R7128, a prodrug of PSI-6130, is a nucleoside analogue polymerase inhibitor of hepatitis c virus (HCV) that is being developed through Pharmasset’s collaboration with Roche.
Cohort 3 will study R7128 1000mg BID in treatment-naive patients with HCV genotype 1. This cohort is intended to provide clinical antiviral activity data in support of pharmacokinetic models from earlier studies. Cohort 4 will study R7128 1500mg BID in patients with HCV genotypes 2 and 3 who did not achieve a sustained virologic response (SVR) with previous interferon-based therapy. Cohorts 3 and 4 will both be dosed in combination with Pegasys (peginterferon alfa-2a) plus Copegus (ribavirin).
Patients in Cohorts 3 and 4 are scheduled to begin dosing by the end of May 2008. Preliminary safety and antiviral activity data from the four-week combination studies are anticipated during the third quarter of 2008.