Improved Immunogenicity Against a Her2/neu-Derived Peptide by Employment of a Pan HLA DR-Binding Epitope and CpG in a BALB/c Mice Model

BACKGROUND: An efficient strategy to improve the immunogenicity of peptide vaccines is the use of a synthetic peptide containing cytotoxic T-lymphocyte (CTL) epitopes with T-helper (Th) inducing-epitopes. OBJECTIVE: Our purpose was to determine the use of human epidermal growth factor receptor-2 (Her2/neu)- specific CTL epitopes plus the pan HLA DR-binding epitope (PADRE) and CpG oligodeoxynucleotides (ODNs) to induce antitumor effects in vaccinated mice. METHOD: Female BALB/c mice were immunized subcutaneously with different vaccines. Three mice per group were euthanized to assess immune responses and the others were transplanted with TUBO cells. Enzyme-linked Immuno Spot assay (ELISpot) and flow cytometry studies were followed by tumor size and survival rate measurements in a TUBO tumor mice model. RESULTS: The results showed that mice vaccinated with the P5 peptide plus PADRE plus CpG produced higher antigen-specific CTL responses than mice vaccinated with the P5 peptide alone. Also, tumors in those mice grew more slowly and the survival rates were greater than mice in the other groups. CONCLUSION: We conclude that peptide vaccines containing epitopes that stimulate both CD4+ and CD8+ T-cells are effective at inducing anti-tumor immunity.