Cell autonomous control of CAR signaling and receptor shedding via ADAM17-mediated proteolysis

Screening of canonical ADAM17 substrates yielded a minimal 15-aa CD62L-derived motif that confers rapid and reversible cleavage of a receptor following T cell activation—termed Activation-Induced Release (AIR). Embedding AIR into tonic-signaling CARs reduced basal CAR expression proportional to the degree of tonic signaling induced, curtailing exhaustion and improving antitumor potency.

In non-tonic signaling CARs, AIR decreased activation-induced cell death and enhanced T cell expansion after stimulation. AIR’s modularity supports higher-order logic-gating; AIR-regulated peptide masks enable antigen-dependent unmasking of an EGFR-targeting CAR. Finally, CRISPR knock-in of AIR into endogenous FAS or TGFBR2 endowed them with activation-induced shedding, which enhanced tumor clearance, while preserving signaling in non-activating conditions.