The purpose of this study in HCV genotype 4-infected participants with compensated cirrhosis is to assess the safety and to compare the percentage of participants achieving a 12-week sustained virologic response (SVR12), [HCV ribonucleic acid (RNA) < lower limit of quantification (LLOQ) 12 weeks following treatment], to a clinically relevant threshold [based on SVR rates for HCV genotype 4-infected participants treated with pegylated interferon (pegIFN)/RBV].

This is a Phase 3, randomized, open-label, multicenter study evaluating the safety and efficacy of ombitasvir/paritaprevir/ritonavir coadministered with RBV for 12, 16, or 24 weeks in HCV genotype 4 (GT4)-infected participants with compensated cirrhosis who are either treatment-naïve or who had previously received only IFN/RBV treatment for HCV.

The study also enrolled HCV GT4-infected participants with compensated cirrhosis who had previously experienced virologic failure with either SOF/pegIFN/RBV or sofosbuvir (SOF)/RBV treatment. These participants were treated with ombitasvir/paritaprevir/ritonavir coadministered with RBV for 24 weeks in this study.

This study was divided into 2 parts with approximately 184 total participants. Part I included participants who were randomized to receive either 12 or 16 weeks of treatment and Part II included participants who received 24 weeks of treatment. Enrollment into Part II opened once randomization in Part I was completed.

Inclusion Criteria:

For Arms A, B and C:

- Participants must meet one of the following:

• Treatment-naive: Participant has never received antiviral treatment for hepatitis C infection OR
• Treatment Experienced (Prior null responders, Partial responders or Relapsers to IFN/RBV);

For Arm D:

- Participant must have prior treatment experience with SOF/pegIFN/RBV or SOF/RBV and meet one of the following categories:

• Prior SOF breakthrough/non-responder: HCV RNA detectable at the end of treatment with SOF/pegIFN/RBV or SOF/RBV;
• Prior SOF relapser: achieved HCV RNA undetectable at end of a prior treatment course SOF/pegIFN/RBV or SOF/RBV, but HCV RNA was detectable within 52 weeks following completion of therapy.

For Arms A, B, C and D:

• Chronic HCV genotype 4 infection with cirrhosis.
• Participant has plasma HCV RNA level > 1,000 IU/mL at Screening

Exclusion Criteria:

• Positive test result at Screening for Hepatitis B surface antigen (HBsAg) or anti-human immunodeficiency virus antibody (HIV Ab).
• Current enrollment in another interventional clinical study, previous enrollment in this study, or previous use of any protease inhibitor, non-nucleoside polymerase inhibitor, or Nonstructural viral protein (NS) 5A inhibitor, either investigational or commercially available (including previous exposure to paritaprevir or ombitasvir), or receipt of any investigational product within 6 weeks prior to study drug administration. Prior use of any direct-acting antiviral will not be allowed, except for Arm D where prior experience with the nucleoside polymerase inhibitor, sofosbuvir with pegIFN/RBV or SOF with RBV is required.
• Any current or past clinical evidence of Child-Pugh B or C classification or clinical history of liver decompensation including ascites, variceal bleeding, or hepatic encephalopathy.
• Confirmed presence of hepatocellular carcinoma.
• Any cause of liver disease other than chronic HCV infection.
• Abnormal laboratory tests.