CD8A and cancer: Immune checkpoint inhibitor PD-1 blockade using anti-PD-L1 antibody (PD-L1-Ab) triggers potent antitumor immunity or rescues T cell exhaustion by blocking the inhibitory PD-1/PD-L1 pathway in CD8+PD-1+ T cells (13, 14), and has also commonly been used in clinical cancer immunotherapy (15).