Hepatitis B core-related antigen kinetics in chronic hepatitis B virus genotype D-infected patients treated with nucleos(t)ide analogues or pegylated-interferon-α

A critique and systematic review of the clinical utility of hepatitis B core-related antigen

BACKGROUND & AIMS

Hepatitis B core-related antigen (HBcrAg) is a new biomarker for chronic hepatitis B (CHB) whose performance has not been critically or systematically appraised. Herein, we performed a systematic review to determine its clinical utility.

METHODS

We evaluated the biological pathway of HBcrAg and performed a systematic review of PubMed for clinical trials, cohort studies, and case-control studies that evaluated the clinical utility of HBcrAg. The effectiveness of HBcrAg in predicting HBV-specific clinical events (e.g. HBeAg seroconversion, phases of CHB, HBsAg loss, treatment response, and relapse after stopping therapy) was examined using receiver-operating characteristic curves. The correlation coefficients of HBcrAg with HBV DNA, quantitative HBsAg (qHBsAg), HBV RNA, and cccDNA were summarised from published studies. Median values were used as estimates.

RESULTS

HBcrAg consists of three precore/core protein products: HBcAg, HBeAg, and a 22 kDa precore protein. HBcrAg assays have been associated with false-positive rates of 9.3% and false-negative rates of between 12-35% for CHB. The new iTACT-HBcrAg is more sensitive but does not reduce the false-positive rate. A PubMed search found 248 papers on HBcrAg, of which 59 were suitable for analysis. The clinical performance of HBcrAg was evaluated using AUROC analyses, with median AUROCs of 0.860 for HBeAg seroconversion, 0.867 for predicting HBeAg(-) hepatitis, 0.645 for HBsAg loss, 0.757 for treatment response, and 0.688 for relapse after stopping therapy. The median correlation coefficient (r) was 0.630 with HBV DNA, 0.414 with qHBsAg, 0.619 with HBV RNA and 0.550 with cccDNA. Correlation decreased during antiviral therapy, but combined biomarkers improved performance.

CONCLUSIONS

HBcrAg has a mixed performance and has a poor correlation with HBsAg loss and antiviral therapy, hence HBcrAg results should be interpreted with caution.

IMPACT AND IMPLICATIONS

Hepatitis B core-related antigen (HBcrAg) has been used to assess management of patients with chronic hepatitis B (CHB) without a systematic and critical Sreview of its performance. Our finding that HBcrAg had a false-positive rate of 9% and a false-negative rate of 12-35% raises concerns, although larger studies are needed for validation. A systematic review showed that the performance of HBcrAg was variable depending on the CHB endpoint; it was excellent at predicting HBeAg seroconversion and HBeAg-negative chronic hepatitis (vs. chronic infection), which should be its main use, but it was poor for relapse after stopping antiviral therapy and for HBsAg loss. HBcrAg results should be interpreted with considerable caution, particularly by physicians, researchers, guideline committees and agencies that approve diagnostic tests.

Drug Discovery Study Aimed at a Functional Cure for HBV

Hepatitis B virus (HBV) causes acute and, most importantly, chronic hepatitis B worldwide. Antiviral treatments have been developed to reduce viral loads but few patients with chronic hepatitis B (CHB) achieve a functional cure. The development of new therapeutic agents is desirable. Recently, many novel agents have been developed, including drugs targeting HBV-DNA and HBV-RNA. This review provides an overview of the developmental status of these drugs, especially direct acting antiviral agents (DAAs). Serological biomarkers of HBV infection are essential for predicting the clinical course of CHB. It is also important to determine the amount and activity of covalently closed circular DNA (cccDNA) in the nuclei of infected hepatocytes. Hepatitis B core-associated antigen (HBcrAg) is a new HBV marker that has an important role in reflecting cccDNA in CHB, because it is associated with hepatic cccDNA, as well as serum HBV DNA. The highly sensitive HBcrAg (iTACT-HBcrAg) assay could be a very sensitive HBV activation marker and an alternative to HBV DNA testing for monitoring reactivation. Many of the drugs currently in clinical trials have shown efficacy in reducing hepatitis B surface antigen (HBsAg) levels. Combination therapies with DAAs and boost immune response are also under development; finding the best combinations will be important for therapeutic development.

