The nucleoside
analog R7128 form Pharmasset, Inc is an experimental HCV polymerase inhibitor
that has shown early promise in a triple combination regimen with Pegasys plus
ribavirin. Pharmasset has initiated a dose-ranging Phase 1 study of R7128 in combination
with Pegasys plus ribavirin in up to 75 treatment-naive, genotype 1 chronic hepatitis
C patients. Following is an edited version of the study announcement from Pharmasset:
R7128 is a prodrug of PSI-6130,
an oral cytidine nucleoside analog polymerase inhibitor of HCV that is in development
through a collaboration between Pharmasset and Roche Laboratories, the manufacturer
of peginterferon alfa-2a (Pegasys) and ribavirin (Copegus).
The purpose
of this study is a preliminary evaluation of safety, tolerability, pharmacokinetics,
and antiviral activity of R7128 in the clinically relevant setting of combination
therapy with the current standard of care for chronic HCV infection [pegylated
interferon plus ribavirin].
The study will include 2 to 3 oral doses of
R7128 (500 mg to 1500 mg) that will be administered twice-daily with Pegasys plus
Copegus for 28 days. There will be 25 patients in each dose cohort with 20 patients
randomized to receive R7128 and 5 patients randomized to receive placebo, all
administered in combination with the standard of care.
After completing
28 days of the triple combination regimen and a follow-up period of 4 weeks of
Pegasys plus Copegus, all patients will then receive 40 weeks of open-label standard
of care dosing under a separate protocol.
"We are excited about the
rapid pace of development of R7128, and the opportunity to evaluate its safety
and potency in combination with the standard of care," stated Dr. Michelle
Berrey, Pharmasset's Vice President, Clinical Development & Chief Medical
Officer.
"The
28-day endpoint will provide meaningful data on early viral kinetics and the proportion
of patients who have undetectable HCV RNA by the end of this treatment period.
We look forward to sharing the preliminary results of this combination study in
the first quarter of 2008 and making plans for future studies of R7128."
Source Pharmasset, Inc.
Pharmasset Commences Dosing in 28-Day Combination Study of R7128 with Pegasys
plus Copegus for Hepatitis C. Press Release. October 3, 2007.
