TEFM-mediated regulation of mitochondrial function enhances CAR-T cell activity in ovarian cancer peritoneal metastasis

Chimeric antigen receptor (CAR)-T cell therapy in solid tumours is frequently limited by progressive functional impairment and inadequate metabolic fitness within the tumour microenvironment. Mitochondrial transcription elongation factor (TEFM) is an essential regulator of mitochondrial gene expression, but its role in CAR-T-cell engineering remains unknown. In this study, we developed TEFM mRNA-loaded lipid nanoparticles (TEFM mRNA-LNPs) to transiently increase TEFM expression in CAR-T cells and investigated their effects on mitochondrial function and antitumour activity. TEFM mRNA-LNP transfection significantly increased intracellular TEFM expression and enhanced CAR-T-cell cytotoxicity, activation and cytokine production in vitro. TEFM augmentation also increased mitochondrial membrane potential, oxygen consumption and ATP production while reducing mitochondrial reactive oxygen species. In an OVCAR-3 intraperitoneal metastasis model, TEFM-engineered CAR-T cells achieved improved tumour control and prolonged mouse survival without overt histopathological abnormalities in major organs. Tumour tissues from mice treated with TEFM CAR-T cells also exhibited increased intratumoural cytokine levels and enhanced local effector activity. Collectively, these findings demonstrate that transient TEFM augmentation improves mitochondrial fitness and potentiates the effector and antitumour activities of CAR-T cells, supporting a mitochondria-directed strategy for the metabolic engineering of adoptive cell therapies.