BATF and IRF4 cooperate to counter exhaustion in tumor-infiltrating CAR T cells

The transcription factors NFAT and AP-1 (Fos-Jun) cooperate to promote the effector functions of T cells, but NFAT in the absence of AP-1 imposes a negative feedback program of T cell hyporesponsiveness (“exhaustion”). Here we show that BATF and IRF4 cooperate to counter T cell exhaustion in mouse tumor models. Overexpression of BATF in CD8(+) T cells expressing a chimeric antigen receptor (CAR) promoted the survival and expansion of tumor-infiltrating CAR T cells, increased the production of effector cytokines, decreased the expression of inhibitory receptors and the exhaustion-associated transcription factor TOX, and supported the generation of long-lived memory T cells that controlled tumor recurrence. These responses were dependent on BATF-IRF interaction, since cells expressing a BATF mutant unable to interact with IRF4 did not survive in tumors and did not effectively delay tumor growth. BATF may improve the anti-tumor responses of CAR T cells by skewing their phenotypes and transcriptional profiles away from exhaustion and towards increased effector function.