Inclusion Criteria:  Provide written, informed consent to participate in the study and follow the study procedures. Male or female patients, age 18 years or older at the time of signing the informed consent form (ICF).  Have histologically or cytologically-confirmed recurrent or metastatic HNSCC that is considered incurable by local therapies.  No prior systemic therapy for recurrent or metastatic disease. The eligible primary tumor locations are oropharynx, oral cavity, hypopharynx, and larynx. Patients may not have a primary tumor site of nasopharynx (any histology) and/or unknown primary. Have measurable disease based on RECIST 1.1 as determined by the local site Investigator. Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1.  Measure Description: GRADE - ECOG PERFORMANCE STATUS  0 - Fully active, able to carry on all pre-disease performance without restriction  1 - Restricted in physically strenuous activity but ambulatory and able to carry out work of a light or sedentary nature, e.g., light housework, office work  2- Ambulatory and capable of all selfcare but unable to carry out any work activities; up and about more than 50% of waking hours  • The tumor must have positive PD-L1 expression (i.e., CPS ≥1)  Exclusion Criteria:  Has disease that is suitable for local therapy administered with curative intent. Has progressive disease within 6 months of completion of curatively intended systemic treatment for locoregionally advanced HNSCC. Has had radiation therapy (or other non-systemic therapy) within 2 weeks prior to initiation of study drug Has a life expectancy of less than 3 months and/or has rapidly progressing disease (e.g., tumor bleeding, uncontrolled tumor pain) as determined by the Investigator. Has a known additional malignancy that is progressing or has required active treatment within 5 years prior to the first dose of study drug Has an active autoimmune disease that has required systemic treatment in the past 2 years Has a diagnosis of immunodeficiency or is receiving systemic steroid therapy Use of an investigational agent or an investigational device within 28 days before the first dose of study drug. Prior treatment with an anti PD-1, anti PD-L1, anti-PD-L2, or anti CTLA-4 antibody, agents that target IL-2 pathway, or any other antibody or drug specifically targeting T-cell co-stimulation or checkpoint pathways.  NOTE: Other protocol defined inclusion/exclusion criteria may apply