Pharmasset Commences Dosing R7128 Cohorts 3 and 4 for the Treatment of Chronic Hepatitis C
Wednesday May 14, 7:05 am ET
- Two 4-week cohorts will evaluate R7128 1000mg BID in HCV genotype 1 treatment-naive patients and R7128 1500mg BID in HCV genotypes 2 or 3 treatment-experienced patients -
PRINCETON, N.J., May 14 /PRNewswire-FirstCall/ -- Pharmasset, Inc. (Nasdaq: VRUS - News) has commenced dosing two additional cohorts of a 4-week Phase 1 study of R7128 in combination with Pegasys® (peginterferon alfa-2a) plus Copegus® (ribavirin) in both treatment-naive and treatment-experienced patients chronically-infected with hepatitis C virus (HCV) genotypes 1, 2 and 3. R7128, a prodrug of PSI-6130, is a nucleoside analogue polymerase inhibitor of HCV that is being developed through Pharmasset's collaboration with Roche.
The purpose of this 4-week study is to evaluate the safety, tolerability, pharmacokinetics and antiviral activity of R7128 in the clinically-relevant setting of combination therapy for chronic HCV infection. The previously planned Cohort 3 will continue dose-exploration with administration of R7128 1000mg twice-daily (BID) in treatment-naive patients with HCV genotype 1. Cohort 4 will evaluate R7128 1500mg BID administered in combination with Pegasys plus Copegus in treatment-experienced patients with genotypes 2 or 3 who did not achieve a sustained virologic response (SVR) with previous interferon-based therapy.
There will be 25 patients in each dose cohort with 20 patients randomized to receive R7128 and 5 patients randomized to receive placebo. After completing 4 weeks of the triple combination regimen and a follow-up period of 4 weeks of Pegasys plus Copegus, patients will receive an additional 16 to 40 weeks of open-label dosing of Pegasys plus Copegus under a separate protocol to complete the standard of care regimen for each genotype. Preliminary safety and antiviral activity data from the 4-week combination treatment period are anticipated during the third quarter of 2008.
"Based on our pharmacokinetic modeling, we believe that the R7128 1000mg BID combination dosing regimen in Cohort 3 may be able to achieve similar antiviral responses as were demonstrated with R7128 1500mg BID in Cohort 2," stated Dr. Michelle Berrey, Pharmasset's Chief Medical Officer. "Cohort 4 will be the first administration of R7128 in patients with HCV genotypes 2 or 3, and thus will serve as proof-of-concept for this population who we believe represent an area of great unmet medical need. If R7128 shows activity in HCV genotype 2 or 3 patients, this would demonstrate a distinct clinical attribute of nucleoside polymerase inhibitors."
Please see www.clinicaltrials.gov or e-mail clinicaltrials@pharmasset.com for more information.
surf's up......crikey
