In the present study, we aim at elucidating the impact of DNA methylation within the CD274/PD-L1 and PDCD1LG2/PD-L2 genes on the respective gene expression and the association with HPV infectionin HNSCC specimens from a large multicentre cohort (provided by The Cancer Genome Atlas Research Network) and a small validation cohort from the University Hospital Bonn. Here, CD274 is linked to head and neck squamous cell carcinoma.