Engineering One-Signal Activated TILs with CD3ζ-CD28 Chimeras Optimizes the Antitumor Efficacy of TIL-Based Immunotherapy

Adoptive T cell therapy (ACT) is a promising therapeutic option that enhances the anti-cancer immune response to recognize and eliminate tumor burden. Recently, ACT modalities with autologous tumor-infiltrating lymphocytes (TILs) have shown robust anti-tumor efficacy in solid tumors. However, this therapeutic strategys application remains suboptimal in stability and faces critical challenges, primarily due to the lack of costimulatory signals. Here, we unveil a novel engineering strategy one-signal-activated TIL (OSAT), which integrates CD3{zeta} with secondary signaling domains, to bypass the classical dual-signal requirement for T cell activation. We demonstrate that OSAT molecules 2 (CD3{zeta}-CD28, M2) and 7 (CD3{zeta}-CD137-CD28, M7) mediate efficient mono-signal activation, and recapitulate both the activation signatures and functional markers of mock T cells stimulated with dual signals. Notably, OSAT exhibited enhanced cytotoxicity and in vivo anti-tumor activity across syngeneic tumor models, especially when combined with PD-1 blockade therapy. Mechanistically, OSAT can be fully activated by first signal stimulation, leading to upregulation of activation and metabolic reprogramming genes, production of IL-2/IFN-{gamma}/TNF-, initiation of cytotoxicity, and enhanced TIL antitumor efficacy. These findings unveil integrating CD3{zeta} with secondary signaling domains as a higher efficacy modification for TILs with therapeutic potential for clinical cancer immunotherapy.