Hepatitis B Virus Reactivation upon Immunosuppression: Is There a Role for Hepatitis B Core-Related Antigen in Patients with Immune-Escape Mutants? A Case Report

The reactivation of hepatitis B virus (HBVr) in patients undergoing pharmacological immunosuppression is a potentially fatal clinical event that may occur in patients with overt or occult HBV infection. The risk of HBVr is mainly determined by the type of immunosuppressive therapy and the HBV serologic profile, with a higher risk in patients positive for the hepatitis B surface antigen (HBsAg), and a lower risk in HBsAg-negative/antibodies to core antigen-positive subjects. Notably, a considerable proportion of patients experiencing HBVr showed a high degree of variability of the HBV S gene, possibly leading to immune escape mutants. These mutations, usually in the “a-determinant” of the HBsAg, can cause diagnostic problems and consequently hamper the appropriate management strategy of patients at risk of HBVr. Here, we describe a case of HBVr in a patient with a diagnosis of chronic myeloid leukemia and a previous history of kidney transplant, providing evidence of the potential usefulness of hepatitis B core-related antigen measurement in patients with HBV immune-escape mutants at risk of viral reactivation.

Critical Updates on Chronic Hepatitis B Virus Infection in 2021

Chronic hepatitis B virus (HBV) infection is a global healthcare burden in the form of chronic liver disease, cirrhosis, liver failure and liver cancer. There is no definite cure for the virus and even though extensive vaccination programs have reduced the burden of liver disease in the future population, treatment options to eradicate the virus from the host are still lacking. In this review, we discuss in detail current updates on the structure and applied biology of the virus in the host, examine updates to current treatment and explore novel and state-of-the-art therapeutics in the pipeline for management of chronic HBV. Furthermore, we also specifically review clinical updates on HBV-related acute on chronic liver failure (ACLF). Current treatments for chronic HBV infection have seen important updates in the form of considerations for treating patients in the immune tolerant phase and some clarity on end points for treatment and decisions on finite therapy with nucleos(t)ide inhibitors. Ongoing cutting-edge research on HBV biology has helped us identify novel target areas in the life cycle of the virus for application of new therapeutics. Due to improvements in the area of genomics, the hope for therapeutic vaccines, vector-based treatments and focused management aimed at targeting host integration of the virus and thereby a total cure could become a reality in the near future. Newer clinical prognostic tools have improved our understanding of timing of specific treatment options for the catastrophic syndrome of ACLF secondary to reactivation of HBV. In this review, we discuss in detail pertinent updates regarding virus biology and novel therapeutic targets with special focus on the appraisal of prognostic scores and treatment options in HBV-related ACLF.

Controversies in Treating Chronic Hepatitis B virus: The Role of Hepatitis B Virus DNA and Surface Antigen Titer

Controversial areas in chronic hepatitis B (CHB) are those where there is uncertainty, or differences of opinion in management, or where evidence may be insufficient. Areas of controversy include whether patients with high viral load but normal liver function tests should be treated to prevent hepatocellular carcinoma (HCC) or liver disease progression to cirrhosis. Another area is whether quantitative hepatitis B surface antigen (qHBsAg) can be used to better characterize phases of CHB and prognosticate. Finally, the utility of qHBsAg in the management of patients on antiviral therapy such as interferon and nucleoside analogues could improve management practices.

Blood-Based Biomarkers in Hepatitis B Virus-Related Hepatocellular Carcinoma, Including the Viral Genome and Glycosylated Proteins

Hepatitis B virus (HBV) infection is a major risk factor for hepatocellular carcinoma (HCC) development and is a global public health issue. High performance biomarkers can aid the early detection of HCC development in HBV-infected individuals. In addition, advances in the understanding of the pathogenesis of HBV infection and in clinical laboratory techniques have enabled the establishment of disease-specific tests, prediction of the progression of liver diseases, including HCC, and auxiliary diagnosis of HCC, using blood-based methods instead of biopsies of liver or HCC tissues. Viral factors such as the HBV genotype, HBV genetic mutations, HBV DNA, and HBV-related antigens, as well as host factors, such as tumor-associated proteins and post-translational modifications, especially glycosylated proteins, can be blood-based, disease-specific biomarkers for HCC development in HBV-infected patients. In this review, we describe the clinical applications of viral biomarkers, including the HBV genome and glycosylated proteins, for patients at a risk of HBV-related HCC, based on their molecular mechanisms. In addition, we introduce promising biomarker candidates for practical use, including colony stimulating factor 1 receptor (CSF1R), extracellular vesicles, and cell-free, circulating tumor DNA. The clinical use of such surrogate markers may lead to a better understanding of the risk of disease progression and early detection of HCC in HBV-infected patients, thereby improving their prognosis.

