Clin Mol Hepatol > Volume 29(2); 2023 > Article
Mak, Hui, Fung, Seto, and Yuen: The role of different viral biomarkers on the management of chronic hepatitis B

ABSTRACT

Chronic hepatitis B infection is a major public health challenge. With the advancement in technology, various components of the viral cycle can now be measured in the blood to assess viral activity. In this review article, we summarize the relevant data of how antiviral therapies impact viral biomarkers, and discuss their potential implications. Viral nucleic acids including hepatitis B virus (HBV) double-stranded deoxy-ribonucleic acid (DNA) and to a lesser extent, pre-genomic RNA, are readily suppressed by nucleos(t)ide analogues (NUCs). The primary role of these markers include risk prediction for hepatocellular carcinoma (HCC) and risk stratification for partial cure, defined as off-therapy virological control, or functional cure, defined as hepatitis B surface antigen (HBsAg) seroclearance plus undetectable serum HBV DNA for ≥6 months. Viral translational products including hepatitis e antigen, quantitative HBsAg and hepatitis B core-related antigen can be reduced by NUCs and pegylated interferon a. They are important in defining disease phase, delineating treatment endpoints, and predicting clinical outcomes including HCC risk and partial/functional cure. As the primary outcome of phase III trials in chronic hepatitis B is set as HBsAg seroclearance, appropriate viral biomarkers can potentially inform the efficacy of novel compounds. Early viral biomarker response can help with prioritization of subjects into clinical trials. However, standardization and validation studies would be crucial before viral biomarkers can be broadly implemented in clinical use.

DISEASE BURDEN OF CHRONIC HEPATITIS B INFECTION

Chronic hepatitis B (CHB) infection affects 292 million people globally, and is a major cause of liver-related morbidities including liver failure, cirrhosis and hepatocellular carcinoma (HCC) [1]. As a significant public health concern, the World Health Organization (WHO) has set goals to reduce the incidence of CHB and associated mortality by year 2030 [2]. The majority of people with CHB acquired the infection perinatally and during early childhood [3] when the immune system is not well equipped to mount a sufficient response against hepatitis B virus (HBV), which then establishes chronicity and becomes a lifelong infection in the vast majority of cases. Without treatment, up to 15–40% CHB subjects will progress to develop the liver-related morbidities. The adverse clinical events could be reduced by approved antiviral therapy which primarily acts by suppression of viral replication or immunomodulation. These mechanisms are being further explored to look for novel drug candidates to treat CHB infection. In addition, newer viral biomarkers have been identified to help evaluate treatment response and determine prognosis among treated patients. In this review, we will discuss the profile and potential applications of various blood-based viral biomarkers in CHB patients receiving antiviral therapy.

THE HBV VIRAL CYCLE

To date, there are no effective treatments to clear HBV from the infected liver due to the peculiar mechanisms of the viral cycle (Fig. 1). HBV is an enveloped, hepatotropic partially double-stranded deoxy-ribonucleic acid (DNA) virus. A mature HBV virion is fully encapsidated and contains relaxed circular (rc) DNA of approximately 3.2 kilobase pairs. Following entry into the hepatocytes via interaction with the sodium taurocholate co-transporting polypeptide [4], the rcDNA is imported to the nucleus [5] and is repaired by host cell DNA repair machinery [6,7] and converted to covalently closed circular DNA (cccDNA), which serves as the template for viral transcription [8]. The HBV genome consists of four overlapping open reading frames, which give rise to viral transcripts that include the pre-genomic RNA (pgRNA) and messenger RNAs for subsequent translation of viral proteins: hepatitis B surface antigen (HBsAg), hepatitis B e antigen (HBeAg), hepatitis B core antigen (HBcAg), X protein (HBx), and HBV polymerase. The pgRNA is packaged in a capsid made from HBcAg, a process also known as encapsidation, followed by reverse transcription into rcDNA and to a lesser extent, double-stranded linear DNA (dslDNA). These viral genomes are then envel-oped and released as infectious virions. The encapsidated rcDNA can be redirected to the nucleus to replenish the intranuclear cccDNA pool [9,10]. The persistence of cccDNA pool in the hepatocytes is the primary reason why it is not possible to eradicate the virus. A minority of mature HBV virions contains dslDNA, which are replication-deficient but are capable of host genome integration at sites of chromosomal DNA breaks. These form stable templates for synthesis of HBsAg and HBx [11], and can become potentially carcinogenic [12].

