PD-1 and PD-L1 antibodies have shown considerable clinical efficacy and durability across a range of malignancy subtypes, including melanoma and lung cancer [9, 58] and most recently in refractory Hodgkin's disease [59], and quite a lot of phase II studies are ongoing in prospect (NCT02572167, NCT02181738, NCT02327078). This evidence concerns the gene PDCD1 and melanoma.