CD274 and head and neck squamous cell carcinoma: Prognostic implications of PD-1 and PD-L1 in staining in SCCHN combined with data from phase 1 anti-PD-1 and anti-PD-L1 trials supports that immune staining of tumors for PD-1 and PD-L1 will help guide immune therapy [63, 109, 110].