Enoblituzumab Plus MGA012 or MGD013 in Squamous Cell Carcinoma of the Head and Neck

Inclusion Criteria: * Histologically proven, recurrent or metastatic SCCHN not curable by local therapy * No prior systemic therapy for SCCHN in the recurrent or metastatic setting (with the exception of systemic therapy completed \> 6 months prior of given as part of multimodal treatment for locally advanced disease) * Primary tumor locations of oropharynx, oral cavity, hypopharynx, or larynx * At least one radiographically measurable lesion * HPV test results available (positive and negative eligible) * ECOG Performance status of 0 or 1 * Adequate end organ function * Positive PD-L1 expression level (CPS ≥ 1%) Exclusion Criteria: * Disease suitable for local therapy administered with curative intent * Progressive disease within 6 months of completion of curatively intended systemic treatment for locoregionally advanced SCCHN * Radiation or other non-systemic therapy within 2 weeks of first dose of study drug * Diagnosis of immunodeficiency, or use of immunosuppresive therapy within 14 days of first dose of study drug