Reversible ON- and OFF-switch chimeric antigen receptors controlled by lenalidomide

Cell-based therapies are emerging as effective agents against cancer and other diseases. As autonomous living drugs, these therapies lack precise control. Chimeric antigen receptor (CAR) T cells effectively target hematologic malignancies but can proliferate rapidly and cause toxicity. We developed ON and OFF switches for CAR T cells using the clinically approved drug lenalidomide, which mediates the proteasomal degradation of several target proteins by inducing interactions between the CRL4(CRBN) E3 ubiquitin ligase and a C2H2 zinc finger degron motif. We performed a systematic screen to identify super-degron tags with enhanced sensitivity to lenalidomide-induced degradation and used these degradable tags to generate OFF-switch degradable CARs. To create an ON switch, we engineered a lenalidomide-inducible dimerization system and developed split CARs that required both lenalidomide and target antigen for activation. Subtherapeutic lenalidomide concentrations controlled the effector functions of ON- and OFF-switch CAR T cells. In vivo, ON-switch split CARs demonstrated lenalidomide-dependent antitumor activity, and OFF-switch degradable CARs were depleted by drug treatment to limit inflammatory cytokine production while retaining antitumor efficacy. Together, the data showed that these lenalidomide-gated switches are rapid, reversible, and clinically suitable systems to control transgene function in diverse gene- and cell-based therapies.

Automated summary

Cell-based therapies, particularly CAR T cells, are increasingly recognized as powerful agents against cancer. By utilizing the drug lenalidomide, researchers have successfully developed ON and OFF switches to control the function of CAR T cells, showing promising clinical applications for these engineered cells.