CXCR3 enhanced murine chimeric antigen receptor T cells in the treatment of solid tumors

Chimeric antigen receptor T cell (CAR-T) therapy has achieved remarkable success in the treatment of hematologic malignancies, but its efficacy against solid tumors remains limited. This limitation primarily arises from the physical and molecular barriers that restrict CAR-T infiltration. The CXCL10-CXCR3 axis plays a critical role in mediating immune cell migration. Notably, elevated CXCR3 expression in solid tumors is correlated with improved immune infiltration and patient survival. Furthermore, the downregulation of CXCR3 in CD8⁺ T cells was observed in tumor microenvironments, limiting their ability to infiltrate tumors. Therefore, we hypothesize that CXCR3-modified CAR-T will exhibit enhanced tumor infiltration capacity, thereby improving the therapeutic efficacy of CAR-T therapy against solid tumors.

We constructed murine CAR-Ts (mCAR-Ts) targeting EGFRvIII (a tumor-specific antigen) and overexpressing CXCR3, which we named EGFRvIII·mCAR-T-CXCR3 cells. These cells were functionally characterized by in vitro cytotoxicity and chemotaxis assays. The tumor suppression efficacy was further evaluated in immunocompetent mice bearing subcutaneous tumors. Immunohistochemical experiments were performed to evaluate the in vivo antitumor mechanisms of EGFRvIII·mCAR-T-CXCR3 cells.

The EGFRvIII·mCAR-T-CXCR3 cells showed enhanced cytotoxic activity and CXCL10-directed migration in vitro. In the murine tumor models, the CXCR3-modified CAR-Ts showed significantly improved tumor suppression compared to the controls, as well as increased intratumoral T-cell infiltration.

CXCR3 overexpression potentiates the anti-tumor capacity of CAR-Ts in solid tumors by enhancing tumor infiltration. This strategy provides a promising approach for overcoming the current limitations of CAR-T therapy.