Development of Targeted, Polymeric Delivery Vehicles for Camptothesin and siRNA Via Boronic Acid-Diol Complexation

Citation

Han, Han (2013) Development of Targeted, Polymeric Delivery Vehicles for Camptothesin and siRNA Via Boronic Acid-Diol Complexation. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/NWSP-0Y35. https://resolver.caltech.edu/CaltechTHESIS:01262013-020116009

Abstract

Our research lab has developed polymer-based nanoparticle delivery systems for the anticancer drug, camptothecin (CPT), CRLX101; and for the small interfering RNA (siRNA), CALAA-01. CRLX101 has shown great success in both animal studies and clinical trials. However, it is incapable of achieving targeted delivery. CALAA-01 has demonstrated effectiveness in a phase I clinical trial. However, it suffers from its rapid in vivo clearance. To address the issues of targeting in the anticancer drug delivery system and the short circulation time in the siRNA delivery system, we have created a new delivery platform involving the use of boronic acid-diol complexation. This thesis is divided into two parts to discuss CPT delivery and siRNA delivery separately.

In Part I, the targeted delivery of CPT via boronic acid-diol complexation is described. CPT was conjugated to a copolymer of mucic acid and PEG (MAP) and self-assembled into MAP-CPT nanoparticles. The targeting agent, Herceptin antibody was attached to boronic acid (BA), this was then complexed with the diol-containing MAP to form a targeted nanoparticle carrying ca. 60 CPT, with a 40 nm diameter and a slightly negative surface charge. The attachment of a single Herceptin per nanoparticle was sufficient to enhance cellular uptake of nanoparticles into BT-474, a HER2 overexpressing cell line by 70% compared to the non-targeted version. Nude mice bearing BT-474 xenograft tumors treated with targeted MAP-CPT nanoparticles resulted in all mice revealing complete tumor regression.

In Part II, the boronic acid-diol complexation delivery platform is applied for the delivery of siRNA. First, the CALAA-01 delivery system for siRNA was further characterized and optimized. Then, a copolymer of mucic acid and dimethylsuberimidate (MAD) was synthesized and used in condensing the anionic siRNA into nanoparticles. Nanoparticles were stabilized by placing a surface PEG layer through boronic acid-diol complexation. Targeting was achieved by conjugating the distal end of the BA-PEG with a targeting agent, Herceptin antibody. MAD/siRNA nanoparticles effectively entered cells and demonstrated low cellular toxicity. MAD/siRNA nanoparticles stabilized with nitroPBA-PEG resulted in a diameter of 130 nm with a slightly negative surface charge. Pharmacokinetic studies in mice demonstrated improved circulation compared to CALAA-01.

Thesis Files