NicheNet predicted several enriched ligand–receptor interactions between APCs and Treg cells in HNSCC: ICOS ligand (ICOSLG) via ICOS, IL-18 via the IL18-R1 and IL-1B via the IL-1 receptors type 1 and type 2 (Fig. 3b, right). This evidence concerns the gene ICOS and head and neck squamous cell carcinoma.