For example, the innate PD-1 inhibitor resistance (IPRES) signature, which includes 26 gene signatures associated with de-differentiation and BRAF/MEK inhibitor resistance, was associated with lack of PD-1 inhibitor response in pre-treatment melanoma biopsies in one study17, but was not associated with PD-1 inhibitor response in other melanoma cohorts11,19. Here, PDCD1 is linked to melanoma.