Multimodality CT/SPECT Evaluation of Micelle Drug Carriers for Treatment of Breast Tumors

Polymer micelles are a nanoparticle drug delivery system that has the potential to improve breast tumor treatment with chemotherapy. These nanoparticles can increase the half-life of incorporated drugs, can target tumors by incorporating tumor specific ligands, and can be tracked with imaging through the inclusion of a radiolabel. In this study, PEGPLA or PEGPCL micelles were modified through the addition of a cRGD targeting ligand and a DOTA chelating molecule for tracking with 111In SPECT imaging. In vitro, cRGD-targeted micelles were incorporated into cells at a faster rate than non-targeted micelles and exhibited cytotoxicity rivaling that of free doxorubicin. Furthermore, SPECT imaging of 111In-labeled micelles administered intravenously to tumor-bearing mice in vivo established the potential for micelle tracking with 111In and confirmed the prolonged distribution half-life of micelles. Future research will focus on further development of this micelle platform with the ultimate goal of simultaneously tracking micelle localization and monitoring antitumor efficacy. Fluorescent tracking of micelles through the incorporation of quantum dots and monitoring antitumor efficacy with fluorescently labeled Annexin V may provide an alternate and superior method of achieving this goal.