Hepatitis B Core-Related Antigen and New Therapies for Hepatitis B

The hepatitis B core-related antigen (HBcrAg) is an unprecedented novel HBV biomarker that plays an essential role in reflecting covalently closed circular DNA (cccDNA) in chronic hepatitis B (CHB) because its levels correlate with intrahepatic cccDNA and serum HBV DNA. In this review, we describe the clinical application of serum HBcrAg in CHB patients, with a particular focus on new therapies targeting intrahepatic HBV replication. (1) HBcrAg can be detected in clinical cases where serum HBV DNA is undetectable during anti-HBV therapy. (2) A highly sensitive HBcrAg assay (iTACT-HBcrAg) may be useful for monitoring HBV reactivation, as an alternative to HBV DNA. (3) Decreased HBcrAg levels have been significantly associated with promising outcomes in CHB patients, reducing the risk of progression or recurrence of hepatocellular carcinoma. Additionally, we focus on and discuss several drugs in development that target HBV replication, and monitoring HBcrAg may be useful for determining the therapeutic efficacies of such novel drugs. In conclusion, HBcrAg, especially when measured by the recently developed iTACT-HBcrAg assay, may be the most appropriate surrogate marker, over other HBV biomarkers, to predict disease progression and treatment response in CHB patients.

Chronic hepatitis B virus infection and fibrosis: novel non-invasive approaches for diagnosis and risk stratification

Despite the availability of an effective vaccination, chronic hepatitis B virus (HBV) infection is still a major health concern worldwide. Chronic HBV infection can lead to fibrosis accumulation and overtime to cirrhosis, the principal risk factor for liver failure and hepatocellular carcinoma development. Liver biopsy is still considered the gold standard for fibrosis assessment, even though it is invasive and not exempt of complications. Overtime, several non-invasive methods for the detection of liver fibrosis have been developed and gradually introduced into clinical practice. However, their main limitation is the poor performance for the detection of intermediate stages of fibrosis. Finally, novel serological biomarkers, polygenic risk scores and imaging methods have been proposed in last years as novel promising tools to correctly identify the degree of liver fibrosis and to monitor liver disease progression. In this narrative review, we provide an overview on the novel non-invasive approaches for the evaluation of liver fibrosis and risk stratification of patients with chronic hepatitis B.

Hepatitis B Core-Related Antigen as Surrogate Biomarker of Intrahepatic Hepatitis B Virus Covalently-Closed-Circular DNA in Patients with Chronic Hepatitis B: A Meta-Analysis

Hepatitis B virus (HBV) covalently-closed-circular (ccc)DNA is the key molecule responsible for viral persistence within infected hepatocytes. The evaluation of HBV cccDNA is crucial for the management of patients with chronic HBV infection and for the personalization of treatment. However, the need for liver biopsy is the principal obstacle for the assessment of intrahepatic HBV cccDNA. In the last decade, several studies have investigated the performance of hepatitis B core-related antigen (HBcrAg) as a surrogate of HBV cccDNA amount in the liver. In this meta-analysis, we collected 14 studies (1271 patients) investigating the correlation between serum HBcrAg and intrahepatic HBV cccDNA. Serum HBcrAg showed a high correlation with intrahepatic HBV cccDNA (r = 0.641, 95% confidence interval (CI) 0.510–0.743, p < 0.001). In a head-to-head comparison, we observed that the performance of HBcrAg was significantly superior to that of hepatitis B surface antigen (r = 0.665 vs. r = 0.475, respectively, p < 0.001). Subgroup analysis showed that the correlation between HBcrAg and intrahepatic HBV cccDNA was high, both in hepatitis B e antigen-positive and -negative patients (r = 0.678, 95% CI 0.403–0.840, p < 0.001, and r = 0.578, 95% CI 0.344–0.744, p < 0.001, respectively). In conclusion, the measurement of serum HBcrAg qualifies as a reliable non-invasive surrogate for the assessment of an intrahepatic HBV cccDNA reservoir.

