CD274 and head and neck squamous cell carcinoma: Clinical trials targeting ICR have shown promising results for multiple cancers, and many biomarkers predict the response to PD-1-based immunotherapy, such as PD-L1 expression, tumour mutational burden (also known as mutation load) and CD8+ T-cell infiltrates.33–35 However, there is still an urgent need for better biomarkers or combinations that improve the response rate of immune-checkpoint therapy in different cancers, including HPV− HNSCC.