PDCD1 and urinary bladder cancer: Immune checkpoint inhibitors, antibodies against cytotoxic T lymphocyte-associated antigen 4 (CTLA4), programmed cell death protein 1 (PD1) or its programmed cell death protein ligand 1 (PDL1), have strong anti-tumor ability in experimental animal models and have shown clinical efficacy in cancers including bladder cancer (47–51).