Techniques: Enhancing hepatocyte uptake of antisense oligonucleotides (ASOs) via conjugation to N-acetylgalactosamine (GalNAc) clusters targeting asialoglycopro

Conjugating ASOs to GalNAc clusters targeting ASGR1 could help improve hepatocyte uptake of antisense therapeutics. The GalNAc cluster consisted of a tris(hydroxymethyl)aminomethane scaffold containing a linker that could be conjugated to the 5' end of an ASO and three N-hexylamide chains that each terminated in GalNAc - a ligand for hepatocyte receptor ASGR1. In a mouse hepatocyte-based competitive binding assay, the GalNAc cluster conjugated to an ASO targeting scavenger receptor class B member 1 (SCARB1) bound ASGR1 with a Ki of 6.1 nM. In transgenic mice expressing human transthyretin (TTR), IV injection of a GalNAc cluster conjugated to an ASO against human TTR produced a higher liver concentration than the unconjugated ASO. In the TTR-transgenic mice or normal mice, conjugates of the GalNAc cluster and ASOs against TTR, SCARB1 and three other targets decreased expression of those genes more potently than the corresponding unconjugated ASOs. Next steps include developing conjugates that enhance ASO delivery to other target tissues (see "Liver-bound," page 9). ...