% of relapsed patients, a limited CAR-T persistence, and additional mechanisms, including the suppression of the tumor microenvironment. Clinic strategies to prevent target antigen loss include sequential treatment with CARs directed at CD20 or CD22, which have caused loss of the second antigen, suggesting targeting other antigens less prone to disappear. CD79b, expressed in NHL, is a target in patients treated with antibody-drug conjugates (ADC). However, the limited efficacy of ADC suggests that a CAR therapy targeting CD79b might improve results.

METHODS

We designed three new CARs against CD79b termed CAR for Lymphoma (CARLY)1, 2 and 3. We compared their efficacy, phenotype, and inflammatory profiles with CART19 (ARI0001) and CARTBCMA (ARI0002h), which can treat NHL. We also analyzed the target antigen's expression loss (CD79b, CD19, and B-cell maturation antigen(BCMA)).

RESULTS

We found that CARLY2 and CARLY3 had high affinity and specificity towards CD79b on B cells. In vitro, all CAR-T cells had similar anti-NHL efficacy, which was retained in an NHL model of CD19- relapse. In vivo, CARLY3 showed the highest efficacy. Analysis of the loss of the target antigen demonstrated that CARLY cells induced CD79b and CD19 downregulation on NHL cells with concomitant trogocytosis of these antigens to T cells, being most notorious in CARLY2, which had the highest affinity towards CD79b and CD19, and supporting the selection of CARLY3 to design a new treatment for patients with NHL. Finally, we created a CAR treatment based on dual targeting of CD79b and BCMA to avoid losing the target antigen. This treatment showed the highest efficacy and did not cause loss of the target antigen.

CONCLUSIONS

Based on specificity, efficacy, and loss of the target antigen, CARLY3 represents a potential novel CAR treatment for NHL.

Microengineered in vitro CAR T cell screens and assays

Established and emergent microengineered in vitro systems enable the evaluation of chimeric antigen receptor (CAR) T cell product purity, avidity, and functionality. Here, we describe such systems and how they have been used to optimize CAR T cell products by selecting highly viable cells, eliminating off-target cells, and tailoring avidity to balance efficacy and safety. The future of CAR T cell therapy development and manufacturing is expected to be anchored in a cyclical process that integrates multiple high-throughput and patient-centered techniques for identifying, enriching, and evaluating T cell subtypes. This article explores several cutting-edge platforms and methodologies relevant to these processes.

Phase separation of chimeric antigen receptor promotes immunological synapse maturation and persistent cytotoxicity

Major challenges of chimeric antigen receptor (CAR)-T cell therapy include poor antigen sensitivity and cell persistence. Here, we report a solution to these issues by exploiting CAR phase separation. We found that incorporation of an engineered T cell receptor CD3ε motif, EB6I, into the conventional 28Z or BBZ CAR induced self-phase separation through cation-π interactions. EB6I CAR formed a mature immunological synapse with the CD2 corolla to transduce efficient antigen and costimulatory signaling, although its tonic signaling remained low. Functionally, EB6I CAR-T cells exhibited improved signaling and cytotoxicity against low-antigen tumor cells and persistent tumor-killing function. In multiple primary and relapsed murine tumor models, EB6I CAR-T cells exerted better antitumor functions than conventional CAR-T cells against blood and solid cancers. This study thus unveils a CAR engineering strategy to improve CAR-T cell immunity by leveraging molecular condensation and signaling integration.

In silico neoantigen screening and HLA multimer-based validation identify immunogenic neopeptide in multifocal lung adenocarcinoma

Background

Mutations commonly occur in cancer cells, arising neoantigen as potential targets for personalized immunotherapy of lung adenocarcinoma (LUAD). However, the substantial heterogeneity observed among individuals and distinct foci within the same patient presents significant challenges in formulating immunotherapy strategies. The aim of the work is to characterize the mutation pattern and identify neopeptides across different patients and diverse foci within the same patients with LUAD.

