CD274 and head and neck squamous cell carcinoma: Mean fold change of PD-L1 expression in the EpCAM-dependent enrichment was 0.84 (range: 0–1.54) in HD, 0.55 (range: 0–1.66) in PD-L1 negative HNSCC patients and 3.24 (range: 1.72–4.99) in PD-L1 positive HNSCC patients.