26 IU/ml and 1592.46s/co, respectively (P>0.05). 39 infants did not appear congenital malformations with normal Apgar score and developmental indicators at birth. At 7 months after birth, no infants developed HBV infection, a 100 %success rate of blocking mother-to-infant transmission of HBV was achieved. Conclusion: Telbivudine treatment effectively and safely prevents mother-to-infant transmission of HBV from chronically infected mothers with a high degree of infectivity late in pregnancy. Disclosures:

The following people have nothing to disclose: Qiuju Sheng, GSK126 in vivo Yang Ding, Han Bai, Jingyan Wang, Chong Zhang, Lianrong Zhao, Xiaoguang Dou Background: Sequential therapy particularly with drugs with low barrier to resistance posed a high risk of emergence of multi-drug resistance (MDR) and presented a management issue and unmet need in chronic hepatitis B (CHB) treatment. We evaluated the antiviral efficacy and BYL719 safety of entecavir (ETV) plus tenofovir (TDF) combination therapy in patients with MDR CHB. Methods: In this prospective, multicenter study, patients with MDR CHB, defined as measurable serum HBV DNA (≥ 60 IU/mL) while on any rescue treatment regimen for at least 24 weeks and the presence of documented genotypic resistance

to both nucleoside analogue(s) and nucleotide analogue at any previous time, were treated with ETV 1.0mg and TDF 300mg combination therapy for 48 weeks. Results: Of the 73 consecutive patients screened in this study, a total of 64 eligible patients, who had previously failed to a median three lines of antiviral therapy (range 2-6), were included. At baseline, median age was 47.0 years, 80.8% were male,

89.1% were HBeAg(+), median HBV DNA was MCE 4.24 (range 2.11-6.73) log10 IU/ml, and mean ALT was 39.7 IU/ml. By week 4, 12, 24 and 48, 15/64 (23.4%), 36/64 (56.3%), 43/64 (67.2%) and 56/63 (85.9%) patients achieved a HBV DNA < 60 IU/ml, respectively. The median reduction of HBV DNA from baseline to 4 weeks and 48 weeks was 1.23 log10 IU/ml and 2.39 log10 IU/ml, respectively. Although 5 patients experienced virological breakthrough, all were transient and no additional/novel mutation was detected in any patients. Two patients lost HBeAg, but no HBeAg seroconversion was observed for 48 weeks. ETV plus TDF combination therapy was well tolerated, and no clinical significant adverse events were noticed during the study period. Conclusions: Our results show that, in difficult-to-treat MDR CHB patients with a high exposure to multiple antiviral drugs, ETV plus TDF combination therapy can provide a very high rate of viral suppression through 48 weeks of treatment.