TYPES OF ANTIVIRAL TREATMENT

There are two types of approved antiviral therapy in CHB: nucleos(t)ide analogues (NUCs) and pegylated interferona (PEG-IFNa). NUCs are DNA polymerase inhibitors that target the step of reverse transcription. As only a single step of the viral replication cycle is inhibited, there is relatively limited effects on the upstream events. The degree of viral suppression is limited to DNA synthesis, whereas cccDNA remains largely unaffected, and it would take a long time for the latter to decline. Therefore, NUCs need to be taken on a long-term basis, as premature withdrawal is associated with high rates of virological rebound [13,14]. The current first-line NUCs include entecavir, tenofovir disoproxil fumarate (TDF) and tenofovir alafenamide, all of which have a high barrier to viral resistance, and are generally well-tolerated.
The mechanisms of action for PEG-IFNa are less well-defined, but is believed to exert both immunomodulatory functions and direct antiviral properties. IFNa treatment induces a non-cytolytic antiviral state in the hepatocytes via regulation of gene expression and protein translation. One of the key mechanisms involve upregulation of APOBEC3 (a cytidine deaminase) which induces G-to-A hypermutations in the HBV genome and thereby inhibits viral replication [15] or even cccDNA degradation [16]. Also, IFNa treatment leads to cccDNAbound histone hypoacetylation and decreased binding to STAT1/STAT2 transcription factors, leading to reduced transcription of pgRNA from the cccDNA template [17]. Although PEG-IFNa can be given for a finite period (48-week course) as opposed to NUCs, HBV DNA suppression was suboptimal. In addition, it is administered subcutaneously and associated with numerous side effects, rendering it a less utilized treatment option in CHB.

SERUM VIRAL MARKERS TO EVALUATE TREATMENT RESPONSE

To assess treatment response, a number of viral biomarkers can be measured in the blood as a surrogate of the ongoing viral replicatory activities (Fig. 1). Well established markers such as HBV DNA and HBsAg have been incorporated as treatment endpoints in the CHB cascade of care (Fig. 2). On-treatment virological suppression, also known as incomplete cure, is the most reachable endpoint and can be achieved in >90% of NUC-treated subjects. Partial cure is defined as off-therapy virological suppression without HBsAg seroclearance, which is observed in around 20% subjects who received a finite course of therapy. Functional cure refers to sustained HBsAg seroclearance plus ≥6 months undetectable HBV DNA, which is associated with improved clinical outcomes but is only achieved by ~1% antiviral-treated subjects annually. Complete cure is defined as eradication of cccDNA, and sterilizing cure is defined as clearance of integrated DNA; both of which are unreachable with the current treatments. With these considerations, functional cure is regarded as the desirable treatment endpoint and has become a benchmark for phase 3 clinical trials of novel CHB therapy, with a threshold of HBsAg loss ≥30% as an arbitrarily acceptable rate of response 6 months after cessation of investigational compounds [18].
The widespread use of blood-based viral biomarker stems from the need to quantify transcriptionally active intrahepatic cccDNA, which requires tissue specimens obtained from liver biopsy. Due to the invasive nature of the procedure, together with concerns from sampling error, intra/inter-observer variability and lack of standardization of the measurement, cccDNA quantification has largely remained as a research tool [19,20]. To this end, a number of blood-based HBV biomarkers has been studied as surrogate markers for cccDNA. They can be broadly classified as viral nucleic acids and translational products of HBV.

