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

Key Inclusion Criteria:

• 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) atscreening

• 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-alfaand/or other oral anti-HBV nucleoside/nucleotide therapy; participants must havediscontinued interferon-alfa therapy ≥ 6 months prior to screening; participantsexperienced on other anti-HBV nucleoside/nucleotide therapy must have discontinuedtherapy ≥ 16 weeks prior to screening to avoid flare if randomized to the placeboarm)

Key Exclusion Criteria:

• Pregnant or lactating

• Decompensated liver disease

• Received interferon therapy within 6 months of screening

• Received anti-HBV nucleoside/nucleotide therapy within 16 weeks of screening

• Alpha-fetoprotein levels > 50 ng/mL

• Evidence of hepatocellular carcinoma (HCC)

• 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 bonedisease

• Long term non-steroidal, anti-inflammatory drug therapy

Note: Other protocol defined Inclusion/Exclusion criteria may apply