HBsAg Quantification in Clinical Practice.

Area of Science:

• Hepatology
• Virology
• Immunology

Background:

• Standardized commercial assays for quantifying hepatitis B surface antigen (qHBsAg) are available.
• HBsAg levels vary across hepatitis B e antigen (HBeAg) phases: high in immune-tolerant, lower in immune-clearance, lowest in inactive carriers, and rising in HBeAg-negative chronic hepatitis B (CHB).

Purpose of the Study:

• To evaluate the utility of qHBsAg kinetics in predicting treatment response and differentiating HBeAg-negative CHB states.
• To explore the role of HBsAg decline in guiding therapy decisions and developing stopping rules for hepatitis B treatment.

Main Methods:

• Analysis of retrospective studies on HBsAg kinetics during different phases of chronic hepatitis B.
• Evaluation of qHBsAg and hepatitis B virus-deoxyribonucleic acid (HBV-DNA) levels in patients treated with pegylated-interferon (PEG-IFN) and nucleos(t)ide analogs.
• Assessment of HBsAg decline as a predictor of treatment response and nonresponse.

Main Results:

• HBsAg decline predicts response to PEG-IFN in HBeAg-positive patients.
• Combined qHBsAg and HBV-DNA levels may differentiate inactive carriers from HBeAg-negative CHB.
• Lower HBsAg decline with nucleos(t)ide analogs suggests active immune response is needed for significant reduction.
• HBsAg fall in HBeAg-negative CHB may inform stopping rules for therapy.

Conclusions:

• HBsAg quantification provides valuable information complementary to HBV-DNA for managing CHB.
• HBsAg kinetics can predict treatment outcomes and aid in treatment discontinuation decisions.
• Prospective studies are needed globally to establish optimal testing times and cutoff levels for HBsAg-based stopping rules.