Viral nucleic acids

HBV DNA

The vast majority of detectable serum circulating HBV DNA is in the form of enveloped/encapsidated rcDNA [21]. In untreated patients, it shows moderate to good correlation with intrahepatic cccDNA (correlation coefficient r 0.36–0.49) [22-25]. The widely used in vitro nucleic acid amplification method allows high sensitivity of DNA detection and quantification, with lower limits reaching or below 1 to 2 log.
Upon NUC therapy, serum HBV DNA declines rapidly to undetectable levels. When assessed at 48 weeks, first-line NUC leads to undetectable serum HBV DNA in 64–76% and 90–94% of HBeAg-positive and HBeAg-negative patients, respectively [26]. For PEG-IFNa, after the complete course of 48 weeks, HBV DNA undetectability can be achieved in only 14% and 19% HBeAg-positive and HBeAg-negative patients, respectively [26].

HBV pgRNA

Circulating HBV RNA are encapsidated pgRNA in virus-like particles [27]. In untreated patients, it shows good to excellent correlation with intrahepatic cccDNA (r=0.59–89) [28-30]. Serum pgRNA can be measured with rapid amplification of complimentary DNA ends-based real-time polymerase chain reaction method [27,31], and the performance of RNA assays has been improved recently to approach the WHO standards [32]. Prior to antiviral treatment, serum HBV pgRNA levels are always 1–2 log lower than serum HBV DNA.
After a period of NUC treatment, the serum HBV RNA levels were decreased to a lesser extent than HBV DNA, leading to a reverse in serum RNA:DNA ratio [33]. Like serum HBV DNA, the correlation with cccDNA will be lost after antiviral therapy. The 48-week decline in HBV RNA was 1.46 log upon NUC treatment [33]. When assessed at 48 weeks of PEG-IFNa therapy among HBeAg-positive patients, the mean HBV RNA declined from 7.73 to 4.66 log [34]. For HBeAg-negative patients, upon PEG-IFNa and assessed at 48 weeks of therapy, a 1.72 log decline was observed from a baseline mean level of 4.4 log [35]. Unlike serum HBV DNA, the current use of HBV pgRNA measurement remains in the research context with no widely accepted standard to facilitate implementation in clinical use, and few comparisons of the various assays have been performed so far [32,33].

Translational products

HBeAg

The qualitative HBeAg has been more clinically relevant, being used to stratify disease phase and as an endpoint of treatment among HBeAg-positive patients (i.e., HBeAg seroclearance or seroconversion). In contrast, the quantitative HBeAg levels are mainly for research purpose, which can be quantified and expressed in Paul-Ehrlich Institute unit per mL (PEI-U/mL).
For HBeAg-positive patients treated with 48 weeks of NUC and PEG-IFNa, 10–21% and 32% achieved HBeAg seroclearance respectively [26]. Quantitative HBeAg levels correlated with serum HBV RNA (r=0.68), DNA (r=0.35), qHBsAg (r=0.20) and HBcrAg (r=0.69) [33]. In patients (predominantly genotype B/C) treated with PEG-IFNa, HBeAg levels declined starting from week 12 of therapy only in patients who achieved subsequent HBeAg seroconversion. HBeAg less than 17.55 PEI-U/mL at week 12 had positive predictive value and negative predictive value of 38% and 95% to predict HBeAg seroconversion at week 48 [36]. In another study involving CHB patients of Chinese ethnicity, baseline HBeAg levels were incorporated into a risk score which also include other biochemical variables (alanine aminotransferase, globulin and gamma-glutamyl transpeptidase) with a C-index of 0.776 to predict HBeAg seroconversion at 1 year [37].

