title: TricycloDNA-modified oligo-2'-deoxyribonucleotides reduce scavenger receptor B1 mRNA in hepatic and extra-hepatic tissues--a comparative study of oligonucleotide length, design and chemistry.
abstract: We report the evaluation of 20-, 18-, 16- and 14-mer phosphorothioate (PS)-modified tricycloDNA (tcDNA) gapmer antisense oligonucleotides (ASOs) in T(m), cell culture and animal experiments and compare them to their gap-matched 20-mer 2'-O-methoxyethyl (MOE) and 14-mer 2',4'-constrained ethyl (cEt) counterparts. The sequence-matched 20-mer tcDNA and MOE ASOs showed similar T(m) and activity in cell culture under free-uptake and cationic lipid-mediated transfection conditions, while the 18-, 16- and 14-mer tcDNA ASOs were moderate to significantly less active. These observations were recapitulated in the animal experiments where the 20-mer tcDNA ASO formulated in saline showed excellent activity (ED(50) 3.9 mg/kg) for reducing SR-B1 mRNA in liver. The tcDNA 20-mer ASO also showed better activity than the MOE 20-mer in several extra-hepatic tissues such as kidney, heart, diaphragm, lung, fat, gastrocnemius and quadriceps. Interestingly, the 14-mer cEt ASO showed the best activity in the animal experiments despite significantly lower T(m) and 5-fold reduced activity in cell culture relative to the 20-mer tcDNA and MOE-modified ASOs. Our experiments establish tcDNA as a useful modification for antisense therapeutics and highlight the role of chemical modifications in influencing ASO pharmacology and pharmacokinetic properties in animals.
authors.affiliation: Isis Pharmaceuticals, Inc., 2855 Gazelle Court, Carlsbad, CA 92010, USA.
authors.forename: Sue
authors.initials: S
authors.lastname: Murray
authors.forename: Damian
authors.initials: D
authors.lastname: Ittig
authors.forename: Erich
authors.initials: E
authors.lastname: Koller
authors.forename: Andres
authors.initials: A
authors.lastname: Berdeja
authors.forename: Alfred
authors.initials: A
authors.lastname: Chappell
authors.forename: Thazha P
authors.initials: TP
authors.lastname: Prakash
authors.forename: Michaela
authors.initials: M
authors.lastname: Norrbom
authors.forename: Eric E
authors.initials: EE
authors.lastname: Swayze
authors.forename: Christian J
authors.initials: CJ
authors.lastname: Leumann
authors.forename: Punit P
authors.initials: PP
authors.lastname: Seth
mesh_terms: D000818:Animals; D002460:Cell Line; D008099:Liver / Q000378:metabolism; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D020319:Oligodeoxyribonucleotides, Antisense / Q000008:administration & dosage / Q000737:chemistry* / Q000493:pharmacokinetics; D012333:RNA, Messenger / Q000378:metabolism; D051122:Scavenger Receptors, Class B / Q000235:genetics* / Q000378:metabolism; D014018:Tissue Distribution
chemical_list: D020319:Oligodeoxyribonucleotides, Antisense; D012333:RNA, Messenger; C454739:Scarb1 protein, mouse; D051122:Scavenger Receptors, Class B