Targeting B7-H3 via chimeric antigen receptor T cells and bispecific killer cell engagers augments antitumor response of cytotoxic lymphocytes

Background: B7-H3, an immune-checkpoint molecule and a transmembrane protein, is overexpressed in non-small cell lung Cancer (NSCLC), making it an attractive therapeutic target. Here, we aimed to systematically evaluate the value of B7-H3 as a target in NSCLC via T cells expressing B7-H3-specific chimeric antigen receptors (CARs) and bispecific killer cell engager (BiKE)-redirected natural killer (NK) cells.

Methods: We generated B7-H3 CAR and B7-H3/CD16 BiKE derived from an anti-B7-H3 antibody omburtamab that has been shown to preferentially bind tumor tissues and has been safely used in humans in early-phase clinical trials. Antitumor efficacy and induced-immune response of CAR and BiKE were evaluated in vitro and in vivo. The effects of B7-H3 on aerobic glycolysis in NSCLC cells were further investigated.

Results: B7-H3 CAR-T cells effectively inhibited NSCLC tumorigenesis in vitro and in vivo. B7-H3 redirection promoted highly specific T-cell infiltration into tumors. Additionally, NK cell activity could be specially triggered by B7-H3/CD16 BiKE through direct CD16 signaling, resulting in significant increase in NK cell activation and target cell death. BiKE improved antitumor efficacy mediated by NK cells in vitro and in vivo, regardless of the cell surface target antigen density on tumor tissues. Furthermore, we found that anti-B7-H3 blockade might alter tumor glucose metabolism via the reactive oxygen species-mediated pathway.

Conclusions: Together, our results suggest that B7-H3 may serve as a target for NSCLC therapy and support the further development of two therapeutic agents in the preclinical and clinical studies.