CD274 and head and neck squamous cell carcinoma: The KEYNOTE-048 study showed that in head and neck squamous cell cancer (HNSCC) patients with a PD-L1 combined positive score (CPS) of ≥1, the addition of immunotherapy to chemotherapy increased the odds of 24-month survival two-fold whereas in those with a CPS of ≥20, chemotherapy had no additional benefit [24].