CD8A and neoplasm: They found that the presence of CD8+ cytotoxic T-cells present along the invasive margin of the tumor, as well as the close proximity of programmed death receptor 1 (PD-1, located on CD8+ T-cells) to programmed death ligand 1 (PD-L1), predicted the therapeutic response to anti–PD-1 blockade and subsequent tumor regression (Tumeh et al., 2014).