Furthermore, using 3 PD-L1 tests for HNSCC tissue microarrays (standard SP263, standard 22C3 and in-house-developed 22C3), significant differences were found among the three tests using clinically relevant cut-off values, i.e., ≥20 and ≥50%, for the combined positive score (CPS) and Tumour positive score (TPS). This evidence concerns the gene CD274 and head and neck squamous cell carcinoma.