PDCD1 and urinary bladder carcinoma: Currently, programmed cell death protein-1 (PD-1), programmed death-ligand 1 (PD-L1), and cytotoxic T-lymphocyte-associated antigen 4 inhibitors are the most studied ICIs, and various PD-1/PD-L1 inhibitors have been approved for the treatment of advanced bladder cancer (9, 10).