CD274 and metastatic melanoma: Three of the most significant therapeutic approaches are represented by sipuleucel-T, an immunotherapeutic vaccine for prostate cancer [62]; ipilimumab, a check point inhibitor of CTLA-4 [63], and anti-programmed death receptor-1 (PD-1) and its ligand PDL-1 antibodies (anti-PD-1/PD-L-1) [64–66] for the treatment of metastatic melanoma.