HBsAg

The majority of HBsAg detected in the serum are subviral particles (SVP), which exceed mature virions by 100–100,000 times [38]. Commercially available assays can detect HBsAg in all forms (SVP or as part of the mature virion). HBsAg can be produced from either cccDNA or integrated DNA [39], with the latter contributing more in HBeAg negative patients. While the qualitative HBsAg informs whether treatment endpoint (functional cure) has been reached, quantitative HBsAg (qHBsAg) allows risk prediction for various clinical outcomes (see below). The lower limit of detection is around 0.05 IU/mL for most commonly used quantitative assays [40-42]. The clinical significance of measuring HBsAg by higher sensitivity assays with the lower limit of detection of 0.005 IU/mL and 0.0005 IU/mL [43-46] remains to be defined. Serum qHBsAg shows moderate to good correlation with intrahepatic cccDNA in untreated patients (correlation coefficient 0.28–0.71) [24,47] depending on the HBeAg status.
HBsAg seroclearance rate at 48 weeks of NUC treatment is 0–1% [26,48], although the event rate will slowly increase upon long-term treatment to <2% per year [48-53]. For PEG-IFNa recipients, the 1-year HBsAg seroclearance rate is 4% [26] and slowly increases with time after treatment completion (2.4% in 6.1 years) [54].
For patients treated with NUCs, the annual decline of qHBsAg was only 0.107 log [51], with only 16.1% patients achieving ≥1 log decline from baseline at 1 year of TDF therapy [55]. In contrast, PEG-IFNa treatment resulted in a larger magnitude of qHBsAg decline. After 48 weeks of PEG-IFNa treatment, a 0.71 log decline in qHBsAg levels was observed [56]. In addition, treatment responders were likely to have more significant decline in qHBsAg levels during the early phase of treatment. In view of this characteristic, qHBsAg profile (baseline level and on-treatment decline) has been incorporated in treatment algorithms to indicate treatment futility and for consideration of treatment cessation. In HBeAg-positive CHB patients, qHBsAg level >20,000 for genotype B/C or no decline of qHBsAg for genotype A/D at 12 weeks of PEG-IFNa fulfils the treatment-stopping criteria. If the week 24 qHBsAg remains >20,000 IU/L, PEG-IFNa should also be stopped regardless of genotype. Similarly, for HBeAg-negative CHB patients with genotype D infection, absence of qHBsAg decline in combination with <2 log reduction in serum HBV DNA at 12 weeks should also be regarded as futile [26].

HBcrAg

Hepatitis B core-related antigen (HBcrAg) is a composite of 3 related proteins that share an identical 149 amino acid sequence: HBcAg, HBeAg and a truncated 22 kDa precore protein (p22Cr) that is a processed product of the precore protein; see Figure 1. The chemiluminescence signal is generated from immunocomplexes formed between HBcrAg and alkaline phosphatase-labelled anti-HBcrAg antibodies, after which the quantity can be derived from known concentrations of recombinant ProHBeAg [57,58]. HBcrAg demonstrates good correlation with intrahepatic cccDNA (r=0.48–0.70) in both untreated and NUC-treated subjects [57].
Measurement of HBcrAg at 48 weeks of first-line NUCs or 52 weeks of PEG-IFNa therapy demonstrated a median decline of 1.37 log [33,59]. Reduction in HBcrAg was correlated with reduction in cccDNA (r=0.503) [60]. The main limitation with HBcrAg is the relatively high lower limit of detection (3 log U/mL), and is not detectable in up to 30% of HBeAg-negative patients [33]. A recent novel HBcrAg assay demonstrated an improved sensitivity of 2.1 log U/mL, and potentially will provide more insights in the viral kinetics and changes upon treatment especially in HBeAg-negative patients [61].
Table 1 summarizes the treatment effects on hepatitis B viral biomarkers at 1 year stratified by treatment type.

POTENTIAL APPLICATION OF VIRAL MARKERS

Blood-based HBV biomarkers are crucial for evaluating treatment candidacy, treatment response in both approved therapies and novel drugs in the pipeline.

