Among them, suppressive immune cells such as regulatory T cells and myeloid-derived suppressor cells (MDSC) were significantly reduced in Subtype B. Next, we compared the expression of immune checkpoint molecules between two HNSCC subtypes and found that out of ten differentially expressed immune checkpoints, CD276, CD47, PDCD1LG2, PVR had a higher expression in Subtype B (Supplementary Fig. S3f). Here, PDCD1LG2 is linked to head and neck squamous cell carcinoma.