Methods

Seven lung adenocarcinoma samples and matched tissues/blood are collected from 4 patients with LUAD for whole exome sequencing, mutation signature analysis, HLA binding prediction and neoantigen screening. Dimeric HLA-A2 molecules were prepared by Bac-to-Bac baculovirus expression system to establish a T cell stimulation system based on HLA-A2-coated artificial antigen-presenting cells for the validation of immunogenic neopeptides.

Results

Similar mutation pattern with predominant missense mutation and high tumor mutation burden was observed across individuals with lung adenocarcinomas and between non-invasive and invasive foci. We screened and identified 3 consistent mutated genes among 100 top genes with highest mutation scores contributed across 4 patients, and 3 mutated peptides among 30 with highest HLA-A2 binding affinity distributed in at least 2 out of 4 foci in the same patient. Notably, LUAD-7-MT peptide encoded by NANOGNB demonstrated higher immunogenicity in promoting CD8+ T cells proliferation and IFN-γ secretion than the corresponding wildtype peptide.

Conclusions

This study provides an in-depth analysis of mutation characteristics of LUAD and establishes a neoantigen screening and validation system for identifying immunogenicity neopeptide across individual patients and diverse foci in the same patient with multifocal LUAD.

Advancements in the design and function of bispecific CAR-T cells targeting B Cell-Associated tumor antigens

Single-targeted CAR-T has exhibited notable success in treating B-cell tumors, effectively improving patient outcomes. However, the recurrence rate among patients remains above fifty percent, primarily attributed to antigen escape and the diminished immune persistence of CAR-T cells. Over recent years, there has been a surge of interest in bispecific CAR-T cell therapies, marked by an increasing number of research articles and clinical applications annually. This paper undertakes a comprehensive review of influential studies on the design of bispecific CAR-T in recent years, examining their impact on bispecific CAR-T efficacy concerning disease classification, targeted antigens, and CAR design. Notable distinctions in antigen targeting within B-ALL, NHL, and MM are explored, along with an analysis of how CAR scFv, transmembrane region, hinge region, and co-stimulatory region design influence Bi-CAR-T efficacy across different tumors. The summary provided aims to serve as a reference for designing novel and improved CAR-Ts, facilitating more efficient treatment for B-cell malignant tumors.

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.

CAR T-cell therapy for B-cell lymphomas: outcomes and resistance mechanisms

Chimeric antigen receptor (CAR) T cells are an exciting curative intent approach to the treatment of non-Hodgkin lymphomas (NHLs). Several products have received FDA approval for 2nd or 3rd line indications, and studies are underway for their use earlier in the disease course. These CAR T cells are ex vivo manufactured autologous cell products that specifically target tumor antigens to optimize tumor specificity and minimize off-tumor side effects-in NHLs, this is typically achieved by targeting B-cell antigens. Engagement of the CAR and corresponding antigen is designed to result in T-cell activation and subsequent tumor clearance. While curative for many NHL patients, too many patients fail to respond to or relapse following CAR T-cell treatment, and salvage options post CAR T-cell therapy are limited. Treatment failures occur because of myriad resistance mechanisms including CAR T-cell dysfunction, generalized immune dysregulation, and intrinsic tumor resistance. Focusing on patients with NHL, we review the clinical outcomes of CAR T-cell therapy and the major resistance mechanisms that lead to poor outcomes. We also review the many innovative and encouraging strategies that are being developed to improve CAR T-cell therapy for NHL.

CAR T cells in solid tumors and metastasis: paving the way forward

CAR T cell therapy, hailed as a breakthrough in cancer treatment due to its remarkable outcomes in hematological malignancies, encounters significant hurdles when applied to solid tumors. While notable responses to CAR T cells remain sporadic in these patients, challenges persist due to issues such as on-target off-tumor toxicity, difficulties in their trafficking and infiltration into the tumor, and the presence of a hostile and immunosuppressive microenvironment. This review aims to explore recent endeavors aimed at overcoming these obstacles in CAR T cell therapy for solid tumors. Specifically, we will delve into promising strategies for enhancing tumor specificity through antigen targeting, addressing tumor heterogeneity, overcoming physical barriers, and counteracting the immune-suppressive microenvironment.

