Taurine bolsters adoptive T cell therapy efficacy against hepatocellular carcinoma by reprogramming T cell function

Adoptive T cell therapy for advanced hepatocellular carcinoma (HCC) is limited by the immunosuppressive tumor microenvironment, which impairs T-cell function. Overcoming this immunosuppression and restoring T-cell functionality are crucial for improving therapeutic efficacy. Here, we investigated the role of taurine in regulating alpha-fetoprotein (AFP)-specific T-cell receptor-engineered T cells (TCR-T) function. Metabolomic profiling revealed that intracellular taurine levels declined during the early phase of T-cell activation, while expression of the taurine transporter SLC6A6 increased over time. In addition, taurine abundance was lower in HCC tissues than in normal liver tissues in vivo, suggesting that taurine availability is reduced during both T-cell activation and tumor progression. Functionally, taurine supplementation enhanced the cytotoxic activity, persistence, and intratumoral infiltration of AFP-specific TCR-T, while reducing exhaustion and apoptosis after repetitive tumor stimulation. In contrast, taurine-limited conditions impaired T-cell proliferation and survival, attenuated antitumor activity in vitro and in vivo, and promoted an exhaustion-prone phenotype. Taurine supplementation also partially restored the function of β-alanine-preconditioned T cells. Mechanistically, transcriptomic and proteomic analyses identified PI3K-AKT signaling as a key pathway associated with taurine-mediated T-cell regulation. Taurine-limited T cells showed reduced AKT phosphorylation and developed a metabolically stressed state characterized by increased mitochondrial respiration, glycolytic activity, reactive oxygen species production and mitochondrial structural abnormalities during activation. Together, these findings identify taurine availability as an important metabolic regulator of engineered T-cell fitness and support taurine-based metabolic conditioning as a potential strategy to improve TCR-T therapy for HCC.