However, data from recent clinical trials showed an overall moderate response rate (ORR) to PD-1 blockade of less than 20% [10,34] and a lack of marked responses in most patients [35], compared with more impressive ORRs of up to 57% in other advanced/pretreated tumor types such as non-small cell lung cancer and melanoma [36,37]. This evidence concerns the gene PDCD1 and melanoma.