PDCD1 and renal cell carcinoma: With the recent understanding of RCC pathogenesis, many new therapeutic strategies are being developed, and a few of them including immunotherapies targeting programmed cell death (PD-1)/programmed death-ligand 1 (PD-L1), as single agents or in combination with anti-CTLA-4 monoclonal antibodies or a multi-target VEGF-TKIs have gained FDA approval as treatment regimens in clinical settings.