Carbonic anhydrase 2-derived drug-responsive domain regulates membrane-bound cytokine expression and function in engineered T cells

Adoptive cell therapies (ACT) have shown reduced efficacy against solid tumor malignancies compared to hematologic malignancies, partly due to the immunosuppressive nature of the tumor microenvironment (TME). ACT efficacy may be enhanced with pleiotropic cytokines that remodel the TME; however, their expression needs to be tightly controlled to avoid systemic toxicities. Here we show T cells can be armored with membrane-bound cytokines with surface expression regulated using drug-responsive domains (DRDs) developed from the 260-amino acid protein human carbonic anhydrase 2 (CA2). The CA2-DRD can be stabilized in vitro and in vivo with the FDA-approved small-molecule CA2 inhibitor acetazolamide (ACZ). We develop conditional degrons using library-based screening of mutants and show characterization of one DRD using crystallography and molecular dynamics (MD) simulations. Using protein-engineering solutions to increase the valency of DRDs fused to the cargo we have developed "modulation hubs" and show tight regulation of membrane-bound cytokines IL2, IL12, IL15, IL21, IL23, and IFNα in genetically engineered T cells. Finally, CA2-DRD regulated IL12 mediates regulated efficacy in a solid tumor model. Regulation of pleotropic cytokines potentially paves the way to safely use these powerful cytokines in ACT for cancer treatment.