A Phase 1/2 Study in Patients With HPV16+ Recurrent/Metastatic Head and Neck Squamous Cell Carcinoma and Other Cancers

Inclusion Criteria All Patients: * Documentation of confirmed HPV 16+ cancer via genotype testing. * ≥ 1 measurable lesion by imaging for tumor response following RECIST * ECOG performance status of 0 to 1. * Prior curative radiation therapy and prior focal palliative completed per protocol-specified wash-out windows. * Screening laboratory values must meet protocol-specified criteria. * Able to provide tumor tissue following last treatment, unless otherwise agreed. Treatment Group E or Group F: * Documentation of confirmed head and neck squamous cell carcinoma. * Eligible to receive pembrolizumab, per standard of care and product label. * Group E: this group includes first line / 1L patients who have not yet received treatment in the metastatic/recurrent setting. * Group F: Tumor progression or recurrence on standard of care therapy, including ≥1 systemic therapy. Imaging Sub-Study (for specific participants at Memorial Sloan Kettering Cancer Center only): * Meeting requirements of inclusion criteria for Treatment Group 1 or Group 3. * At least 1 non-irradiated measurable lesion documented through imaging. Exclusion Criteria: All patients: * Metastatic central nervous system disease, and/or carcinomatous meningitis. * Any serious or uncontrolled medical disorder that, in the opinion of the Investigator, may increase the risk associated with study participation / treatment administration. * Concurrent malignancy that is clinically significant or requires active inter…