• Patients must sign the written pre-screening informed consent form (ICF) before any pre-screening procedures.

• Patients who present histologically confirmed recurrent or metastatic HPV16+ HNSCC that is considered incurable by local therapies.

• Patients who have a tumor that expresses PD-L1 \[CPS ≥1\] as determined by the European Conformity (CE)-marked/Food and Drug Administration-approved CDx PD-L1 immunohistochemistry 22C3 pharmDx performed according to the manufacturer's instructions for use.

• Patients must not have had prior systemic anticancer therapy administered in the incurable recurrent or metastatic setting. Systemic therapy which was completed more than 180 days prior to randomization, if given as part of multimodal treatment for locally advanced disease, is allowed.

• Patients who have measurable disease based on RECIST 1.1 as determined by the site and confirmed by BICR. Tumor lesions situated in a previously irradiated area may be considered measurable, if progression has been demonstrated in such lesions disease by RECIST 1.1.

• All patients must provide a tumor tissue sample (formalin fixed paraffin embedded \[FFPE\] blocks or both slides and curls) from archival tissue. Alternatively, a fresh biopsy sample could be provided if a biopsy sample is performed as part of the patient's standard clinical practice before the first dose of trial treatment. The sample should be preferably derived from a current site of metastatic or recurrent disease. Otherwise, a sample from the primary tumor can be submitted.