title: A dose-ranging study of the efficacy and tolerability of entecavir in Lamivudine-refractory chronic hepatitis B patients.
abstract: OBJECTIVE
  Entecavir is a nucleoside analogue with potent in vitro activity against lamivudine-resistant hepatitis B virus (HBV). This randomized, dose-ranging, phase 2 study compared the efficacy and safety of entecavir with lamivudine in lamivudine-refractory patients.
  
  
  METHODS
  Hepatitis B e antigen (HBeAg)-positive and -negative patients (n = 182), viremic despite lamivudine treatment for > or =24 weeks or having documented lamivudine resistance substitutions, were switched directly to entecavir (1.0, 0.5, or 0.1 mg daily) or continued on lamivudine (100 mg daily) for up to 76 weeks.
  
  
  RESULTS
  At week 24, significantly more patients receiving entecavir 1.0 mg (79%) or 0.5 mg (51%) had undetectable HBV DNA levels by branched chain DNA assay compared with lamivudine (13%; P < .0001). Entecavir 1.0 mg was superior to entecavir 0.5 mg for this end point (P < .01). After 48 weeks, mean reductions in HBV DNA levels were 5.06, 4.46, and 2.85 log(10) copies/mL on entecavir 1.0, 0.5, and 0.1 mg, respectively, significantly higher than 1.37 log(10) copies/mL on lamivudine. Significantly higher proportions of patients achieved normalization of alanine aminotransferase levels on entecavir 1.0, 0.5, and 0.1 mg (68%, 59%, and 47%, respectively) than on lamivudine (6%). One virologic rebound due to resistance occurred (in the 0.5-mg group).
  
  
  CONCLUSIONS
  In HBeAg-positive and HBeAg-negative lamivudine-refractory patients, treatment with entecavir 1.0 and 0.5 mg daily was well tolerated and resulted in significant reductions in HBV DNA levels and normalization of alanine aminotransferase levels. One milligram of entecavir was more effective than 0.5 mg in this population.
authors.affiliation: National Cheng Kung University Medical College, Tainan, Taiwan. ttchang@mail.ncku.edu.tw
authors.forename: Ting-Tsung
authors.initials: TT
authors.lastname: Chang
authors.forename: Robert G
authors.initials: RG
authors.lastname: Gish
authors.forename: Stephanos J
authors.initials: SJ
authors.lastname: Hadziyannis
authors.forename: Janusz
authors.initials: J
authors.lastname: Cianciara
authors.forename: Mario
authors.initials: M
authors.lastname: Rizzetto
authors.forename: Eugene R
authors.initials: ER
authors.lastname: Schiff
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Pastore
authors.forename: Bruce R
authors.initials: BR
authors.lastname: Bacon
authors.forename: Thierry
authors.initials: T
authors.lastname: Poynard
authors.forename: Shobha
authors.initials: S
authors.lastname: Joshi
authors.forename: Kenneth S
authors.initials: KS
authors.lastname: Klesczewski
authors.forename: Alexandra
authors.initials: A
authors.lastname: Thiry
authors.forename: Ronald E
authors.initials: RE
authors.lastname: Rose
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Colonno
authors.forename: Robert G
authors.initials: RG
authors.lastname: Hindes
mesh_terms: D000328:Adult; D000956:Antigens, Viral / Q000097:blood; D000998:Antiviral Agents / Q000627:therapeutic use*; D004279:DNA, Viral / Q000235:genetics / Q000302:isolation & purification; D004305:Dose-Response Relationship, Drug; D004311:Double-Blind Method; D005006:Ethnicity; D005260:Female; D006147:Guanine / Q000031:analogs & derivatives / Q000627:therapeutic use; D006513:Hepatitis B e Antigens / Q000097:blood; D006515:Hepatitis B virus / Q000235:genetics / Q000302:isolation & purification; D019694:Hepatitis B, Chronic / Q000188:drug therapy*; D006801:Humans; D019259:Lamivudine / Q000627:therapeutic use*; D008297:Male; D008875:Middle Aged
chemical_list: D000956:Antigens, Viral; D000998:Antiviral Agents; D004279:DNA, Viral; D006513:Hepatitis B e Antigens; D019259:Lamivudine; C413685:entecavir; D006147:Guanine