Editorial: Measurement of HBsAg concentration during antiviral therapy of hepatitis B: who, when, and why

Clinical performance of a new hepatitis B surface antigen quantitative assay with automatic dilution

Hepatitis B virus surface antigen (HBsAg) levels reflect disease status and can predict the clinical response to antiviral treatment; however, the emergence of HBsAg mutant strains has become a challenge. The Abbott HBsAg quantification assay provides enhanced detection of HBsAg and HBsAg mutants. We aimed to evaluate the performance of the Abbott HBsAg quantification assay with automatic sample dilutions (shortened as automatic Architect assay), compared with the Abbott HBsAg quantification assay with manual sample dilutions (shortened as manual Architect assay) and the Roche HBsAg quantification assay with automatic sample dilutions (shortened as Elecsys). A total of 130 sera samples obtained from 87 hepatitis B virus (HBV)-infected patients were collected to assess the correlation between the automatic and manual Architect assays. Among the 87 patients, 41 provided 42 sera samples to confirm the linearity and reproducibility of the automatic Architect assay, and find out the correlation among the Elecsys and two Architect assays. The coefficients of variation (0.44-9.53%) and R(2) = 0.996-1, which were both determined using values obtained from the automatic Architect assay, showed good reproducibility and linearity. Results of the two Architect assays demonstrated a feasible correlation (n = 130 samples; R = 0.898, p < 0.01). With regard to subgroups, correlations between the two Architect assays were better in the hepatitis B e antigen (HBeAg)-negative group (HBeAg-negative group vs. HBeAg-positive group: R = 0.885 vs. R = 0.865, both p < 0.01) and low HBV DNA group (low DNA group vs. high DNA group: R = 0.886 vs. R = 0.844, both p < 0.01). Significant correlations were also found between the results of the Elecsys and Architect assays (R > 0.93 in all cases). In conclusion, the correlation between the automatic and manual dilution Architect assays was feasible, particularly in the HBeAg-negative and low DNA groups. With lower labor costs and less human error than the manual version, the Abbott automatic dilution Architect assay provided a good clinical performance with regard to the HBsAg levels.

Hepatitis B surface antigen levels at 6 months after treatment can predict the efficacy of lamivudine-adefovir combination therapy in patients with lamivudine-resistant chronic hepatitis B

BACKGROUND/AIMS

Quantitation of hepatitis B surface antigen (HBsAg) is an increasingly popular method to determine the treatment response in chronic hepatitis B (CHB) patients. The clinical value of HBsAg level measurement during rescue therapy for lamivudine (LMV)-resistant CHB patients have not been evaluated to date. Therefore, this study investigated the correlation between HBsAg level and treatment response in LMV-resistant CHB patients treated with adefovir (ADV) add-on therapy.

METHODS

LMV-resistant CHB patients treated with LMV-ADV combination therapy for over 2 years were included. HBsAg levels were measured at 6 month intervals until 1 year, and annually thereafter. Treatment response was assessed by determining the virological response (VR, undetectable HBV DNA levels) during treatment.

RESULTS

Fifty patients were included, of which 40 showed a VR. HBsAg levels were not different significantly at baseline (4.0 vs. 3.6 Log10 IU/mL, P=0.072). However, the HBsAg level decreased after 6 months of treatment in patients with a VR and became different significantly between the groups thereafter (3.9 vs. 3.3 at 6 months, P=0.002; 3.8 vs. 3.2 at 1 year, P=0.004; 3.9 vs. 3.2 at 2 years, P=0.008; 3.7 vs. 3.1 at 3 years, P =0.020).

CONCLUSIONS

The HBsAg level at 6 months after treatment can help predict treatment response.

HBsAg level and clinical course in patients with chronic hepatitis B treated with nucleoside analogue: five years of follow-up data

BACKGROUND/AIMS

Quantification of the hepatitis B surface antigen (HBsAg) is increasingly used to determine the treatment response in patients with chronic hepatitis B (CHB). However, there are limited data about the clinical implications of Quantification of HBsAg long-term nucleoside analogue treatment for CHB. We investigated the clinical correlation between HBsAg level and clinical course in patients with CHB who are treated long-term with nucleoside analogues.

METHODS

Patients with CHB who started lamivudine or entecavir monotherapy before June 2007 were enrolled. HBsAg was quantified at baseline, at 6 months, and at 1, 2, 3, 4, and 5 years of treatment. We compared data between the groups according to the presence or absence of a virological response (VR) and resistance.

RESULTS

Forty-eight patients were analyzed. There was no definite reduction in HBsAg level during the early period of treatment; differences in HBsAg levels between baseline and each time point were significant only at 5 years (P=0.028). In a subgroup analysis, this difference was significant only in non-resistant patients at 5 years (P=0.041).

