Mitoxantrone-loaded albumin microspheres for localized intratumoral chemotherapy of breast cancer

The safety and efficacy of conventional chemotherapy is limited by its toxicity. The direct intratumoral injection of free or microsphere-loaded antineoplastic drugs is a promising modality for the treatment of solid tumors. Intratumoral chemotherapy delivers high localized doses of cytotoxic drugs to the tumor tissues than does systemic (intravenous) chemotherapy and it decreases systemic drug concentrations and toxicities. The use of drug-loaded microspheres also provides a prolonged release of drug into the surrounding tumor tissues, increasing exposure of the neoplasm to therapeutic levels of the cytotoxic drug.; Mitoxantrone and 5-fluorouracil-loaded albumin microspheres were synthesized. The microspheres were synthesized using a suspension crosslinking technique and a glutardehyde crosslinking agent. The particle-size distribution of the microspheres was controlled by adjusting the emulsion energy and the concentration of cellulose acetate butyrate, the emulsion stabilization agent. Both microsphere size and crosslink density (glutaraldehyde concentration) were found to affect the in vitro release of loaded drugs in in vitro infinite sink conditions.; The in vivo efficacy and toxicity of intratumoral chemotherapy with free and microsphere-loaded mitoxantrone were evaluated in a 16/C murine mammary adenocarcinoma model. Intratumoral chemotherapy with free mitoxantrone significantly improved survival and decreased toxicity compared to intravenously delivered drug. The efficacy of two size distributions of mitoxantrone-loaded albumin microspheres, corresponding to mean diameters of 5 to 10 μm and 20 to 40 μm, were evaluated delivered both alone and in combination with free mitoxantrone. Intratumoral injection of mitoxantrone-loaded microspheres was found to allow the safe delivery of increased doses compared to free drug. The maximum tolerated doses were approximately 40 mg/kg compared to 12 mg/kg, respectively. Intratumoral chemotherapy using free and/or microsphere-loaded mitoxantrone significantly improved survival time compared to controls. Cure rates as high as 80% were achieved after a single treatment with some microsphere formulations compared to 0% for untreated controls. The combination of mitoxantrone-loaded microspheres followed by the surgical excision of the tumor produced the most promising results with up to 100% survival in some treatment groups. Based on results of these studies, the initiation of a Phase-I clinical trial in human breast cancer patients may be warranted.