The study that led to the approval of ipilimumab by the U.S. Food and Drug Administration (FDA) was a three-arm randomized trial comparing the combination of ipilimumab with gp100 peptide vaccine versus gp100 vaccine alone versus ipilimumab alone in 676 patients affected by metastatic melanoma who had failed prior therapy [42]. Here, PMEL is linked to metastatic melanoma.