Suboptimal Responders to Adefovir Switching to Entecavir

Inclusion criteria

• Chronic infection with hepatitis B virus (HBV)(detectable hepatitis B surface antibody (HBsAg) at screening and at least 24 weeks prior to screening, or detectable HBsAg for <24 weeks and negative for immunoglobulin M core antibody)
• Documentation of hepatitis B e antigen (HBeAg) positive or negative status
• Naive to nucleoside/nucleotide analogues, with the exception of adefovir
• Suboptimal response to adefovir treatment
• No lamivudine/telbivudine, entecavir, or adefovir resistance-associated substitutions at screening
• Male or female gender, aged 16 years and older
• Compensated liver function
• Serum alanine aminotransferase level <10*upper limit of normal at screening

Exclusion criteria

• Women who are pregnant or breastfeeding
• Evidence of decompensated cirrhosis
• Coinfection with HIV, hepatitis C virus, or hepatitis D virus
• Recent history of pancreatitis (within 24 weeks prior to the first dose of study medication)
• Chronic renal insufficiency, defined as a creatinine clearance <50 mL/min
• Current abuse of illegal drugs or alcohol, sufficient in the investigator's opinion to prevent adequate compliance with study therapy or to increase the risk of hepatotoxicity or pancreatitis
• Other serious medical conditions that might preclude completion of this study or that require chronic administration of prohibited medications
• Serum creatinine level >1.5 mg/dL; hemoglobin level <10.0 g/dL; platelet count <70,000/mm^3; absolute neutrophil count <1500 cells/mm^3; serum alpha fetoprotein level >100 ng/mL
• Except adefovir, any prior therapy with nucleoside or nucleotide analogue antiviral agents with activity against hepatitis B (eg, lamivudine, entecavir), or any other experimental anti-HBV antiviral, or any China Traditional Medicine
• Therapy with interferon, thymosin alpha, or other immunostimulators within 24 weeks of randomization
• Required chronic administration of medications that cause immunosuppression, that are associated with a high risk of nephrotoxicity or hepatotoxicity, or that affect renal excretion.