PD-1 monoclonal antibodies such as pembrolizumab and nivolumab inhibit this PD-1/PD-L1 interaction and have thus been incorporated into many therapeutic regimens for a variety of advanced malignancies, including melanoma, lung cancer, hepatocellular carcinoma, renal cell carcinoma, and urothelial carcinoma. Here, PDCD1 is linked to melanoma.