Background: Quantitative HBsAg has been regarded as helpful in monitoring and predicting treatment
outcome in chronic hepatitis B. The decline of HBsAg is more pronounced in patients receiving Peg-IFN than in
those receiving nucleos(t)ide analogues (NUCs). In patients receiving NUCs, the clearance of HBsAg seems very
rare especially in Asian populations with genotype B or C infection.
Methods: We retrospectively evaluated different qHBsAg kinetics in 200 patients receiving a nucleos(t)ide
analogue for chronic hepatitis B infection with persistently undetectable HBV DNA. HBsAg was quantified at
baseline and during antiviral therapy (weeks 24, 48, 96) in HBeAg positive patients (n=84) and HBeAg negative
Results: For HBeAg positive patients, the reduction of HBsAg in patients with entecavir therapy was
pronounced than in those with lamivudine, telbivudine, or lamivudine plus tenofovir therapy (mean decline 0.82
versus 0.72, 0.35 and 0.49 log IU/mL at week 96 respectively, p= 0.41). In patients who had HBeAg seroconversion,
the mean declines in HBsAg levels during 96 weeks with entecavir, telbivudine, and lamivudine plus tenofovir
therapy were significantly more than in those who had no HBeAg seroconversion (1.31, 0.46 and 0.75 log IU/mL,
p=0.015, 0.025 and 0.013, respectively), with the exception of patients treated with lamivudine alone (0.94 log IU/
mL, p=0.39). During the first year of treatment, two patterns of HBsAg decline were observed: a rapid decline (≥
0.5 log IU/mL) and a slow decline (<0.5 log IU/mL). One of 3 patients in the lamivudine group and 2 of 6 patients
in the entecavir group with rapid HBsAg decline achieved HBsAg loss during the 96 weeks. For HBeAg negative
patients, the mean HBsAg declines during 96 weeks of treatment with lamivudine, entecavir, telbivudine, or
lamivudine plus tenofovir were not significantly different (p=0.46). However, all 3 patients with lamivudine therapy
and 1 of 3 patients with telbivudine therapy who had a rapid HBsAg decline ultimately achieved HBsAg loss.
Conclusion: In clinical practice, HBsAg quantification and a rapid decline in serum HBsAg level during
the first year can be used to predict HBsAg loss in patients who have effective suppression of viral replication
during nucleos(t)ide analogue therapy.