Purpose / DescriptionIn this randomized, open-label, phase 3 trial, 420 adults with genotype 1, 4, or 6 hepatitis C infection and a history of treatment failure with peginterferon and ribavirin received elbasvir-grazoprevir (50/100 mg), with or without ribavirin, for 12 or 16 weeks. Among participants who received a 12-week regimen, the SVR12 rate was 94% for elbasvir-grazoprevir with ribavirin and 92% for elbasvir-grazoprevir without ribavirin. In the 16-week treatment arms, the SVR12 rate was 97% and 92% for elbasvir-grazoprevir, with and without ribavirin respectively. Notably, of the 12 patients with genotype 1a who experienced viral relapse, 10 had evidence of a baseline NS5A resistance-associated variant.