The purposes of this study are:

1. To evaluate the efficacy and safety of low-dose versus standard-dose of ribavirin in combination with peginterferon alfa-2a given for 16 weeks in hepatitis C virus (HCV) genotype 2 infected, treatment-naïve chronic hepatitis C patients after achieving a rapid virologic response (RVR,defined as seronegativity of HCV RNA at week 4 of treatment).
2. To evaluate the efficacy and safety of 24-week versus 48-week regimen of peginterferon alfa-2a plus standard-dose of ribavirin in HCV genotype 2 infected, treatment-naïve chronic hepatitis C patients who have no RVR.

The recommended regimen for treating HCV genotype 2 patients is peginterferon plus low dose ribavirin (800 mg/day) for 24 weeks. Recently studies have demonstrated that a shorter treatment duration of 12-16 weeks of peginterferon plus standard weight-based dose of ribavirin (800-1400 mg/day) is as effective as a 24-week regimen among HCV genotype 2 patients with a RVR at week 4 of treatment (rate of sustained virological response, SVR, approximately 90%). However, for patients without a RVR at week 4 the efficacy of 24 week treatment remains unsatisfied. Individualized therapy with tailored regimen according to baseline and on-treatment virological factors, without compromising efficacy, is the future strategy in the management of chronic hepatitis C.

The aims of the present study are

1. To evaluate the efficacy and safety of low-dose versus standard-dose of ribavirin in combination with peginterferon alfa-2a given for 16 weeks in hepatitis C virus (HCV) genotype 2 infected, treatment-naïve chronic hepatitis C patients after achieving a rapid virologic response (RVR,defined as seronegativity of HCV RNA at week 4 of treatment).
2. To evaluate the efficacy and safety of 24-week versus 48-week regimen of peginterferon alfa-2a plus standard-dose of ribavirin in HCV genotype 2 infected, treatment-naïve chronic hepatitis C patients who have no RVR.

Inclusion Criteria:

• Male and female patients 18 years of age
• Patients have never been treated with traditional interferon plus ribavirin or peginterferon plus ribavirin
• Serologic evidence of chronic hepatitis C infection by an anti-HCV antibody test
• Detectable serum HCV-RNA and HCV viral genotype 2
• Liver biopsy findings consistent with the diagnosis of chronic hepatitis C infection with or without compensated cirrhosis (Exception: hemophiliacs in whom biopsy is medically contra-indicated do not require biopsy.)
• Compensated liver disease (Child-Pugh Grade A clinical classification)
• Negative urine or blood pregnancy test (for women of childbearing potential) documented within the 24-hour period prior to the first dose of study drug
• All fertile males and females receiving ribavirin must be using two forms of effective contraception during treatment and during the 6 months after treatment end

Exclusion Criteria:

• Women with ongoing pregnancy or breast feeding
• Therapy with any systemic anti-neoplastic or immunomodulatory treatment (including supraphysiologic doses of steroids and radiation) 6 months prior to the first dose of study drug
• Any investigational drug 6 weeks prior to the first dose of study drug
• Co-infection with active hepatitis A, hepatitis B and/or human immunodeficiency virus (HIV)
• History or other evidence of a medical condition associated with chronic liver disease other than HCV (e.g., hemochromatosis, autoimmune hepatitis, metabolic liver disease, alcoholic liver disease, toxin exposures)
• Signs or symptoms of hepatocellular carcinoma
• History or other evidence of bleeding from esophageal varices or other conditions consistent with decompensated liver disease
• Neutrophil count < 1500 cells/mm3 or platelet count < 90,000 cells/mm3 at screening
• Serum creatinine level > 1.5 times the upper limit of normal at screening
• History of severe psychiatric disease, especially depression. Severe psychiatric disease is defined as treatment with an antidepressant medication or a major tranquilizer at therapeutic doses for major depression or psychosis, respectively, for at least 3 months at any previous time or any history of the following: a suicidal attempt, hospitalization for psychiatric disease, or a period of disability due to a psychiatric disease
• History of a severe seizure disorder or current anticonvulsant use
• History of immunologically mediated disease, chronic pulmonary disease associated with functional limitation, severe cardiac disease, major organ transplantation or other evidence of severe illness, malignancy, or any other conditions which would make the patient, in the opinion of the investigator, unsuitable for the study
• History of thyroid disease poorly controlled on prescribed medications, elevated thyroid stimulating hormone (TSH) concentrations with elevation of antibodies to thyroid peroxidase and any clinical manifestations of thyroid disease
• Evidence of severe retinopathy (e.g. CMV retinitis, macula degeneration)
• Evidence of drug abuse (including excessive alcohol consumption) within one year of study entry
• Inability or unwillingness to provide informed consent or abide by the requirements of the study
• Male partners of women who are pregnant
• Hgb < 11 g/dL in women or < 12 g/dL in men at screening
• Any patient with major thalassemia
• Patients with documented or presumed coronary artery disease or cerebrovascular disease should not be enrolled if, in the judgment of the investigator, an acute decrease in hemoglobin by up to 4 g/dL (as may be seen with ribavirin therapy) would not be well-tolerated