Serum hepatitis B surface antigen quantitation can reflect hepatitis B virus in the liver and predict treatment response

Background & Aims: We aimed to evaluate serum hepatitis B surface antigen (HBsAg) quantitation as a surrogate marker for covalently closed circular DNA (cccDNA) and intrahepatic hepatitis B virus (HBV) DNA, and as a predictor of sustained virologic response to peginterferon and lamivudine combination therapy. Methods: Twenty-six hepatitis B e antigen-positive chronic hepatitis B patients receiving combination treatment of 32-week peginterferon alfa-2b and 2-year lamivudine were studied. All patients had liver biopsy before and after treatment for cccDNA and intrahepatic HBV DNA measurement. Sustained virologic response was defined as sustained hepatitis B e antigen seroconversion and HBV DNA less than 10,000 copies/mL at the end of treatment until 1 year posttreatment. Results: Seven patients developed sustained virologic response. At base-line, HBsAg correlated well with both log (cccDNA) (r = 0.54, P = .004) and log [total intrahepatic HBV DNA] (r = 0.43, P = .028). The median reduction of HBsAg was 1287 IU/mL (range, 12,223-26,763 IU/mL). Reduction of HBsAg has good correlation with reduction in log [cccDNA] (r = 0.68, P < .0001) and reduction in log [total intrahepatic HBV DNA] (r = 0.65, P < .0001). Patients with lower baseline cccDNA, intrahepatic HBV DNA, and HBsAg level but not serum HBV DNA level tend to develop sustained virologic response. A baseline HBsAg level of less than 10,000 IU/mL had sensitivity, specificity, and positive and negative predictive values for sustained virologic response of 86%, 56%, 43%, and 92%, respectively. Conclusions: Serum HBsAg levels correlate well with the cccDNA and intrahepatic HBV DNA. Low pretreatment HBsAg is better than HBV DNA to predict good response to peginterferon and lamivudine treatment.