Q. Zheng 1 1 Center for Liver Diseases, The First Affiliated Hospital, Fujian Medical University, Fuzhou, P. R. China Background: The objective of this study was to evaluate the early virologic response for prediction of achievement of HBeAg seroconversion and hepatitis B virus (HBV) DNA negativity after two years of lamivudine treatment in chronic hepatitis B (CHB) patients. Methods: In this retrospective study, adult patients with chronic hepatitis B (255 HBeAg-positive and 122 HBeAg-negative) were treated with lamivudine (100 mg/day), and followed-up up to 72 months. Response and resistance to the treatment were assessed during the treatments with lamivudine. Results: It was found that gender, age, baseline levels of ALT and HBV DNA, serum HBV DNA at week 24 (P =0.019 , OR = 0.442) were closely related to the achievement of HBeAg seroconversion, undetectable HBV DNA level and emergence of drug resistance after 2 years of lamivudine treatment. HBeAg positive patients with baseline serum HBV DNA in 10 6 -10 8 copies/ml and serum HBV DNA 10 3 copies/ml at week 24 showed high response rate of ALT normalization rate (91.7%), undetectable HBV DNA rate (84.5%), HBeAg seroconversion rate (55.2%), as well as low drug resistance rate (25.4%) after 2 years of treatment. Similarly, HBeAg negative patients with serum HBV DNA 10 3 copies/ml at week 24 could achieve high 2-year response rate of ALT normalization rate (72.41%), undetectable HBV DNA rate (82.3%), and low drug resistance rate (15.5%). Conclusion: Serum HBV DNA 10 3 copies/ml at 24-week provide the best prediction of 2-year lamivudine treatment response. Background/aims: Unlike oral antivirals, a finite course of (peg)interferon can induce sustained post-treatment response in patients with chronic hepatitis B (CHB), with increasing rates of HBsAg clearance observed in patients who respond during post-treatment follow-up. HBsAg clearance is considered to be the closest outcome to a cure, being associated with improved histological outcome, reduced incidence of HCC and increased survival. Methods: In a randomised multinational study, patients (HBeAg-negative) received 180µg PEGASYS+placebo (n=177); 180µg PEGASYS+100mg lamivudine (n=179); or 100mg lamivudine (n=181) for 48 weeks, and were assessed 6 months post-treatment. From this initial study, 230 of those who had received PEGASYS±lamivudine and 85 patients who had received lamivudine monotherapy participated in a long-term observational study to investigate post-treatment response. HBsAg clearance at yearly post-treatment follow-up visits up to 5 years post-treatment was analysed. Results: HBsAg clearance in patients treated with PEGASYS±lamivudine increased post-treatment (3% at 1 year to 6%, 8%, 11% and 12.2% at years 2, 3, 4 and 5). At year 5, 28 PEGASYS-treated patients (12.2%) had cleared HBsAg compared with 3 (3.5%) of lamivudine-treated patients (P=0.022). 16/28 PEGASYS-treated patients had anti-HBsAg (HBsAg seroconversion). Detailed analysis of the 5-year follow-up data will be presented. Conclusion: The ability of a finite course of PEGASYS to induce sustained response with increasing HBsAg clearance rates in responders during post-treatment follow-up supports its use as first-line therapy in HBeAg-negative patients with CHB. Background/aims: Recent studies suggest that quantification of HBsAg levels early during treatment can be used to predict post-treatment response to PEGASYS. Elecsys ® HBsAg II (Roche) is a sensitive assay for the detection of HBsAg. This assay can be used for the quantification of HBsAg levels using a simple dilution algorithm. We compared results obtained using the Elecsys ® HBsAg II method with those of a commonly used quantification assay. Methods: HBsAg levels obtained using the Elecsys ® HBsAg II assay were compared with those obtained using the Abbott Architect ® HBsAg assay for a total of 40 samples from patients infected with HBV genotypes A (n=8), C (n=1), D (n=29) and F (n=2). Samples were diluted 1:100 in diluent provided by the manufacturer. Samples with HBsAg levels >250 IU/mL were retested at a final dilution of 1:1000. Samples with HBsAg levels <0.05 IU/mL were retested undiluted. Results: Overall, HBsAg levels measured with the two assays correlated well (R 2 =0.9718) over a wide range (3-3x10 5 IU/mL). Discrepancies in HBsAg levels >±20% were reported for a minority of the samples (n=15), mainly distributed evenly above and below the ideal line (n=11). In the four low titre (range 3-9x10 3 IU/mL) samples with greatest discrepancy Elecsys ® underestimated values (in two cases by >50%). Conclusion: The Elecsys ® HBsAg II assay provides a simple and reliable means for determining HBsAg levels. This simple assay format could be used to provide useful information during on-treatment monitoring of HBsAg levels in patients with chronic hepatitis B undergoing therapy.