Pharmasset Completes Enrollment for Phase 1 Study of Experimental
Nucleoside Polymerase Inhibitor R7128 for Treatment of Chronic Hepatitis C
Pharmasset,
Inc. has completed patient enrollment for an ongoing multiple ascending dose study
of R7128
for the treatment of hepatitis C virus (HCV) infection. An experimental oral
nucleoside HCV polymerase inhibitor, R7128 is currently being evaluated in a Phase
1 clinical trial as part of Pharmasset's collaboration with Roche to develop new
HCV therapies.
Following
are edited excerpts from an announcement by Pharmasset about the study: The
primary objective of the multiple ascending dose study is to assess the safety,
tolerability, and pharmacokinetics of R7128 after once-daily or twice-daily dosing
for 14 days in up to 40 patients chronically infected with HCV genotype 1 who
have previously failed interferon therapy. The secondary objective is to assess
antiviral efficacy by measuring the change in HCV RNA in these patients.
Pharmasset
expects to release preliminary 14-day safety and efficacy treatment data from
the multiple ascending dose study in September 2007. Results for the entire Phase
1 single ascending and multiple ascending dose study are expected to be presented
at various scientific conferences throughout the remainder of 2007.
As
recently announced, Roche has initiated long-term chronic toxicology studies in
support of the potential advancement of R7128 into Phase 2 clinical trials.
About
R7128
R7128
is a polymerase inhibitor being developed for the treatment of chronic hepatitis
C virus (HCV) infection. R7128 is a prodrug of PSI-6130, which demonstrated potency
in preclinical studies. PSI-6130 is a pyrimidine nucleoside analog inhibitor of
HCV RNA polymerase, an enzyme that is necessary for hepatitis C viral replication.
Results from an oral single ascending dose study in 24 healthy male volunteers
showed that PSI-6130 was generally well tolerated with no serious adverse events
in doses up to 3000 mg.
R7128
Phase 1 Study Overview
The
Phase 1 clinical trial is a multiple center, observer-blinded, randomized and
placebo-controlled study to investigate the pharmacokinetics, pharmacodynamics,
safety, tolerability, and food effect of R7128 in healthy volunteers and in patients
chronically infected with HCV genotype 1. This Phase 1 study is comprised of two
parts:
Part 1 is a single ascending dose study conducted in 38 healthy
volunteers. The primary objective of Part 1 is to assess the safety, tolerability,
and pharmacokinetics of R7128 following single ascending doses under fasting conditions.
The secondary objective of Part 1 is to explore the effect of food on the pharmacokinetics
of R7128.
Preliminary data from the single ascending dose portion of the
study indicate:
• All doses of
R7128 studied were generally well-tolerated.
•
All patients completed the study with no gastrointestinal adverse
events or serious adverse events reported during the study.
•
No hematological or laboratory abnormalities of clinical significance
were noted.
Part
2 is a multiple ascending dose study being conducted in up to 40 patients chronically
infected with HCV genotype 1 who have previously failed interferon therapy. The
primary objective of Part 2 is to assess the safety, tolerability and pharmacokinetics
of R7128 after once-daily or twice-daily dosing for 14 days. The secondary
objective is to assess antiviral efficacy by measuring the change in HCV RNA.
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 B virus (HBV), hepatitis C virus (HCV), and human immunodeficiency
virus (HIV).
Pharmasset is currently developing three product candidates:
clevudine for
the treatment of chronic HBV infection, which is expected to enter U.S., European
and South American Phase 3 registration clinical trials and is already approved
for HBV in South Korea and marketed by Bukwang Pharmaceuticals under the brand
name Levovir; R7128, an oral treatment for HCV, in a Phase 1 clinical trial through
a strategic collaboration with Roche; and racivir
for the treatment of HIV in combination with other approved HIV drugs, which
has completed a Phase 2 clinical trial.
08/07/07
Source Pharmasset, Inc. Pharmasset Completes Enrollment of Phase 1 Study of R7128
for HCV. Press Release. August 2, 2007.
