Recombinase-Based Genetic Circuits for Adoptive T Cell Therapy

Cell-based therapies that employ engineered T cells—including the expression of chimeric antigen receptors (CARs)—to target cancer cells have demonstrated promising responses in clinical trials. However, engineered T cell responses must be regulated to prevent severe side effects such as cytokine storms and off-target responses. Here we present a class of recombinase-based gene circuits that will enable inducible switching between two states of adoptive T cell therapy using an FDA-approved drug, creating a generalizable platform that can be used to control when and how strongly a gene is expressed. These circuits are robust and exhibit memory such that induced T cells will maintain any changes made even when the drug inducer is removed. This memory feature avoids prolonged drug inducer exposure, thus improving the safety of the inducible gene switches by reducing the complexity and potential side effect associated with administering the drug inducer. We have utilized these circuits to control the expression of an α-Her2-CAR, demonstrating the ability of these circuits to regulate CAR expression and T cell activity. Our platform addresses a critical need for advanced and flexible gene expression control in human T cells that minimizes drug exposure duration, and can be extended to regulate other genes in T cells for therapeutic applications beyond cancer immunotherapy.