Advances in cell therapy: progress and challenges in hematological and solid tumors

Cell-based therapies harness the endogenous ability of the immune system to fight cancer and have shown promising results in the treatment of hematological malignancies. However, their clinical application beyond B cell malignancies is hampered by numerous hurdles, ranging from relapsed disease to a hostile tumor microenvironment (TME). Recent advances in cell engineering and TME modulation may expand the applicability of these therapies to a wider range of cancers, creating new treatment possibilities. Breakthroughs in advanced gene editing and sophisticated cell engineering, have also provided promising solutions to longstanding challenges. In this review, we examine the challenges and future directions of the most prominent cell-based therapies, including chimeric antigen receptor (CAR)-T cells, tumor-infiltrating lymphocytes (TILs), and natural killer (NK) cells, and emerging modalities. We provide a comprehensive analysis of emerging cell types and combination strategies translated into clinical trials, offering insights into the next generation of cell-based cancer treatments.

Complete loss of lineage defining antigens in two cases of B-cell malignancies following CAR-T therapy

Targeted immunotherapy is a promising approach in treating high-risk and refractory/relapsed lymphoid malignancies. Although this strategy has shown a significant success in treating non-Hodgkin B-cell lymphomas and plasma cell myeloma, relapse with loss of targeted antigen can occur. Rarely, complete loss of multiple lineage specific markers can happen. We are describing 2 cases of B-cell neoplasms along with contributing immunohistochemistry, cytogenetic, and molecular results. Post-targeted CAR-T therapy, both cases, one aggressive B-cell lymphoma and the other plasma cell myeloma, lost B-cell, and plasma cell antigens, respectively. Complete loss of lineage specific markers post-targeted therapy is a rare event that makes the diagnosis of the relapsed neoplasm challenging. In this article, we also reviewed the literature and highlighted possible mechanisms of antigen loss following targeted therapy.

Leucine zipper-based immunomagnetic purification of CAR T cells displaying multiple receptors

Resistance to chimaeric antigen receptor (CAR) T cell therapy develops through multiple mechanisms, most notably antigen loss and tumour-induced immune suppression. It has been suggested that T cells expressing multiple CARs may overcome the resistance of tumours and that T cells expressing receptors that switch inhibitory immune-checkpoint signals into costimulatory signals may enhance the activity of the T cells in the tumour microenvironment. However, engineering multiple features into a single T cell product is difficult because of the transgene-packaging constraints of current gene-delivery vectors. Here we describe a cell-sorting method that leverages leucine zippers for the selective single-step immunomagnetic purification of cells co-transduced with two vectors. Such 'Zip sorting' facilitated the generation of T cells simultaneously expressing up to four CARs and coexpressing up to three 'switch' receptors. In syngeneic mouse models, T cells with multiple CARs and multiple switch receptors eliminated antigenically heterogeneous populations of leukaemia cells coexpressing multiple inhibitory ligands. By combining diverse therapeutic strategies, Zip-sorted multi-CAR multi-switch-receptor T cells can overcome multiple mechanisms of CAR T cell resistance.

Targeting overexpressed antigens in glioblastoma via CAR T cells with computationally designed high-affinity protein binders

Chimeric antigen receptor (CAR) T cells targeting receptors on tumour cells have had limited success in patients with glioblastoma. Here we report the development and therapeutic performance of CAR constructs leveraging protein binders computationally designed de novo to have high affinity for the epidermal growth factor receptor (EGFR) or the tumour-associated antigen CD276, which are overexpressed in glioblastoma. With respect to T cells with a CAR using an antibody-derived single-chain variable fragment as antigen-binding domain, the designed binders on CAR T cells promoted the proliferation of the cells, the secretion of cytotoxic cytokines and their resistance to cell exhaustion, and improved antitumour performance in vitro and in vivo. Moreover, CARs with the binders exhibited higher surface expression and greater resistance to degradation, as indicated by bulk and single-cell transcriptional profiling of the cells. The de novo design of binding domains for specific tumour antigens may potentiate the antitumour efficacy of CAR T cell therapies for other solid cancers.