CONCLUSIONS

There was no definite decrease in the HBsAg level during the early period of nucleoside analogue treatment, with long-term treatment being required to observe a significant reduction.

Quantitative hepatitis B surface antigen analysis in hepatitis B e antigen-positive nucleoside-naive patients treated with entecavir

BACKGROUND

Entecavir is a potent nucleoside analogue for treating chronic hepatitis B (CHB). Quantitative hepatitis B surface antigen (qHBsAg) levels are predictive of response to interferon-α in CHB treatment; however, the clinical utility of qHBsAg in nucleoside/nucleotide analogue-based CHB therapy is not fully characterized. This study assessed changes in qHBsAg in patients treated with entecavir in the Phase III study ETV-022.

METHODS

This retrospective post hoc analysis included nucleoside/nucleotide-naive, hepatitis B e antigen (HBeAg)-positive patients receiving entecavir (0.5 mg daily) in ETV-022 who had samples available for qHBsAg analysis through week 48. qHBsAg, HBV DNA and alanine aminotransferase levels were assessed for the overall patient cohort, for cohorts with or without HBeAg loss or HBsAg loss by week 48, and by HBV genotype.

RESULTS

Overall, 95 patients from ETV-022 had available samples for qHBsAg analysis through week 48. In all cohorts, 48 weeks of entecavir therapy resulted in effective HBV DNA suppression. In the overall cohort, qHBsAg declined by -0.92 log10 IU/ml through week 48. The decline in qHBsAg was more pronounced in patients with subsequent HBeAg loss or HBsAg loss, and in patients infected with HBV genotype D or A. On-treatment qHBsAg changes did not correlate with changes in HBV DNA; no on-treatment or baseline factor was found to be predictive of HBeAg loss or HBsAg loss.

CONCLUSIONS

Through 48 weeks of entecavir therapy, qHBsAg declined predominantly in those patients who achieved seroclearance of HBeAg or HBsAg. However, unlike with interferon-α-based therapy, early qHBsAg decline was not predictive of serological response at year 1 of entecavir treatment.

Analysis of mutations in the S gene of hepatitis B virus strains in patients with chronic infection by online bioinformatics tools

Hepatitis B virus (HBV) genomes show a high rate of mutations. This can lead to a variety of amino acid changes in the surface and polymerase genes, causing changes in viral protein conformation that can result in diminished antibody binding or decreased secretion of surface antigen (HBsAg). HBV monitoring increasingly relies on HBsAg detection and quantification, and therefore epidemiological data on HBsAg mutations are needed. We therefore analyzed the frequency of HBsAg mutations possibly influencing the quantification of HBsAg (MUPIQHs) in an unselected patient collective. To this end, we determined the HBV surface and polymerase gene sequences of an unselected patient collective of 237 individuals chronically infected with HBV and analyzed the MUPIQHs in these sequences using three different online HBV sequence analysis tools. We found that 17 or 34% of the patients, depending on the online interpretation algorithm used, harbored MUPIQHs and that MUPIQHs were not significantly associated with the duration of disease, treatment, or HBV genotype. Thus, this study shows that a substantial amount of HBV sequences derived from unselected patients chronically infected with HBV carry MUPIQHs, and therefore the reliability of routine quantitative and qualitative HBsAg tests needs to be reevaluated.

Collaborative study to establish a proficiency panel of hepatitis B surface antigens for evaluating in vitro diagnostics

Hepatitis B virus (HBV) infection is a critical health issue. In hospitals, in vitro diagnostic devices (IVDs) are used to detect HBV infections. The Taiwan Food and Drug Administration has prepared a candidate hepatitis B surface antigen (HBsAg) proficiency panel as an analytical standard to evaluate the sensitivity of the postmarketing surveillance of HBV IVDs. The sensitivity and stability of the proficiency panel, which comprises 5 HBsAg positive sera (SN-A to E) and 1 negative serum, was determined by a collaborative study involving 8 collaboratories. The potency of the candidate proficiency panel was consistent among all collaboratories. The potencies of sera SN-A to E in semiquantitative and quantitative analyses were 2.823-0.011 and 2.229-0.009 IU/mL, respectively. The mean coefficients of variation (CV) of intra and interday precision among the collaboratories were <7%. Accelerated degradation and long-term storage tests were used as stability assays. The candidate HBsAg proficiency panel exhibited good stability under different storage conditions, while all CVs were <6%. In conclusion, this candidate HBsAg proficiency panel is credible and reliable. Therefore, it can be used for postmarketing surveillance of HBV IVDs and quality assessment by clinical researchers and IVD manufacturers.