Cancer Immune Evasion Research Articles

VISTA-mediated immune evasion in cancer.

Over the past decade, V-domain immunoglobulin suppressor of T-cell activation (VISTA) has been established as a negative immune checkpoint molecule. Since the role of VISTA in inhibiting T-cell activation was described, studies have demonstrated other diverse regulatory functions in multiple immune cell populations. Furthermore, its relevance has been identified in human cancers. The role of VISTA in cancer immune evasion has been determined, but its mechanisms in the tumor microenvironment remain to be further elucidated. Understanding its contributions to cancer initiation, progression, and resistance to current treatments will be critical to its utility as a target for novel immunotherapies. Here, we summarize the current understanding of VISTA biology in cancer.

Deciphering the role of NcRNAs in Pancreatic Cancer immune evasion and drug resistance: a new perspective for targeted therapy

Pancreatic cancer (PC) is a very aggressive digestive system tumor, known for its high mortality rate, low cure rate, low survival rate and poor prognosis. In particular, pancreatic ductal adenocarcinoma (PADC), which accounts for more than 90% of PC cases, has an overall 5-year survival rate of only 5%, which is an extremely critical situation. Early detection and effective treatment of PC is extremely difficult, which leads many patients to despair. In the current medical context, targeted therapy, as an important strategy for cancer treatment, is expected. However, the problems of immune escape and drug resistance in PC have become two major obstacles that are difficult to be overcome by targeted therapy. How to break through these two difficulties has become a key issue to be solved in the field of PC therapy. In recent years, non-coding RNAs (ncRNAs) have continued to heat up in the field of cancer research. NcRNAs play a pivotal role in gene regulation, cell differentiation, development, and disease processes, and their important roles in the genesis, development, and therapeutic response of PC have been gradually revealed. More importantly, ncRNAs have many advantages as therapeutic targets, such as high specificity and low side effects, making them a new favorite in the field of PC therapy. Therefore, the aim of this paper is to provide new ideas and methods for the targeted therapy of PC by reviewing the mechanism of action of four major ncRNAs (circRNAs, lncRNAs, miRNAs, siRNAs) in both immune escape and drug resistance of PC. It is expected that an effective way to overcome immune escape and drug resistance can be found through in-depth study of ncRNA, bringing a ray of hope to PC patients.

CD47 and Calreticulin Expression in Breast Cancer Subtypes and Anti-CD47 Inhibitory Effects in Macrophage-mediated Phagocytosis.

Macrophage-mediated cancer immune evasion is modulated by the balance between "the cluster of differentiation 47 (CD47), an anti-phagocytic signal" and "calreticulin (CALR), a pro-phagocytic signal". CD47 is highly expressed in various types of cancer. However, the expression profiles of CD47 and CALR in breast cancer, especially in different hormone receptor subtypes, and the effects of CD47 blockade in macrophage-mediated therapy are not well understood. The expression levels of CD47 and CALR were investigated in breast cancer and adjacent normal tissues using immunohistochemistry. To study the effects of CD47 blockade therapy, CD47 and CALR expression in breast cancer cell lines were determined. In vitro macrophage-mediated phagocytosis of breast cancer upon treatment with a monoclonal CD47 antibody (B6H12) were performed. CD47 and CALR were overexpressed in breast cancer tissues and their up-regulation was associated with hormone receptor subtypes. Patients with Luminal A breast cancer had higher levels of CD47, while patients with triple-negative breast cancer (TNBC) had higher levels of CALR. The levels of CD47 and CALR were also elevated in breast cancer cell lines of Luminal A (MCF-7) and TNBC (MDA-MB-231) subtypes. Interestingly, the expression ratio of surface CD47/CALR was significantly higher in MCF-7. Moreover, in vitro phagocytosis assays revealed that blockage of CD47 enhanced macrophage-mediated activity in both cancer cells with dramatically higher degrees of phagocytosis in MCF-7. The expression profiles of CD47 and CALR in breast cancer subtypes and the benefit of CD47 blocking-based immunotherapy are herein provided.

