Interleukin 29 (IL-29) is a substance that is produced in the body to help fight viral infections. The purpose of this study is to test the safety and antiviral effects of PEG-rIL-29 (a man-made form of IL-29) when it is given either by itself at different doses or in combination with the approved dose of ribavirin (an antiviral drug) to subjects with hepatitis C infection who have received no prior treatment for this disease or who have relapsed following previous treatment with PEGylated interferon alpha (PEG-IFN-α), or other form of IFN-α, and ribavirin.

This is a 3-part study of PEG-rIL-29 in subjects with chronic genotype 1 hepatitis C virus infection who have either received no prior treatment with a PEGylated IFN-α (or other form of IFN-α) or who have relapsed following prior treatment with a PEGylated IFN-α (or other form of IFN-α) and ribavirin. Part 1 of the study will evaluate the safety and tolerability of escalating doses of PEG-rIL-29 when given as a single agent either every other week or weekly over a 4-week period to treatment-relapsed subjects. Part 2 of the study will evaluate dose levels and/or schedules of PEG-rIL-29 in combination with daily oral ribavirin administered over a 4-week period to treatment-relapsed subjects. Part 3 of the study will evaluate dose levels and/or schedules of PEG-rIL-29 in combination with daily oral ribavirin administered over a 4-week period to subjects who have received no prior treatment.

Inclusion Criteria:

• Relapsed subjects (Parts 1 and 2) -- Prior treatment for HCV with PEG-IFN-alpha (or other IFN-alpha) and ribavirin for at least 12 weeks. Naive subjects (Part 3) -- No prior treatment with PEG-IFN-alpha (or other IFN-alpha)
• Genotype 1 HCV RNA greater than or equal to 100,000 IU/mL. Mixed genotype HCV infection is not allowed
• Documented liver biopsy ≤2 years of study enrollment with Ishak score ≤4
• No evidence of hepatocellular carcinoma documented by abdominal imaging within 12 months of study entry
• no evidence of clinically significant diastolic or systolic dysfunction or other clinically significant abnormalities on echocardiogram or ECG
• Negative drug and alcohol tests except for physician prescribed or approved medication
• If male, or female of child-bearing potential, agrees to use 2 forms of medically accepted contraception while on study

Exclusion Criteria:

• Evidence of decompensated liver disease
• History of hypersensitivity to IFN-alpha or ribavirin
• Active substance abuse, such as alcohol, inhaled or injection drugs within the previous 6 months
• Undergone surgery or received blood products within 30 days prior to study enrollment
• Prior history of cardiomyopathy, coronary artery disease including angina, interventive procedure for coronary artery disease including angioplasty, stent procedure or cardiac bypass surgery, prior myocardial infarction, or ventricular tachycardia
• Prior or current history of hemoglobinopathy or hemolytic anemia