Tunable control of CAR T cell activity through tetracycline mediated disruption of protein-protein interaction

Chimeric antigen receptor (CAR) T cells are a promising form of cancer immunotherapy, although they are often associated with severe toxicities. Here, we present a split-CAR design incorporating separate antigen recognition and intracellular signaling domains. These exploit the binding between the tetracycline repressor protein and a small peptide sequence (TIP) to spontaneously assemble as a functional CAR. Addition of the FDA-approved, small molecule antibiotic minocycline, acts as an off-switch by displacing the signaling domain and down-tuning CAR T activity. Here we describe the optimization of this split-CAR approach to generate a CAR in which cytotoxicity, cytokine secretion and proliferation can be inhibited in a dose-dependent and reversible manner. Inhibition is effective during on-going CAR T cell activation and inhibits activation and tumor control in vivo. This work shows how optimization of split-CAR structure affects function and adds a novel design allowing easy CAR inhibition through an FDA-approved small molecule.

Automated summary

A novel split-CAR design was proposed in this study, utilizing the binding between the tetracycline repressor protein and a small peptide sequence for spontaneous assembly of a functional CAR, with the addition of a small molecule antibiotic for CAR T activity modulation. The optimized split-CAR structure allows for dose-dependent and reversible inhibition of cytotoxicity, cytokine secretion, and proliferation.