HCV positive subjects documented by serum HCV RNA concentration > 100,000 IU/mL within 21 days of first study treatment Receipt of adequate previous PEG-IFN and RBV therapy for a minimum of 12 weeks (PEG-IFN alpha-2a doses of > 180 μg/wk or PEG-IFN alpha-2b 1.5 µg/kg/wk and at least 800 mg RBV daily) not resulting in a minimum of a 2 log decrease in HCV RNA concentrations while on treatment (null responders). Or, receipt of adequate previous treatment PEG-IFN and RBV therapy for a minimum of 24 weeks (PEG-IFN alpha-2a doses of ≥ 180 μg/wk or PEG-IFN alpha-2b 1.5 µg/kg/wk and at least 800 mg RBV daily) resulting in a minimum of a 2 log decrease in serum HCV RNA concentrations by 12 weeks of treatment but not resulting in an undetectable viral load after 24 weeks of treatment (partial responders). If dose modifications were necessary during the treatment due to adverse events, the subject must have received at least 80% of the PEG-IFN dose and 80% of the RBV dose to be eligible for the study.