A Randomized, Double-Blind Study Evaluating Tenofovir Disoproxil Fumarate (DF) Monotherapy Versus the Combination of Emtricitabine and Tenofovir DF for the Treatment of Chronic Hepatitis B

INTERVENTION: The current study will be looking at the efficacy, safety and tolerability of tenofovir DF monotherapy versus the once‐daily combination of tenofovir DF plus emtricitabine in patients who have chronic Hepatitis B Virus [Hepatitis B e Antigen (HBeAg) negative or positive disease]. Subjects will be randomized in a 1:1 ratio to treatment arms A or B. Tenofovir DF 300 mg will be provided open‐label while emtricitabine 200 mg will be provided in a blinded fashion: Treatment B: Open label tenofovir DF 300 mg once daily +emtricitabine 200 mg once daily. Subjects will be instructed to take 1 pill from each bottle once daily: one tablet (open label tenofovir DF) and one capsule (emtricitabine 200 mg). All subjects will continue on study medication until Week 48. At Week 48, Gilead Sciences will provide open label tenofovir DF 300 mg for study subjects in countries where the drug is not commercially available, until such access is available. Subjects who wish to discontinue therapy will be followed off treatment for 24 weeks or until the initiation of alternate commercial therapy. CONDITION: Chronic Hepatitis B PRIMARY OUTCOME: The primary objective of this study is to compare the antiviral efficacy against hepatitis B virus of tenofovir DF monotherapy versus tenofovir DF plus emtricitabine combination therapy. The parameter being virological suppression, i.e., HBV DNA < Lower Limit of Quantitation (LLOQ) at Week 48. SECONDARY OUTCOME: To compare the incidence of drug resistant mutations between treatment arms. To evaluate the biochemical and serological response to tenofovir DF monotherapy versus tenofovir DF plus emtricitabine combination therapy. To evaluate the safety and tolerability of tenofovir DF monotherapy versus tenofovir DF plus emtricitabine combination therapy INCLUSION CRITERIA: To be eligible for participation, at screening subjects with chronic Hepatitis B Virus (HBV) infection [Hepatitis B Surface Antigen (HBsAg) > 6 months or HBsAg positive > 3 months and negative for Immunoglobulin M (IgM), Antibodies to Hepatitis B Core Antigen (anti‐HBc) and positive for Immunoglobin G (IgG) anti‐HBc], HBV DNA levels > or = 10^8 copies/mL, Alanine Transferase (ALT) levels > or = Upper Limit of Normal (ULN), creatinine clearance > or = 70 mL/min, alpha‐fetoprotein < 50 ng/mL.