In the four trials, sofosbuvir was administered to nearly 1,000 patients with chronic HCV infection as part of an all-oral 12-week or 16-week treatment regimen in combination with ribavirin (
RBV) in genotypes 2 and 3, or with
RBV and pegylated interferon (peg-IFN) for 12 weeks in genotypes 1, 4, 5 and 6. Overall SVR12 rates (sustained viral response 12 weeks after completing therapy) from 50 to 90 percent were observed. Patients who achieve SVR12 are considered cured of their HCV infection.