Background & aims: The aim of the study was to assess the clinical utility of serum HBsAg quantification as a surrogate biomarker for the prediction of sustained virological response (SVR) in chronic hepatitis B (CHB) patients treated with Pegylated Interferon alfa-2a (Peg-IFN α-2a).
Methods: We performed a prospective cohort study which included 57 patients with CHB treated 48 weeks with Peg-IFN α-2a and followed for another 24 weeks. HBsAg was quantified at the baseline, during treatment and at the end of follow-up. SVR was defined as HBV-DNA below 2,000 IU/ml at 24 weeks after the end of therapy.
Results: The majority of patients had HBeAg-negative CHB (68%, n=39). Positive predictive factors for SVR at baseline were low levels of HBsAg (3.72 log10 IU/ml, p=0.032) and HBV-DNA (3.96 log10 IU/ml, p=0.035). During treatment, patients who achieved SVR showed a marked decrease in serum HBsAg in comparison with nonresponders (at week 48 mean decrease of 1.06 +/- 1.3 log10 IU/ml versus 0.04 ± 0.5 log10 UI/ml, p=0.005). On therapy, HBV-DNA reduction ≥ 2 log10 IU/ml with any decrease of HBsAg level at week 12 had a positive predictive value (PPV) of 80% (95% CI: 51.91-95.43%) for SVR, while HBV-DNA decline < 2 log10 IU/ml without any decline of HBsAg had a negative predictive value (NPV) of 85.71% (95% CI: 42.23-97.63%) for SVR.
Conclusions: HBsAg quantification combined with HBV-DNA assessment could become an early useful tool to optimize the management of CHB patients treated with Peg-IFN α-2a, according to response guided therapy.