Study to Evaluate the Antiviral Efficacy, Safety and Tolerability of Tenofovir Disoproxil Fumarate Versus Placebo in Pediatric Participants With Chronic Hepatitis B Infection

Prior treatment

• Received interferon therapy within 6 months of screening
• Received anti-HBV nucleoside/nucleotide therapy within 16 weeks of screening
• Long term non-steroidal, anti-inflammatory drug therapy
  • Note: Other protocol defined Inclusion/Exclusion criteria may apply

Other illness

• Decompensated liver disease
• Co-infection with human immunodeficiency virus (HIV), acute hepatitis A virus (HAV), hepatitis C virus (HCV), or hepatitis D virus (HDV)
• Chronic liver disease not due to HBV
• History of significant renal, cardiovascular, pulmonary, neurological or bone disease

Other

• Pregnant or lactating
• Alpha-fetoprotein levels \> 50 ng/mL
• Evidence of hepatocellular carcinoma (HCC)

• Male or Female, 2 to \< 12 years of age
• Weight ≥ 10 kg
• Chronic HBV infection ≥ 6 months
• Hepatitis B e antigen (HBeAg)-positive or HBeAg-negative
• HBV Viral Load ≥ 100,000 copies/mL
• Alanine aminotransferase (ALT) ≥ 1.5 x the upper limit of the normal range (ULN) at screening
• Creatinine Clearance ≥ 80 mL/min/1.73m\^2
• Absolute neutrophil count (ANC) ≥ 1,500/mm\^3, hemoglobin ≥ 10 g/dL
• Negative pregnancy test at screening
• No prior tenofovir DF therapy (participants may have received prior interferon-alfa and/or other oral anti-HBV nucleoside/nucleotide therapy; participants must have discontinued interferon-alfa therapy ≥ 6 months prior to screening; participants experienced on other anti-HBV nucleoside/nucleotide therapy must have discontinued therapy ≥ 16 weeks prior to screening to avoid flare if randomized to the placebo arm)