CAR-T cell therapy in Multiple Myeloma: current status and future challenges

The treatment of multiple myeloma has changed dramatically in recent years, with huge strides forward made in the field. Chimeric antigen receptor T-cell therapy targeting the B cell maturation antigen (BCMA) is now widely approved in relapsed refractory patients and is moving into earlier treatment lines. In this review, we discuss the evidence underpinning current regulatory approvals and consider mechanisms through which CAR-T cell efficacy could be improved. These include tackling BCMA-loss, harnessing the immunosuppressive tumour microenvironment, manufacturing concerns including the potential role of other cellular sources, safety issues such as cytokine release syndrome and neurotoxicity, and optimal patient selection.

High-throughput screening for optimizing adoptive T cell therapies

Adoptive T cell therapy is a pivotal strategy in cancer immunotherapy, demonstrating potent clinical efficacy. However, its limited durability often results in primary resistance. High-throughput screening technologies, which include both genetic and non-genetic approaches, facilitate the optimization of adoptive T cell therapies by enabling the selection of biologically significant targets or substances from extensive libraries. In this review, we examine advancements in high-throughput screening technologies and their applications in adoptive T cell therapies. We highlight the use of genetic screening for T cells, tumor cells, and other promising combination strategies, and elucidate the role of non-genetic screening in identifying small molecules and targeted delivery systems relevant to adoptive T cell therapies, providing guidance for future research and clinical applications.

The mechanisms of B-cell acute lymphoblastic leukemia relapsing following chimeric antigen receptor-T cell therapy; the plausible future strategies

Research has demonstrated the high mortality and morbidity associated with B-Acute lymphoblastic lymphoma (B-ALL). Researchers have developed several therapeutic approaches to combat the disorder. Recently, researchers developed chimeric antigen receptors (CARs)-T cells, which recognize antigens independently of major histocompatibility complexes (MHCs) and activate at a higher level with additional persistence. However, relapsing B-ALL has been reported in several cases. This review article was aimed to collecting recent information regarding the mechanisms used by B-ALL-related lymphocytes to escape from CAR-T cells and the plausible resolution projects.

Synergistic integration of mRNA-LNP with CAR-engineered immune cells: Pioneering progress in immunotherapy

Chimeric antigen receptor T cell (CAR-T) therapy has emerged as a revolutionary approach in the treatment of malignancies. Despite its remarkable successes, this field continues to grapple with challenges such as scalability, safety concerns, limited therapeutic effect, in vivo persistence, and the need for precise control over CAR expression. In the post-pandemic era of COVID-19 vaccine immunization, the application of messenger RNA (mRNA) encapsulated within lipid nanoparticles (LNPs) has recently garnered significant attention as a potential solution to address these challenges. This review delves into the dynamic landscape of mRNA-LNP technology and its potential implications for CAR-engineered immune cell-based immunotherapy.

A Cancer-Specific Anti-Podoplanin Monoclonal Antibody, PMab-117-mG2a Exerts Antitumor Activities in Human Tumor Xenograft Models

