Engineering TME-gated inducible CAR-T cell therapy for solid tumors.

Autonomous "living drug" Chimeric Antigen Receptor (CAR)-T cell therapy has revolutionized cancer medicine. However, concerns about on-target off-tumor T cell activation and resulting toxicities require advanced precise regulatory control systems for CAR-T. Here, we present a novel strategy using a genetic "AND" gate that integrates chemically-induced proximity (CIP) and tumor-activated prodrug approaches to generate the next generation CAR-T cell, namely TME-iCAR-T cell, that are capable of sensing multiple tumor-specific characteristics (i.e., tumor antigens and tumor microenvironment (TME) signals) to precisely execute therapeutic functions within the TME. This design was built on the abscisic acid (ABA)-based CIP and its associated reactivity-based caging/sensing technology. Hypoxia-responsive small molecule prodrugs were developed by conjugating ABA with different nitroaromatic derivatives, which render ABA inactive until the unique sensing moieties are removed by specific cancer signals in the TME. We demonstrated that TME-iCAR-T cells respond specifically to the chosen tumor signal combination in vitro and resulted in remarkable cancer signals-restricted activation and cytotoxicity to cancer cells. We also showed their controllability and antitumor efficacy in vivo using a xenograft prostate tumor model. Our highly modular multi-criteria control system in CAR-T represents a new promising strategy to enhance the tumor selectivity and safety of future cell-based immunotherapies.