This study evaluated the safety, tolerability, antiviral activity, and pharmacokinetics of ABT-450 (also known as paritaprevir) with ritonavir (ABT-450/r) and ABT-267 (also known as ombitasvir) in adult Japanese patients with chronic hepatitis C virus genotype 1b (HCV GT1b) or genotype 2 (HCV GT2) infection who were previous treated with pegylated interferon/ribavirin (pegIFN/RBV).

This multicenter, randomized, open-label, parallel-arm, combination treatment study consisted of a Treatment and Post-treatment Phase, divided into 2 cohorts: 1) chronic HCV GT1b- infected, pegIFN/RBV treatment-exposed Japanese adults; and 2) HCV GT2-infected, pegIFN/RBV treatment-exposed Japanese adults. The Treatment Phase evaluated the antiviral activity, safety, and pharmacokinetics of a range of ABT-450/r and ABT-267 doses for 12 to 24 weeks. The Post-treatment Phase evaluated the evolution and persistence of viral resistance to ABT-267 and ABT-450.

Inclusion Criteria:

• Females must be practicing specific forms of birth control on study treatment, or be post-menopausal for more than 2 years or surgically sterile
• Chronic hepatitis C, genotype 1b (HCV-GT1b) or genotype 2 (HCV GT2) infection (HCV RNA level greater than 10,000 IU/mL at screening) previously treated with pegylated interferon/ribavirin (pegIFN/RBV).
• Subject's hepatitis C virus genotype is subgenotype 1b and subject was a null responder or partial responder, OR
• Subject's hepatitis C virus genotype is subgenotype 2 and subject was a null responder, partial responder, or relapser (Null responder: received at least 10 weeks of pegIFN/RBV for the treatment of HCV and failed to achieve a 2 log10 IU/mL reduction in HCV RNA at Week 12; Partial responders: received at least 20 weeks of pegIFN/RBV for the treatment of HCV and achieved ≥ 2 log10 IU/mL reduction in HCV RNA at Week 12, but failed to achieve HCV RNA undetectable (HCV RNA < lower limit of detection [< LLOD]) at the end of treatment; Relapsers: received at least 1 course of pegIFN/RBV for the treatment of HCV and was undetectable at the end of treatment, but HCV RNA was detectable within 24 weeks of treatment follow-up).

Exclusion Criteria:

• Significant liver disease with any cause other than HCV as the primary cause
• Positive screen for drugs or alcohol.
• Positive hepatitis B surface antigen or anti-human immunodeficiency virus antibody.
• Use of contraindicated medications within 2 weeks of dosing
• Previous use of any investigational or commercially available anti-Hepatitis C virus agent other than pegIFN/RBV, including previous exposure to ABT-450 or ABT-267.

Baseline characteristics were summarized by treatment arm for all participants who received at least 1 dose of study drug.

Treatment-emergent AEs (TEAEs) were collected from first dose of study drug administration to 30 days after last dose (up to 28 weeks); SAEs were collected from the time that informed consent was obtained to 30 days after last dose (total up to 77 weeks).

TEAEs were collected from the first dose of study drug to 30 days after last dose (12-week treatment: up to 16 weeks; 24-week treatment: up to 28 weeks); SAEs were collected from the time that informed consent was obtained to 30 days after last dose (12-week treatment: total up to 65 weeks; 24-week treatment: total up to 77 weeks).