PDCD1 and cancer: Recently the results of a phase I/II study aiming to reinvigorate the immune response to evaluate the efficacy and safety of immune-checkpoint inhibitors in cholangiocarcinoma were reported.[28] PD-1, also known as CD279, is a co-inhibitory cell surface receptor that abrogates antitumor immune responses and promotes tumor immune escape from cytotoxic T cells during carcinogenesis.[29] Therefore, blockade of the PD-1/PD-L1 pathway by interfering with the binding between PD-1 and its ligands is a potential strategy for cancer therapy.