PDCD1 and kidney cancer: The immune checkpoint molecules, such as programmed cell death 1 (PD-1), PD-1 ligand 1 (PD-L1) and cytotoxic T-lymphocyte associated antigen 4 (CTLA-4), have demonstrated a remarkable, durable response in bladder cancer [25, 26], prostate cancer [27, 28] and kidney cancer [29, 30].