A Study to Compare Tenofovir Disoproxil Fumarate Versus Adefovir Dipivoxil for the Treatment of HBeAg-Positive Chronic Hepatitis B

The primary objectives of this study are to compare the efficacy, safety, and tolerability of tenofovir disoproxil fumarate (TDF) versus adefovir dipivoxil (ADV) for the treatment of HBeAg-positive chronic hepatitis B. Participants will receive TDF or ADV for 48 weeks (double-blind). After 48 weeks, eligible participants switched to open-label TDF for up to 480 weeks.


Eligibility Criteria:
Key Inclusion Criteria:

A patient must meet all of the following inclusion criteria to be eligible for participation in this study:

* Chronic hepatitis B virus (HBV) infection, defined as positive serum hepatitis B s-antigen (HBsAg) for more than 6 months
* 18 through 69 years of age, inclusive
* Active hepatitis B e-antigen (HBeAg) positive chronic HBV infection, with all of the following:

  * HBeAg positive at screening
  * Alanine aminotransferase (ALT) levels \> 2 × ULN and ≤ 10 × the upper limit of the normal range (ULN)
  * Serum HBV DNA \> 1 million copies/mL at screening
  * creatinine clearance ≥ 70 mL/min
  * hemoglobin ≥ 8 g/dL
  * neutrophils ≥ 1,000 /mL
* Knodell necroinflammatory score ≥ 3 and a Knodell fibrosis score \< 4; however, up to 96 patients with cirrhosis, ie, a Knodell fibrosis score equal to 4, will be eligible for enrollment
* Negative serum β-human chorionic gonadotropin (hCG)
* Nucleotide naïve, ie, no prior nucleotide (TDF or ADV) therapy for \> 12 weeks
* Nucleoside naïve, ie, no prior nucleoside (any nucleoside) therapy for \> 12 weeks
* Willing and able to provide written informed consent
* Liver biopsy performed within 6 months of baseline and has readable biopsy slides or agrees to have a biopsy performed prior to baseline

Key Exclusion Criteria:

A patient who meets any of the following exclusion criteria is not to be enrolled in this study:

* Pregnant women, women who are breast feeding or who believe they may wish to become pregnant during the course of the study
* Males and females of reproductive potential who are unwilling to use an effective method of contraception during the study; for males, condoms should be used and for females, a barrier contraception method should be used
* Decompensated liver disease defined as conjugated bilirubin \> 1.5 x ULN, prothrombin time (PT) \> 1.5 x ULN, platelets \< 75,000/mL, serum albumin \< 3.0 g/dL, or prior history of clinical hepatic decompensation (eg, ascites, jaundice, encephalopathy, variceal hemorrhage)
* Received any nucleoside, nucleotide (TDF or ADV) or interferon (pegylated or not) therapy within 6 months prior to the pre-treatment biopsy
* Evidence of hepatocellular carcinoma (HCC), ie, α-fetoprotein \>50 ng/mL
* Coinfection with hepatitis C virus (HCV), human immunodeficiency virus (HIV), or hepatitis delta virus (HDV)
* Significant renal, cardiovascular, pulmonary, or neurological disease
* Received solid organ or bone marrow transplantation
* Is currently receiving therapy with immunomodulators (eg, corticosteroids, etc.), investigational agents, nephrotoxic agents, or agents susceptible of modifying renal excretion
* Has proximal tubulopathy

Note: Other protocol defined Inclusion/Exclusion criteria may apply.