A Two-Arm, Open-label, Randomized Phase II Study of Pembrolizumab (MK-3475) Monotherapy Versus Standard Chemotherapy in Platinum Pre-treated, Recurrent or Metastatic Nasopharyngeal Cancer (NPC) (Keynote-122)

This is a study of pembrolizumab (MK-3475) versus standard treatment (capecitabine, gemcitabine, or docetaxel) for the treatment of recurrent or metastatic nasopharyngeal cancer (NPC). Participants will be randomly assigned to receive either pembrolizumab or Investigator\'s choice of standard treatment. The primary study hypothesis is that pembrolizumab treatment prolongs Overall Survival (OS) when compared to standard treatment. With Amendment 7 (effective 2-March-2022), upon study completion, participants will be discontinued and may be enrolled in an extension study.