Entecavir/Pegylated Interferon in Immune Tolerant Children With Chronic Hepatitis B Virus (HBV) Infection

Inclusion Criteria

• Enrolled in & completed the baseline evaluation in NCT01263600 OR completed necessary components of NCT01263600 baseline evaluation by the end of the baseline visit.
• 3 to 10^7 IU/mL on at least 2 occasions at least 12 weeks apart during the 52 weeks before baseline visit. The HBV DNA levels must be within 6 weeks of baseline visit.
• ALT ≤60 U/l in males or ≤40 U/l in females, measured on at least 2 occasions, at screening (within 6 weeks prior to baseline visit) & at least 12 weeks prior to the screening visit & within the 52 weeks prior to baseline visit.
• Compensated liver disease, with normal total bilirubin (except if Gilbert's syndrome), direct bilirubin ≤0.5 mg/dL, International Normalized Ratio (INR) ≤1.5, and serum albumin ≥3.5 g/dL.
• Creatinine clearance 90 ml/min.
• Absence of hepatocellular carcinoma on liver ultrasound in the past 48 weeks.

Exclusion criteria

• Presence of infection with Hepatitis C virus (HCV)-RNA or anti-HCV, anti-Hepatitis D virus (HDV), or HIV at screening.
• Presence of another cause of liver disease or hepatocellular cancer (HCC) (serum alpha-fetoprotein >50ng /ml).
• Evidence of decompensated liver disease (Childs B-C).
• History or other evidence of a medical condition associated with chronic liver disease (e.g., hemochromatosis, autoimmune hepatitis, alcoholic liver disease, toxin exposures).
• Females who are pregnant or breastfeeding.
• Adolescent females unwilling or unable to use an acceptable method of contraception if sexually active during the treatment period.
• Children currently breastfeeding while their mother is taking lamivudine, or those who were exposed to lamivudine for ≥24 weeks via maternal lamivudine treatment during pregnancy and/or while breastfeeding.
• Previous liver or other organ transplantation including engrafted bone marrow transplant.
• Hematological abnormalities during the screening period that contraindicate full dosing with study drugs, e.g absolute neutrophil count < 1.5 x 10^9 cells/L or platelet count < 120 x 10^9 cells/L.
• Known allergy to study drugs; peginterferon alfa-2a or entecavir.
• Treatment with systemic acyclovir or famciclovir within the previous 6 months.
• Need for ongoing use of any antivirals with activity against HBV during the course of the study or history of receiving treatment for HBV.
• Any use of illegal drugs OR use of alcoholic beverages which in the opinion of a study physician is sufficient to prevent adequate compliance with study procedures or increase the risk of pancreatitis or hepatotoxicity.
• History of immunologically mediated disease (e.g. inflammatory bowel disease, idiopathic thrombocytopenic purpura, lupus erythematosus, autoimmune haemolytic anemia, scleroderma, severe psoriasis, rheumatoid arthritis).
• History or other evidence of bleeding from esophageal varices or consistent with decompensated liver disease.
• History or other evidence of chronic pulmonary disease associated with functional limitation.
• History of significant cardiovascular diseases.
• History of a severe seizure disorder or current anticonvulsant use.
• History or other evidence of severe retinopathy.
• History of thyroid disease poorly controlled on prescribed medications. Participants with elevated thyroid stimulating hormone concentrations with elevation of antibodies to thyroid peroxidase and any clinical manifestations of thyroid disease are excluded.
• Concomitant use or use during ≤ 6 months prior to the first dose of study drug of anti-neoplastic, immunosuppressive, nephrotoxic or hepatotoxic medication, methadone, theophylline or medications that may affect renal excretion or hepatic metabolism are not permitted.
• Concomitant use of complementary or alternative medications purported to have antiviral activity.
• A participant may not be co-enrolled in another clinical trial where an investigational drug is administered.
• Any other condition or situation that in the opinion of a study physician would