- Nair, Jayaprakash K;
- Willoughby, Jennifer LS;
- Chan, Amy;
- Charisse, Klaus;
- Alam, Rowshon;
- Wang, Qianfan;
- Hoekstra, Menno;
- Kandasamy, Pachamuthu;
- Kel’in, Alexander V;
- Milstein, Stuart;
- Taneja, Nate;
- O’Shea, Jonathan;
- Shaikh, Sarfraz;
- Zhang, Ligang;
- van der Sluis, Ronald J;
- Jung, Michael E;
- Akinc, Akin;
- Hutabarat, Renta;
- Kuchimanchi, Satya;
- Fitzgerald, Kevin;
- Zimmermann, Tracy;
- van Berkel, Theo JC;
- Maier, Martin A;
- Rajeev, Kallanthottathil G;
- Manoharan, Muthiah
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.