The killing effect of novel bi-specific Trop2/PD-L1 CAR-T cell targeted gastric cancer

Due to their high heterogeneity and complex tumor microenvironment, the treatment of solid tumors by CAR-T cell technology is limited. This study developed bi-specific Trop2/PD-L1 specific third-generation CAR-T cells by lentiviral infection. The specific killing ability of the bi-specific CAR-T cells against Trop2(+) and PD-L1(+) expressed on the gastric cancer cell line by CCK-8 assay, was confirmed in vitro. The killing ability of bi-specific Trop2/PD-L1 CAR-T cells was higher than that of mono-specific CAR-T cells (Trop2 CAR-T and PD-L1 CAR-T) and the independent control group (CD19-CAR-T and CIK). The bi-specific Trop2/PD-L1 CAR-T cells produced IFN-γ and IL-2 in response to the overexpression of Trop2 and PD-L1 in gastric cancer cells through ELASA assay. The levels of cytokines (IFN-γ and IL-2) released by bi-specific Trop2/PD-L1 CAR-T cells were the highest among all other types of CAR-T cells and the independent control group. To further demonstrate the ability of bi-specific Trop2/PD-L1 CAR-T cells in vivo, this study testified to the anti-tumor effect of several types of CAR-T cells through a xenograft model bearing human gastric tumors. The results indicated that bi-specific Trop2/PD-L1 CAR-T cells can significantly reduce the tumor growth through intratumoral injection, with a higher inhibition effect than Trop2 specific CAR-T cells and the independent control group (CD19-CAR-T and untreated group). These results suggest that novel bi-specific Trop2/PD-L1 CAR-T cells are able to target Trop2/PD-L1 and checkpoint blockade, and reveal the killing effect on gastric cancer, therefore improving the killing effect of CAR-T cells in solid tumors.