Hepatitis B surface antigen quantification: why and how to use it in 2011 - a core group report

Area of Science:

• Hepatology
• Virology
• Biomarker Discovery

Background:

• Quantitative serum hepatitis B surface antigen (HBsAg) assays are now commercially available, renewing interest in their clinical utility.
• HBsAg levels offer insights into hepatitis B virus (HBV) cccDNA transcriptional activity, not just viral load.
• HBsAg levels are generally higher in hepatitis B e antigen (HBeAg)-positive individuals.

Purpose of the Study:

• To evaluate the role of quantitative HBsAg as a biomarker for prognosis and treatment response in chronic hepatitis B.
• To establish HBsAg cutoffs for predicting treatment outcomes and identifying inactive carriers.
• To compare the efficacy of different treatments (interferon vs. nucleos(t)ide analogues) on HBsAg reduction.

Main Methods:

• Analysis of quantitative serum HBsAg levels in relation to HBV DNA, HBeAg status, and HBV genotypes.
• Assessment of HBsAg decline during peginterferon and nucleos(t)ide analogue (NA) therapies.
• Evaluation of HBsAg levels as predictors of sustained response, inactive carrier state, and relapse risk.

Main Results:

• Specific HBsAg thresholds (<1000 IU/ml for genotype D, <100 IU/ml for genotypes B/C) are associated with an inactive carrier state in HBeAg-negative patients with low HBV DNA.
• Peginterferon treatment leads to more pronounced HBsAg reduction compared to NA therapy.
• Early HBsAg decline during NA therapy may predict long-term HBsAg clearance and lower relapse risk after treatment cessation.

Conclusions:

• Quantitative HBsAg is a promising biomarker for monitoring chronic hepatitis B, reflecting cccDNA activity and treatment response.
• Defined HBsAg levels can help identify inactive carriers and predict treatment outcomes, guiding therapy adjustments.
• Serum HBsAg should be utilized in conjunction with HBV DNA levels for comprehensive patient management.