Multi-Center, Randomized, Open-Label Study of G/P +/- RBV for NS5A + SOF Previously Treated GT1 HCV Subjects

Inclusion Criteria: 1. Male or female at least 18 years of age at time of screening. 2. A history of previous treatment with an NS5A-inhibitor plus sofosbuvir therapy ± RBV for chronic HCV genotype 1 infection. 3. Treatment must have been completed at least 1 month prior to Screening Visit. 4. Screening laboratory result indicating chronic HCV GT1 infection. Subjects must be able to understand and adhere to the study visit schedule and all other protocol requirements and must voluntarily sign and date an informed consent. Exclusion Criteria: 1. History of severe, life-threatening or other significant sensitivity to any drug. 2. Female who is pregnant, planning to become pregnant during the study or breastfeeding; or male whose partner is pregnant or planning to become pregnant during the study. 3. Recent (within 6 months prior to study drug administration) history of drug or alcohol abuse that could preclude adherence to the protocol in the opinion of the investigator. 4. Positive test result at Screening for hepatitis B surface antigen (HBsAg) or anti-human immunodeficiency virus antibody (HIV Ab) in patient without known history of HIV infection. 5. HCV genotype performed during screening indicating co-infection with more than one HCV genotype. 6. History or presence of liver decompensation.