Abstract LB-143: Sustained siRNA delivery by mesoporous silicon particles

RNA interference (RNAi) is a powerful approach for silencing genes associated with a variety of pathologic conditions; however, in vivo RNAi delivery has remained a major challenge due to lack of safe, efficient, and sustained systemic delivery. Here, we report on a novel approach to overcome these limitations using a multistage vector comprised of mesoporous silicon particles (S1MP) loaded with neutral nanoliposomes (DOPC) containing siRNA targeted against the oncoprotein, EphA2 that is overexpressed in a majority of cancers, including ovarian. Our delivery methodology resulted in sustained EphA2 gene silencing for at least 3 weeks in two independent orthotopic mouse models of ovarian cancer following a single intravenous administration of S1MP loaded with EphA2-siRNA-DOPC. Furthermore, a single administration of S1MP loaded with-EphA2-siRNA-DOPC substantially reduced tumor burden, angiogenesis and cell proliferation as compared to a non-coding control siRNA alone (SKOV3ip1: 54%, HeyA8: 57%), with no significant changes in serum chemistries or in pro-inflammatory cytokines. In summary, we have provided the first in vivo therapeutic validation of a novel, multistage siRNA delivery system for sustained gene silencing with broad applicability to pathologies beyond ovarian neoplasms. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr LB-143.