Good analytical concordance has been previously demonstrated among three validated, commercially available PD-L1 IHC assays (VENTANA SP263, PD-L1 IHC 22C3 pharmDx, and PD-L1 IHC 28–8 pharmDx) across multiple TC PD-L1 protein expression cutoffs using samples from patients with NSCLC [31] or head and neck squamous cell carcinoma (HNSCC) [24]. This evidence concerns the gene CD274 and head and neck squamous cell carcinoma.