Solid tumour CAR-T cells engineered with fusion proteins targeting PD-L1 for localized IL-12 delivery
John P. Murad, Lea Christian, Reginaldo Cruz Alves Rosa, Yuwei Ren, Alyssa J. Buckley, Eric Hee Jun Lee, Lupita S. Lopez, Anthony K. Park, Jason Yang, Yukiko Yamaguchi, Candi Trac, Lauren Adkins, Wen-Chung Chang, Catalina Martínez, Carl H. June, Stephen J. Forman, Jun Ishihara, John K. Lee, Lawrence A. Stern, Saul J. Priceman
Abstract
Chimeric antigen receptor (CAR)-T cell efficacy in solid tumours is limited due in part to the immunosuppressive tumour microenvironment (TME). To improve antitumour responses, we hypothesized that enabling CAR-T cells to secrete bifunctional fusion proteins consisting of a cytokine modifier such as TGFβtrap, IL-15 or IL-12, combined with an immune checkpoint inhibitor such as αPD-L1, would provide tumour-localized immunomodulation to improve CAR-T cell functionality. Here we engineer CAR-T cells to secrete TGFβtrap, IL-15 or IL-12 molecules fused to αPD-L1 scFv and assess in vitro functionality and in vivo safety and efficacy in prostate and ovarian cancer models. CAR-T cells engineered with αPD-L1–IL-12 are superior in safety and efficacy compared with CAR-T cells alone and those engineered with αPD-L1 fused with TGFβtrap or IL-15. Further, αPD-L1–IL-12 engineered CAR-T cells improve T cell trafficking and tumour infiltration, and localize IFNγ production, TME modulation and antitumour responses, with reduced systemic inflammation-associated toxicities. We believe our αPD-L1–IL-12 engineering strategy presents an opportunity to improve CAR-T cell clinical efficacy and safety across multiple solid tumour types. CAR-T cells engineered with αPD-L1–IL-12 fusion proteins show antitumour activity in mouse models of prostate and ovarian cancer.