Mitochondrial potential as a biomarker of T cell fitness and function in cancer immunotherapy

TCRβ and single cell RNA sequencing of primary tumors identified and characterized peripheral blood T cell clones associated with the tumor microenvironment. As anticipated, ICI therapy increased the frequency of effector T cells in patients who experienced clinical benefit. TMREhigh peripheral blood T cells with tumor-matching TCRβ sequences had elevated oxidative phosphorylation gene signatures.

Gene signatures of stress and exhaustion, such as Tigit and Cmc1, were also elevated in the TMREhigh CD8 T cell populations while gene expression patterns in TMRElow cells suggested mitochondrial fitness and cell longevity. Importantly, clinical benefit from ICI was negatively correlated with the TMREhigh CD8 T cell gene expression signature. These findings highlight the presence of a T cell population of with elevated MMP that correlates with T cell exhaustion-like states and failed response to immunotherapy.