In malignant melanoma, non-small cell lung cancer, and head and neck squamous cell carcinoma, PD-L1 immunohistochemistry22,23,28,29 including the presence of PD-L1-expressing immune cells in the tumour microenvironment52,53, mismatch repair (MMR)/MSI29,31, and TMB29–31 have been reported as biomarkers of ICI response. The gene discussed is CD274; the disease is head and neck squamous cell carcinoma.