Pharmasset and Roche win FDA approval for Phase IIb hepatitis trial

The Phase IIb trial is anticipated to enroll about 400 treatment-naive, genotype-1 or genotype 4 hepatitis C virus (HCV)-infected patients. The trial will evaluate the dose and duration of treatment of R7128 in combination with Pegasys plus Copegus. The primary efficacy endpoint of the trial will be the proportion of patients that achieve a sustained virologic response (SVR), defined as undetectable (measured by Roche TaqMan assay) HCV RNA 24 weeks after completion of treatment.

Patients in the 24-week arms will discontinue treatment at week 24 if they achieved a rapid virological response (RVR), defined as undetectable level of HCV RNA at week four (RVR-guided). Patients that do not achieve an RVR will continue on the standard of care until week 48, the company said.

According to the current study design, patients will be enrolled as two cohorts, with randomization of the second larger cohort being initiated based on 12-week safety data of the first cohort. The company expects to provide updates on the progress of the trial during 2009.

Michelle Berrey, Pharmasset’s chief medical officer, said: “R7128 is the most advanced nucleoside polymerase inhibitor in development and we believe this class of drug brings a number of advantages to HCV-infected patients.

“R7128’s higher barrier to resistance and activity across multiple viral genotypes, as well as the promising short-term safety and tolerability, may bring patients a new option for therapy. We look for this trial to better define the optimal treatment duration with R7128 in combination with the standard of care.”