E2F1-induced autocrine IL-6 inflammatory loop mediates cancer-immune crosstalk that predicts T cell phenotype switching and therapeutic responsiveness

Melanoma is a metastatic, drug-refractory cancer with the ability to evade immunosurveillance. Cancer immune evasion involves interaction between tumor intrinsic properties and the microenvironment. The transcription factor E2F1 is a key driver of tumor evolution and metastasis. To explore E2F1’s role in immune regulation in presence of aggressive melanoma cells, we established a coculture system and utilized transcriptome and cytokine arrays combined with bioinformatics and structural modeling. We identified an E2F1-dependent gene regulatory network with IL6 as a central hub. E2F1-induced IL-6 secretion unleashes an autocrine inflammatory feedback loop driving invasiveness and epithelial-to-mesenchymal transition. IL-6-activated STAT3 physically interacts with E2F1 and cooperatively enhances IL-6 expression by binding to an E2F1-STAT3-responsive promoter element. The E2F1-STAT3/IL-6 axis strongly modulates the immune niche and generates a crosstalk with CD4+ cells resulting in transcriptional changes of immunoregulatory genes in melanoma and immune cells that is indicative of an inflammatory and immunosuppressive environment. Clinical data from TCGA demonstrated that elevated E2F1, STAT3, and IL-6 correlate with infiltration of Th2, while simultaneously blocking Th1 in primary and metastatic melanomas. Strikingly, E2F1 depletion reduces the secretion of typical type-2 cytokines thereby launching a Th2-to-Th1 phenotype shift towards an antitumor immune response. The impact of activated E2F1-STAT3/IL-6 axis on melanoma-immune cell communication and its prognostic/therapeutic value was validated by mathematical modeling. This study addresses important molecular aspects of the tumor-associated microenvironment in modulating immune responses, and will contribute significantly to the improvement of future cancer therapies.

Stemness in solid malignancies: coping with immune attack.

Immunotherapy has become a key new pillar of cancer treatment, and this has sparked interest in understanding mechanisms of cancer immune evasion. It has long been appreciated that cancers are constituted by heterogeneous populations of tumour cells. This feature is often fuelled by specialized cells that have molecular programs resembling tissue stem cells. Although these cancer stem cells (CSCs) have capacity for unlimited self-renewal and differentiation, it is increasingly evident that some CSCs are capable of achieving remarkable immune resistance. Given that most immunotherapy regiments have overlooked CSC-specific immune-evasive mechanisms, many current treatment strategies often lead to cancer relapse. This Review focuses on advancements in understanding how CSCs in solid tumours achieve their unique immune-evasive properties, enabling them to drive tumour regrowth. Moreover, as cancers often arise from tissue stem cells that acquired oncogenic mutations, we discuss how tissue stem cells undergoing malignant transformation activate intrinsic immune-evasive mechanisms and establish close interactions with suppressive immune cells to escape immune surveillance. In addition, we summarize how in advanced disease stages, CSCs often hijack features of normal stem cells to resist antitumour immunity. Finally, we provide insights in how to design a new generation of cancer immunotherapies to ensure elimination of CSCs.

Inhibition of UBE2N in regulatory T-cells boosts immunity against cancer.

Regulatory T (Treg) cells prevent autoimmunity and facilitate cancer immune evasion. Depletion of Tregs is a promising cancer therapy, but risks of autoimmune reactions hamper its clinical translation. Here, we demonstrate that temporally induced deletion of Ube2n in Tregs (Ube2n Treg-KO ) of adult mice results in a robust expansion and activation of cytotoxic CD8 + T-cells in response to cancer cell challenges, producing a long-lasting survival benefit without autoimmune complications. The anti-tumor effect persists following adoptive T-cell transfer to T-cell-deficient Rag1-knockout mice. Single-cell transcriptomic analysis revealed that UBE2N deletion shifted immunosuppressive Tregs to effector-like T-cells. This shift is characterized by the downregulation of c-Myc target genes, resembling that observed in tumor-infiltrating Tregs of melanoma patients. Further analyses confirm that UBE2N maintains c-Myc protein stability via suppression of K48-Ubiquitin-mediated proteasomal degradation. Taken together, our studies uncover a hitherto unexplored and potentially druggable UBE2N/c-Myc signaling axis to eradicate Treg-enabled cancer immune escape.

