Safe, long-term hepatic expression of anti-HCV shRNA in a nonhuman primate model.
The hepatitis C virus (HCV) chronically infects 2% of the world population and effective treatment is limited by long duration and significant side-effects. Here, we describe a novel drug, intended as a "single-shot " therapy, which expresses three short hairpin RNAs (shRNAs) that simultaneously target multiple conserved regions of the HCV genome as confirmed in vitro by knockdown of an HCV replicon system. Using a recombinant adeno-associated virus (AAV) serotype 8 vector for delivery, comprehensive transduction of hepatocytes was achieved in vivo in a nonhuman primate (NHP) model following a single intravenous injection. However, dose ranging studies performed in 13 NHP resulted in high-expression levels of shRNA from wild-type (wt) Pol III promoters and dose-dependent hepatocellular toxicity, the first demonstration of shRNA-related toxicity in primates, establishing that the hepatotoxicity arises from highly conserved features of the RNA interference (RNAi) pathway. In the second generation drug, each promoter was re-engineered to reduce shRNA transcription to levels that circumvent toxicity but still inhibit replicon activity. In vivo testing of this modified construct in 18 NHPs showed conservation of hepatocyte transduction but complete elimination of hepatotoxicity, even with sustained shRNA expression for 50 days. These data support progression to a clinical study for treatment of HCV infection.
Tacere Therapeutics, San Jose, California, USA. Electronic address: dsuhy@tacerebio.com.
David A
DA
Suhy
Tacere Therapeutics, San Jose, California, USA.
Shih-Chu
SC
Kao
Tacere Therapeutics, San Jose, California, USA.
Tin
T
Mao
Pfizer Global Research and Development, Drug Safety Research and Development, Cambridge, Massachusetts, USA.
Laurence
L
Whiteley
Pfizer Global Research & Development, Kent, UK.
Hubert
H
Denise
Pfizer Global Research & Development, Kent, UK.
Bernard
B
Souberbielle
Pfizer Global Research and Development, Drug Safety Research and Development, Cambridge, Massachusetts, USA.
Andrew D
AD
Burdick
Pfizer Global Research and Development, Drug Safety Research and Development, Cambridge, Massachusetts, USA.
Kyle
K
Hayes
Division of Hematology and Center for Cellular and Molecular Therapeutics, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA; Department of Pathology and Laboratory Medicine, Children's Hospital of Philadelphia, and Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA.
J Fraser
JF
Wright
Pfizer Global Research & Development, Kent, UK.
Helen
H
Lavender
Tacere Therapeutics, San Jose, California, USA.
Peter
P
Roelvink
Tacere Therapeutics, San Jose, California, USA.
Alexander
A
Kolykhalov
Pfizer Global Research & Development, Kent, UK.
Kevin
K
Brady
Pfizer Global Research & Development, Kent, UK.
Sterghios A
SA
Moschos
Division of Hematology and Center for Cellular and Molecular Therapeutics, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA.
Bernd
B
Hauck
Division of Hematology and Center for Cellular and Molecular Therapeutics, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA.
Olga
O
Zelenaia
Department of Pathology and Laboratory Medicine, Children's Hospital of Philadelphia, and Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA.
Shangzhen
S
Zhou
Tacere Therapeutics, San Jose, California, USA.
Curt
C
Scribner
Division of Hematology and Center for Cellular and Molecular Therapeutics, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA; Howard Hughes Medical Institute, University of Pennsylvania School of Medicine, The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA.
Katherine A
KA
High
Tacere Therapeutics, San Jose, California, USA.
Sara H
SH
Renison
Pfizer Global Research & Development, Kent, UK.
Romu
R
Corbau
D000818:Animals; D004258:DNA Polymerase III / Q000235:genetics; D000229:Dependovirus / Q000235:genetics; D005818:Genetic Engineering; D015316:Genetic Therapy; D005822:Genetic Vectors; D016679:Genome, Viral; D016174:Hepacivirus / Q000235:genetics*; D019698:Hepatitis C, Chronic / Q000628:therapy* / Q000821:virology; D022781:Hepatocytes / Q000473:pathology / Q000821:virology*; D007275:Injections, Intravenous; D008099:Liver / Q000473:pathology / Q000821:virology*; D008252:Macaca fascicularis; D051379:Mice; D011401:Promoter Regions, Genetic; D034741:RNA, Small Interfering / Q000235:genetics*; D012367:RNA, Viral / Q000037:antagonists & inhibitors* / Q000235:genetics; D012093:Replicon; D014161:Transduction, Genetic; D014779:Virus Replication
D034741:RNA, Small Interfering; D012367:RNA, Viral; D004258:DNA Polymerase III