Evaluation of explant responses to STING ligands: personalized immunosurgical therapy for head and neck squamous cell carcinoma.

Surgeons have unique in situ access to tumors enabling them to apply immunotherapies to resection margins as a means to prevent local recurrence. Here we developed a surgical approach to deliver STING ligands to the site of a purposeful partial tumor resection using a gel-based biomaterial. In a range of head and neck squamous cell carcinoma (HNSCC) murine tumor models, we demonstrate that while control-treated tumors recur locally, tumors treated with STING-loaded biomaterials are cured. The mechanism of tumor control required activation of STING and induction of type I IFN in host cells, not cancer cells, and resulted in CD8 T cell-mediated cure of residual cancer cells. In addition, we used a novel tumor explant assay to screen individual murine and human HNSCC tumor responses to therapies ex vivo. We then utilized this information to personalize the biomaterial and immunotherapy applied to previously unresponsive tumors in mice. These data demonstrate that explant assays identify the diversity of tumor-specific responses to STING ligands, and establishes the utility of the explant assay to personalize immunotherapies according to the local response