Deficiency of metabolic regulator PKM2 activates the pentose phosphate pathway and generates TCF1+ progenitor CD8+ T cells to improve immunotherapy

TCF1high progenitor CD8+ T cells mediate the efficacy of immunotherapy; however, the mechanisms that govern their generation and maintenance are poorly understood. Here, we show that targeting glycolysis through deletion of pyruvate kinase muscle 2 (PKM2) results in elevated pentose phosphate pathway (PPP) activity, leading to enrichment of a TCF1high progenitor-exhausted-like phenotype and increased responsiveness to PD-1 blockade in vivo. PKM2KO CD8+ T cells showed reduced glycolytic flux, accumulation of glycolytic intermediates and PPP metabolites and increased PPP cycling as determined by 1,2-13C glucose carbon tracing. Small molecule agonism of the PPP without acute glycolytic impairment skewed CD8+ T cells toward a TCF1high population, generated a unique transcriptional landscape and adoptive transfer of agonist-treated CD8+ T cells enhanced tumor control in mice in combination with PD-1 blockade and promoted tumor killing in patient-derived tumor organoids. Our study demonstrates a new metabolic reprogramming that contributes to a progenitor-like T cell state promoting immunotherapy efficacy. TCF1+ progenitor-exhausted CD8+ T cell populations mediate durable antitumor immunity. Upon antigenic stimulation, effector T cells upregulate aerobic glycolysis to support their cytotoxic phenotype. Here, Mittal and colleagues find that loss of metabolic regulator PKM2 enriches for TCF1+ progenitor-exhausted-like cells and improves responsiveness to PD-1 blockade.