PDCD1 and metastatic melanoma: In recent trials, IFN-α was combined with ICI: no clinical efficacy for resected melanoma was observed when an adjuvant treatment of IFN-α was compared to Pembrolizumab [72], while promising evidence of clinical benefit was reported when PEG-IFN was combined with Pembrolizumab in PD-1-naïve metastatic melanoma [73].