Thromb Haemost 2015; 113(06): 1300-1311
DOI: 10.1160/TH14-06-0505
Coagulation and Fibrinolysis
Schattauer GmbH

Titrating haemophilia B phenotypes using siRNA strategy: evidence that antithrombotic activity is separated from bleeding liability

Joseph M. Metzger*
1   In vivo Pharmacology, Merck Co., Inc., Kenilworth, New Jersey, USA
,
Marija Tadin-Strapps*
2   RNA Therapeutics, Merck Co., Inc., West Point, Pennsylvania, USA
,
Anil Thankappan
2   RNA Therapeutics, Merck Co., Inc., West Point, Pennsylvania, USA
,
Walter R. Strapps
2   RNA Therapeutics, Merck Co., Inc., West Point, Pennsylvania, USA
,
Marti DiPietro
2   RNA Therapeutics, Merck Co., Inc., West Point, Pennsylvania, USA
,
Karen Leander
2   RNA Therapeutics, Merck Co., Inc., West Point, Pennsylvania, USA
,
Zuo Zhang
3   Genetically Engineered Models, Kenilworth, New Jersey, USA
,
Myung K. Shin
3   Genetically Engineered Models, Kenilworth, New Jersey, USA
,
John Levorse
4   Cardiometabolic Disease Merck Co., Inc., Kenilworth, New Jersey, USA
,
Kunal Desai
4   Cardiometabolic Disease Merck Co., Inc., Kenilworth, New Jersey, USA
,
Yiming Xu
4   Cardiometabolic Disease Merck Co., Inc., Kenilworth, New Jersey, USA
,
KehDih Lai
4   Cardiometabolic Disease Merck Co., Inc., Kenilworth, New Jersey, USA
,
Weizhen Wu
4   Cardiometabolic Disease Merck Co., Inc., Kenilworth, New Jersey, USA
,
Zhu Chen
4   Cardiometabolic Disease Merck Co., Inc., Kenilworth, New Jersey, USA
,
Tian-Quan Cai
1   In vivo Pharmacology, Merck Co., Inc., Kenilworth, New Jersey, USA
,
Nina Jochnowitz
1   In vivo Pharmacology, Merck Co., Inc., Kenilworth, New Jersey, USA
,
Ross Bentley
1   In vivo Pharmacology, Merck Co., Inc., Kenilworth, New Jersey, USA
,
Lizbeth Hoos
1   In vivo Pharmacology, Merck Co., Inc., Kenilworth, New Jersey, USA
,
Yuchen Zhou
1   In vivo Pharmacology, Merck Co., Inc., Kenilworth, New Jersey, USA
,
Laura Sepp-Lorenzino
2   RNA Therapeutics, Merck Co., Inc., West Point, Pennsylvania, USA
,
Dietmar Seiffert
2   RNA Therapeutics, Merck Co., Inc., West Point, Pennsylvania, USA
,
Patrick Andre
4   Cardiometabolic Disease Merck Co., Inc., Kenilworth, New Jersey, USA
› Author Affiliations
Further Information

Publication History

Received: 11 June 2014

Accepted after major revision: 20 January 2015

Publication Date:
22 November 2017 (online)

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Summary

Haemophilia A and B are characterised by a life-long bleeding predisposition, and several lines of evidence suggest that risks of atherothrombotic events may also be reduced. Establishing a direct correlation between coagulation factor levels, thrombotic risks and bleeding propensity has long been hampered by an inability to selectively and specifically inhibit coagulation factor levels. Here, the exquisite selectivity of gene silencing combined with a gene knockout (KO) approach was used to define the relative contribution of factor IX (fIX) to thrombosis and primary haemostasis in the rat. Using a lipid nanoparticle (LNP) formulation, we successfully delivered fIX siRNAs to the liver by intravenous administration. The knockdown (KD) of target gene mRNA was achieved rapidly (within 24 hour post-siRNA dosing), sustained (maintained for at least 7 days post dosing) and not associated with changes in mRNA expression levels of other coagulation factors. We found that intermediate levels of liver fIX mRNA silencing (60–95 %) translating into a 50–99 % reduction of plasma fIX activity provided protection from thrombosis without prolonging the cuticle bleeding time. Over 99 % inhibition of fIX activity was required to observe increase in bleeding, a phenotype confirmed in fIX KO rats. These data provide substantial evidence of a participation of fIX in the mechanisms regulating thrombosis prior to those regulating primary haemostasis, therefore highlighting the potential of fIX as a therapeutic target. In addition, hepatic mRNA silencing using LNP-encapsulated siRNAs may represent a promising novel approach for the chronic treatment and prevention of coagulation-dependent thrombotic disorders in humans.

* These authors contributed equally to this manuscript.