Decision on treatment candidacy

Not all CHB subjects are eligible for antiviral treatment. In the various clinical guidelines, serum viral biomarkers are essential to determine treatment candidacy. Serum HBV DNA remains the most important parameter, although qualitative HBeAg is included in the American Association for the Study of Liver Diseases (AASLD) and APASL guidelines to decide on the threshold of HBV DNA above which treatment is indicated. In general, serum HBV DNA >20,000 IU/mL (for HBeAg-positive subjects) or >2,000 IU/mL (for HBeAg-negative subjects) plus elevated serum alanine aminotransferase or presence of other risk features would be considered eligible for treatment. In cirrhotic patients, the HBV DNA threshold for treatment would be much lowered [26,62,63]. Higher serum HBcrAg were independently associated with immune tolerance over immune clearance among HBeAg-positive patients (8.2 vs 7.6 log) [64]. In contrast, lower serum qHBsAg levels were independently associated with inactive carrier state and HBsAg seroclearance [65-68]. These biomarkers might play a role to identify patients requiring antiviral therapy in the HBeAg-positive and HBeAg-negative phase, respectively.
In the setting of prevention of mother-to-child-transmission, the WHO recommends HBV DNA testing to decide whether antiviral prophylaxis should be given during pregnancy [69]. HBV DNA >200,000 IU/mL is regarded the threshold to initiate TDF treatment. Where antenatal HBV DNA testing is unavailable, both HBeAg (qualitative) and qHBsAg can be used as a surrogate marker to determine eligibility of TDF prophylaxis. HBeAg positivity has a sensitivity of 88.2% and specificity of 92.6% to detect HBV DNA >200,000 IU/mL [70]. Likewise, serum qHBsAg >4 log is 85.1% sensitive and 96.5% specific for HBV DNA >200,000 IU/mL [71,72].
A recently developed Xpert® HBV Viral Load assay for HBV DNA has shown promise to accurately quantify HBV DNA in dried blood spots, with 85.4% having estimable viral loads to within 1 log of the corresponding serum load, with a limit of detection of 7.5 IU/mL [73,74]. This approach would be very helpful in many resource-limited settings especially where the GeneXpert® system is already in place for the purpose of analysing other pathogens such as SARS-CoV-2 or Mycobacterium tuberculosis & rifampin resistance. Another point-of-care rapid diagnostic test (RDT) for HBcrAg has recently been developed using stored sera as a simplified assessment tool especially in settings where HBV DNA or qHBsAg are not routinely available. With a detection limit of 4.3 log U/mL, the RDT-HBcrAg can identify highly viremic patients that fulfil treatment criteria according to clinical guidelines, with sensitivity 90.5–96.6% and specificity 83.2–96.8% [75]. The RDT-HBcrAg kit has a low production cost (<USD 5), reasonable operating temperature (18–39°C) with simple sample handling without needing any specific equipment or molecular laboratory facilities. More validation studies for this kit as well as the cost-effectiveness of this approach in resource-limited settings should be evaluated.

Dose adjustment and regimen modification

With the understanding of the on-treatment profile of HBV DNA and qHBsAg, both are essential markers to be monitored during the course of therapy [26]. In NUC recipients, HBV DNA monitoring is essential to detect virological breakthrough which would suggest either primary resistance or non-compliance to treatment. In PEG-IFNa recipients, stopping rules are defined according to qHBsAg levels as discussed above.

