Abstract 5376: Systematic analysis of peptide linker length and liposomal polyethylene glycol coating on cellular uptake of peptide-targeted liposomal nanoparticles

Abstract

Abstract In an effort to improve tumor targeting and cellular uptake of nanoparticle-based drug carriers, nanoparticles are functionalized with active targeting molecules such as antibodies, antibody fragments, small ligands, and peptides. However, active targeting approaches have not consistently shown successful outcomes. Nanoparticle design factors including: traditional methods of generating active targeting nanoparticles, PEG coatings, linkers used to conjugate targeting ligands, and various types of targeting ligands used further contribute to the inconsistencies observed with targeted nanoparticle therapies. In order to dissect the individual effects of these parameters, we employed a multifaceted synthetic strategy to prepare peptide-targeted liposomal nanoparticles with high purity, reproducibility, and precisely controlled stoichiometry of functionalities to evaluate the role of liposomal PEG coating, peptide EG-linker length, and peptide valency on cellular uptake in a systematic manner. We analyzed these parameters in two distinct disease models where the liposomes were functionalized with either HER2- or VLA-4-antagonistic peptides to target HER2-overexpressing breast cancer cells or VLA-4-overexpressing myeloma cells, respectively. When targeting peptides were tethered to nanoparticles with an EG45 (∼PEG2000) linker in a manner similar to a more traditional formulation, their cellular uptake was not enhanced compared to non-targeted versions regardless of the liposomal PEG coating used. Conversely, reduction of the liposomal PEG to PEG350 and the peptide linker to EG12 dramatically enhanced cellular uptake by ∼9-fold in breast cancer cells, while an EG6 peptide linker enhanced cellular uptake by ∼150-fold in multiple myeloma cells. Uptake efficiency is highly dependent on peptide valency, reaching a maximum and a plateau with ∼2% peptide density in the breast cancer model. Taken together, these results demonstrate the significance of using the right design elements such as the appropriate peptide EG-linker length in coordination with the appropriate liposomal PEG coating and optimal ligand density in efficient cellular uptake of liposomal nanoparticles. Citation Format: Jared Stefanick, Jonathan Ashley, Tanyel Kiziltepe, Basar Bilgicer. Systematic analysis of peptide linker length and liposomal polyethylene glycol coating on cellular uptake of peptide-targeted liposomal nanoparticles. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 5376. doi:10.1158/1538-7445.AM2014-5376