title: Co-injection of a targeted, reversibly masked endosomolytic polymer dramatically improves the efficacy of cholesterol-conjugated small interfering RNAs in vivo.
abstract: Effective in vivo delivery of small interfering (siRNA) has been a major obstacle in the development of RNA interference therapeutics. One of the first attempts to overcome this obstacle utilized intravenous injection of cholesterol-conjugated siRNA (chol-siRNA). Although studies in mice revealed target gene knockdown in the liver, delivery was relatively inefficient, requiring 3 daily injections of 50 mg/kg of chol-siRNA to obtain measurable reduction in gene expression. Here we present a new delivery approach that increases the efficacy of the chol-siRNA over 500-fold and allows over 90% reduction in target gene expression in mice and, for the first time, high levels of gene knockdown in non-human primates. This improved efficacy is achieved by the co-injection of a hepatocyte-targeted and reversibly masked endosomolytic polymer. We show that knockdown is absolutely dependent on the presence of hepatocyte-targeting ligand on the polymer, the cognate hepatocyte receptor, and the cholesterol moiety of the siRNA. Importantly, we provide evidence that this increase in efficacy is not dependent on interactions between the chol-siRNA with the polymer prior to injection or in the bloodstream. The simplicity of the formulation and efficacy of this mode of siRNA delivery should prove beneficial in the use of siRNA as a therapeutic.
authors.affiliation: Arrowhead Madison Inc., Arrowhead Research Corporation, Madison, Wisconsin, USA.
authors.forename: So C
authors.initials: SC
authors.lastname: Wong
authors.forename: Jason J
authors.initials: JJ
authors.lastname: Klein
authors.forename: Holly L
authors.initials: HL
authors.lastname: Hamilton
authors.forename: Qili
authors.initials: Q
authors.lastname: Chu
authors.forename: Christina L
authors.initials: CL
authors.lastname: Frey
authors.forename: Vladimir S
authors.initials: VS
authors.lastname: Trubetskoy
authors.forename: Julia
authors.initials: J
authors.lastname: Hegge
authors.forename: Darren
authors.initials: D
authors.lastname: Wakefield
authors.forename: David B
authors.initials: DB
authors.lastname: Rozema
authors.forename: David L
authors.initials: DL
authors.lastname: Lewis
mesh_terms: D000116:Acetylgalactosamine / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000493:pharmacokinetics; D000818:Animals; D001055:Apolipoproteins B / Q000097:blood / Q000235:genetics; D037263:Asialoglycoprotein Receptor / Q000235:genetics / Q000378:metabolism; D002784:Cholesterol / Q000008:administration & dosage* / Q000493:pharmacokinetics; D011992:Endosomes / Q000187:drug effects*; D005167:Factor VII / Q000235:genetics / Q000378:metabolism; D005260:Female; D055785:Gene Knockdown Techniques; D018014:Gene Transfer Techniques; D022781:Hepatocytes / Q000378:metabolism; D008055:Lipids / Q000097:blood; D008099:Liver / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D008253:Macaca mulatta; D008297:Male; D051379:Mice; D008813:Mice, Inbred ICR; D018345:Mice, Knockout; D011145:Polyvinyls / Q000008:administration & dosage* / Q000493:pharmacokinetics; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000008:administration & dosage* / Q000235:genetics / Q000493:pharmacokinetics; D011973:Receptors, LDL / Q000235:genetics / Q000378:metabolism
chemical_list: D001055:Apolipoproteins B; D037263:Asialoglycoprotein Receptor; D008055:Lipids; D011145:Polyvinyls; D034741:RNA, Small Interfering; D011973:Receptors, LDL; D005167:Factor VII; D002784:Cholesterol; D000116:Acetylgalactosamine