PDCD1 and head and neck squamous cell carcinoma: Many trials have been carried out to determine the effective efficacy of anti-PD-1 therapies in advanced HN cancers: the Phase Ib trial KEYNOTE-012, in which pembrolizumab was administered to 60 patients affected by R/M HNSCC, resulted in an overall response rate (ORR) of 18%, 25% in human papillomavirus (HPV)-positive and 14% in HPV-negative patients [106].