Nivolumab Plus Epacadostat in Combination With Chemotherapy Versus the EXTREME Regimen in Squamous Cell Carcinoma of the Head and Neck (CheckMate 9NA/ECHO-310)

Inclusion Criteria: * Histologically confirmed SCCHN from any of the following primary sites: oral cavity, oropharynx, hypopharynx, and larynx. * Must have recurrent or metastatic disease that is not amenable to therapy with curative intent (surgery and/or radiation therapy with or without chemotherapy). * No prior treatment with systemic anti-cancer therapy for SCCHN unless protocol-defined conditions are met. * Eastern Cooperative Oncology Group (ECOG) Performance Status of 0 to1. * Measurable disease by computed tomography (CT) or magnetic resonance imaging (MRI) per RECIST v1.1. * Documentation of program death ligand-1 (PD-L1) status prior to randomization. Exclusion Criteria: * Recurrent or metastatic carcinoma of the nasopharynx and paranasal sinuses, squamous cell carcinoma that originated from the skin and salivary gland or non-squamous histologies (e.g., mucosal melanoma) and SCCHN of unknown primary origin. * Untreated central nervous system (CNS) metastases. * Carcinomatous meningitis. * Active, known or suspected autoimmune disease. * Physical and laboratory test findings outside the protocol-defined range.