title: Virological response to adefovir monotherapy and the risk of adefovir resistance.
abstract: OBJECTIVE
  To evaluate virological response to adefovir (ADV) monotherapy and emergence of ADV-resistant mutations in lamivudine (LAM)-resistant chronic hepatitis B patients.
  
  
  METHODS
  Seventy-seven patients with documented LAM resistance who were treated with 10 mg/d ADV for > 96 wk were analyzed for ADV resistance.
  
  
  RESULTS
  At week 48 and 96, eight (10%) and 14 (18%) of 77 LAM-resistant patients developed the ADV-resistant strain (rtA181V/T and/or rtN236T mutations), respectively. Hepatitis B virus (HBV) DNA levels during therapy were significantly higher in patients who developed ADV resistance than in those who did not. Incidence of ADV resistance at week 96 was 11%, 8% and 6% among patients with complete virological response (HBV DNA level < 60 IU/mL); 0%, 5% and 19% among patients with partial virological response (HBV DNA level ≥ 60 to 2000 IU/mL); and 32%, 34% and 33% among patients with inadequate virological response (HBV DNA levels > 2000 IU/mL) at week 12, week 24 and week 48, respectively. HBV DNA levels > 2000 IU/mL at week 24 showed best performance characteristics in predicting ADV resistance.
  
  
  CONCLUSIONS
  Development of ADV resistance mutations was associated with HBV DNA levels, which could identify patients with LAM resistance who are likely to respond to ADV monotherapy.
authors.affiliation: Department of Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, 135-710 Seoul, South Korea.
authors.forename: Dong Hyun
authors.initials: DH
authors.lastname: Sinn
authors.forename: Hyang Ie
authors.initials: HIe
authors.lastname: Lee
authors.forename: Geum-Youn
authors.initials: GY
authors.lastname: Gwak
authors.forename: Moon Seok
authors.initials: MS
authors.lastname: Choi
authors.forename: Kwang Cheol
authors.initials: KC
authors.lastname: Koh
authors.forename: Seung Woon
authors.initials: SW
authors.lastname: Paik
authors.forename: Byung Chul
authors.initials: BC
authors.lastname: Yoo
authors.forename: Joon Hyeok
authors.initials: JH
authors.lastname: Lee
mesh_terms: D000225:Adenine / Q000031:analogs & derivatives* / Q000494:pharmacology / Q000627:therapeutic use; D000328:Adult; D000998:Antiviral Agents / Q000494:pharmacology* / Q000627:therapeutic use*; D004279:DNA, Viral / Q000097:blood / Q000235:genetics; D024882:Drug Resistance, Viral / Q000502:physiology*; D005260:Female; D006515:Hepatitis B virus / Q000187:drug effects* / Q000235:genetics / Q000502:physiology; D019694:Hepatitis B, Chronic / Q000188:drug therapy* / Q000821:virology; D006801:Humans; D019259:Lamivudine / Q000627:therapeutic use; D008297:Male; D008875:Middle Aged; D009154:Mutation; D063065:Organophosphonates / Q000494:pharmacology* / Q000627:therapeutic use*; D012189:Retrospective Studies
chemical_list: D000998:Antiviral Agents; D004279:DNA, Viral; D063065:Organophosphonates; D019259:Lamivudine; C053001:adefovir; D000225:Adenine