CD8A and melanoma: In melanoma patients, TCF1+ CD8+ TILs expressed lower levels of PD-1 than TCF1− CD8+ TILs (Gattinoni et al., 2011), and the presence of TCF1+ CD8+ TILs was associated with better clinical response to immune checkpoint blockade therapy (Sade-Feldman et al., 2018).