DNA hypomethylating agents can reverse terminal T cell differentiation 2186

Description A major barrier to the effectiveness of T cell-based immunotherapy is CD8 T cell exhaustion, a state of impaired cytotoxicity, decreased cytokine production, and limited proliferative capacity that occurs in settings of chronic antigen exposure. Epigenetic reinforcement of T cell exhaustion occurs through the acquisition of repressive DNA methylation. Therefore, we investigate whether hypomethylating agents can reverse T cell dysfunction via DNA demethylation. We hypothesize that the fate and subset specificity of human and mouse effector memory CD8 T-cells can be epigenetically altered to reverse repressive epigenetic programs. Here, we used a novel DNMT1 inhibitor (DNMT1i), GSK-3685032, to overcome the fate restrictions unique to effector memory CD8 T-cells. Our methylation profiling data shows that treating this subset of CD8 T-cells with the DNMT1i results in a robust loss of acquired DNA methylation, notably at stem-associated loci TCF7 and LEF1. Transcriptional analysis revealed that DNMT1i-treated effector memory CD8 T-cells have increased multipotency and memory-associated gene signatures post-treatment. Gene set enrichment analysis reinforced our findings, implicating STAT5 and IL-2 signaling as key pathways enriched in the DNMT1i-treated effector memory T-cells. Collectively, we describe an epigenetic approach that facilitates the reversal of DNA methylation to alter the fate of CD8 T cell subsets for prolonged host protection during immunotherapy. Funding Sources Supported by NIH 1R01CA237311; American Lebanese Syrian Associated Charities (ALSAC)