To date, several monoclonal antibodies targeting the PD-1/PD-L1 signaling pathway have obtained first- and later-line US Food and Drug Administration (FDA) approval in various solid and hematological malignancies, including non-small cell lung cancer, melanoma, renal cell carcinoma, urothelial carcinoma, gastric and gastroesophageal junction adenocarcinoma, head and neck squamous cell carcinoma, and others, in which response rates range from 15-30% (in most solid tumors) to 45–60% (in melanoma and microsatellite instability-high tumors) (44, 47). This evidence concerns the gene PDCD1 and melanoma.