1. Histologically or cytologically confirmed, primary or recurrent, head and neck squamous cell carcinoma, including variants. Patients must have at least one measureable lesion in accordance with RECIST 1.1 (tumor diameter ≥ 1 cm; short-axis lymph node diameter ≥ 1.5 cm) OR by caliper measurement (tumor diameter ≥ 1 cm). Any diagnostic pretreatment biopsy sample is acceptable including FNA.