Cabozantinib Enhances CAIX Specific CAR-T cells Against Renal Cancer by Augmenting Tumor Immune Microenvironment

Despite demonstrating promising outcomes in treating hematologic malignancies, the efficacy of chimeric antigen receptor-modified T (CAR-T) cell therapy remains limited when applied to solid tumors due to tumor immune microenvironment (TIME). Strategies to augment CAR-T cell efficacy against solid tumors have been investigated by ameliorating TIME to a certain extent. In this study, Cabozantinib was utilized in combination with CAR-T cells targeting carbonic anhydrase IX (CAIX) for the treatment of renal cancer. Our findings indicate that combination therapy with CAIX-CAR-T and Cabozantinib demonstrated synergistic efficacy against an orthotopic xenograft tumor model and a subcutaneous tumor model of renal cell carcinoma in mice. Mechanistically, it was observed that CAR-T cells combined with Cabozantinib led to an increase in the infiltration of tumor-infiltrating T cells, while reducing tumor-associated macrophages and M2 polarization. Additionally, Cabozantinib blocked the programmed cell death-1 (PD-1)/programmed death-ligand 1 (PD-L1) axis by decreasing the expression of PD-L1 in tumor cells and PD-1 in T cells. Furthermore, Cabozantinib promoted CAR-T cell effector function and reduced T cell exhaustion. This combination therapy represents a novel approach to enhancing CAR-T cell efficacy against solid tumors and holds significant promise for advancing CAR-T cell therapy in clinical settings.