Trogocytosis of CAR molecule regulates CAR-T cell dysfunction and tumor antigen escape

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.

Tailoring CAR surface density and dynamics to improve CAR-T cell therapy

Chimeric antigen receptor (CAR)-T cell therapy has revolutionized the treatment landscape for relapsed and/or refractory B-cell neoplasms, garnering Food and Drug Administration/European Medicines Agency approval for six commercial products. Despite this success, challenges persist, including a relapse rate of 30-50% in hematologic tumors, limited clinical efficacy in solid tumors, and severe side effects. This review addresses the critical need for therapeutic enhancement by focusing on the often-overlooked strategy of modulating CAR protein density on the cell membrane. We delve into the key factors influencing CAR surface expression, such as CAR downmodulation following antigen encounter and antigen-related factors. The dynamics of CAR downmodulation remain underexplored; however, recent data point to its modification as a useful tool for improving functionality. Notably, transcriptional control of CAR expression and the incorporation of specific elements into the CAR design have emerged as interesting strategies to tailor CAR expression profiles. Therefore, controlling CAR dynamic density may represent an attractive strategy for achieving optimal therapeutic outcomes.

New approaches of chimeric antigen receptor (CAR)-immune cell-based therapy in gastric cancer; highlight CAR-T and CAR-NK

One characteristic that makes gastric cancer (GC) against other cancers is the intricate immune system's reaction, particularly to tenacious inflammation. Consequently, the immunological function is essential to the growth of this malignancy. Tumor immunotherapy has yielded several encouraging outcomes, but despite this, different patients continue to not respond to treatment, and a far larger number become resistant to it. Also, activated CAR-T cells express a majority of immunological checkpoint factors, containing PD1, CTLA4, and LAG3, which counteracts the anti-tumor actions of CAR-T cells. Moreover, cytokine release syndrome is one of the possible adverse responses of CAR-T cell therapy. Therefore, producing universal allogeneic T lymphocytes with potent anti-tumor activity is essential. This study demonstrates current research on this cutting-edge technology, including the composition and mode of action of CAR-NK and CAR-T cells in GC. Also, in this study, we examined recent studies about various specific GC biomarkers that target CAR-T cells and CAR-NK 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.

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.

Gp350-targeted CAR-T therapy in EBV-positive Burkitt lymphoma: pre-clinical development of gp350 CAR-T

BACKGROUND

Epstein-Barr virus (EBV) is an oncovirus belonging to the herpesvirus family, associated with the pathogenesis of multiple malignancies, particularly Burkitt lymphoma (BL). The virus remains latent in host cells and plays a critical role in tumor progression through various mechanisms. A key glycoprotein, gp350, expressed during the lytic phase of EBV, is instrumental in viral entry into B cells and presents a unique antigenic target, making it a promising candidate for immunotherapeutic approaches, such as chimeric antigen receptor T-cell (CAR-T) therapy.

METHODS

In this study, we engineered CAR-T cells targeted against the gp350 glycoprotein and assessed their therapeutic potential through a series of in vitro and in vivo experiments. The efficacy of the gp350-CAR-T cells was evaluated by comparing their cytotoxic effects against both EBV-positive and -negative tumor cell lines. We utilized a xenograft model of Burkitt lymphoma to monitor the impact of gp350-CAR-T cell administration on tumor progression and overall survival.

RESULTS

The engineered gp350-CAR-T cells demonstrated potent cytotoxicity specifically against EBV-positive tumor cell lines. In our in vivo xenograft model, administration of gp350-CAR-T cells resulted in significant inhibition of tumor growth, highlighting their capability to effectively target and eliminate EBV-positive lymphomas. This selectivity underscores the potential of utilizing gp350 as a specific target for immunotherapy.

