Efficacy of tenofovir switch therapy for nucleos(t)ide-experienced patients with chronic hepatitis B.

BACKGROUND: Tenofovir disoproxil fumarate has been used in chronic hepatitis B patients with suboptimal virologic response to nucleos(t)ide analogues. The efficacy of tenofovir switch therapy has not been well studied in Asian patients. AIM: To evaluate the efficacy of tenofovir switch therapy in nucleos(t)ide-experienced patients, and identify the factors associated with treatment response of tenofovir switch therapy. METHODS: Nucleos(t)ide-experienced hepatitis B e antigen-positive and -negative patients prescribed with tenofovir were retrospectively identified and recruited for prospective analysis. Hepatitis B virus (HBV) DNA and other biochemical parameters were monitored in regular 3-6 monthly follow-up visits. Primary efficacy endpoint was maintained-virologic response with tenofovir switch therapy, defined as undetectable HBV DNA (<20 IU/mL) until the last follow-up visit. RESULTS: An overall of 214/252 (84.9%) patients achieved maintained-virologic response after 22 (7-55) months of tenofovir switch therapy. On multivariate analysis, a lower HBV DNA level at the time of switching to tenofovir was an independent factor associated with treatment efficacy. Maintained-virologic response after switching to tenofovir was achieved in 177/190 (93.2%) patients with HBV DNA <20 000 IU/mL vs. 37/62 (59.7%) patients with HBV DNA ≥20 000 IU/mL (P < 0.001). Absence of genotypic resistance to lamivudine or adefovir dipivoxil was not associated with improved treatment outcome. CONCLUSIONS: Tenofovir switch therapy is an effective treatment strategy in nucleos(t)ide-experienced chronic hepatitis B patients. However, in patients with HBV DNA ≥20 000 IU/mL at the time of switching to tenofovir, the chance of achieving maintained undetectable HBV DNA is significantly reduced.