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33
Inhibition of Hepatitis B Virus Replication by the HBV
Core Inhibitor NVR 3-778
Angela Lam, Suping Ren, Robert Vogel, Christine Espiritu, Mollie
Kelly, Vincent Lau, George D. Hartman, Lalo Flores, Klaus Klumpp;
Novira Therapeutics Inc., Doyleston, PA
Background: Hepatitis B virus (HBV) chronically infects more
than 350 million people worldwide, and is a major cause of
severe liver disease including cirrhosis and hepatocellular carcinoma.
NVR 3-778 represents a new class of HBV core inhibitors
and is currently in clinical development for the treatment of
chronic hepatitis B. We present the preclinical characterization
of NVR 3-778 and its antiviral properties in cells expressing
HBV. Methods: HBV core assembly was examined using fluorescence
quenching and electron microscopy. HBV replication
inhibition was measured as reduction of secreted HBV DNA in
HBV producing HepG2.2.15 cells. The production, encapsidation
and secretion of HBV RNA was determined using Northern
blot and Quantigene assays. Antiviral activity of NVR 3-778
against nucleoside resistant HBV variants was determined by
cell based phenotyping. HBV broad spectrum antiviral activity
was examined by testing NVR 3-778 across all HBV genotypes
(A-H). Results: NVR 3-778 inhibited HBV replication in
HepG2.2.15 cells and could fully block the production of HBV
DNA.. The compound could effectively induce mis-assembly of
recombinant HBV core protein and electron microscopy indicated
the formation of capsid-like particles. In HBV expressing
cells, NVR 3-778 blocked the encapsidation of HBV pgRNA,
HBV DNA formation, and the release of HBV DNA and RNA
containing particles. NVR 3-778 was similarly active against
wild-type and HBV nucleos(t)ide resistant variants with defined
amino acid changes within the reverse transcriptase protein:
rtL180M/M204V, rtN236T, rtA181V, rtA181V/N236T, and
rtL180M/M204V/N236T. Furthermore, in transfection assays
NVR 3-778 inhibited HBV replication across representative
HBV strains from genotypes A to H (EC50 values from 0.20 to
0.58 mM). Conclusions: Preclinical antiviral profiling studies
showed that the antiviral HBV replication inhibitor NVR 3-778
could induce mis-assembly of core protein into capsid-like particles
in vitro. Treatment of HBV producing cells with NVR 3-778
was associated with inhibition of pgRNA encapsidation. Consequently,
the downstream processes of HBV DNA production
and secretion of infectious HBV DNA-containing virions (Dane
particles) were inhibited. In addition, NVR 3-778 also blocked
the secretion of HBV RNA-containing particles. NVR 3-778 was
active against HBV variants resistant to nucleos(t)ide analogs
and was broadly active across all HBV genotypes. These results
support the clinical development of NVR 3-778 as a potential
new therapy for chronic hepatitis B patients alone or in combination
with nucleoside analogs or other antiviral agents.
Disclosures:
Angela Lam - Employment: Novira Therapeutics, Merck & Co
Christine Espiritu - Employment: Novira Therapeutics
Mollie Kelly - Independent Contractor: Novira Therapeutics
George D. Hartman - Management Position: Novira Therapeutics
Klaus Klumpp - Board Membership: Riboscience LLC; Employment: Novira Therapeutics
Inc
The following authors have nothing to disclose: Suping Ren, Robert Vogel, Vincent
Lau, Lalo Flores
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发表于 2015-10-8 09:50
