De novo designed receptor transmembrane domains enhance CAR-T cell cytotoxicity and attenuate cytokine release

designed receptor transmembrane domains (TMDs) present opportunities for precise control of cellular functions. We develop a strategy for generating programmed membrane proteins (proMPs): single-pass α-helical TMDs that form oligomeric complexes through computationally defined and crystallographically validated interfaces. To demonstrate their usefulness, we program specific oligomeric interactions into a chimeric antigen receptor (to generate proCARs) and analyze the cytotoxic potency and cytokine release profiles of proCAR-T cells. We show that dimeric and trimeric proCAR-expressing T cells have significantly enhanced antitumor cytotoxicity compared to a monomeric proCAR and a reference CAR similar to those currently used in the clinic. Independently of oligomeric state, all proCAR-T cells exhibited strongly attenuated inflammatory cytokine release. These results have important implications for both safety and efficacy of cellular immunotherapies and highlight the advantages of programming precise structural features in engineered receptors through protein design. The proMPs provide an exceptionally modular route to tuning receptor function and can be easily incorporated into existing CAR designs.