Treatment with an immature dendritic cell-targeting vaccine supplemented with IFN-alpha and an inhibitor of DNA methylation markedly enhances survival in a murine melanoma model

摘要

Background The chemokine MIP-3 alpha (CCL20) binds to CCR6 on immature dendritic cells. DNA vaccines fusing MIP-3 alpha to melanoma-associated antigens have shown improved efficacy and immunogenicity in the B16F10 mouse melanoma model. Here, we report that the combination of type-I interferon therapy (IFN alpha) with 5-Aza-2 '-deoxycitidine (5Aza) profoundly enhanced the therapeutic efficacy of a MIP-3 alpha-Gp100-Trp2 DNA vaccine. Methods Beginning on day 5 post-transplantation of B16F10 melanoma, vaccine was administered intramuscularly (i.m.) by electroporation. CpG adjuvant was given 2 days later. 5Aza was given intraperitoneally at 1 mg/kg and IFN alpha therapy either intratumorally or i.m. as noted. Tumor sizes, tumor growth, and mouse survival were assessed. Tumor lysate gene expression levels and tumor-infiltrating lymphocytes (TILs) were assessed by qRT-PCR and flow cytometry, respectively. Results Adding IFN alpha and 5Aza treatments to mice vaccinated with MIP-3 alpha-Gp100-Trp2 leads to reduced tumor burden and increased median survival (39% over vaccine and 95% over controls). Tumor lysate expression of CCL19 and CCR7 were upregulated ten and fivefold over vaccine, respectively. Vaccine-specific and overall CD8+ TILs were increased over vaccine (sevenfold and fourfold, respectively), as well as the proportion of TILs that were CD8+ (twofold). Conclusions Efficient targeting of antigen to immature dendritic cells with a chemokine-fusion vaccine offers an alternative to classic and dendritic cell vaccines. Combining this approach with IFN alpha and 5Aza treatment significantly improved vaccine efficacy. This improved efficacy correlated with changes in chemokine gene expression and CD8+ TIL infiltration and was dependent on the presence of all therapeutic components.