A Study of Pembrolizumab (MK-3475) Plus Platinum and Gemcitabine as First Line Treatment of Recurrent/Metastatic Head and Neck Squamous Cell Carcinoma (PIPER)

Pembrolizumab 200mg will be administered on Day 1 every 3 weeks for up to 24months

Cisplatin at 35 mg/m2 IV using a split dose regimen on Day 1 and Day 8 of each 3-week cycle, up to 6 cycles.

Carboplatin at AUC 5 IV on Day 1 of each 3-week cycle, up to 6 cycles.

Gemcitabine 1250mg/m2 IV on Day 1 and Day 8 of each 3-week cycle, up to 6 cycles