(841) A new TLR-7 agonist stimulates anticancer immunity through the activation of epithelial cell cytokine response.

Introduction/Rationale: Lung cancer remains one of the deadliest types of cancer, supporting the development of new therapeutic approaches. While various immunotherapies were developed in the past decade, their efficacy remains limited. Recently, we demonstrated that the neoadjuvant treatment with nanoparticle FB-631, a TLR-7 agonist which is well tolerated in humans, significantly prevented tumor cell implantation in the lung and the development of metastases in the CMT-167 mouse model of lung adenocarcinoma. This was achieved in part by improving the natural killer cell and CD8 T cell responses in the lung. To further address the mechanisms by which FB-631 mitigates cancer development, we verified whether this drug also favors an anticancer immune response in lung epithelial cells.

Methods: We first verified whether mouse and human lung epithelial cells (CMT-167 and H226) incorporate FB-631 using star red-coupled nanoparticle and fluorescence microscopy. Then, the production of anticancer cytokines by epithelial cells was evaluated using flow cytometry.

Results: We demonstrated that FB-631 enters mouse (CMT-167) and human (H226) epithelial cells, allowing its interaction with and stimulation of intracellular TLR-7. Furthermore, we observed that CMT-167 cell stimulation with FB-631 increases the percentage of cells expressing IFN-g, IL-1a and IL-6. Finally, we also report higher per cell-expression of TNF-a, IL-1a and IL-6 in CMT-167 epithelial cells.

Conclusion: Those results suggest that FB-631activates TLR-7 by entering epithelial cells, triggering an anticancer cytokine production in this cell line. These results will be complemented by assays in human epithelial cells, to support the transferability of this technology to human lung cancer.