Targeting Aggressive Prostate Carcinoma Cells with Mesothelin-CAR-T Cells.

Background: Advancing chimeric antigen receptor (CAR) T cell therapy for solid tumors remains a major challenge in cancer immunotherapy. Prostate cancer (PCa), particularly in its aggressive forms, may be a suitable target for CAR-T therapy given the range of associated tumor antigens. However, due to the high plasticity and heterogeneity of aggressive PCa and the complexity of the tumor environment, there is a need to broaden the repertoire of targetable antigens and deepen our understanding of CAR-T behavior in stressed microenvironmental conditions. Growing evidence supports mesothelin as a promising cancer-associated marker and a compelling target for CAR-T cell approaches in solid tumors. Objectives and Methods: Here, we employed gene expression datasets to investigate mesothelin expression in both primary and metastatic PCa tumors. Additionally, we evaluated mesothelin expression across various preclinical PCa models and assessed the therapeutic efficacy of second-generation mesothelin-targeted CAR-T (meso-CAR-T) cells under both normoxic and hypoxic conditions, with hypoxia as a representative tumor-associated stress condition. Results: Our results revealed a significant enrichment of mesothelin in 3-10% of metastatic prostate tumors, contrasting with its minimal expression in primary tumors. In line with these findings, we observed increased mesothelin expression in an aggressive variant of the 22Rv1 cell line, which displayed an epithelial-mesenchymal plasticity (EMP) phenotype. Meso-CAR-T cells demonstrated potent cytotoxicity and remarkable selectivity toward these carcinoma cells under both severe hypoxia (1% O₂) or normoxia (21% O₂), highlighting their ability to withstand metabolic stress within the tumor microenvironment. Conclusions: Our study underscores the potential of meso-CAR-T cells as a promising strategy for targeting specific subtypes of metastatic prostate cancer.