title: Clonal evolution of hepatitis B virus polymerase gene mutations during lamivudine-adefovir combination treatment.
abstract: OBJECTIVE
  To identify hepatitis B virus polymerase gene mutations during antiviral therapy using lamivudine-adefovir sequential monotherapy followed by lamivudine-adefovir combination therapy.
  
  
  METHODS
  The patient cohort included four adult chronic hepatitis B patients who had undergone sequential monotherapy, first with lamivudine (LMV) and then, after developing viral breakthrough, with adefovir (ADV) therapy. All of the patients had non-response or viral breakthrough after LMV-ADV sequential monotherapy, which resulted in the switching of their antiviral regimen to LMV-ADV combination therapy. Eleven serum samples from the four patients who showed non-response to rescue LMV-ADV combination therapy were collected sequentially at a time before the antiviral treatment and then during the LMV monotherapy, ADV monotherapy, and LMV-ADV combination therapy. For the genotypic analysis, the whole 1310-bp polymerase gene region was amplified, cloned and sequenced.
  
  
  RESULTS
  All patients had been previously treated with 100 mg of LMV once daily for a 15- to 26-mo period. The emergence of resistance mutations to LMV, such as rtM204V/I and/or rtL180M, were found in all patients. Their antiviral regimens were switched to ADV monotherapy as the second line treatment. All patients had viral breakthrough or non-response after the LMV-ADV sequential monotherapy. ADV-resistant mutations were detected after 13 to 19 mo of LMV-ADV sequential monotherapy. The rtA181V/T mutations were predominantly identified during the ADV treatment in the LMV-resistant patients. Twenty-seven of 38 clones were combined with an amino acid change at rt181; three clones had mutations in rt236 and one clone had a combined mutation. The rtA181V/T mutations were not suppressed by the LMV-ADV combination therapy. Thirty-nine of 64 clones showed an rtA181V/T mutation and six clones showed combined mutations in rt181 and rt236. Mutations in rt204 re-emerged during the combination treatment. The rt181 and rt204 mutations did not co-exist in one clone.
  
  
  CONCLUSIONS
  Add-on lamivudine therapy with adefovir for adefovir resistance may not suppress the pre-existing adefovir-resistant mutation that develops during lamivudine-adefovir sequential monotherapy.
authors.affiliation: Department of Internal Medicine, Konkuk University School of Medicine, Seoul 143-729, South Korea.
authors.forename: Soon Young
authors.initials: SY
authors.lastname: Ko
authors.forename: Byung Kook
authors.initials: BK
authors.lastname: Kim
authors.forename: So Young
authors.initials: SY
authors.lastname: Kwon
authors.forename: Kyun-Hwan
authors.initials: KH
authors.lastname: Kim
authors.forename: Jeong Han
authors.initials: JH
authors.lastname: Kim
authors.forename: Won Hyeok
authors.initials: WH
authors.lastname: Choe
authors.forename: Chang Hong
authors.initials: CH
authors.lastname: Lee
mesh_terms: D000225:Adenine / Q000031:analogs & derivatives* / Q000627:therapeutic use; D000328:Adult; D000998:Antiviral Agents / Q000627:therapeutic use*; D060965:Clonal Evolution; D004338:Drug Combinations; D024882:Drug Resistance, Viral / Q000235:genetics; D057915:Drug Substitution; D015684:Gene Products, pol / Q000235:genetics*; D005838:Genotype; D006515:Hepatitis B virus / Q000187:drug effects* / Q000201:enzymology / Q000235:genetics; D019694:Hepatitis B, Chronic / Q000175:diagnosis / Q000188:drug therapy* / Q000821:virology; D006801:Humans; D019259:Lamivudine / Q000627:therapeutic use*; D008297:Male; D008875:Middle Aged; D009154:Mutation; D010755:Organophosphates / Q000627:therapeutic use*; D063065:Organophosphonates / Q000627:therapeutic use*; D010641:Phenotype; D013997:Time Factors; D016896:Treatment Outcome
chemical_list: D000998:Antiviral Agents; D004338:Drug Combinations; D015684:Gene Products, pol; D010755:Organophosphates; D063065:Organophosphonates; C066027:P protein, Hepatitis B virus; C584355:lamivudine-adefovir combination; D019259:Lamivudine; C053001:adefovir; D000225:Adenine