A Study of Switch From Nucleotide to Peginterferon Alfa-2a in CHB Patients Achieving HBeAg Loss and HBV DNA <200IU/ml

Inclusion Criteria: * Patients on-treatment with NAs (ADV, ETV or LAM) for 1-3 years, having achieved HBeAg loss at screening, and HBV DNA \<200IU/ml for at least 48 weeks * Male and female patients ≥ 18 to 65 years of age * Chronic hepatitis B (positive HBsAg for at least 6 months prior to NA therapy start) * Compensated liver disease (Child-Pugh \<6) * Absence of hepatocellular carcinoma on liver imaging and/or alfa fetoprotein \< 50 ng/ml * Negative urine or blood pregnancy test for women of childbearing potential within 24 hours of first PEG IFN study medication administration * Able and willing to provide informed consent and abide by the requirements of the study Exclusion Criteria: * Neutrophil count \<1.5 x 109cells/L or platelet count \<90 x 109cells/L * Co-infections with HIV, HAV, HCV, HDV or HEV * Women with ongoing pregnancy or breast feeding, or wishing to become pregnant during the study period * Prolonged and excessive alcohol intake (\> 40g/day for men and \> 30g/day for women) * Active intravenous drug abuse * History or current treatment with telbivudine * Treatment with immunomodulators (e.g. Interferon) for less than one year before study enrollment * Treatment with immunosuppressors (including systemic corticosteroids) or anti-neoplastic treatment (including radiation therapy) \<=6 months prior to the first dose of study drug or the expectation that such treatment will be needed at any time during the study * Serum concentrations of ceruloplasmin or alfa-antitrypsin consistent with an increased risk of metabolic disease * History or other evidence of chronic pulmonary disease associated with functional limitation * History of severe cardiac disease * History of the severe seizure disorder or current anticonvulsivant use * History of thyroid disease poorly controlled on prescribed medications. Patients with elevated thyroid stimulating hormone concentrations with elevation of antibodies to thyroid peroxidase and any clinical manifestations of thyroid disease * History or other evidence of severe retinopathy * History of autoimmune disease or presence of a significant level of auto-antibodies * Renal insufficiency (creatinine clearance of \< 50 ml/min according to the Cockroft and Gault equation), kidney transplant, hemodialysis * History of depression or uncontrolled psychiatric disorders * Subjects protected by law or not in a position to give consent * Patients with reproductive potential not willing to use an effective method of contraception. * Evidence of an active or suspected cancer or a history of malignancy (other than basocellular carcinoma or in-situ cervical carcinoma)