LAUSR

Serum Hepatitis B core‐related antigen (HBcrAg) level moderately correlates with cccDNA. We examined whether HBcrAg can add value in monitoring the effect of peginterferon (PEG‐IFN) therapy for HBeAg‐negative chronic hepatitis B (CHB) infection. Thus, serum HBcrAg level was measured in 133 HBeAg‐negative, mainly Caucasian CHB patients, treated with 48 weeks of PEG‐IFN alfa‐2a. We assessed its association with response (ALT normalization & HBV DNA < 2000 IU/mL) at week 72. HBcrAg level strongly correlated with HBV DNA level (r = 0.8, P < 0.001) and weakly with qHBsAg and ALT (both r = 0.2, P = 0.01). At week 48, mean HBcrAg decline was −3.3 log U/mL. Baseline levels were comparable for patients with and without response at week 72 (5.0 vs 4.9 log U/mL, P = 0.59). HBcrAg decline at week 72 differed between patients with and without response (−2.4 vs −1.0 log U/mL, P = 0.001), but no cut‐off could be determined. The pattern of decline in responders resembled that of HBV DNA, but HBcrAg decline was weaker (HBcrAg −2.5 log U/mL; HBV DNA: −4.0 log IU/mL, P < 0.001). For early identification of nonresponse, diagnostic accuracy of HBV DNA and qHBsAg decline at week 12 (AUC 0.742, CI‐95% [0.0.629‐0.855], P < 0.001) did not improve by adding HBcrAg decline (AUC 0.747, CI‐95% [0.629‐0.855] P < 0.001), nor by replacing HBV DNA decline by HBcrAg decline (AUC 0.754, CI‐95% [0.641‐0.867], P < 0.001). In conclusion, in Caucasian patients with HBeAg‐negative CHB, decline of HBcrAg during PEG‐IFN treatment was stronger in patients with treatment response. However, HBcrAg was not superior to HBV DNA and qHBsAg in predicting response during PEG‐IFN treatment.