Gilead announced topline results from the Phase 3 POSITRON study examining a 12-week course of once-daily sofosbuvir plus ribavirin (RBV) in patients with genotype 2 or 3 chronic hepatitis C virus (HCV) infection who are not candidates to take interferon (IFN). Sofosbuvir is a once-daily nucleotide analog polymerase inhibitor.

In the study, HCV genotype 2 or 3 patients who were interferon intolerant, interferon ineligible or unwilling to take interferon were randomized (3:1) to receive 12 weeks of either sofosbuvir 400mg once daily plus weight-based RBV twice daily (n=207) or matching placebo (n=71). Of the 207 patients randomized to the sofosbuvir/RBV arm, 15% had compensated cirrhosis (more advanced liver disease) and 53% were infected with genotype 2. The study found that 78% of patients (n=161/207) remained HCV RNA undetectable 12 weeks after completing therapy (SVR12). SVR12 rates were 93% in genotype 2 and 61% in genotype 3. In the small percentage of patients with cirrhosis at baseline who received sofosbuvir/RBV, 61% achieved SVR12. All patients receiving sofosbuvir/RBV became HCV RNA negative on treatment and relapse accounted for all virologic failures. No patient in the placebo group achieved an SVR12.

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