CD274 and head and neck squamous cell carcinoma: Following the initial approval of programmed death-1 (PD-1) inhibitors for head and neck squamous cell carcinoma (HNSCC) in 2016, ICB targeting the PD-1/PD-L1 axis, such as pembrolizumab or nivolumab, has been associated with improved survival rates in patients with HNSCC, and has become a primary therapeutic option for recurrent and/or metastatic HNSCC2.