Effects of tenofovir disoproxil fumarate in hepatitis B e antigen-positive patients with normal levels of alanine aminotransferase and high levels of hepatitis B virus DNA.

BACKGROUND & AIMS: Little is known about the benefit of antiviral therapy for hepatitis B e antigen (HBeAg)-positive patients with high viral load and normal levels of alanine aminotransferase. We evaluated the effects of single and combination therapies in immune-tolerant patients with chronic hepatitis B. METHODS: In a double-blind study, nucleos(t)ide-naïve patients with high levels of hepatitis B virus (HBV) DNA who were positive for HBeAg and had normal levels of alanine aminotransferase were randomly assigned to groups given either oral tenofovir disoproxil fumarate (TDF, 300 mg) and placebo (n = 64) or a combination of TDF (300 mg) and emtricitabine (200 mg, n = 62) for 192 weeks. The primary end point was proportion of patients with serum levels of HBV DNA <69 IU/mL at week 192. RESULTS: The study population (mean age was 33 years; 89% were Asian) was predominantly infected with HBV genotypes B and C (93%), 99% were HBeAg positive with a mean baseline level of HBV DNA of 8.41 log10 IU/mL. At week 192, 55% of patients (35 of 64) in the TDF+placebo group and 76% of patients (47 of 62) in the TDF+emtricitabine group had levels of HBV DNA <69 IU/mL (P = .016). No patients were found to have viral resistance to therapy. HBeAg seroconversion occurred in 3 patients (5%), all in the TDF+placebo group; no patient had loss of hepatitis B surface antigen. In multivariate analysis, female sex (odds ratio = 7.05; P = .002) and TDF+emtricitabine treatment (odds ratio = 3.9; P = .01) were associated with a favorable response. Both regimens were well tolerated. CONCLUSIONS: In HBeAg-positive patients with chronic HBV infection, high viral loads, normal levels of alanine aminotransferase, and therapy with the combination of TDF and emtricitabine provided better viral suppression than TDF alone, although rates of HBeAg seroconversion and hepatitis B surface antigen loss were low.

Selection of clinically relevant protease inhibitor-resistant viruses using the genotype 2a hepatitis C virus infection system.

Treatment of patients infected with hepatitis C virus (HCV) with direct acting antivirals can lead to the emergence of drug-resistant variants that may pose a long-term threat to viral eradication. HCV replicons have been used to select resistance mutations; however, genotype 2a JFH-1-based viruses provide the opportunity to perform resistance selection in a bona fide infection system. In this study, we used a tissue culture-adapted J6/JFH-1 virus to select resistance to the NS3 protease inhibitors BILN-2061 and VX-950. Lunet-CD81 cells were infected with J6/JFH-1 virus and maintained in the presence of inhibitors until high-titer viral supernatant was produced. Viral supernatants were passaged over naive cells at escalating drug concentrations, and the resulting viruses were then characterized. Three NS3 resistance mutations were identified in BILN-2061-resistant viruses: A156G, D168A, and D168V. Interestingly, D168A, D168V, and A156T/V, but not A156G, were selected in parallel using a genotype 2a replicon. For VX-950, the T54A and A156S NS3 resistance mutations were identified in the virus selections, whereas only A156T/V emerged in genotype 2a replicon selections. Of note, VX-950 resistance mutations selected using the 2a virus (T54A and A156S) were also observed during VX-950 clinical studies in genotype 2 patients. We also performed viral fitness evaluations and determined that the mutations selected in the viral system did not confer marked reductions in virus production kinetics or peak titers. Overall, the HCV infection system is an efficient tool for drug resistance selections and has advantages for the rapid identification and characterization of clinically relevant resistance mutations.