NPM1 inhibits tumoral antigen presentation to promote immune evasion and tumor progression

BackgroundTumor cells develop multiple mechanisms to facilitate their immune evasion. Identifying tumor-intrinsic factors that support immune evasion may provide new strategies for cancer immunotherapy. We aimed to explore the function and the mechanism of the tumor-intrinsic factor NPM1, a multifunctional nucleolar phosphoprotein, in cancer immune evasion and progression.MethodsThe roles of NPM1 in tumor progression and tumor microenvironment (TME) reprogramming were examined by subcutaneous inoculation of Npm1-deficient tumor cells into syngeneic mice, and then explored by CyTOF, flow cytometry, immunohistochemistry staining, and RNA-seq. The in-vitro T-cell killing of OVA-presenting tumor cells by OT-1 transgenic T cells was observed. The interaction of NPM1 and IRF1 was verified by Co-IP. The regulation of NPM1 in IRF1 DNA binding to Nlrc5, Ciita promoter was determined by dual-luciferase reporter assay and ChIP-qPCR.ResultsHigh levels of NPM1 expression predict low survival rates in various human tumors. Loss of NPM1 inhibited tumor progression and enhanced the survival of tumor-bearing mice. Npm1-deficient tumors showed increased CD8+ T cell infiltration and activation alongside the reduced presence of immunosuppressive cells. Npm1 deficiency increased MHC-I and MHC-II molecules and specific T-cell killing. Mechanistically, NPM1 associates with the transcription factor IRF1 and then sequesters IRF1 from binding to the Nlrc5 and Ciita promoters to suppress IRF1-mediated expression of MHC-I and MHC-II molecules in tumor cells.ConclusionsTumor-intrinsic NPM1 promotes tumor immune evasion via suppressing IRF1-mediated antigen presentation to impair tumor immunogenicity and reprogram the immunosuppressive TME. Our study identifies NPM1 as a potential target for improving cancer immunotherapy.

IGF2BP3 boosts lactate generation to accelerate gastric cancer immune evasion.

The CD8+ T cells mediated antitumor immunity plays a critical function on gastric cancer (GC) immunotherapy. However, the mechanism of N6-methyladenosine (m6A) and lactate in GC immune microenvironment are still unclear. Here, present research investigated the role of Insulin like growth factor II mRNA binding protein 3 (IGF2BP3) in GC and its in-depth mechanisms in the antitumor immunity. Data illustrated that high IGF2BP3 level was associated to GC poor prognosis and tumor infiltration. Functional assays demonstrated that IGF2BP3 overexpression could promote the lactate accumulation, and impair the CD8+ T cells' antitumor immunity activity in co-culture system. Correspondingly, IGF2BP3 silencing enhanced the CD8+ T cells' antitumor immunity activity towards co-cultured GC cells. Mechanistically, IGF2BP3 could bind the m6A site on LDHA mRNA, thereby promoting its mRNA stability. Rescue assays elucidated that IGF2BP3/LDHA axis impaired the CD8+ T cells antitumor immunity by triggering lactate excess tumor microenvironment. In conclusion, our findings demonstrate that IGF2BP3 impairs the CD8+ T cells antitumor immunity by targeting LDHA/lactate axis, providing a novel therapeutic insight for GC immunotherapy.

The hallmarks of cancer immune evasion.

According to the widely accepted "three Es" model, the host immune system eliminates malignant cell precursors and contains microscopic neoplasms in a dynamic equilibrium, preventing cancer outgrowth until neoplastic cells acquire genetic or epigenetic alterations that enable immune escape. This immunoevasive phenotype originates from various mechanisms that can be classified under a novel "three Cs" conceptual framework: (1) camouflage, which hides cancer cells from immune recognition, (2) coercion, which directly or indirectly interferes with immune effector cells, and (3) cytoprotection, which shields malignant cells from immune cytotoxicity. Blocking the ability of neoplastic cells to evade the host immune system is crucial for increasing the efficacy of modern immunotherapy and conventional therapeutic strategies that ultimately activate anticancer immunosurveillance. Here, we review key hallmarks of cancer immune evasion under the "three Cs" framework and discuss promising strategies targeting such immunoevasive mechanisms.

CircGSK3β mediates PD-L1 transcription through miR-338-3p/PRMT5/H3K4me3 to promote breast cancer cell immune evasion and tumor progression

