Inclusion Criteria:

• * Has histologically or cytologically confirmed diagnosis of metastatic, recurrent head and neck squamous cell carcinoma (HNSCC) that is considered incurable by local therapies.
• * Has tumor PD-L1 expression of CPS ≥20. Tumor tissue must be provided for PD-L1 biomarker analysis.
• * Has human papilloma virus (HPV) testing results for oropharyngeal cancer by p16 immunohistochemistry (IHC) testing.
• * Has measurable disease per RECIST 1.1 guidelines.
• * Has the primary tumor location of the oral cavity, oropharynx, hypopharynx, or larynx.
• * Has an Eastern Cooperative Oncology Group (ECOG) Performance Status of 0 or 1.
• * Female patients of childbearing potential must have a negative highly sensitive pregnancy test within 72 hours prior to randomization and must not be breastfeeding.
• * Male and female patients of childbearing potential must be willing to completely abstain from heterosexual sex or agree to use a highly effective method of contraception.

Exclusion Criteria:

• * Has primary tumor site (any histology) of nasopharynx or salivary glands or occult primary site.
• * Has received prior systemic therapy (eg, prior chemo-, immune-, or biologic therapy) for locally advanced unresectable or metastatic HNSCC.
• * Prior systemic therapy completed \>6 months prior to signing informed consent is allowed if given as part of multimodal treatment for locoregionally advanced disease with curative intent, and no PD/recurrence occurred within 6 months of its completion. Prior systemic immunotherapy in the locoregionally advanced disease with curative intent, including but not limited to anti-PD-(L)1 agents, is allowed if PD/recurrence occurred ≥12 months after its completion.
• * Has clinically active central nervous system metastases and/or carcinomatous meningitis.
• * Has a diagnosis of immunodeficiency or is receiving systemic steroid therapy or any other form of immunosuppressive therapy within 7 days prior to the first dose of study treatment.
• * Rapidly progressing disease or with features that may confer a high risk of tumor-associated hemorrhage or uncontrolled tumor pain.
• * Current or history of immune-related disease that required systemic treatment in past 2 years, except for replacement therapy.