PD-1/PD-L1 blockers, such as pembrolizumab and nivolumab (anti-PD-1), and atezolizumab, durvalumab, and avelumab (anti-PD-L1), have shown activity in clinical trials, and are gaining approval for an expanding array of indications, including metastatic melanoma, advanced non-small-cell lung cancer, renal cell carcinoma, and classic Hodgkin’s lymphoma [112]. The gene discussed is PDCD1; the disease is metastatic melanoma.