The transcription factor thymocyte selection-associated high-mobility group box (TOX) was identified as potential regulator of immune checkpoint genes based on scRNAseq data, and its experimental overexpression in primary CD8+ T-cells indeed increased their expression of checkpoint genes and diminished their proliferation and cytotoxic activity towards PD-L1 positive HNSCC cell lines in vitro [92]. Here, CD8A is linked to head and neck squamous cell carcinoma.