In randomized studies, immunotherapy with programmed cell death protein 1 (PD-1) inhibitors such as nivolumab and pembrolizumab has been shown to be effective in patients with advanced HNSCC; however, the percentage of positive tumour cells and the percentage of positive immune cells have been decisive for its indication for approval [7–9]. This evidence concerns the gene PDCD1 and head and neck squamous cell carcinoma.