Novel biomarkers for the management of chronic hepatitis B

Hepatitis B virus (HBV) cannot be eliminated completely from infected hepatocytes because of the presence of intrahepatic covalently closed circular DNA (cccDNA). As chronic hepatitis B (CHB) can progress to cirrhosis and hepatocellular carcinoma (HCC), it is important to manage CHB to prevent HCC development in high-risk patients with high viral replicative activity or advanced fibrosis. Serum biomarkers are noninvasive and valuable for the management of CHB. Hepatitis B core-related antigen (HBcrAg) correlates with serum HBV DNA and intrahepatic cccDNA. In CHB patients with undetectable serum HBV DNA or loss of HBsAg, HBcrAg still can be detected and the decrease in HBcrAg levels is significantly associated with hopeful outcomes. Therefore, HBcrAg can predict HCC occurrence or recurrence. Measurement of the Mac-2 binding protein glycosylation isomer (M2BPGi) has been introduced for the evaluation of liver fibrosis. Because elevated M2BPGi in CHB is related to liver fibrosis and the prediction of HCC development, monitoring its progression is essential. Because alpha fetoprotein (AFP) has insufficient sensitivity and specificity for early-stage HCC, a combination of AFP plus protein induced by vitamin K absence factor II, or AFP plus Lens culinaris agglutinin-reactive fraction of alpha-fetoprotein might improve the diagnosis of HCC development. Additionally, Dickkopf-1 and circulating immunoglobulin G antibodies are the novel markers to diagnose HCC or assess HCC prognosis. This review provides an overview of novel HBV biomarkers used for the management of intrahepatic viral replicative activity, liver fibrosis, and HCC development.

Hepatitis B Virus: Advances in Prevention, Diagnosis, and Therapy. Clin Microbiol Rev. 2020;33. [PMID: 32102898 DOI: 10.1128/cmr.00046-19]

Currently, despite the use of a preventive vaccine for several decades as well as the use of effective and well-tolerated viral suppressive medications since 1998, approximately 250 million people remain infected with the virus that causes hepatitis B worldwide. Hepatitis C virus (HCV) and hepatitis B virus (HBV) are the leading causes of liver cancer and overall mortality globally, surpassing malaria and tuberculosis. Linkage to care is estimated to be very poor both in developing countries and in high-income countries, such as the United States, countries in Western Europe, and Japan. In the United States, by CDC estimates, only one-third of HBV-infected patients or less are aware of their infection. Some reasons for these low rates of surveillance, diagnosis, and treatment include the asymptomatic nature of chronic hepatitis B until the very late stages, a lack of curative therapy with a finite treatment duration, a complex natural history, and a lack of knowledge about the disease by both care providers and patients. In the last 5 years, more attention has been focused on the important topics of HBV screening, diagnosis of HBV infection, and appropriate linkage to care. There have also been rapid clinical developments toward a functional cure of HBV infection, with novel compounds currently being in various phases of progress. Despite this knowledge, many of the professional organizations provide guidelines focused only on specific questions related to the treatment of HBV infection. This focus leaves a gap for care providers on the other HBV-related issues, which include HBV's epidemiological profile, its natural history, how it interacts with other viral hepatitis diseases, treatments, and the areas that still need to be addressed in order to achieve HBV elimination by 2030. Thus, to fill these gaps and provide a more comprehensive and relevant document to regions worldwide, we have taken a global approach by using the findings of global experts on HBV as well as citing major guidelines and their various approaches to addressing HBV and its disease burden.

Analytical and clinical evaluation of a novel assay for anti-HBc IgG measurement in serum of subjects with overt and occult HBV infection

OBJECTIVES

We assessed the analytical and clinical performance of the Lumipulse® G HBcAb-N (Fujirebio, Japan) assay for IgG antibodies to hepatitis B core antigen (anti-HBc IgG) measurement in serum of subjects with overt and occult HBV infection (OBI).

MATERIALS/METHODS

Serum anti-HBc IgG was assessed in 181 anti-HBc-positive subjects: 119 chronic hepatitis B (CHB) patients in different infection phases and 62 subjects (35 CHB and 27 OBI) with available liver specimens for HBV covalently-close-circular (ccc) DNA analysis.

RESULTS

The anti-HBc IgG assay showed a linear dynamic range (R² = 0.9967); lower limit of detection and quantitation were 0.5 IU/mL and 0.8 IU/mL. Reproducibility was 4.9% and accuracy 98.7%. Anti-HBc IgG levels varied according to HBV infection phase, linearly declined during antiviral treatment and resulted correlated to intrahepatic HBV cccDNA (r = 0.752, P < 0.001).

