PDCD1 and metastatic melanoma: The third cluster includes nivolumab, adverse events, management, ipilimumab, pembrolizumab, metastatic melanoma, melanoma, open-label, chemotherapy, blockade, association, advanced melanoma, antibodies, cell lung-cancer, cancer-immunotherapy, pd-1, safety, receptor, ipilimumab-induced hypophysitis, squamous-cell carcinoma, docetaxel.