Each cycle is 4 weeks. Cetuximab is given alone in lead-in period at Day -14 before Cycle 1 only. In all subsequent doses starting Cycle 1 Day 1, nivolumab and cetuximab will be given concurrently. Dose limiting toxicity (DLT) assessment will be performed during Cycle 1 and will start with the initiation of the combination of cetuximab and nivolumab (4 weeks).