Epacadostat, an IDO1 selective inhibitor, was evaluated in a randomized, placebo-controlled, double-blind, phase 3 trial (ClinicalTrials.gov Identifier: NCT02752074) in patients with unresectable stage III or IV melanoma previously untreated with PD-1 or PD-L1 inhibitors [134]. The gene discussed is IDO1; the disease is melanoma.