CONCLUSIONS

The quantitative anti-HBc IgG assay exhibited appropriate analytical performance and may represent a diagnostic complement in CHB patients and OBI subjects.

Non-invasive biomarkers for chronic hepatitis B virus infection management

Chronic hepatitis B virus (HBV) infection remains a major health burden with over 250 million cases worldwide. This complex infection can lead to chronic hepatitis, liver cirrhosis and hepatocellular carcinoma. Complete recovery is seldom achieved due to the persistence in infected hepatocytes of covalently closed circular (ccc)DNA, which is not targeted by current antiviral therapies. Routine circulating biomarkers used for clinical monitoring of patients do not accurately reflect the cccDNA pool and transcriptional activity. New biomarkers, such as serum HB core-related Ag and circulating HBV RNAs, are under development. In this review, we discuss surrogate non-invasive biomarkers for evaluating intrahepatic cccDNA abundance and transcriptional activity. We also present their relevance for improving the classification of patients with regards to their natural history and for evaluating novel compounds to assess target engagement and to define new virological endpoints.

The Role of Hepatitis B Core-Related Antigen

Hepatitis B virus (HBV) cannot be completely eliminated from infected hepatocytes due to the existence of intrahepatic covalently closed circular DNA (cccDNA). Serological biomarkers reflect intrahepatic viral replicative activity as non-invasive alternatives to liver biopsy. Hepatitis B core-related antigen (HBcrAg) is a novel biomarker that has an important role in chronic hepatitis B (CHB), because it correlates with serum HBV DNA and intrahepatic cccDNA. In clinical cases with undetectable serum HBV DNA or loss of HBsAg, HBcrAg still can be detected and the decrease in HBcrAg levels is significantly associated with promising outcomes for CHB patients. HBcrAg can predict spontaneous or treatment-induced hepatitis B envelope antigen (HBeAg) seroconversion, persistent responses before and after cessation of nucleos(t)ide analogues, potential HBV reactivation, HBV reinfection after liver transplantation, and risk of hepatocellular carcinoma progression or recurrence. In this review, the clinical applications of HBcrAg in CHB patients based on its virological features are described. Furthermore, new potential therapeutic anti-HBV agents that affect intrahepatic cccDNA are under development, and the monitoring of HBcrAg might be useful to judge therapeutic effects. In conclusion, HBcrAg might be a suitable surrogate marker beyond other HBV markers to predict the disease progression and treatment responses of CHB patients.

Proposed model for the prediction of intrahepatic covalently closed circular DNA level in patients with chronic hepatitis B

AIM

We sought to create a prediction model for intrahepatic covalently closed circular DNA (IH-cccDNA) level in chronic hepatitis B (CHB) patients and to validate the model's predictive accuracy.

METHODS

Patients who did not receive previous nucleoside analogue (NA) therapy were assigned to the training cohort (n = 57), and those who received previous NA therapy were assigned to the validation cohort (n = 69). Factors linked to IH-cccDNA levels in the training cohort were analyzed and a formula to predict IH-cccDNA levels was constructed. Next, the reproducibility of that formula was assessed.

RESULTS

In the multivariate analysis for the prediction of IH-cccDNA level in the training cohort, fasting blood sugar (FBS) (P = 0.0227), hepatitis B e antigen (HBeAg) (P = 0.0067) and log₁₀ (HB surface antigen [HBsAg]) (P = 0.0497) were significant, whereas HB core-related antigen (HBcrAg) tended to be significant (P = 0.0562). The formula was constructed and named the FBS-cres score based on the variables used (FBS, HBcrAg, HBeAg, and HBsAg). The FBS-cres score was calculated as: 3.1686 - (0.0148 × FBS) + (0.1982 × HBcrAg) + (0.0008168 × HBeAg) + (0.1761 × log₁₀ (HBsAg)). In the training cohort, a significant correlation was noted between HBcrAg and IH-cccDNA levels (P < 0.0001, r = 0.67), whereas the FBS-cres score was more closely correlated to IH-cccDNA level (P < 0.0001, r = 0.81). In the validation cohort, significant correlation was found between HBcrAg and IH-cccDNA levels (P = 0.0012, r = 0.38), whereas the FBS-cres score was more closely linked to IH-cccDNA levels (P < 0.0001, r = 0.51). Similar tendencies were observed in all subgroup analyses.

CONCLUSION

Our proposed model for the prediction of IH-cccDNA level could be helpful in CHB patients.

