Adenoviral GM-CSF gene transduction into breast cancer cells induced long-lasting antitumor immunity in mice

Background: Recently, immunogene therapy is regarded as a novel treatment that overcome the limitation of preexisting adjuvant therapy and demonstrated the potentiality for total elimination of cancer cells by seeking the concealing tumor cells. The aim of this study was to examine the enhancement of antitumor immunity of irradiated granulocyte macrophage-colony-stimulating factor (GM-CSF)-gene-transduced mouse breast cancer cells. Methods: For studies of prophylactic vaccine effects, Balb/c mouse were vaccinated subcutaneous with saline or irradiated mouse breast cancer cells, BalbMC, (1×10∧6/mouse) infected without or with recombinant adenovirus harboring GM-CSF gene (Adv/GM-CSF) on day -7. Mice were challenged with parental cells (1×10∧6/mouse) on day 0 in the flank opposite the vaccination site. Results: BalbMC cells, secreted GM-CSF after infection with Adv/GM-CSF. Vaccination with irradiated GM-CSF-secreting BalbMC completely protected syngeneic mouse challenged with live parental cells. On the other hand, vaccination with irradiated BalbMC, protected 60% of mice from tumor development after challenge with parental cells. None of the tumor-free mouse initially vaccinated with irradiated GM-CSF-producing BalbMC cells developed tumor upon repeated challenge with parental cells during the entire observation period. Conclusion: Our study demonstrated the feasibility of this immunotherapeutic approaches as a novel adjuvant cancer therapy after surgery for breast cancer.