3. Histologically confirmed HPV -positive mucosal squamous cell head and neck cancer. Tumor tissue samples and the HPV test results must be available prior to first dose of Study Treatment . • For pre-surgical subjects, p16 positivity must be confirmed prior to first dose • For subjects post chemoradiation therapy, HPV-16 and/or HPV-18 positivity (as assessed by p16 IHC AND oncogenic HPV ISH or PCR) must be confirmed prior to first dose. 4.