Circular RNA (circRNA) plays a pivotal role in breast cancer onset and progression. Understanding the biological functions and underlying molecular mechanisms of dysregulated circRNAs in breast cancer is crucial for elucidating its pathogenesis and identifying potential therapeutic targets. In this study, we investigated the role and molecular mechanism of circGSK3β in breast cancer. We found that circGSK3β is highly expressed in breast cancer cell lines, where it promotes cell proliferation, migration, and invasion, thereby driving breast cancer progression. Furthermore, we observed a close association between circGSK3β expression levels and immune evasion in breast cancer cells. Mechanistically, circGSK3β acts as a competing endogenous RNA (ceRNA) by interacting with miR-338-3p, thereby promoting breast cancer cell proliferation, migration, and invasion. Additionally, circGSK3β positively regulates the expression of the target gene PRMT5 through its interaction with miR-338-3p. This, in turn, enhances H3K4me3 recruitment to the promoter region of PD-L1, resulting in upregulation of PD-L1 expression and consequent immune evasion in breast cancer. In summary, our findings underscore the significance of the circGSK3β-miR-338-3p-PRMT5-H3K4me3 axis in promoting breast cancer progression and immune evasion. CircGSK3β emerges as a critical player in breast cancer pathogenesis, potentially serving as a diagnostic and prognostic marker, and offering novel insights into the role of circRNAs in breast cancer progression.

Aberrant cytoplasmic expression of UHRF1 restrains the MHC-I-mediated anti-tumor immune response

Immunotherapy successfully complements traditional cancer treatment. However, primary and acquired resistance might limit efficacy. Reduced antigen presentation by MHC-I has been identified as potential resistance factor. Here we show that the epigenetic regulator ubiquitin-like with PHD and ring finger domains 1 (UHRF1), exhibits altered expression and aberrant cytosolic localization in cancerous tissues, where it promotes MHC-I ubiquitination and degradation. Cytoplasmic translocation of UHRF1 is induced by its phosphorylation on a specific serine in response to signals provided by factors present in the tumor microenvironment (TME), such as TGF-β, enabling UHRF1 to bind MHC-I. Downregulation of MHC-I results in suppression of the antigen presentation pathway to establish an immune hostile TME. UHRF1 inactivation by genetic deletion synergizes with immune checkpoint blockade (ICB) treatment and induces an anti-tumour memory response by evoking low-affinity T cells. Our study adds to the understanding of UHRF1 in cancer immune evasion and provides a potential target to synergize with immunotherapy and overcome immunotherapeutic resistance.

Harnessing Epigenetic Mechanisms to Overcome Immune Evasion in Cancer: The Current Strategies and Future Directions.

Combining epigenetic alterations with cancer immunotherapy offers a promising approach to improve therapeutic outcomes by targeting the complex biology of tumors. Epigenetic mechanisms such as DNA methylation, histone modifications, and non-coding RNAs (ncRNAs) play a dual role in maintaining immune homeostasis and promoting cancer progression. Changes like hypomethylation in tumor cells can contribute to immune evasion and treatment resistance. Advances in epigenetic tools, particularly clustered regularly interspaced short palindromic repeat (CRISPR) and their associated protein (Cas9)-based epigenetic editing, allow for precise gene expression control, opening new avenues for research and therapy. The improved accuracy of CRISPR/dCas9 systems, when paired with appropriate delivery methods such as viral vectors or nanoparticles, has facilitated innovative combination therapies involving immune checkpoint inhibitors and epigenetic drugs. These combinations enhance the immune system's ability to recognize and destroy cancer cells. Despite these advancements, challenges like off-target effects, delivery issues, and resistance remain. Current research is focused on identifying new therapeutic targets, improving delivery systems, and using real-time feedback to refine treatment. Overall, combining immunotherapy with epigenetic modifications holds significant potential for personalized cancer treatment, paving the way for more effective and individualized therapeutic strategies that target both the immune system and the tumor microenvironment. Further development in this area is expected to revolutionize cancer therapy and improve patient outcomes.

Self-assembled PROTACs enable protein degradation to reprogram the tumor microenvironment for synergistically enhanced colorectal cancer immunotherapy

Both β-catenin and STAT3 drive colorectal cancer (CRC) growth, progression, and immune evasion, and their co-overexpression is strongly associated with a poor prognosis. However, current small molecule inhibitors have limited efficacy due to the reciprocal feedback activation between STAT3 and β-catenin. Inspired by the PROteolysis TArgeting Chimera (PROTAC), a promising pharmacological modality for the selective degradation of proteins, we developed a strategy of nanoengineered peptide PROTACs (NP-PROTACs) to degrade both β-catenin and STAT3 effectively. The NP-PROTACs were engineered by coupling the peptide PROTACs with DSPE-PEG via disulfide bonds and self-assembled into nanoparticles. Notably, the dual degradation of β-catenin and STAT3 mediated by NP-PROTACs led to a synergistic antitumor effect compared to single-target treatment. Moreover, NP-PROTACs treatment enhanced CD103+ dendritic cell infiltration and T-cell cytotoxicity, alleviating the immunosuppressive microenvironment induced by β-catenin/STAT3 in CRC. These results highlight the potential of NP-PROTACs in facilitating the simultaneous degradation of two pathogenic proteins, thereby providing a novel avenue for cancer therapy.

