PDCD1 and head and neck squamous cell carcinoma: Furthermore, other anti-PD-1 mAb, pembrolizumab (humanized IgG4 kappa anti-PD-1 mAb), has been approved by the FDA for the treatment of many types of cancer, including unresectable or metastatic melanoma in 2014 (300), advanced NSCLC in 2015 (301), recurrent or metastatic HNSCC in 2016 (302), and locally advanced or metastatic urothelial carcinoma in 2017 (303).