title: Lamivudine-to-entecavir switching treatment in type B chronic hepatitis patients without evidence of lamivudine resistance.
abstract: OBJECTIVE
  A considerable number of chronic hepatitis B (CH-B) patients remain under continuous lamivudine treatment, although switching treatment to entecavir could be beneficial. We investigated the antiviral efficacy of switching treatment to entecavir in CH-B patients without apparent evidence of lamivudine resistance during the preceding lamivudine treatment.
  
  
  METHODS
  Forty-four CH-B patients, who underwent lamivudine treatment for more than 6 months and showed no evidence of lamivudine resistance, switched to entecavir. Serial changes in hepatitis B virus (HBV) DNA were correlated with the patients' baseline HBV DNA at the commencement of entecavir administration. The entecavir-resistant substitution was examined by PCR-direct sequencing. The median follow-up period of entecavir treatment was 20 (10-23) months.
  
  
  RESULTS
  All 31 patients with baseline HBV DNA <2.6 logcopies/ml maintained HBV DNA-negative status during entecavir treatment. Of seven patients having HBV DNA of 2.6-<4.0 logcopies/ml, all achieved undetectable HBV DNA at the end of follow-up. As for six patients having HBV DNA >or=4.0 logcopies/ml, three patients achieved undetectable HBV DNA, whereas virological breakthrough was observed in one patient at month 15. An entecavir-resistant virus having rtM204V, rtL180M and rtS202G substitutions was detected in this patient.
  
  
  CONCLUSIONS
  The lamivudine-to-entecavir switching treatment may be generally recommendable in CH-B patients without evidence of lamivudine resistance during the preceding lamivudine treatment. However, great care should be taken with respect to the emergence of entecavir-resistance, especially in patients who do not respond well to the preceding lamivudine treatment.
authors.affiliation: Department of Gastroenterology and Hepatology, Osaka University Graduate School of Medicine, Suita, Japan.
authors.forename: Nao
authors.initials: N
authors.lastname: Kurashige
authors.forename: Kazuyoshi
authors.initials: K
authors.lastname: Ohkawa
authors.forename: Naoki
authors.initials: N
authors.lastname: Hiramatsu
authors.forename: Takayuki
authors.initials: T
authors.lastname: Yakushijin
authors.forename: Kiyoshi
authors.initials: K
authors.lastname: Mochizuki
authors.forename: Tsugiko
authors.initials: T
authors.lastname: Oze
authors.forename: Shinichi
authors.initials: S
authors.lastname: Kiso
authors.forename: Tatsuya
authors.initials: T
authors.lastname: Kanto
authors.forename: Tetsuo
authors.initials: T
authors.lastname: Takehara
authors.forename: Akinori
authors.initials: A
authors.lastname: Kasahara
authors.forename: Yoshinori
authors.initials: Y
authors.lastname: Doi
authors.forename: Akira
authors.initials: A
authors.lastname: Yamada
authors.forename: Kazuto
authors.initials: K
authors.lastname: Fukuda
authors.forename: Masahide
authors.initials: M
authors.lastname: Oshita
authors.forename: Eiji
authors.initials: E
authors.lastname: Mita
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Fukui
authors.forename: Toshihiko
authors.initials: T
authors.lastname: Nagase
authors.forename: Harumasa
authors.initials: H
authors.lastname: Yoshihara
authors.forename: Yasuharu
authors.initials: Y
authors.lastname: Imai
authors.forename: Michio
authors.initials: M
authors.lastname: Kato
authors.forename: Takeshi
authors.initials: T
authors.lastname: Kashihara
authors.forename: Norio
authors.initials: N
authors.lastname: Hayashi
mesh_terms: D000328:Adult; D000368:Aged; D000998:Antiviral Agents / Q000627:therapeutic use*; D004279:DNA, Viral / Q000097:blood; D024882:Drug Resistance, Viral; D005260:Female; D005500:Follow-Up Studies; D006147:Guanine / Q000031:analogs & derivatives* / Q000627:therapeutic use; D006515:Hepatitis B virus / Q000187:drug effects; D019694:Hepatitis B, Chronic / Q000188:drug therapy*; D006801:Humans; D019259:Lamivudine / Q000627:therapeutic use*; D008297:Male; D008875:Middle Aged; D016133:Polymerase Chain Reaction; D017422:Sequence Analysis, DNA
chemical_list: D000998:Antiviral Agents; D004279:DNA, Viral; D019259:Lamivudine; C413685:entecavir; D006147:Guanine