CpG immunostimulatory oligodeoxynucleotide 1826 enhances antitumor effect of interleukin 12 gene-modified tumor vaccine in a melanoma model in mice

Clin Cancer Res. 2004 Jun 15;10(12 Pt 1):4165-75. doi: 10.1158/1078-0432.CCR-04-0022.


Purpose: The effectiveness of interleukin (IL)-12-secreting tumor vaccines in the treatment of mouse tumors could be enhanced by concurrent application of cytokines and costimulatory molecules. We investigated the therapeutic potential of IL-12 gene-transduced melanoma vaccine in combination with CpG immunostimulatory oligodeoxynucleotide (ODN) 1826, an adjuvant known to favor development of Th1-biased immune response, in a B78-H1 (B78) melanoma model in mice.

Experimental design: Mice injected with B78 melanoma cells were treated with irradiated IL-12 gene-transduced B78 cells [B78/IL-12(X)] and/or ODN 1826. Mechanisms responsible for the antitumor effects of the treatment were investigated using fluorescence-activated cell sorter analysis, a standard (51)Cr releasing assay, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay, and ELISA.

Results: Single injection of B78/IL-12(X) cells had no effect on tumor growth, whereas seven consecutive daily injections of ODN 1826 markedly inhibited tumor progression with occasional curative effects. When used in combination, B78/IL-12(X) cells and ODN 1826 caused additional tumor growth reduction and eradication of tumors in 62% of treated mice. The combined treatment activated local inflammatory response against tumor but also induced systemic antitumor immunity. In vitro studies have shown that when used together, B78/IL-12(X) cells and ODN 1826 induced a potent Th1 response and suggested the role of IFN-gamma in activation of the host immune response. The antitumor effects in double-treated mice were accompanied by the development of cytotoxic effectors in the spleen and activation of macrophages.

Conclusions: The results provided the evidence that the combination of IL-12 gene-modified melanoma vaccine and ODN 1826 induces synergistically systemic and local antitumor immunity.

MeSH terms

  • Animals
  • Antineoplastic Agents / pharmacology*
  • Cancer Vaccines*
  • Cell Line, Tumor
  • CpG Islands*
  • Cytokines / biosynthesis
  • DNA / pharmacology*
  • Disease Progression
  • Enzyme-Linked Immunosorbent Assay
  • Flow Cytometry
  • Fluorescent Dyes / pharmacology
  • Histocompatibility Antigens Class II / chemistry
  • Humans
  • Interferon-gamma / metabolism
  • Interleukin-12 / genetics*
  • Interleukin-12 / metabolism*
  • Lymphatic Metastasis
  • Macrophages / metabolism
  • Melanoma / genetics*
  • Melanoma, Experimental / metabolism
  • Mice
  • Mice, Inbred C57BL
  • Oligodeoxyribonucleotides
  • Oligonucleotides / chemistry*
  • Spleen / cytology
  • Spleen / metabolism
  • Tetrazolium Salts / pharmacology
  • Th1 Cells
  • Thiazoles / pharmacology
  • Time Factors


  • Antineoplastic Agents
  • Cancer Vaccines
  • CpG ODN 1826
  • Cytokines
  • Fluorescent Dyes
  • Histocompatibility Antigens Class II
  • Oligodeoxyribonucleotides
  • Oligonucleotides
  • Tetrazolium Salts
  • Thiazoles
  • Interleukin-12
  • Interferon-gamma
  • DNA
  • thiazolyl blue