PDCD1 and cancer: Both immunoscores and immunosignatures in tumor microenvironments—mainly containing CD8+ cytotoxic T lymphocytes (CTLs), programmed cell death 1 (PD-1) and its ligand 1 (PD-L1), and interferon (INF)-γ, in addition to other cytokines and antibodies—can predict treatment response and outcome in various cancer types [10, 11].