Notably, in clinical investigations of head and neck squamous cell carcinoma (HNSCC), multiple studies have evaluated TLR8/9 agonists—including the TLR8 agonist motolimod and TLR9 agonists SD-101, IMO-2055, and EMD1201081—in combination with cetuximab or PD-1 inhibitors. Here, TLR9 is linked to head and neck squamous cell carcinoma.