Fumi et al. confirmed that intratumoral administration of 1V270 (TLR7 agonist) or SD-101(TLR9 agonist) and blocking PD-1 can suppress the development of primary tumors and prevent tumor metastasis in the head and neck squamous cell carcinoma (HNSCC) model. Here, TLR9 is linked to head and neck squamous cell carcinoma.