Treatment was well tolerated. Most adverse events were mild in severity and considered unrelated to TDF. No subject had confirmed 0.5 mg/dL increase in serum creatinine, or creatinine clearance <50 mL/min. Conclusions: TDF is effective and well-tolerated in Asian-American CHB patients in a real-life setting, consistent with larger registration trials except HBsAg loss occurred in a small percentage of Asian-American ZD1839 cost patients. Improvement in liver fibrosis was seen in a proportion of patients

at week 48. No genotypic resistance to antiviral drug was developed up to week 1 44. Disclosures: Calvin Pan – Advisory Committees or Review Panels: BMS, Gilead; Consulting: BMS, Gilead; Grant/Research Support: BMS, Gilead, Genentech; Speaking and Teaching: BMS, Gilead, Genentech, Onyx, Vertex Ho Bae – Grant/Research Support: Gilead; Speaking

and Teaching: Gilead, BMS, Genentech Huy N. Trinh – Advisory Committees or Review Panels: BMS, Gilead; Grant/Research Support: BMS, Gilead; Speaking and Teaching: BMS, Gilead, vertex; Stock Shareholder: Gilead Xiaoli Ma – Consulting: Gilead Sciemces, Inc, Bristol-Myers Squibb, Inc Truong-Sinh BTK inhibitor Leduc – Advisory Committees or Review Panels: Gilead, BMS; Grant/Research Support: Gilead; Speaking and Teaching: Gilead, BMS, Merck, Vertex Ke-Qin Hu – Grant/Research Support: BMS, Gilead, Merck, Vertex, Genentech; Speaking and Teaching: BMS, Gilead, Merck, Vertex, Genentech The following people have nothing to disclose: Zheng Zeng, Li-Jun Mi, Sing Chan Background:

Serum HBsAg is a useful tool to describe the natural course and antiviral response in chronic hepatitis B (CHB) patients especially when HBV DNA has become undetectable due to effective treatment. We assessed the predictive use of quantitative HBV serum markers in the LDT600A2410 Roadmap study with telbivudine (LDT) monotherapy and teno-fovir (TDF) add-on. Methods / Oxymatrine Patients: mITT population was 100 HBeAg-positive CHB patients. Quantitative HBsAg/HBeAg from screening, W24, W52, W76 and W1 04/EoT was correlated with serological (HBe/sAg loss), combined (normal ALT, undetectable HBV-DNA) and complete (normal ALT, undetectable HBV-DNA, HBeAg loss) EoT response. Off treatment follow-up data up to two years was available from 6/7 patients with HBsAg loss. Results: W24 predictive factors for combined (n=82) and complete (n=45) W104/EoT response were W24 HBeAg <10 PEIU/L (n=54, positive predictive value, PPV 85% and 67%, negative predictive value, NPV 22% and 76%) and undetectable HBV DNA (PPV 87% and 64%, NPV 24% and 73%). HBeAg <10 PEIU/L showed a higher AUC (0.7908) and lower p-value (p<0.0001) for the prediction of complete response compared to undetectable HBV DNA at W24 (0.6979, p=0.0007). ROC curves for HBV DNA negativity and for HBeAg <10 PEIU/L did not differ significantly (p=0.095).