Serum hepatitis B core-related antigen as a treatment predictor of pegylated interferon in patients with HBeAg-positive chronic hepatitis B

Background & Aims: The role of quantitative serum hepatitis B core-related antigen (HBcrAg) in patients with chronic hepatitis B (CHB) receiving pegylated interferon (PEG-IFN) is unclear. This study was aimed at comparing its usefulness with quantitative HBsAg in patients with HBeAg-positive CHB receiving PEG-IFN therapy. Methods: A total 46 patients treated with PEG-IFN for 48 weeks were retrospectively analysed. Intrahepatic covalently closed circular DNA (cccDNA) from paired liver biopsies and serial serum HBsAg and HBcrAg during therapy were assessed. Results: Virological response (VR), defined as HBeAg clearance and HBV DNA <2000 IU/ml at 24 weeks post treatment, was achieved in 15 (32.6%) patients. Responders had significantly higher cccDNA decline from baseline compared with non-responders. Baseline HBsAg and HBcrAg were correlated with cccDNA (r = 0.424, P = 0.020 and r = 0.564, P = 0.001, respectively), and changes in the corresponding markers during therapy were correlated with cccDNA reduction (r = 0.579, P = 0.001 and r = 0.503, P = 0.005, respectively). Responders showed more rapid decline of both markers during therapy compared with non-responders. In multivariate analysis, serum HBcrAg at week 12 was identified as a predictor of VR. The optimal cut-off value for HBcrAg (log(10) 8.0 U/ml) provided negative predictive value (NPV) of achieving VR at weeks 12 and 24 of 94.4 and 100%, respectively, while using HBsAg > 20 000 IU/ml provided NPV of 80 and 100% respectively. Conclusions: The convenient quantitative HBcrAg represented a reliable marker of intrahepatic cccDNA. Monitoring HBcrAg levels during PEG-IFN therapy may help identify patients with a very low probability of response comparable to, if not better than, quantitative HBsAg.