title: Virological response and incidence of adefovir resistance in lamivudine-resistant patients treated with adefovir dipivoxil.
abstract: OBJECTIVE
  The incidence of adefovir dipivoxil (ADV) resistance in patients with lamivudine (3TC)-resistant mutants who received ADV therapy remains unclear. The aims of this study were to determine the virological response to ADV, the incidence and the risk factors of ADV resistance, and the associated factors of initial virological response (IVR) in lamivudine-resistant patients.
  
  
  METHODS
  Forty-six consecutive lamivudine-resistant chronic hepatitis B patients treated with ADV for more than 12 months with or without 3TC overlapping were prospectively examined for virological response and adefovir resistance.
  
  
  RESULTS
  IVR was documented in 24 (52.2%) of patients. Of the 46 patients, 11 had ADV resistance (5 rtN236T, 5 rtA181T, 1 rtA181T and rtN236T). The cumulative incidence of ADV resistance at month 6, 12, 18 and 24 was 0%, 6.5%, 24.6% and 38.3% respectively. Compared with those without ADV resistance, patients with ADV resistance had a significantly higher rate of liver cirrhosis. Based on Cox regression analysis, the significant risk factor of ADV resistance was younger age (OR=0.92, 95% CI=0.86-0.99, P=0.023) and liver cirrhosis (OR=5.3, 95% CI=1.12-25.09, P=0.036). In addition, patients with ADV resistance were associated with higher HBV DNA levels and lower HBV DNA reduction in first 6 months of ADV treatment than those without ADV resistance.
  
  
  CONCLUSIONS
  Only half of our patients achieved IVR on ADV treatment. The incidence of ADV resistance was high in 3TC-resistant patients treated with ADV.
authors.affiliation: Division of Hepatogastroenterology, Department of Internal Medicine, Chang Gung Memorial Hospital - Kaohsiung Medical Center, Chang Gung Univeristy College of Medicine, Kaohsiung, Taiwan.
authors.forename: Chien-Hung
authors.initials: CH
authors.lastname: Chen
authors.forename: Jing-Houng
authors.initials: JH
authors.lastname: Wang
authors.forename: Chuan-Mo
authors.initials: CM
authors.lastname: Lee
authors.forename: Chao-Hung
authors.initials: CH
authors.lastname: Hung
authors.forename: Tsung-Hui
authors.initials: TH
authors.lastname: Hu
authors.forename: Jyh-Chwan
authors.initials: JC
authors.lastname: Wang
authors.forename: Sheng-Nan
authors.initials: SN
authors.lastname: Lu
authors.forename: Chi-Sin
authors.initials: CS
authors.lastname: Changchien
mesh_terms: D000225:Adenine / Q000031:analogs & derivatives* / Q000494:pharmacology / Q000627:therapeutic use; D000328:Adult; D000368:Aged; D000998:Antiviral Agents / Q000494:pharmacology / Q000627:therapeutic use*; D004259:DNA-Directed DNA Polymerase / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D024882:Drug Resistance, Viral / Q000235:genetics; D004359:Drug Therapy, Combination; D005260:Female; D006515:Hepatitis B virus / Q000187:drug effects* / Q000201:enzymology; D019694:Hepatitis B, Chronic / Q000188:drug therapy* / Q000821:virology; D006801:Humans; D019259:Lamivudine / Q000494:pharmacology / Q000627:therapeutic use*; D008297:Male; D008875:Middle Aged; D009154:Mutation; D063065:Organophosphonates / Q000494:pharmacology / Q000627:therapeutic use*; D018894:Reverse Transcriptase Inhibitors / Q000494:pharmacology / Q000627:therapeutic use*; D016896:Treatment Outcome
chemical_list: D000998:Antiviral Agents; D063065:Organophosphonates; D018894:Reverse Transcriptase Inhibitors; D019259:Lamivudine; D004259:DNA-Directed DNA Polymerase; D000225:Adenine; C106812:adefovir dipivoxil