Objective Little clinical data are available regarding the optimal treatment of patients who harbour entecavir (ETV)-resistant HBV.

Design In this multicentre randomised trial, patients who had HBV with ETV resistance-associated mutations and serum HBV DNA concentrations >60 IU/mL were randomised to receive tenofovir disoproxil fumarate (TDF, 300 mg/day) monotherapy (n=45) or TDF and ETV (1 mg/day) combination therapy (n=45) for 48 weeks.

Results Baseline characteristics were comparable between groups, including HBV DNA levels (median, 4.02 log₁₀ IU/mL) and hepatitis B e antigen-positivity (89%). All patients had at least one ETV-resistance mutation: rtT184A/C/F/G/I/L/S (n=49), rtS202G (n=43) and rtM250L/V (n=7), in addition to rtM204V/I (n=90). All except one patient in the TDF group completed 48 weeks of treatment. At week 48, the proportion of patients with HBV DNA <15 IU/mL, the primary efficacy endpoint, was not significantly different between the TDF and TDF+ETV groups (71% vs 73%; p>0.99). The mean change in HBV DNA levels from baseline was not significantly different between groups (−3.66 vs −3.74 log₁₀ IU/mL; p=0.81). Virological breakthrough occurred in one patient on TDF, which was attributed to poor drug adherence. At week 48, six and three patients in the TDF and TDF+ETV groups, respectively, retained their baseline resistance mutations (p>0.99). None developed additional resistance mutations. Safety profiles were comparable in the two groups.

Conclusions TDF monotherapy for 48 weeks provided a virological response comparable to that of TDF and ETV combination therapy in patients infected with ETV-resistant HBV.

Trial registration number ClinicalTrials.gov ID NCT01639092.