PDCD1 and melanoma: In clinical trials, anti-PD-1/PD-L1 blockade resulted in objective clinical responses in patients with melanoma [16,17,18], non-small-cell lung cancer (NSCLC) [19,20,21], renal cell carcinoma (RCC) [22,23], bladder cancer [24,25], and Hodgkin’s lymphoma [26].