Enhancement of B7-H3 chimeric antigen receptor-T cell efficacy via the coexistence effect of IL-7, IL-15 and CCL19 for pancreatic and lung xenograft tumors

In current clinical applications, there are challenges with using chimeric antigen receptor (CAR)-T cells to effectively treat solid tumors. These challenges include promoting the infiltration and proliferation of CAR-T cells, as well as extending their survival and generating immune memory. To address these issues, we developed CAR-T cells that can coexpress interleukin-7 (IL-7), interleukin-15 (IL-15), and C-C motif chemokine ligand 19 (CCL19). Gene cloning technology, the humanized single-chain variable fragment (scFv) method, and lentiviral transfection tools were used to construct the specific CAR-T cells co-expressing IL-7, IL-15 and CCL19, and B7-H3 (H3-7/15 × 19-CAR-T cells). Our results revealed that H3-7/15 × 19-CAR-T cells could target B7 family protein H3 (B7-H3) antigen with a high affinity (1.77 × 10^-10 mol/L) and release cytokines (e.g., IL-7 and IL-15) and chemokines (e.g., CCL19). Moreover, H3-7/15 × 19-CAR-T cells cocultured with B7-H3-positive tumor cells exhibited outstanding proliferation, maintained their memory phenotype, and induced tumor cell apoptosis in vitro. Furthermore, H3-7/15 × 19-CAR-T cells exhibited good infiltration with long-lasting survival and antitumor efficacy in vivo. H3-7/15 × 19-CAR-T cells significantly improved the therapeutic efficacy of traditional CAR-T cells, including CD19- and H3-CAR-T cells, acting in pancreatic cancer- and non-small cell lung cancer-derived xenograft tumor models based on NOD-Prkdcem26Cd52Il2rgem26Cd22/Nju (NCG) mice. In summary, H3-7/15 × 19-CAR-T cells possess potential for clinical transformation and represent a new strategy for treating solid tumors.