Combination immunotherapy with extract of heated 4T1 and naloxone in mouse model of breast cancer

Abstract

Background/aim: This study was designed to investigate the efficacy of a new vaccine against breast cancer, which was made by mixing the extract of heated 4T1 cells and naloxone, as an adjuvant. Materials and methods: Female BALB/c mice of 6–8 weeks old were challenged subcutaneously in the right flanks with 4T1 cells. When all animals developed a palpable tumor, immunotherapy was initiated. Mice in the experimental groups received, twice with a 1-week interval, either the extract of heated 4T1 alone or in combination with naloxone, and mice in the negative control group received phosphate-buffered saline. One week after the last immunotherapy, half of the mice were euthanized in order to determine the immune response profile. The remaining animals were kept until the time when death occurred spontaneously. Results: The combined-treated mice with mammary tumors showed a more favorable survival curve and slower rate of tumor development compared to the mice with tumors that received only heated 4T1 and/or negative control mice. Moreover, the combined immunization significantly amplified the respiratory burst potential and the secretion of IFN-γ, and, conversely, diminished the secretion of IL-4, IL-10, and TGF-β in the splenocyte population compared to splenocytes from other groups. Conclusion: The combined naloxone and heated 4T1 cells promote beneficial outcomes in the mouse model of breast cancer.