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HepC Newsletter
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Dema-@aol.com
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Jun 10, 2009 22:39 PDT
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NATAP http://natap.org/
_______________________________________________
Pharmasset Initiates Phase 1b Multiple Ascending Dose Clinical Trial of
PSI-7851 in Chronic Hepatitis C Patients
-- PSI-7851 was generally safe and well tolerated in Phase 1a single
ascending dose trial -- Further results from single ascending and multiple
ascending dose trials are expected in second half 2009
PRINCETON, N.J., June 9, 2009 /PRNewswire-FirstCall via COMTEX News
Network/ -- Pharmasset, Inc. (Nasdaq: VRUS) announced today that it had completed
the single ascending dose study and begun dosing in a multiple ascending
dose trial with PSI-7851, a nucleotide analog polymerase inhibitor for the
treatment of chronic hepatitis C virus (HCV) infection. This study is
designed to assess the safety, tolerability and antiviral activity of PSI-7851
over 3 days in HCV-infected individuals.
"We are encouraged by the safety and pharmacokinetics of PSI-7851 thus
far," stated Michelle Berrey, MD, MPH, Pharmasset's Chief Medical Officer. "We
believe PSI-7851, Pharmasset's lead second generation nucleotide, has the
potential to be administered once a day at low milligram doses, while also
continuing to demonstrate the many benefits nucleos(t)ides have over other
classes of HCV direct acting antivirals, including a high barrier to
resistance, pan-genotype potency, and ability to combine with other classes of
compounds."
PSI-7851 Phase 1 Program Overview
The Phase 1 program is investigating the safety, tolerability and
pharmacokinetics of PSI-7851 in healthy subjects following single doses (Phase 1a)
and in patients chronically infected with HCV genotype 1 following repeat
dosing for 3 days (Phase 1b). The Phase 1b study will additionally
investigate hep atitis C viral dynamics and monitor for the development of drug resi
stance.
Subjects in the phase 1a single ascending dose study received single doses
of PSI-7851 ranging from 25mg to 800mg or a matching placebo. Preliminary
data from the phase 1a single ascending dose study demonstrated:
-- No serious adverse events or discontinuations;
-- No dose-related adverse events;
-- No grade III / IV lab abnormalities;
-- No clinically significant changes in vital signs or ECGs.
A Phase 1b multiple ascending dose trial has now been initiated in patients
with chronic HCV genotype 1 infection. Subjects will be enrolled at
multiple centers and randomized to PSI-7851 (8 per cohort) or placebo (2 per
cohort). Based upon the results from the SAD study, the first dose of PSI-7851
to be tested will be 50mg once daily. The primary objective is to assess
the safety, tolerability and pharmacokinetics of PSI-7851 after repeat dosing
over 3 days. The secondary objective is to evaluate the decrease in HCV
RNA.
Results from both studies are expected in the second half of 2009.
About PSI-7851
PSI-7851 is a uridine nucleotide analog currently in development for the
treatment of chronic HCV infection. PSI-7851 has demonstrated potent in vitro
anti-HCV activity with EC50 values of 90 +/- 60 nM, which is approximately
15- to 20-fold more potent than Pharmasset's first generation nucleoside
polymerase inhibitor, R7128. In vitro studies of PSI-7 851 have not shown
evidence of any mitochondrial or other cellular toxicities that may be
associated with some nucleoside analogs. The half-life of the triphosphate in
primary human hepatocytes is approximately 38 hours, which suggests the
possibility for once-daily dosing. Like R7128, PSI-7851 has demonstrated in vitro
activity against all of the most common HCV genotypes.
About Pharmasset
Pharmasset is a clinical-stage pharmaceutical company committed to
discovering, developing, and commercializing novel drugs to treat viral
infections. Pharmasset's primary focus is on the development of oral therapeutics for
the treatment of hepatitis C virus (HCV) and, secondarily, on the
development of Racivir(R) for the treatment of human immunodeficiency virus (HIV).
Our research and development efforts focus on nucleos(t)ide analogs, a
class of compounds which act to inhibit the enzymes required for viral
replication. We currently have three clinical-stage product candida tes: R7128, a
nucleoside analog for chronic HCV infections, has init iated a Phase 2b
clinical trial in combination with Pegasys plus Copegus through a strategic
collaboration with Roche; PSI-7851, an unpartnered, next generation HCV
nucleotide analog, which recently began Phase 1 clinical studies and Racivir, for
the treatment of HIV that has completed a Phase 2 clinical trial.
Pegasys(R) and Copegus(R) are registered trademarks of Roche.
Contact
Richard E. T. Smith, Ph.D.
VP, Investor Relations and Corporate Communications
richard-@pharmasset.com
Office: +1 (609) 613-4181
Forward-Looking Statements
Pharmasset "Safe Harbor" Statement under the Private Securities Litigation
Reform Act of 1995: Statements in this press release regarding our business
that are not historical facts are "forward-looking statements" that
involve risks and uncertainties, including without limitation, the risk that
adverse events could cause the cessation or delay of any of the ongoing or
planned clinical trials and/or our development of our product candidates, the
risk that the results of previously conducted studies involving our product
candidates will not be repeated or observed in ongoing or future studies
involving our product candidates, the risk that our collaboration with Roche
will not continue or will not be successful and the risk that any one or
more of our product candidates will not be successfully developed and
commercialized. For a discussion of these risks and uncertainties, any of which
could cause our actual results to differ from thos e contained in the
forward-looking statements, see the section of our Annual Report on Form 10-K for
the fiscal year ended September 30, 2008 and our Quarterly Report on Form
10-Q for the period ended March 31, 2009 filed with the Securities and
Exchange Commission entitled "Risk Factors" and discussions of potential risks
and uncertainties in our subsequent filings with the Securities and Exchange
Commission.
SOURCE Pharmasset, Inc.
http://www.pharmasset.com
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