CD8A and head and neck squamous cell carcinoma: Based on transcriptome data from the Cancer Genome Atlas, characterization of the immune status of HNSCC revealed a prominent immune infiltration in the tumors with the highest levels of CD8+ T cells and activated NK cells, as well as the marked expression of regulatory T cells and related immune checkpoints including PD-1, CTLA-4, GITR, ICOS, and IDO [5].