Hepatitis B surface antigen: association with sustained response to peginterferon alfa-2a in hepatitis B e antigen-positive patients.

ABSTRACT

PURPOSE: Patients with hepatitis B e antigen (HBeAg)-positive chronic hepatitis B, who achieve HBeAg seroconversion 6 months after completing 48 weeks of peginterferon alfa-2a therapy, have an increased chance of clearing hepatitis B surface antigen (HBsAg) during long-term treatment-free follow-up. This analysis aimed to determine whether HBsAg quantification during treatment could be used to identify posttreatment response. METHODS: Patients (n = 399) treated with peginterferon alfa-2a (180 µg/week) alone or in combination with lamivudine (100 mg/day) for 48 weeks during a large, randomized study were included in this retrospective analysis. Receiver-operating characteristic analyses were used to identify baseline and on-treatment HBsAg levels associated with response (HBeAg seroconversion 6 months posttreatment). RESULTS: Baseline HBsAg levels were lower in patients achieving posttreatment response than in nonresponders (3.97 and 4.21 IU/mL, respectively, p = 0.039). Two baseline HBsAg cutoff levels (5,000 and 50,000 IU/mL) provided a positive predictive value of 42% and a negative predictive value of 77%. HBsAg decline was significantly greater during and posttreatment in responders than in nonresponders (p < 0.0001). HBeAg seroconversion rates 6 months posttreatment were significantly higher in patients with HBsAg < 1,500 IU/mL at weeks 12 and 24 (56.7 and 54.4%, respectively) versus patients with HBsAg 1,500-20,000 IU/mL (32.3 and 26.1%, respectively) or HBsAg < 20,000 IU/mL (16.3 and 15.4%, respectively) (all p < 0.0001 and <0.0001). CONCLUSIONS: HBsAg levels at baseline strongly associated with posttreatment response were not identified. Low HBsAg levels during peginterferon alfa-2a therapy were associated with high rates of posttreatment response. On-treatment HBsAg quantification may, therefore, help guide patient management in the future.