Pyruvate kinase M2 activation reprograms mitochondria in CD8 T cells, enhancing effector functions and efficacy of anti-PD1 therapy

Mitochondria regulate T cell functions and response to cancer immunotherapy. We show that pharmacologically induced PKM2 activation enhances mitochondria-dependent effector functions in mouse and human CD8 T cells and CAR-T cells. Multi-omics analysis and 13C-glucose tracer experiments showed that PKM2 activation alters one-carbon metabolism with decreased levels of methionine leading to hypomethylation of mitochondrial and nuclear DNA and enhanced expression of genes supporting mitochondrial biogenesis and respiratory complex formation in CD8 T cells. Functionally, PKM2 activation increased the recall responses and anti-tumor functions of CD8 T cells after adoptive cell therapy. Using preclinical melanoma and colon cancer models, we found that PKM2-agonist induced CD8 T cell-dependent anti-tumor responses that synergized with PD1 blockade therapy. Immunologically, PKM2 agonists resulted in enhanced activation and decreased exhaustion of effector T cells while reducing the numbers of suppressive FoxP3+ Treg cells in the tumor microenvironment. Anti-PD1 combination further enhanced the frequency and activation of tumor specific CD8 T cells in the tumors. Together, we show that PKM2 agonism modulates mitochondrial structure and function, leading to enhanced effector functions of cytotoxic lymphocytes. Hence, targeting PKM2 via pharmacologically available small molecules can be a clinically viable strategy for the enhancement of therapeutic potential of in-situ immune responses, adoptive cell therapy, and immune checkpoint blockade therapy