AE: adverse events; CI: confidence interval; DCR: disease control rate; ECOG PS: Eastern Cooperative Oncology Group performance status; HNSCC: head and neck squamous cell cancer; HPV: human papilloma virus; HR: hazard ratio; ICI: immune checkpoint inhibitor; IRAE: immune-related adverse events; IQR: interquartile range; ORR: overall response rate; OS: overall survival; P: pembrolizumab; C: chemotherapy; PD-L1: programmed death ligand-1; PFS: progression-free survival; R/M/U: recurrent/metastatic/unresectable. This evidence concerns the gene CD274 and head and neck squamous cell carcinoma.