The combination of high CD8+ TIL infiltration and positive PD-L1 expression, also referred to as type I tumour microenvironment or adaptive immune resistance [174], confers a favourable prognosis in patients with head and neck SCC, indicating that this is the most favourable immune microenvironment to mediate effective host immune responses that can restrain tumour growth. This evidence concerns the gene CD274 and neoplasm.