CONCLUSION

Our findings advocate for the clinical application of gp350-directed CAR-T therapy as a prospective treatment strategy for patients with relapsed or refractory EBV-positive tumors. Given the encouraging preclinical results, further research is warranted to optimize CAR-T cell production processes and extend the potential of this therapy to other EBV-associated malignancies, paving the way for improved outcomes in affected patient populations.

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.

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.

CYP3A5 promotes glioblastoma stemness and chemoresistance through fine-tuning NAD+/NADH ratio

BACKGROUND

Glioblastoma multiforme (GBM) exhibits a cellular hierarchy with a subpopulation of stem-like cells known as glioblastoma stem cells (GSCs) that drive tumor growth and contribute to treatment resistance. NAD(H) emerges as a crucial factor influencing GSC maintenance through its involvement in diverse biological processes, including mitochondrial fitness and DNA damage repair. However, how GSCs leverage metabolic adaptation to obtain survival advantage remains elusive.

METHODS

A multi-step process of machine learning algorithms was implemented to construct the glioma stemness-related score (GScore). Further in silico and patient tissue analyses validated the predictive ability of the GScore and identified a potential target, CYP3A5. Loss-of-function or gain-of-function genetic experiments were performed to assess the impact of CYP3A5 on the self-renewal and chemoresistance of GSCs both in vitro and in vivo. Mechanistic studies were conducted using nontargeted metabolomics, RNA-seq, seahorse, transmission electron microscopy, immunofluorescence, flow cytometry, ChIP‒qPCR, RT‒qPCR, western blotting, etc. The efficacy of pharmacological inhibitors of CYP3A5 was assessed in vivo.

RESULTS

Based on the proposed GScore, we identify a GSC target CYP3A5, which is highly expressed in GSCs and temozolomide (TMZ)-resistant GBM patients. This elevated expression of CYP3A5 is attributed to transcription factor STAT3 activated by EGFR signaling or TMZ treatment. Depletion of CYP3A5 impairs self-renewal and TMZ resistance of GSCs. Mechanistically, CYP3A5 maintains mitochondrial fitness to promote GSC metabolic adaption through the NAD⁺/NADH-SIRT1-PGC1α axis. Additionally, CYP3A5 enhances the activity of NAD-dependent enzyme PARP to augment DNA damage repair. Treatment with CYP3A5 inhibitor alone or together with TMZ effectively suppresses tumor growth in vivo.

CONCLUSION

Together, this study suggests that GSCs activate STAT3 to upregulate CYP3A5 to fine-tune NAD⁺/NADH for the enhancement of mitochondrial functions and DNA damage repair, thereby fueling tumor stemness and conferring TMZ resistance, respectively. Thus, CYP3A5 represents a promising target for GBM treatment.

CAR T Cell Nanosymbionts: Revealing the Boundless Potential of a New Dyad

Cancer treatment has traditionally focused on eliminating tumor cells but faces challenges such as resistance and toxicity. A promising direction involves targeting the tumor microenvironment using CAR T cell immunotherapy, which has shown potential for treating relapsed and refractory cancers but is limited by high costs, resistance, and toxicity, especially in solid tumors. The integration of nanotechnology into ICAM cell therapy, a concept we have named "CAR T nanosymbiosis", offers new opportunities to overcome these challenges. Nanomaterials can enhance CAR T cell delivery, manufacturing, activity modulation, and targeting of the tumor microenvironment, providing better control and precision. This approach aims to improve the efficacy of CAR T cells against solid tumors, reduce associated toxicities, and ultimately enhance patient outcomes. Several studies have shown promising results, and developing this therapy further is essential for increasing its accessibility and effectiveness. Our "addition by subtraction model" synthesizes these multifaceted elements into a unified strategy to advance cancer treatment paradigms.

