IDO1 and melanoma: However, in another study enrolling 706 patients with unresectable stage III or IV melanomas, epacadostat 100 mg twice daily plus pembrolizumab does not improve progression-free survival or overall survival compared with placebo, indicating that the adoption of IDO1 inhibition as a strategy to enhance anti-PD-1 therapy activity in melanoma needs further verification (NCT02752074) (160).