title: Multivalent N-acetylgalactosamine-conjugated siRNA localizes in hepatocytes and elicits robust RNAi-mediated gene silencing.
abstract: Conjugation of small interfering RNA (siRNA) to an asialoglycoprotein receptor ligand derived from N-acetylgalactosamine (GalNAc) facilitates targeted delivery of the siRNA to hepatocytes in vitro and in vivo. The ligands derived from GalNAc are compatible with solid-phase oligonucleotide synthesis and deprotection conditions, with synthesis yields comparable to those of standard oligonucleotides. Subcutaneous (SC) administration of siRNA-GalNAc conjugates resulted in robust RNAi-mediated gene silencing in liver. Refinement of the siRNA chemistry achieved a 5-fold improvement in efficacy over the parent design in vivo with a median effective dose (ED50) of 1 mg/kg following a single dose. This enabled the SC administration of siRNA-GalNAc conjugates at therapeutically relevant doses and, importantly, at dose volumes of ≤1 mL. Chronic weekly dosing resulted in sustained dose-dependent gene silencing for over 9 months with no adverse effects in rodents. The optimally chemically modified siRNA-GalNAc conjugates are hepatotropic and long-acting and have the potential to treat a wide range of diseases involving liver-expressed genes.
authors.affiliation: Alnylam Pharmaceuticals , 300 Third Street, Cambridge, Massachusetts 02142, United States.
authors.forename: Jayaprakash K
authors.initials: JK
authors.lastname: Nair
authors.forename: Jennifer L S
authors.initials: JL
authors.lastname: Willoughby
authors.forename: Amy
authors.initials: A
authors.lastname: Chan
authors.forename: Klaus
authors.initials: K
authors.lastname: Charisse
authors.forename: Md Rowshon
authors.initials: MR
authors.lastname: Alam
authors.forename: Qianfan
authors.initials: Q
authors.lastname: Wang
authors.forename: Menno
authors.initials: M
authors.lastname: Hoekstra
authors.forename: Pachamuthu
authors.initials: P
authors.lastname: Kandasamy
authors.forename: Alexander V
authors.initials: AV
authors.lastname: Kel'in
authors.forename: Stuart
authors.initials: S
authors.lastname: Milstein
authors.forename: Nate
authors.initials: N
authors.lastname: Taneja
authors.forename: Jonathan
authors.initials: J
authors.lastname: O'Shea
authors.forename: Sarfraz
authors.initials: S
authors.lastname: Shaikh
authors.forename: Ligang
authors.initials: L
authors.lastname: Zhang
authors.forename: Ronald J
authors.initials: RJ
authors.lastname: van der Sluis
authors.forename: Michael E
authors.initials: ME
authors.lastname: Jung
authors.forename: Akin
authors.initials: A
authors.lastname: Akinc
authors.forename: Renta
authors.initials: R
authors.lastname: Hutabarat
authors.forename: Satya
authors.initials: S
authors.lastname: Kuchimanchi
authors.forename: Kevin
authors.initials: K
authors.lastname: Fitzgerald
authors.forename: Tracy
authors.initials: T
authors.lastname: Zimmermann
authors.forename: Theo J C
authors.initials: TJ
authors.lastname: van Berkel
authors.forename: Martin A
authors.initials: MA
authors.lastname: Maier
authors.forename: Kallanthottathil G
authors.initials: KG
authors.lastname: Rajeev
authors.forename: Muthiah
authors.initials: M
authors.lastname: Manoharan
mesh_terms: D000116:Acetylgalactosamine / Q000737:chemistry*; D000818:Animals; D020868:Gene Silencing; D022781:Hepatocytes / Q000737:chemistry*; D051379:Mice; D008810:Mice, Inbred C57BL; D015394:Molecular Structure; D034741:RNA, Small Interfering / Q000737:chemistry* / Q000235:genetics*
chemical_list: D034741:RNA, Small Interfering; D000116:Acetylgalactosamine