CD8A and head and neck squamous cell carcinoma: Moreover, in multiple cancer types, MHC class I loss-of-function mutations, including mutations in the HLA genes and β-2 micro-globulin, are associated with decreases in markers of CD8+ T cell activity [47], suggesting that the mutations identified in the HNSCC TCGA project as well as in HNSCC cell line panels [66,67] also lead to decreased CD8+ T-cell activity in this tumor type.