Abstract 4399: Utilizing cobalt coordination chemistry as a traceless prodrug strategy in targeted drug delivery

Abstract

Abstract We recently reported the synthesis of albumin nanoparticles using cobalt as a traceless, reductively labile crosslinker. Here, we report in vitro characterization of particle uptake for fluorescently labeled cobalt crosslinked albumin nanoparticles (Co-Alb-FITC NPs) via image-based flow cytometry as well as preliminary toxicity data. Uptake of Co-Alb-FITC NPs by gastric carcinoma cells (SNU-5) was rapid, but could be dramatically reduced through the addition of an inhibitor of macropinocytosis. High levels of non-specific uptake of other particle types were also observed suggesting SNU-5 cells possess high macropinocytic activity. Cancers harboring mutated Ras (>20% of all cancers) are known to take up protein via macropinocytosis to satisfy metabolic demands. Because SNU-5 cells are not known harbor mutated Ras, our findings may indicate that other cancers rely on this mechanism as well, which would have important implications for observing selectivity in active nanoparticle targeting strategies. The Co-Alb NPs themselves were found to exhibit no inherent toxicity. Based on these initial findings, Co-Alb NPs were loaded with the active metabolite of camptothecin, SN-38, to explore their potential as a delivery vector for hydrophobic drugs. An albumin-topotecan prodrug conjugate was also synthesized by crosslinking the amine group in topotecan with lysine residues in the protein, which should be applicable to other amine-containing therapeutics. Characterization of drug loading and release will be discussed along with preliminary in vitro characterization. Citation Format: Robby A. Petros, Duong T. Nguyen, Ronaldo J. Cavazos, Clifford S. Morrison, Jana B. Lampe, Alesha N. Harris, Brian K. McFarlin. Utilizing cobalt coordination chemistry as a traceless prodrug strategy in targeted drug delivery. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 4399. doi:10.1158/1538-7445.AM2015-4399