Podoplanin (PDPN) overexpression is associated with poor clinical outcomes in various tumors. PDPN is involved in malignant tumor progression by promoting invasiveness and metastasis. Therefore, PDPN is considered a promising target of monoclonal antibody (mAb)-based therapy. Because PDPN also plays an essential role in normal cells such as kidney podocytes, cancer specificity is required to reduce adverse effects on normal cells. We developed a cancer-specific mAb (CasMab) against PDPN, PMab-117 (rat IgM, kappa), by immunizing rats with PDPN-overexpressed glioblastoma cells. The recombinant mouse IgG2a-type PMab-117 (PMab-117-mG2a) reacted with the PDPN-positive tumor PC-10 and LN319 cells but not with PDPN-knockout LN319 cells in flow cytometry. PMab-117-mG2a did not react with normal kidney podocytes and normal epithelial cells from the lung bronchus, mammary gland, and corneal. In contrast, one of the non-CasMabs against PDPN, NZ-1, showed high reactivity to PDPN in both tumor and normal cells. Moreover, PMab-117-mG2a exerted antibody-dependent cellular cytotoxicity in the presence of effector splenocytes. In the human tumor xenograft models, PMab-117-mG2a exhibited potent antitumor effects. These results indicated that PMab-117-mG2a could be applied to antibody-based therapy against PDPN-expressing human tumors while reducing the adverse effects.

HLA-G can be transfered via trogocytosis from leukemic cells to T cells in chronic lymphocytic leukemia

In chronic lymphocytic leukemia (CLL) immune escape mechanism allows leukemia cells to proliferate and expand and it might also be responsible for disease progression. Some molecules involved in the regulation of an immune system might represent prognostic value for CLL patients. Among numerous immune escape mechanisms it was shown that the expression of human leukocyte antigen G (HLA-G) might represent one of the agents damaging cellular immune response. In the present study, the expression of the HLA-G molecule and ILT-2 receptor on the surface of leukemic cells, as well as a plasma concentration of soluble HLA-G (sHLA-G) was evaluated. Also, we investigated whether HLA-G could be transferred from leukemic cells to T cells by the mechanism of trogocytosis. We showed higher proportion of leukemic cells expressing HLA-G and increased levels of sHLA-G in CLL patients compared to that of B-cells in healthy volunteers (HVs). Results of our work showed a time-dependent increase in HLA-G expression on CD4+ T cells co-incubated with HLA-G-positive CD19+ cells. Longer coincubation times did significantly increase these proportions (p < 0.001). We have shown that a higher proportion of HLA-G-expressing CD4+ T cells correlated with the clinical stage of the disease according to the Rai classification. Interestingly, we found a higher CD4+HLA-G+ percentage in the group with unmutated immunoglobulin heavy chain variable region (IGHV) genes compared to the group with mutated IGHV gene after 48 h co-culture. In summary, increasing evidence has revealed that, in addition to HLA-G expressed on tumor cells, intercellular transfer of HLA-G among cancer cells and immune cells through trogocytosis plays important roles in mechanism of immune escape, disease progression and poor clinical outcome.

Trogocytosis in CAR immune cell therapy: a key mechanism of tumor immune escape

Immune cell therapy based on chimeric antigen receptor (CAR) technology platform has been greatly developed. The types of CAR immune cell therapy have expanded from T cells to innate immune cells such as NK cells and macrophages, and the diseases treated have expanded from hematological malignancies to non-tumor fields such as infectious diseases and autoimmune diseases. Among them, CAR-T and CAR-NK therapy have observed examples of rapid remission in approved clinical trials, but the efficacy is unstable and plagued by tumor resistance. Trogocytosis is a special phenomenon of intercellular molecular transfer that is common in the immune system and is achieved by recipient cells through acquisition and internalization of donor cell-derived molecules and mediates immune effects. Recently, a novel short-term drug resistance mechanism based on trogocytosis has been proposed, and the bidirectional molecular exchange between CAR immune cells and tumor cells triggered by trogocytosis partially explains the long-term relapse phenomenon after treatment with CAR immune cells. In this review, we summarize the research progress of trogocytosis in CAR immunotherapy, discuss the influencing factors of trogocytosis and its direct and indirect interference with CAR immune cells and emphasize that the interference of trogocytosis can further release the potential of CAR immune cell therapy.

