Purpose / DescriptionIn this randomized, placebo-controlled phase 3 trial, treatment-naïve and treatment-experienced adults with chronic hepatitis C genotype 1, 2, 4, 5, or 6 infection were randomized in a 5:1 ratio to receive either sofosbuvir-velpatasvir or placebo. In the treatment arm (n=624), 19% had compensated cirrhotic and 28% were treatment-experienced. The overall SVR12 rate was 99% (618 of 624), with a range of 97 to 100% across the genotypes. Only two viral relapses occurred and these involved participants with genotype 1a and 1b. Among the 121 patients with cirrhosis, 99% (120 of 121) achieved an SVR 12. The presence of baseline NS5A resistance-associated variants, present in 42% of evaluated participants, did not appear to influence SVR12. There was no significant difference in the rate of adverse events between the treatment and placebo arms.