Novel Cluster and Monomer-Based GalNAc Structures Induce Effective Uptake of siRNAs in Vitro and in Vivo

Bioconjug Chem. 2018 Jul 18;29(7):2478-2488. doi: 10.1021/acs.bioconjchem.8b00365. Epub 2018 Jul 2.

Abstract

GalNAc conjugation is emerging as a dominant strategy for delivery of therapeutic oligonucleotides to hepatocytes. The structure and valency of the GalNAc ligand contributes to the potency of the conjugates. Here we present a panel of multivalent GalNAc variants using two different synthetic strategies. Specifically, we present a novel conjugate based on a support-bound trivalent GalNAc cluster, and four others using a GalNAc phosphoramidite monomer that was readily assembled into tri- or tetravalent designs during solid phase oligonucleotide synthesis. We compared these compounds to a clinically used trivalent GalNAc cluster both in vitro and in vivo. In vitro, cluster-based and phosphoramidite-based scaffolds show a similar rate of internalization in primary hepatocytes, with membrane binding observed as early as 5 min. All tested compounds provided potent, dose-dependent silencing, with 2-4% of injected dose recoverable from liver after 1 week. The two preassembled trivalent GalNAc clusters showed higher tissue accumulation and gene silencing relative to di-, tri-, or tetravalent GalNAc conjugates assembled via phosphoramidite chemistry.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acetylgalactosamine / chemistry*
  • Animals
  • Cell Membrane / metabolism
  • Cells, Cultured
  • Gene Silencing / drug effects
  • Hepatocytes / metabolism
  • Liver / metabolism
  • Macromolecular Substances
  • Mice
  • Oligonucleotides, Antisense / chemical synthesis
  • Oligonucleotides, Antisense / pharmacokinetics
  • Organophosphorus Compounds
  • RNA, Small Interfering / pharmacokinetics*
  • Solid-Phase Synthesis Techniques

Substances

  • Macromolecular Substances
  • Oligonucleotides, Antisense
  • Organophosphorus Compounds
  • RNA, Small Interfering
  • phosphoramidite
  • Acetylgalactosamine