Anti-cancer effect of hyperthermia on breast cancer by magnetite nanoparticle-loaded anti-HER2 immunoliposomes

Background We have constructed anti-HER2 immunoliposomes containing magnetite nanoparticles (HML) that generate heat in an alternating magnetic field (AMF). The effective targeting and cytocidal abilities of HML have been achieved using cell culture models. This study aimed to investigate feasibility of this modality for breast cancer treatment using tumor-bearing mouse models. Material and methods The subcutaneous cancer nodules of BT474 (high HER2 expression) or SKOV3 (low HER2 expression) cells in nude mice were employed as models. HMLs were injected into these cancer nodules and were then exposed to an AMF for 30 min twice at 24 h intervals. Accumulation of magnetite and tumor growth rates were examined. Histological findings of the thermal effect were also examined. Results HMLs accumulated in only BT474 tumors. The tumor temperature increased to 45°C whereas the body temperature remained at around 38°C. Tumor regression was observed in the hyperthermic group and was sustained for 10 weeks after hyperthermia. Conclusion These results suggest that hyperthermia using HML is an effective and specific therapy for breast cancer overexpressing HER2. This therapy may provide an alternative way to treat recurrent cancer refractory to other modalities.