Prediction of virologic response to tenofovir mono-rescue therapy for multidrug resistant chronic hepatitis B

Most guidelines suggest combination therapy including nucleoside and nucleotide analogues for the treatment of chronic hepatitis B (CHB) with multidrug resistance (MD-R). However, long-term combination treatment can evoke high costs and safety problems. Therefore, we investigated the efficacy of tenofovir disoproxil fumarate (TDF) mono-rescue therapy for viral suppression in patients with CHB exhibiting MD-R. We reviewed patients with CHB exhibiting antiviral drug resistance treated by TDF mono-rescue therapy from December 2012 to June 2014. The patients were categorized into three groups: lamivudine-resistance (LAM-R) group (n=290), and LAM-R+adefovir-resistance (ADV-R) group (n=43), and LAM-R+entecavir-resistance (ETV-R) group (n=113). We compared the virologic response rate according to the multiplicity of resistance and investigated the predictive factors of a virologic response. For a median of 15 months (range, 6-24 months) of TDF mono-rescue therapy, the cumulative virologic response rates were 82.8, 81.4, and 84.1% in the LAM-R, LAM-R+ADV-R, and LAM-R+ETV-R groups, respectively (P=0.239). Multivariate analysis revealed that multiplicity of resistance did not influence the achievement of a virologic response (P=0.218). However, the baseline HBV DNA level significantly influenced the achievement of a virologic response for the treatment of CHB with MD-R (P<0.001). TDF mono-rescue therapy is an appropriate treatment for CHB with MD-R, and the baseline HBV DNA level is a significant predictive factor for a virologic response. These factors should be considered before treating CHB with MD-R.