CAR-NK cells for gastrointestinal cancer immunotherapy: from bench to bedside

BACKGROUND

Gastrointestinal (GI) cancers represent a significant health burden worldwide. Their incidence continues to increase, and their management remains a clinical challenge. Chimeric antigen receptor (CAR) natural killer (NK) cells have emerged as a promising alternative to CAR-T cells for immunotherapy of GI cancers. Notably, CAR-NK cells offer several advantages, including reduced risk of graft-versus-host disease, lower cytokine release syndrome, and the ability to target cancer cells through both CAR-dependent and natural cytotoxic mechanisms.

MAIN BODY

This review comprehensively discusses the development and applications of CAR-NK cells in the treatment of GI cancers. We explored various sources of NK cells, CAR design strategies, and the current state of CAR-NK cell therapy for GI cancers, highlighting recent preclinical and clinical trials. Additionally, we addressed existing challenges and propose potential strategies to enhance the efficacy and safety of CAR-NK cell therapy.

CONCLUSIONS

Our findings highlight the potential of CAR-NK cells to revolutionize GI cancer treatment and pave the way for future clinical applications.

Human OX40L-CAR-Tregs target activated antigen-presenting cells and control T cell alloreactivity

Regulatory T cells (Tregs) make major contributions to immune homeostasis. Because Treg dysfunction can lead to both allo- and autoimmunity, there is interest in correcting these disorders through Treg adoptive transfer. Two of the central challenges in clinically deploying Treg cellular therapies are ensuring phenotypic stability and maximizing potency. Here, we describe an approach to address both issues through the creation of OX40 ligand (OX40L)-specific chimeric antigen receptor (CAR)-Tregs under the control of a synthetic forkhead box P3 (FOXP3) promoter. The creation of these CAR-Tregs enabled selective Treg stimulation by engagement of OX40L, a key activation antigen in alloimmunity, including both graft-versus-host disease and solid organ transplant rejection, and autoimmunity, including rheumatoid arthritis, systemic sclerosis, and systemic lupus erythematosus. We demonstrated that OX40L-CAR-Tregs were robustly activated in the presence of OX40L-expressing cells, leading to up-regulation of Treg suppressive proteins without induction of proinflammatory cytokine production. Compared with control Tregs, OX40L-CAR-Tregs more potently suppressed alloreactive T cell proliferation in vitro and were directly inhibitory toward activated monocyte-derived dendritic cells (DCs). We identified trogocytosis as one of the central mechanisms by which these CAR-Tregs effectively decrease extracellular display of OX40L, resulting in decreased DC stimulatory capacity. OX40L-CAR-Tregs demonstrated an enhanced ability to control xenogeneic graft-versus-host disease compared with control Tregs without abolishing the graft-versus-leukemia effect. These results suggest that OX40L-CAR-Tregs may have wide applicability as a potent cellular therapy to control both allo- and autoimmune diseases.

Structural Basis for the Recognition of GPRC5D by Talquetamab, a Bispecific Antibody for Multiple Myeloma

Multiple myeloma (MM) is a complex hematological malignancy characterized by abnormal antibody production from plasma cells. Despite advances in the treatment, many patients experience disease relapse or become refractory to treatment. G-protein-coupled receptor class C group 5 member D (GPRC5D), an orphan GPCR predominantly expressed in MM cells, is emerging as a promising target for MM immunotherapy. Talquetamab, a Food and Drug Administration-approved T-cell-directing bispecific antibody developed for treatment of MM, targets GPRC5D. Here, we elucidate the structure of GPRC5D complexed with the Fab fragment of talquetamab, using cryo-electron microscopy, providing the basis for recognition of GPRC5D by the bispecific antibody. GPRC5D forms a symmetric homodimer with the interface between transmembrane helix (TM) 4 of one protomer and TM4/5 of the other protomer. A single talquetamab Fab interacts with the GPRC5D dimer with its orientation toward the dimer interface. All six complementarity-determining regions of talquetamab engage with extracellular loops and TM3/5/7. In particular, the side-chain of an arginine residue from the antibody penetrates into a shallow pocket on the extracellular surface of GPRC5D. The structure offers insights for optimizing antibody design against GPRC5D for relapsed or refractory MM therapy.