Here, we point out that KLRG1 expression is concentrated on the most differentiated and potent CD8 T cells, unlike PD-1, and its expression is anti-correlated to PD-1 as well as all major coinhibitory and costimulatory checkpoint receptors across tumor infiltrating (TILS) CD8 T cells in a wide variety of cancers. Here, KLRG1 is linked to neoplasm.