Characterizing the effect of GalNAc and phosphorothioate backbone on binding of antisense oligonucleotides to the asialoglycoprotein receptor.
Targeted delivery of antisense oligonucleotides (ASO) to hepatocytes via the asialoglycoprotein receptor (ASGR) has improved the potency of ASO drugs ∼30-fold in the clinic (1). In order to fully characterize the effect of GalNAc valency, oligonucleotide length, flexibility and chemical composition on ASGR binding, we tested and validated a fluorescence polarization competition binding assay. The ASGR binding, and in vitro and in vivo activities of 1, 2 and 3 GalNAc conjugated single stranded and duplexed ASOs were studied. Two and three GalNAc conjugated single stranded ASOs bind the ASGR with the strongest affinity and display optimal in vitro and in vivo activities. 1 GalNAc conjugated ASOs showed 10-fold reduced ASGR binding affinity relative to three GalNAc ASOs but only 2-fold reduced activity in mice. An unexpected observation was that the ASGR also appears to play a role in the uptake of unconjugated phosphorothioate modified ASOs in the liver as evidenced by the loss of activity of GalNAc conjugated and unconjugated ASOs in ASGR knockout mice. Our results provide insights into how backbone charge and chemical composition assist in the binding and internalization of highly polar anionic single stranded oligonucleotides into cells and tissues.
Ionis Pharmaceuticals Inc., 2855 Gazelle Court, Carlsbad, CA 92010, USA.
Karsten
K
Schmidt
Ionis Pharmaceuticals Inc., 2855 Gazelle Court, Carlsbad, CA 92010, USA.
Thazha P
TP
Prakash
Ionis Pharmaceuticals Inc., 2855 Gazelle Court, Carlsbad, CA 92010, USA.
Aaron J
AJ
Donner
Ionis Pharmaceuticals Inc., 2855 Gazelle Court, Carlsbad, CA 92010, USA.
Garth A
GA
Kinberger
Ionis Pharmaceuticals Inc., 2855 Gazelle Court, Carlsbad, CA 92010, USA.
Hans J
HJ
Gaus
Ionis Pharmaceuticals Inc., 2855 Gazelle Court, Carlsbad, CA 92010, USA.
Audrey
A
Low
Ionis Pharmaceuticals Inc., 2855 Gazelle Court, Carlsbad, CA 92010, USA.
Michael E
ME
Østergaard
Ionis Pharmaceuticals Inc., 2855 Gazelle Court, Carlsbad, CA 92010, USA.
Melanie
M
Bell
Ionis Pharmaceuticals Inc., 2855 Gazelle Court, Carlsbad, CA 92010, USA.
Eric E
EE
Swayze
Ionis Pharmaceuticals Inc., 2855 Gazelle Court, Carlsbad, CA 92010, USA.
Punit P
PP
Seth
D000116:Acetylgalactosamine / Q000737:chemistry*; D000818:Animals; D037263:Asialoglycoprotein Receptor / Q000235:genetics / Q000378:metabolism*; D001483:Base Sequence; D001665:Binding Sites; D001667:Binding, Competitive; D001681:Biological Assay; D001692:Biological Transport; D004247:DNA / Q000737:chemistry* / Q000378:metabolism; D004277:DNA, Single-Stranded / Q000737:chemistry* / Q000378:metabolism; D005454:Fluorescence Polarization; D006001:Glycoconjugates / Q000737:chemistry / Q000378:metabolism; D022781:Hepatocytes / Q000166:cytology / Q000378:metabolism; D006801:Humans; D007700:Kinetics; D008099:Liver / Q000166:cytology / Q000378:metabolism; D051379:Mice; D018345:Mice, Knockout; D008862:Microsomes, Liver / Q000378:metabolism; D016376:Oligonucleotides, Antisense / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D054735:Phosphorothioate Oligonucleotides / Q000737:chemistry* / Q000378:metabolism; D061251:Primary Cell Culture; D011485:Protein Binding; D055672:Static Electricity
D037263:Asialoglycoprotein Receptor; D004277:DNA, Single-Stranded; D006001:Glycoconjugates; D016376:Oligonucleotides, Antisense; D054735:Phosphorothioate Oligonucleotides; D004247:DNA; D000116:Acetylgalactosamine