Systematic Engineering of TROP2-Targeted CAR T-Cell Therapy Overcomes Resistance Pathways in Solid Tumors

Abstract

Antibody-based therapies have revolutionized cancer treatment but have several limitations. These include downregulation of the target antigen, mutation of the target epitope, and, in the case of antibody-drug conjugates (ADC), resistance to the chemotherapy warhead. As TROP2-targeted therapy with ADCs yields responses in TROP2+ solid tumors, but the responses lack the durability observed with other immunotherapy-based approaches, we developed TROP2-targeting chimeric antigen receptor (CAR) T cells as an alternative. The TROP2-directed CAR T cells showed high potency against multiple solid tumor models. Moreover, TROP2-directed CAR T-cell therapy preserved high potency in models of ADC resistance and could be further engineered to prevent cell therapy resistance. This was achieved by leveraging fully human single-domain (VH-only) binder discovery to rationally engineer dual epitope binding-based (biparatopic) CARs. This work highlights the potency of CAR T-cell therapies and how rational engineering leveraging dual-VH targeting domains can overcome resistance pathways to current therapies. In future work, the CAR engineering approaches presented here can serve as a platform to be partnered with other strategies to address the suppressive tumor microenvironment.