Coopting T cell proximal signaling molecules enables Boolean logic-gated CAR T cell control

Abstract

While CAR T cells have altered the treatment landscape for B cell malignancies, the risk of on-target, off-tumor toxicity has hampered their development for solid tumors because most target antigens are shared with normal cells. Researchers have attempted to apply Boolean logic gating to CAR T cells to prevent on-target, off-tumor toxicity; however, a truly safe and effective logic-gated CAR has remained elusive. Here, we describe a novel approach to CAR engineering in which we replace traditional ITAM-containing CD3ζ domains with intracellular proximal T cell signaling molecules. We demonstrate that certain proximal signaling CARs, such as a ZAP-70 CAR, can activate T cells and eradicate tumors in vivo while bypassing upstream signaling proteins such as CD3ζ. The primary role of ZAP-70 is to phosphorylate LAT and SLP-76, which form a scaffold for the propagation of T cell signaling. We leveraged the cooperative role of LAT and SLP-76 to engineer Logic-gated Intracellular NetworK (LINK) CAR, a rapid and reversible Boolean-logic AND-gated CAR T cell platform that outperforms other systems in both efficacy and the prevention of on-target, off-tumor toxicity. LINK CAR will dramatically expand the number and types of molecules that can be targeted with CAR T cells, enabling the deployment of these powerful therapeutics for solid tumors and diverse diseases such as autoimmunity and fibrosis. In addition, this work demonstrates that the internal signaling machinery of cells can be repurposed into surface receptors, a finding that could have broad implications for new avenues of cellular engineering.