Early Serum HBsAg Kinetics as Predictor of HBsAg Loss in Patients with HBeAg-Negative Chronic Hepatitis B after Treatment with Pegylated Interferonα-2a

Hepatitis B surface antigen (HBsAg) loss is an ideal treatment endpoint for patients with chronic hepatitis B (CHB). We investigated the predictive value of on-treatment HBsAg levels for HBsAg loss in hepatitis B e antigen (HBeAg)-negative CHB patients who received 120-week PEG-IFNα-2a treatment. Serum HBV DNA, HBsAg, and anti-HBs levels were assayed at baseline and every 3 months during the treatment. Of 81 patients, 12 achieved HBsAg loss, 20 achieved HBsAg < 100 IU/mL, and 49 maintained HBsAg ≥ 100 IU/mL. HBsAg loss rate was only 3.7% at 48 weeks, while it reached to 11.1% and 14.8% after treatment of 96 weeks and 120 weeks. The cutoff HBsAg levels at 12 weeks predicting HBsAg loss at 96 weeks and 120 weeks of treatment were 400 IU/mL and 750 IU/mL, with AUC 0.725 and 0.722, positive predictive value (PPV) 29.41% and 30.56%, and negative predictive value (NPV) 93.75% and 97.78%, respectively. The cutoff HBsAg levels at 24 weeks predicting HBsAg loss at 96 weeks and 120 weeks of treatment were 174 IU/mL and 236 IU/mL respectively, with AUC 0.925 and 0.922, PPV 40.0% and 46.15%, and both NPV 100%. The predictive ability of the cutoff HBsAg levels at 24 weeks was better than that at 12 weeks for HBsAg loss at either 96 or 120 weeks (χ^{2} = 3.880, P = 0.049 and χ^{2} = 4.412, P = 0.036). These results indicate that extended therapy is critical to HBsAg loss in HBeAg-negative CHB patients during PEG-IFN treatment, and the HBsAg level at 24 weeks can be used to predict HBsAg loss during tailoring PEG-IFN therapy.