Monoclonal antibodies that target the PD-1/PD-L1 immunological checkpoint have gained prominence in recent years with the FDA approval of several drugs, such as the PD-1 inhibitors pembrolizumab [169,170,171,172], nivolumab [173,174,175,176], and cemiplimab [177] and the PD-L1 blockers atezolizumab (https://www.fda.gov/drugs/informationondrugs/approveddrugs/ucm525780.htm (accessed on 25 September 2018)) and durvalumab [178] for Hodgkin’s lymphoma and a number of solid tumor types, including melanoma, bladder cancer, and squamous cell carcinomas of the head and neck. This evidence concerns the gene CD274 and melanoma.