The number of Food and Drug Administration (FDA)-approved agents blocking PD-L1/PD-1 axis is rapidly enlarging with indications for treatment of a broad spectrum of malignancies, ranging from classical Hodgkin lymphoma to head and neck squamous cell carcinoma (HNSCC), melanoma and urothelial cancers, both as monotherapy and in combination with other agents. Here, PDCD1 is linked to melanoma.