Tumor Microenvironment-Derived Exosomes: A Double-Edged Sword for Advanced T Cell-Based Immunotherapy.

The tumor microenvironment (TME) plays a crucial role in cancer progression and immune evasion, partially mediated by the activity of the TME-derived exosomes. These extracellular vesicles are pivotal in shaping immune responses through the transfer of proteins, lipids, and nucleic acids between cells, facilitating a complex interplay that promotes tumor growth and metastasis. This review delves into the dual roles of exosomes in the TME, highlighting both their immunosuppressive functions and their emerging therapeutic potential. Exosomes can inhibit T cell function and promote tumor immune escape by carrying immune-modulatory molecules, such as PD-L1, yet they also hold promise for cancer therapy as vehicles for delivering tumor antigens and costimulatory signals. Additionally, the review discusses the intricate crosstalk mediated by exosomes among various cell types within the TME, influencing both cancer progression and responses to immunotherapies. Moreover, this highlights current challenges and future directions. Collectively, elucidating the detailed mechanisms by which TME-derived exosomes mediate T cell function offers a promising avenue for revolutionizing cancer treatment. Understanding these interactions allows for the development of targeted therapies that manipulate exosomal pathways to enhance the immune system's response to tumors.

Harnessing B7-H6 for Anticancer Immunotherapy: Expression, Pathways, and Therapeutic Strategies.

Cancer therapies have evolved from traditional chemotherapy to more precise molecular-targeted immunotherapies, which have been associated with improved side effects and outcomes. These modern strategies rely on cancer-specific biomarkers that differentiate malignant from normal cells. The B7 family of immune checkpoint molecules is crucial for cancer immune evasion and a prime therapeutic target. B7-H6, a recently identified member of the B7 family, has emerged as a promising therapeutic target. Unlike other B7 proteins, B7-H6 is not expressed in healthy tissues but is upregulated in several cancers. It binds to NKp30, activating natural killer (NK) cells and triggering immune responses against cancer cells. This review explores the expression of B7-H6 in different cancers, the factors that regulate its expression, and its intrinsic and extrinsic pathways. Additionally, we discuss potential anticancer therapies targeting B7-H6, highlighting its significance in advancing precision medicine. Understanding the role of B7-H6 in cancer immunity may inform the development of appropriate therapies that exploit its cancer-specific expression.

TP53 Mutation-Mediated Immune Evasion in Cancer: Mechanisms and Therapeutic Implications.

Mutation in p53 is the most frequent event in cancer development and a leading cause of cancer therapy resistance due to evasion of the apoptosis cascade. Beyond chemotherapies and radiation therapies, growing evidence indicates that p53-mutant tumors are resistant to a broad range of immune-based therapies, such as immune checkpoint inhibitors, chimeric antigen receptor (CAR) T, and hematopoietic stem cell transplantation (HSCT). This highlights the role of p53 mutations in driving immune evasion of tumor cells. In this review, we first summarize recent studies revealing mechanisms by which p53-mutant tumors evade immune surveillance from T cells, natural killer (NK) cells, and macrophages. We then review how these mutant tumor cells reshape the tumor microenvironment (TME), modulating bystander cells such as macrophages, neutrophils, and regulatory T (Treg) cells to foster immunosuppression. Additionally, we review clinical observations indicative of immune evasion associated with p53 loss or mutations. Finally, we discuss therapeutic strategies to enhance immune response in p53 wild-type (WT) or mutant tumors.

