Engineering human protein switches for functional control of CARs and transcription factors via oral drug administration

Abstract While CAR T cells have revolutionized the treatment of certain hematologic malignancies, they can cause severe toxicities, which are expected to be exacerbated with next-generation CAR Ts engineered for improved proliferation, persistence, and efficacy. Therefore, regulatory systems are urgently needed to be able to control these living drugs directly in patients. Here, we engineered a molecular switch, in which the interaction of two human proteins is efficiently induced with the orally available and non-toxic drug A1120. We demonstrate the versatility of this switch by regulating CAR signaling and transcriptional activity in human T cells in vitro and in vivo. Both systems were tightly controlled in the absence of the drug but strongly activated upon administration of the small molecule. Since this switch enables the regulation of diverse systems including CARs and transcription factors, we anticipate that it represents an important step towards next-generation cellular therapies with improved safety and efficacy. Competing Interest Statement M.L. and M.W.T. receive funding from Miltenyi Biotec. E.S., C.U.Z., M.W.T. and M.L. are inventors on patents related to hRBP4- and nanobody-based molecular switches. J.Z. is a founder, shareholder, and scientific adviser of Quantro Therapeutics. The Zuber Lab receives research support and funding from Boehringer Ingelheim. A.M-L., F.E. and B.E. are full-time employees of Miltenyi Biotec. J.M. was an employee of Miltenyi Biotec at the time of this study. The remaining authors declare no competing interests. Footnotes ↵+ Faculty of Life Sciences, Reutlingen University, Germany