Anti-IL-10-mediated Enhancement of Antitumor Efficacy of a Dendritic Cell-targeting MIP3α-gp100 Vaccine in the B16F10 Mouse Melanoma Model Is Dependent on Type I Interferons

The chemokine MIP3 (CCL20) binds to CCR6 on immature dendritic cells. Vaccines fusing MIP3 to gp100 have been shown to be effective in therapeutically reducing melanoma tumor burden and prolonging survival in a mouse model. Other studies have provided evidence that interleukin-10 (IL-10) neutralizing antibodies (IL-10) enhance immunologic melanoma therapies by modulating the tolerogenic tumor microenvironment. In the current study, we have utilized the B16F10 syngeneic mouse melanoma model to demonstrate for the first time that a therapy neutralizing IL-10 enhances the antitumor efficacy of a MIP3-gp100 DNA vaccine, leading to significantly smaller tumors, slower growing tumors, and overall increases in mouse survival. The additive effects of IL-10 were not shown to be correlated to vaccine-specific tumor-infiltrating lymphocytes (TILs), total TILs, or regulatory T cells. However, we discovered an upregulation of IFN-4 transcripts in tumors and a correlation of increased plasmacytoid dendritic cell numbers with reduced tumor burden in IL-10-treated mice. Interferon receptor knockout (IFNR1(-/-)) mice received no benefit from IL-10 treatment, demonstrating that the additional therapeutic value of IL-10 is primarily mediated by type I IFNs. Efficient targeting of antigen to immature dendritic cells with a chemokine-fusion vaccine provides an effective anticancer therapeutic. Combining this approach with an IL-10 neutralizing antibody therapy enhances the antitumor efficacy of the therapy in a manner dependent upon the activity of type I IFNs. This combination of a vaccine and immunomodulatory agent provides direction for future optimization of a novel cancer vaccine therapy.