CCR5 and IL-12 co-expression in CAR T cells improves antitumor efficacy by reprogramming tumor microenvironment in solid tumors.

Chimeric antigen receptor (CAR) T cell therapy for solid tumors faces significant challenges, including inadequate infiltration, limited proliferation, diminished effector function of CAR T cells, and an immunosuppressive tumor microenvironment (TME). In this study, we utilized The Cancer Genome Atlas database to identify key chemokines (CCL4, CCL5, and CCR5) associated with T cell infiltration across various solid tumor types. The CCL4/CCL5-CCR5 axis emerged as significantly correlated with the presence of T cells within tumors, and enhancing the expression of CCR5 in CAR T cells bolstered their migratory capacity. Furthermore, single-cell immunoprofiling of tumor tissues revealed that macrophages within the TME primarily interact with CD8 T cells, impeding their tumor response. However, CAR T cells engineered to secrete Interleukin (IL)-12 can counteract macrophage-mediated immunosuppression and augment T cell functionality. To address these obstacles, we employed esophageal carcinoma as a model to develop mesothelin-targeted CAR T cells co-expressing CCR5 and IL-12 (CARTmeso-5-12), subsequently assessing their antitumor capabilities in vitro and in vivo. The CARTmeso-5-12 cells demonstrated enhanced tumor infiltration due to overexpression of CCR5, and IL-12 secretion further amplified CAR T cell efficacy by attenuating the suppressive influence of tumor-infiltrating macrophages, thus improving tumor eradication.