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-T therapy for ovarian cancer: Recent advances and future directions

Ovarian cancer (OC) is a common gynecological tumor with high mortality, which is difficult to control its progression with conventional treatments and is prone to recurrence. Recent studies have identified OC as an immunogenic tumor that can be recognized by the host immune system. Immunotherapy for OC is being evaluated, but approaches such as immune checkpoint inhibitors have limited efficacy, adoptive cell therapy is an alternative therapy, in which CAR(chimeric antigen receptor)-T therapy has been applied to the clinical treatment of hematological malignancies. In addition, CAR-NK and CAR-macrophage (CAR-M) have also shown great potential in the treatment of solid tumors. Here, we discuss recent advances in preclinical and clinical studies of CAR-T for OC treatment, introduce the efforts made by researchers to modify the structure of CAR in order to achieve effective OC immunotherapy, as well as the research status of CAR-NK and CAR-M, and highlight emerging therapeutic opportunities that can be utilized to improve the survival of patients with OC using CAR-based adoptive cell therapy.

Rab5 Overcomes CAR T Cell Dysfunction Induced by Tumor-Mediated CAR Capture

Continuous interaction between chimeric antigen receptor (CAR) T cell (CART) and tumors often result in CART dysfunction and tumor escape. We observed that tumors can take up CAR molecules, leaving CARTs without surface-expressed CARs and thus unable to kill tumors after prolonged exposure. Overexpression of Rab5 resulted in augmented clathrin-independent endocytosis, preventing loss of surface-expressed CARs, and enhanced CART activity. Interestingly, we observed membrane protrusions on the CART cell surface which disappeared after multiple tumor challenges. Rab5 maintained these protrusions after repeated tumor engagements and their presence correlated with effective tumor clearance, suggesting a link between endocytosis, membrane protrusions, and cytolytic activity. In vivo , Rab5-expressing CARTs demonstrated improved activity and were able to clear an otherwise refractory mesothelin-expressing solid cancer in humanized mice by maintaining CAR surface expression within the tumor. Thus, pairing Rab5 with CAR expression could improve the clinical efficacy of CART therapy. Highlights "CAR-jacking" occurs when surface CAR is internalized by target tumor cells.Rab5 overexpression prevents "CAR-jacking" and enhances CART function.Rab5 promotes CAR endocytic recycling and maintains membrane protrusions.Rab5-expressing CARTs exhibit enhanced therapeutic efficacy against solid tumors.

A Review of CAR-T Combination Therapies for Treatment of Gynecological Cancers

CAR-T cell therapy offers a promising way for prolonged cancer remission, specifically in the case of blood cancers. However, its application in the treatment of solid tumors still faces many limitations. This review paper provides a comprehensive overview of the challenges and strategies associated with CAR-T cell therapy for solid tumors, with a focus on gynecological cancer. This study discusses the limitations of CAR-T therapy for solid tumor treatment, such as T cell exhaustion, stromal barrier, and antigen shedding. Additionally, it addresses possible approaches to increase CAR-T efficacy in solid tumors, including combination therapies with checkpoint inhibitors and chemotherapy, as well as the novel approach of combining CAR-T with oncolytic virotherapy. Given the lack of comprehensive research on CAR-T combination therapies for treating gynecological cancers, this review aims to provide insights into the current landscape of combination therapies for solid tumors and highlight the potential of such an approach in gynecology.

Challenges and strategies associated with CAR-T cell therapy in blood malignancies

Cellular immunotherapy, particularly CAR-T cells, has shown potential in the improvement of outcomes in patients with refractory and recurrent malignancies of the blood. However, achieving sustainable long-term complete remission for blood cancer remains a challenge, with resistance and relapse being expected outcomes for many patients. Although many studies have attempted to clarify the mechanisms of CAR-T cell therapy failure, the mechanism remains unclear. In this article, we discuss and describe the current state of knowledge regarding these factors, which include elements that influence the CAR-T cell, cancer cells as a whole, and the microenvironment surrounding the tumor. In addition, we propose prospective approaches to overcome these obstacles in an effort to decrease recurrence rates and extend patient survival subsequent to CAR-T cell therapy.