A Phase 1/2 Randomized, Blinded, Placebo Controlled Study of Ipilimumab in Combination With Epacadostat or Placebo in Subjects With Unresectable or Metastatic Melanoma

Inclusion Criteria:

* Male or female subjects, aged 18 years or older with unresectable or metastatic melanoma.
* A life expectancy of \>12 weeks.
* Laboratory ranges and medical criteria met, as defined within the protocol.
* Subject may have received more than 1 prior regimen of systematic treatment for unresectable or metastatic melanoma.
* For Phase 2 period of the study only, Subjects must have archival tumor tissue available and collected with the prior 6 months or accessible disease for pre-treatment, study biopsy.

Exclusion Criteria:

* Pregnant or nursing women.
* Current investigational trial participation with another investigational product or subjects who have received any anticancer medications within 21 days prior to screening (6 weeks for mitomycin-C or nitrosoureas.)
* Subjects receiving monoamine oxidase inhibitors (MAOI)s; subjects who have ever had Serotonin Syndrome after receiving one or more serotonergic drugs.
* Subjects who have received prior immune checkpoint inhibitors (eg anti-CTLA-4, anti-programmed death 1 (PD-1), anti-programmed death-ligand 1 (PD-L1) and others) who have had Grade 3 or 4 hepatotoxicity, immune colitis requiring infliximab, endocrine toxicity not controlled by replacement, any other Grade 4 immune adverse events (AEs) or ocular toxicity
* Subjects with protocol-specified active autoimmune process except vitiligo or thyroiditis.
* Subjects with concurrent conditions that would jeopardize the safety of the safety of the subject or compliance with the protocol.