The NOTCH-FOXM1 Axis Plays a Key Role in Mitochondrial Biogenesis in the Induction of Human Stem Cell Memory-like CAR-T Cells

Recent studies have shown that stem cell memory T (TSCM) cell-like properties are important for the successful adoptive immune therapy by the chimeric antigen receptor-engineered-T (CAR-T) cells. We previously reported that both human and murine activated T cells are converted into stem cell memory-like T (iTSCM) cells by co-culture with stromal OP9 cells expressing the NOTCH-ligand. However, the mechanism of NOTCH-mediated iTSCM reprogramming remains to be elucidated. Here, we report that the NOTCH/OP9 system efficiently converts conventional human CAR-T cells into TSCM-like CAR-T, “CAR-iTSCM” cells, and that the mitochondrial metabolic reprogramming plays a key role in this conversion. The NOTCH signals promote mitochondrial biogenesis and fatty acid synthesis during iTSCM formation, which are essential for the properties of iTSCM cells. We identified fork head box M1 (FOXM1) as a downstream target of NOTCH, which is responsible for these metabolic changes and the subsequent iTSCM differentiation. Like NOTCH-induced CAR-iTSCM cells, FOXM1-induced CAR-iTSCM cells possess superior antitumor potential compared to conventional CAR-T cells. We propose that the NOTCH- or FOXM1-driven CAR-iTSCM formation is an effective strategy for improving cancer immunotherapy. We activated CD8+ T cells by aCD3/28 dynabeads for 7 days. After TCR stimulation, to activate Notch signaling, activated T cells were co-cultured with OP9-hDLL1 cells. NICD- or FOXM1ΔN-transduced T cells were cultured in OP9-hDLL1 conditioned medium.