CD274 and head and neck squamous cell carcinoma: The European Commission followed in 2017 with the approval of nivolumab and shortly thereafter with the approval of pembrolizumab monotherapy for the treatment of recurrent or metastatic HNSCC in adults, whose tumors express PD-L1 with a ≥ 50% tumor proportion score (TPS) and that have progressed after platinum-containing chemotherapy.