The expansion of MDSCs induced by exosomal PD-L1 promotes the progression of gastric cancer

BackgroundMyeloid-derived suppressor cells (MDSCs) are the major factor in gastric cancer (GC) immune evasion. Nevertheless, the molecular process underlying the expansion of MDSCs induced by tumor-derived exosomes (TDEs) remains elusive.MethodsThe levels of exosomal and soluble PD-L1 in ninety GC patients were examined via enzyme-linked immunosorbent assay (ELISA) to determine their prognostic value. To investigate the correlation between exosomal PD-L1 and MDSCs, the percentage of MDSCs in the peripheral blood of 57 GC patients was assessed via flow cytometry. Through ultracentrifugation, the exosomes were separated from the GC cell supernatant and detected via Western blotting, nanoparticle tracking analysis (NTA), and transmission electron microscopy (TEM). The function of exosomal PD-L1 in MDSCs was evaluated via immunofluorescence, Western blotting and flow cytometry in a GC cell-derived xenograft (CDX) model.ResultsThe overall survival (OS) of GC patients in the high exosomal PD-L1 group was significantly lower than that of patients in the low exosomal PD-L1 group (P = 0.0042); however, there was no significant correlation between soluble PD-L1 and OS in GC patients (P = 0.0501). Furthermore, we found that the expression of exosomal PD-L1 was positively correlated with the proportions of polymorphonuclear MDSCs (PMN-MDSCs, r = 0.4944, P < 0.001) and monocytic MDSCs (M-MDSCs, r = 0.3663, P = 0.005) in GC patients, indicating that exosomal PD-L1 might induce immune suppression by promoting the aggregation of MDSCs. In addition, we found that exosomal PD-L1 might stimulate MDSC proliferation by triggering the IL-6/STAT3 signaling pathway in vitro. The CDX model confirmed that exosomal PD-L1 could stimulate tumor development and MDSC amplification.ConclusionsExosomal PD-L1 has the potential to become a prognostic and diagnostic biomarker for GC patients. Mechanistically, MDSCs can be activated by exosomal PD-L1 through IL-6/STAT3 signaling and provide a new strategy against GC through the use of exosomal PD-L1 as a treatment target.

Recapitulating the Cancer-Immunity Cycle on a Chip.

The cancer-immunity cycle is a fundamental framework for understanding how the immune system interacts with cancer cells, balancing T cell recognition and elimination of tumors while avoiding autoimmune reactions. Despite advancements in immunotherapy, there remains a critical need to dissect each phase of the cycle, particularly the interactions among the tumor, vasculature, and immune system within the tumor microenvironment (TME). Innovative platforms such as organ-on-a-chip, organoids, and bioprinting within microphysiological systems (MPS) are increasingly utilized to enhance the understanding of these interactions. These systems meticulously replicate crucial aspects of the TME and immune responses, providing robust platforms to study cancer progression, immune evasion, and therapeutic interventions with greater physiological relevance. This review explores the latest advancements in MPS technologies for modeling various stages of the cancer-immune cycle, critically evaluating their applications and limitations in advancing the understanding of cancer-immune dynamics and guiding the development of next-generation immunotherapeutic strategies.

16P PTEN deficiency leads to colorectal cancer immune evasion via atypical Keap1/Nrf2 pathway

16P PTEN deficiency leads to colorectal cancer immune evasion via atypical Keap1/Nrf2 pathway

Collagen extracellular matrix promotes gastric cancer immune evasion by activating IL4I1-AHR signaling

BackgroundGastric cancer (GC) remains a significant global health challenge with poor prognosis, partly due to its ability to evade the immune system. The extracellular matrix (ECM), particularly collagen, plays a crucial role in tumor immune evasion, but the underlying mechanisms are not fully understood. This study investigates the role of collagen ECM in promoting immune evasion in gastric cancer by activating the IL4I1-AHR signaling pathway. MethodsWe cultured gastric cancer cells in 3D collagen gels and assessed their immune evasion capabilities by co-culturing with HER2-specific CAR-T cells. The expression of IL4I1 and its metabolites was analyzed, and the role of integrin αvβ1 in mediating the effects of collagen was explored. Additionally, the impact of IL4I1-induced AHR activation on CAR-T cell exhaustion was evaluated, both in vitro and in vivo. ResultsWe found that gastric cancer cells cultured on collagen exhibited increased resistance to CAR-T cell cytotoxicity, which was associated with upregulated immune checkpoint molecules and downregulated effector cytokines on CAR-T cells. This was linked to increased IL4I1 expression, which was further induced by integrin αvβ1 signaling within the 3D collagen environment. IL4I1 metabolites, particularly KynA, promoted CAR-T cell exhaustion by activating the AHR pathway, leading to decreased cytotoxicity and tumor growth inhibition. ConclusionsOur study reveals a novel mechanism by which the collagen ECM facilitates immune evasion in gastric cancer through the activation of IL4I1-AHR signaling, contributing to CAR-T cell exhaustion. Targeting this pathway could potentially enhance the efficacy of CAR-T cell therapy in gastric cancer.