Remarkably, tumor regression was noted in both injected and non-injected sites, encompassing visceral lesions.617 For head and neck squamous cell carcinoma (HNSCC), the combined use of the TLR9 agonist SD-101 and PD-1 blockade was found to be safe and induced a certain objective response rate (24%), even in patients with low baseline IFNγ-related gene expression in tumors (NCT02521870).618,619 Notably, a higher objective response rate of 44% was observed in HPV+ patients. This evidence concerns the gene TLR9 and head and neck squamous cell carcinoma.