Inclusion Criteria:

          1. Male and female subjects

          2. 18 years and older

          3. Histologically or cytologically confirmed recurrent or metastatic squamous cell
             carcinoma of the head and neck (oral cavity, oropharynx, hypopharynx or larynx) that
             is incurable by local therapy.

          4. Subjects who are treatment-naive or pretreated (prior anti-PD-1 or anti-PD-L1
             required) in the recurrent/metastatic setting.

          5. Subject eligibility will be based on PD-L1 expression as determined by a specified IHC
             assay.

        Exclusion Criteria:

          1. Any concurrent chemotherapy, immunotherapy, biologic, or hormonal therapy for cancer
             treatment, receipt of last dose of an approved anticancer therapy within 21 days

          2. Concurrent or prior use of immunosuppressive medication within 14 days

          3. Active or prior documented autoimmune or inflammatory disease within 3 years with some
             exceptions.