Change in Serum Hepatitis B Surface Antigen Level and Its Clinical Significance in Treatment-naïve, Hepatitis B e Antigen-positive Patients Receiving Entecavir

Background/Aim: We investigated changes in hepatitis B surface antigen (HBsAg) level and its correlation with clinical outcomes in treatment-naive chronic hepatitis B (CHB) patients undergoing entecavir therapy. Patients and Methods: Among 51 hepatitis B e antigen (HBeAg)-positive treatment-naive CHB patients receiving entecavir for more than 1 year, 28 were enrolled. HBsAg levels were measured at baseline, 6 months, and 12 months after treatment using the Architect HBsAg QT assay (Abbott, dynamic; range: 0.05 to 125,000 IU/mL). Serum alanine aminotransferase, HBeAg, anti-HBe, and hepatitis B virus (HBV) DNA (Cobas Taqman: low detection limit 1.84 log 10 copies/mL) were measured at baseline and every 3 months. The HBsAg response was defined as an HBsAg level that decreased more than 1 log 10 IU/mL from baseline level at 12 months after entecavir treatment. Results: Twenty-eight patients were treated for a median period of 21 months (range: 18 to 24mo). Serum HBsAg level showed a mean of 4.0, 3.7, and 3.6 log 10 IU/mL at pretreatment, 6, and 12 months, respectively, and declined significantly (P < 0.001). Serum HBV DNA level showed a mean of 8.1, 3.1, and 2.4 log 10 copies/mL at pretreatment, 6, and 12 months, respectively, and declined significantly (P < 0.001). The decline in HBsAg level was significantly correlated with that of the HBV DNA level at 12 months from baseline (γ=0.391, P=0.044). Five patients showed an HBsAg response, and cumulative incidence of HBeAg loss at 1 year after entecavir treatment was 80% versus 30% in patients with an HBsAg response and those without, respectively (P=0.034). Conclusions: Monitoring changes in quantitative HBsAg level could be a useful parameter for assessing the response to entecavir therapy in HBeAg-positive treatment-naive CHB patients.