Macrophage-Derived Extracellular Vesicles as Drug Delivery Systems for Triple Negative Breast Cancer (TNBC) Therapy

Efficient targeted delivery of anticancer agents to TNBC cells remains one of the greatest challenges to developing therapies. The lack of tumor-specific markers, aggressive nature of the tumor, and unique propensity to recur and metastasize make TNBC tumors more difficult to treat than other subtypes. We propose to exploit natural ability of macrophages to target cancer cells by means of extracellular vesicles (EVs) as drug delivery vehicles for chemotherapeutic agents, paclitaxel (PTX) and doxorubicin (Dox). We demonstrated earlier that macrophage-derived EVs loaded with PTX (EV-PTX) and Dox (EV-Dox) target cancer cells and exhibited high anticancer efficacy in a mouse model of pulmonary metastases. Herein, we report a manufacture and characterization of novel EV-based drug formulations using different loading procedures that were optimized by varying pH, temperature, and sonication conditions. Selected EV-based formulations showed a high drug loading, efficient accumulation in TNBC cells in vitro, and pronounced anti-proliferation effect. Drug-loaded EVs target TNBC in vivo, including the orthotopic mouse T11 tumors in immune competent BALB/C mice, and human MDA-MB-231 tumors in athymic nu/nu mice, and abolished tumor growth. Overall, EV-based formulations can provide a novel solution to a currently unmet clinical need and reduce the morbidity and mortality of TNBC patients.