The Use of Toll-like Receptor 4 Agonist to Reshape the Immune Signature in Ovarian Cancer

Background: Dendritic cell (DC) mono-immunotherapy has not been successful so far in ovarian cancer. The addition of a toll-like receptor (TLR) agonist has the potential to boost the innate immune system, in addition to the adoptive immune response initiated by DCs. Materials and Methods: ID8-fLuc C57BL/6 mice were injected with DCs loaded with hypericin-based photodynamic therapy-treated tumor lysate. A TLR4 agonist [ lipopolysaccharide (LPS)] was administered by different schedules). After two and three DC vaccinations, immune analysis was performed. Results: There was no survival benefit from therapy with TLR4 agonist. Moreover, if LPS administrations started one week after tumor inoculation, the overall survival was even worse than that of untreated controls. Immune analyses revealed an intratumoral increase in natural killer cells and a decrease in regulatory T-cells, but an immunosuppressive signature in the ascites. Conclusion: Addition of LPS as an adjuvant to DC immunotherapy of ovarian cancer does not result in survival benefit.