Very slow decline of hepatitis B virus surface antigen and core related antigen in chronic hepatitis B patients successfully treated with nucleos(t)ide analogues

We investigated the decline of hepatitis B virus surface antigen (HBsAg) and core related antigen (HBcrAg) in chronic hepatitis B patients sussessfully treated with nucleos(t)ide analogues. In patients with plasma viral suppression, the baseline median levels of HBsAg and HBcrAg were 3.1 and 3.0 log U/mL, respectively. The levels in naïve patients were 4.2 and 3.6 log U/mL for HBsAg and HBcrAg, respectively. No significant decline was observed in patients with viral suppression within a year period. A low reduction was observed during the first months after treatment initiation, especially regarding HBcrAg. The dynamics of these antigens after viral suppression should be further investigated.

Review article: hepatitis B core-related antigen (HBcrAg): an emerging marker for chronic hepatitis B virus infection

BACKGROUND

Chronic hepatitis B (CHB) cannot be completely eradicated due to the presence of covalently closed circular DNA (cccDNA) in the nuclei of infected hepatocytes. While quantification of intrahepatic cccDNA requires liver biopsies, serological markers can be non-invasive alternatives to reflect intrahepatic viral replicative activity. Recently, hepatitis B core-related antigen (HBcrAg) has been advocated as a novel serum marker for disease monitoring and prognostication of CHB.

AIM

To examine the virological aspect and clinical application of HBcrAg with respect to the natural history and treatment of CHB.

METHODS

We reviewed all papers published in the PubMed journal list and abstracts from major international meetings that included the keyword "HBcrAg" or "hepatitis B core-related antigen" until March 2017. Selected studies were compared and summarised on the basis of existing theories, as well as the authors' experience.

RESULTS

HBcrAg exhibited good correlation with intrahepatic (ih) cccDNA, ih total hepatitis B virus (HBV) DNA, serum HBV DNA and to a lesser extent HBV surface antigen (HBsAg). In situations where serum HBV DNA levels become undetectable or HBsAg loss is achieved, HBcrAg can still be detectable. This marker is helpful in differentiation of HBeAg-negative chronic hepatitis from HBeAg-negative chronic infection, predicting spontaneous or treatment-induced HBeAg seroconversion, sustained response to nucleos(t)ide analogue (NA), risk of HBV reactivation in occult HBV infection under immunosuppressive therapies, and risk of hepatocellular carcinoma (HCC) development as well as post-operative HCC recurrence.

CONCLUSIONS

HBcrAg is a potential surrogate marker of cccDNA. It may soon become a useful marker for disease monitoring, predicting treatment response and disease outcome of chronic hepatitis B.

Hepatitis B virus core-related antigen as a surrogate marker for covalently closed circular DNA

BACKGROUND & AIMS

Hepatitis B virus (HBV) covalently closed circular DNA (cccDNA) is a key to viral persistence in chronic hepatitis B infection. Serum hepatitis B core-related antigen (HBcrAg) is a novel marker for HBV disease. We aimed to determine whether HBcrAg could be a surrogate marker for intrahepatic cccDNA.

METHODS

Three hundred and five liver biopsies and the corresponding sera collected from 138 nucleos(t)ide analogues-treated patients were analysed. 124 patients had paired liver biopsies at baseline and 1-year post-treatment, and 43 patients had a third biopsy after 6-12 years of treatment. Serum HBcrAg, HBV DNA and hepatitis B surface antigen (HBsAg), and intrahepatic HBV DNA and cccDNA were measured.

RESULTS

HBcrAg strongly correlated with cccDNA (r=.70), intrahepatic total HBV DNA (r=.67) and serum HBV DNA (r=.69; all P<.0001). In the 130 samples with undetectable serum HBV DNA, HBcrAg was detectable in 101 (78%) samples, and HBcrAg levels still correlated positively with cccDNA (r=.42, P<.0001). At ≥6 years of therapy, the median logarithmic reduction in HBcrAg was 2.7 log kU/mL, which was comparable to the magnitude of reduction in cccDNA. Twenty-one patients had undetectable cccDNA after ≥6 years of treatment, in whom 15 (71%) had detectable HBcrAg (range: 1.2-537 kU/mL).

CONCLUSIONS

Serum HBcrAg is a reliable surrogate marker for intrahepatic cccDNA. HBcrAg could be a very sensitive marker to reflect the cccDNA content and persistence of disease even with the cccDNA levels below the detection limit of assays.