A multistage nanodelivery system for therapeutic applications and medical imaging: in vivo biodistribution and efficacy study in a murine orthotopic breast cancer model

Abstract #2160

The ability to deliver therapeutic compounds specifically to diseased sites is crucial for effectively treating human illnesses. Nanotechnology is emerging as a tool for resolving challenges in the delivery of poorly administrable drugs by transforming them into nanometer-sized particles (nanotherapeutics). The progress thus far gave rise to a large number of nanotherapeutics, but the accomplishment of the original objective, which is to increase drug concentration at target sites, has not been fully realized. A series of biological barriers pose as insurmountable obstacles which limit or completely abolish the ability to selectively deliver a therapeutic agent. We hypothesized that a multi-stage system for systemic delivery (MSDS) could be designed to interact with and successfully overcome sequential biological barriers. We developed a MSDS using biodegradable, biocompatible silicon particles optimally sized and shaped to travel into the blood flow, avoid RES, marginate and adhere to tumor vasculature. The first stage carriers (FSCs) contain nanopores of specific size that can load, carry, release over time, and deliver multiple types of second stage nanoparticles (SSNs). The nanoparticles can be optimized to reach, through vessels fenestrations, the tumor environment and finally release their therapeutic payload into target cells.
 
 The ease in chemically modifying the silicon surface permits the attachment of fluorescent and radiolabeled imaging molecules to the FSCs. Fluorescent and magnetic SSNs can be loaded into the pores of the FSCs. Once assembled, the resulting MSDS can be imaged using different in vivo imaging modalities from its administration to its final localization into the body. We further modified our FSCs with PEG molecules to increase their circulation time and with antibodies directed against the VEGFR2 membrane protein to increase the localization of the MSDS in tumor associated vessels. We monitored the biodistribution of all MSDSs and characterized their biocompatibility in the different tissues. Finally, we loaded the pores of the FSCs with a lipidic nanoformulation of the potent anti cancer drug doxorubicin (dox-liposomes and dox-micelles) and followed the efficacy of this treatment. Taken together, these studies provide first time evidence that silicon nanoporous particles can be used as effective carriers for the simultaneous delivery of different nanotherapeutics in vivo.

Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 2160.