FOXO1 is a master regulator of memory programming in CAR T cells.

A major limitation of chimeric antigen receptor (CAR) T cell therapies is the poor persistence of these cells in vivo. The expression of memory-associated genes in CAR T cells is linked to their long-term persistence in patients and clinical efficacy, suggesting that memory programs may underpin durable CAR T cell function. Here we show that the transcription factor FOXO1 is responsible for promoting memory and restraining exhaustion in human CAR T cells.