Both treatment strategies were well tolerated. Disclosures: Qin Ning – Advisory Committees or Review Panels: ROCHE, NOVARTIS, BMS, MSD, GSK; Consulting: ROCHE, NOVARTIS, BMS, MSD, GSK; Grant/Research Support: ROCHE, NOVARTIS, BMS; Speaking and Teaching: ROCHE, NOVAR-TIS, BMS, MSD, GSK The following people have nothing to disclose: Wei Guo, Di Wu, Peng Wang, Jing-Feng Chen, Yan-hong Xu, Weiming Yan, Ke Ma, Meifang Han, Jianxin Song, Junying Qi, Jiaquan Huang, Yuancheng Huang, Xiping Zhao, Dong Xu Background/Aims: CDK inhibitor The antiviral effect of monotherapy with tenofovir disoproxil fumarate (TDF) is controversial for patients with hepatitis B virus (HBV) resistant
to nucloes(t)ide analogues. Methods: Patients who were treated with TDF monotherapy for HBV with
documented genotypic resistance mutations were included. Results: At baseline, 325 (81%) patients had mono-resistance to lamivudine, while others had multi-drug resistance to lamivudine and adefovir (n=43, 10%) or lamivudine and ente-cavir (n=32, 8%). Most (287, 72%) were being treated with combination therapies including lamivudine, adefovir, and entecavir. Their mean HBV DNA level was 2.5 +/− 2.0 log10 IU/mL. During 1 year of TDF monotherapy, 378 (95%) patients cumulatively achieved virological response (VR, HBV DNA <60 IU/mL) by modified intention-to-treat analysis. The rates of VR were not different between patients with mono-resistance to lamivudine and those with www.selleckchem.com/products/fg-4592.html multi-drug resistance (95.2% vs. 92.0%, P =0.27). Sixteen patients who did not achieve VR also showed a significant reduction in their mean HBV DNA levels from baseline (-3.42 log10 IU/mL, P <0.01). Five patients experienced viral breakthrough, and all were related with low adherence to medication. The rate of HBV DNA undetectabil-ity
was not influenced by the degree of previous resistance mutations (P >0.05). Four Urease patients discontinued TDF because of gastrointestinal symptoms (n=3) or for pregnancy (n=1). Otherwise, no significant clinical or laboratory adverse event was reported. Conclusions: In this cohort study, most patients infected with HBV that has genotypic resistance mutations to lamivudine, adefovir, or entecavir rapidly achieved VR within 48 weeks of TDF monotherapy, regardless of the nature of previous resistance mutations. No patient developed additional resistance mutations. Disclosures: Young-Suk Lim – Advisory Committees or Review Panels: Bayer Healthcare, Gilead Sciences; Grant/Research Support: Bayer Healthcare, BMS, Gilead Sciences, Novartis Han Chu Lee – Grant/Research Support: Medigen Biotechnology Co., Novartis, Roche, Bayer HealthCare, Bristol-Myers Squibb, INC research, Boehringer Ingelheim, Taiho Pharmaceutical Co., Yuhan Co.