In Vitro Drug Susceptibility Analysis of Hepatitis B Virus Clinical Quasispecies Populations▿

Analysis of the replication and drug resistance of patient serum hepatitis B virus (HBV) populations can contribute to the therapeutic management of chronic hepatitis B. We developed a procedure for cloning serum HBV quasispecies populations and for phenotypic analysis of the cloned populations for in vitro drug susceptibility. Equivalent sequences were compared to the respective serum HBV DNAs of the cloned quasispecies by population sequencing. Analysis of individual clones revealed that each population contained a diversity of HBV quasispecies. Furthermore, secreted HBV in the supernatant following transfection of the quasispecies populations remained mostly unchanged from the respective input populations. HBV obtained from patients who had developed resistance to adefovir or lamivudine, as demonstrated by development of the rtA181V or rtL180M/M204V mutations in HBV polymerase, respectively, were tested. Phenotypic analysis demonstrated that a population containing the HBV rtA181V mutation showed a 2.9-fold increase in the 50% effective concentration (EC50) for adefovir compared to the wild-type baseline isolate, while the lamivudine-resistant HBV quasispecies population showed a >1,000-fold increase in the lamivudine EC50. In summary, a strategy of cloning full genome HBV quasispecies populations from patient sera was developed, which could provide a useful tool in clinical HBV drug resistance phenotyping and studies of the evolution of clinical viral species

Tenofovir disoproxil fumarate versus adefovir dipivoxil for chronic hepatitis B

Background: Tenofovir disoproxil fumarate (DF) is a nucleotide analogue and a potent inhibitor of human immunodeficiency virus type 1 reverse transcriptase and hepatitis B virus (HBV) polymerase. Methods: In two double-blind, phase 3 studies, we randomly assigned patients with hepatitis B e antigen (HBeAg)-negative or HBeAg-positive chronic HBV infection to receive tenofovir DF or adefovir dipivoxil (ratio, 2:1) once daily for 48 weeks. The primary efficacy end point was a plasma HBV DNA level of less than 400 copies per milliliter (69 IU per milliliter) and histologic improvement (i.e., a reduction in the Knodell necroinflammation score of 2 or more points without worsening fibrosis) at week 48. Secondary end points included viral suppression (i.e., an HBV DNA level of <400 copies per milliliter), histologic improvement, serologic response, normalization of alanine aminotransferase levels, and development of resistance mutations. Results: At week 48, in both studies, a significantly higher proportion of patients receiving tenofovir DF than of those receiving adefovir dipivoxil had reached the primary end point (P<0.001). Viral suppression occurred in more HBeAg-negative patients receiving tenofovir DF than patients receiving adefovir dipivoxil (93% vs. 63%, P<0.001) and in more HBeAg-positive patients receiving tenofovir DF than patients receiving adefovir dipivoxil (76% vs. 13%, P<0.001). Significantly more HBeAg-positive patients treated with tenofovir DF than those treated with adefovir dipivoxil had normalized alanine aminotransferase levels (68% vs. 54%, P = 0.03) and loss of hepatitis B surface antigen (3% vs. 0%, P = 0.02). At week 48, amino acid substitutions within HBV DNA polymerase associated with phenotypic resistance to tenofovir DF or other drugs to treat HBV infection had not developed in any of the patients. Tenofovir DF produced a similar HBV DNA response in patients who had previously received lamivudine and in those who had not. The safety profile was similar for the two treatments in both studies. Conclusions: Among patients with chronic HBV infection, tenofovir DF at a daily dose of 300 mg had superior antiviral efficacy with a similar safety profile as compared with adefovir dipivoxil at a daily dose of 10 mg through week 48. (ClinicalTrials.gov numbers, NCT00116805 and NCT00117676.). Copyrigh

Three-Year Efficacy and Safety of Tenofovir Disoproxil Fumarate Treatment for Chronic Hepatitis B

BACKGROUND & AIMS: Tenofovir disoproxil fumarate (TDF), a nucleotide analogue and potent inhibitor of hepatitis B virus (HBV) polymerase, showed superior efficacy to adefovir dipivoxil in treatment of chronic hepatitis B through 48 weeks. We evaluated long-term efficacy and safety of TDF monotherapy in patients with chronic hepatitis B who were positive or negative for hepatitis B e antigen (HBeAg(+) or HBeAg(-)). METHODS: After 48 weeks of double-blind comparison of TDF to adefovir dipivoxil, patients who underwent liver biopsy were eligible to continue the study on open-label TDF for 7 additional years; data presented were collected up to 3 years (week 144) from 85% of participants. Primary efficacy end points at week 144 included levels of HBV DNA and alanine aminotransferase, development of resistance mutations, and presence of HBeAg or hepatitis B surface antigen (HBsAg). RESULTS: At week 144, 87% of HBeAg(-) and 72% of HBeAg(+) patients treated with TDF had levels of HBV DNA <400 copies/mL. Among patients who had previously received adefovir dipivoxil and then received TDF, 88% of the HBeAg(-) and 71% of the HBeAg(+) patients had levels of HBV DNA <400 copies/mL; overall, 81% and 74%, respectively, maintained normalized levels of alanine aminotransferase and 34% had lost HBeAg. Amino acid substitutions in HBV DNA polymerase that are associated with resistance to tenofovir were not detected in any patient. Cumulatively, 8% of HBeAg(+) patients lost HBsAg. TDF maintained a favorable safety profile for up to 3 years. CONCLUSIONS: TDF was safe and effective in the long-term management of HBeAg(+) and HBeAg(-) patients with chronic hepatitis B