OBJECTIVETo investigate chronic hepatitis B (CHB) patients infected with the antiviral-resistant rtA181 mutation hepatitis B virus (HBV) who have been unresponsive to general therapy to determine the effects of individualized therapy.

METHODSFifty-four patients with confirmed rtA181 mutation and who experienced virological breakthrough during nucleus(t)ide analogue (NUC) treatment were enrolled in this prospective cohort study. Their serum levels of HBV DNA, hepatitis B surface antigen (HBsAg), and alanine transaminase (ALT) were tested. Each patient was genotyped by pyrosequencing for 10 mutation sites in the HBV P gene that have been previously correlated to NUC efficacy. Each patient's antiviral therapy and response history was analyzed in regard to their particular mutation pattern. The serological index was determined for carriers of the rtA181T/V mutation. The secondary individualized treatment included adding/switching to entecavir (ETV; group A) or adding telbivudine (LdT; group B) upon confirmation of drug resistance. Effect of individualized treatment was analyzed by T test and Mann-Whitney U test for continuous variables with normal or skewed distributions, respectively. Categorical variables were analyzed by the Chi-squared ( x² ) or Fisher's exact tests.

RESULTSThe rtA181T mutation was found in 64.8% (35/54) of patients with rtA181 mutation HBV. The most frequent previously administered medications were adefovir dipivoxil (ADV) and lamivudine (LAM). Multi-site rtA181 mutations occurred more frequently in the patients with multi-NUCs history (57.6%) than in those with single NUCs history (28.6%) (x²=4.342, P less than 0.05). Serum HBV DNA level at virological breakthrough was lower than that at baseline of the first antiviral treatment (5.66+/-1.01 vs. 6.75+/-0.81 log10 copies/ml; t=-4.210, P less than 0.01). The serum HBsAg level was higher in carriers of the rtA181T mutation than in carriers of the rtA181V mutation (3.80+/-0.45 vs. 3.46+/-0.60 log10 IU/ml; t=2.109, P less than 0.05). In patients with serum HBV DNA more than or equal to 6 log10 copies/ml at viral breakthrough, 100% (8/8) of patients in the secondary treatment group A and 75% (3/4) patients in the secondary treatment group B exhibited virological response at week 24 after intervention. Undetectable HBV DNA was achieved in three patients of group A and one patient of group B. In patients with serum HBV DNA less than 6 log10 copies/ml at viral breakthrough, 100% (14/14) of patients in group A and 71.4% (5/7) of patients in group B exhibited biological response at week 24 after intervention. The serum HBV DNA level decreased to undetectable levels in 12 patients of group A and four patients of group B.

CONCLUSIONThe rtA181 mutation pattern correlates with previous antiviral therapy response. In addition, multi-site rtA181 mutations occur more frequently in patients with a history of multi-NUCs therapy. Adding or switching rtA181 carriers to ETV produces a more robust virological suppression than adding LdT.