Risk stratification for HCC

Viral biomarkers give important clues in the risk of HCC among treated CHB subjects. Serum qHBsAg has been shown to associated with HCC risk. The hazard ratio for developing HCC was 13.7 for low viremic (HBV DNA <2,000 IU/mL) HBeAg-negative patients with serum qHBsAg ≥3 log compared to those with serum qHBsAg <3 log [76]. Moreover, HBsAg seroclearance, i.e., functional cure, is associated with significantly reduced HCC risk, especially in subjects who achieved this endpoint before the age of 50 and regardless of whether the patient was given antiviral therapy [77,78]. Serum viral load (HBV DNA) is a well-known risk factor for HCC and demonstrated a biological gradient in the REVEAL-HBV cohort [79]. Long term NUC treatment has been shown to reduce the risk of HCC [80]. Since HBV DNA is no longer detectable in the serum (in the majority of cases) upon NUC treatment, other viral biomarkers have been explored to assess the risk of HCC in antiviral-treated CHB patients. In this context, serum HBcrAg and pgRNA might aid risk stratification in addition to serum HBV DNA and qHBsAg levels [81,82]. While serum HBcrAg is reduced in all NUC-treated CHB patients [83], a high post-treatment HBcrAg was associated with >2 fold increase in risk of HCC [84]. Similarly, on-treatment detectable serum pgRNA is associated with 3.5-fold higher risk of HCC in 2 years’ time [85].

Prediction of partial/functional cure

Among HBeAg-positive patients, a higher baseline serum HBcrAg was independently associated with NA-induced HBeAg seroconversion [64], while a lower HBcrAg at week 12 of PEG-IFN was predictive of HBeAg seroclearance and HBV DNA <2,000 IU/mL at 24 weeks post-treatment [60]. HBeAg seroclearance/seroconversion is the pre-requisite for cessation of long-term NUC among HBeAg-positive patients, after HBV DNA undetectability for a certain period, in order to achieve incomplete cure. Numerous studies have explored the success rate and predictors for off-therapy virological control [14,86]. Apart from host factors, viral factors might provide insights in risk of virological or clinical relapse after stopping long term NUC. Low end-of-therapy (EOT) serum qHBsAg, preferably <100 IU/mL, has been consistently shown to predict partial cure [87-89]. In addition, low EOT serum HBcrAg [90], undetectable EOT serum HBV pgRNA [91], or a combination of both [92,93], identified a subgroup of patients who would be able to stop long-term NUC with a lower chance of flare. Some patients with a favourable viral biomarker profile would benefit from such approach and achieve functional cure [94,95]. In fact, assessing viral biomarkers (serum HBcrAg and pgRNA) as early as week 4 of NUC treatment is able to highlight a group of patients who would achieve a low serum qHBsAg (<100 IU/mL) or HBsAg seroclearance in the long run [96]. This approach can help to identify subjects during the early phase who should not stop NUC and should be prioritized into clinical trials.

Evaluation of efficacy and target engagement for novel compounds

The treatment landscape of CHB is expected to change with the numerous novel agents being explored; detailed discussion of these therapeutic approaches has been reviewed elsewhere [97,98]. These drugs target alternative steps in the viral replication cycle, stimulate host immune response, or act on both pathways. As mentioned above, functional cure is the desirable treatment endpoint for phase 3 clinical trials of novel CHB therapy [18].
At the time of writing, several novel compounds have demonstrated promising results on sustainable HBsAg suppression. RNA interference-based therapy with either small interfering RNAs or antisense oligonucleotide (ASO) were able to knock down HBsAg levels by more than 1 log within <48 weeks of treatment [98]. For instance, JNJ-3989, a siRNA, when given with NUC led to HBsAg reduction by ≥1 log from baseline in 39/40 (97.5%) subjects at nadir, which persisted in 38% patients at 1 year post EOT [99]. The mean declines of HBeAg, HBcrAg and HBV RNA from baseline to 16 weeks were 1.47 log PEIU/mL, 1.2 log kU/mL and 1.93 log U/mL respectively. Bepirovirsen, an ASO, was able to induce functional cure in 9–10% participants assessed at 24 weeks post-EOT [100].
However, despite the large number of ongoing trials, no compounds have reached the benchmark of inducing functional cure in ≥30% subjects. It is therefore important to understand the mechanisms of action for various novel compounds and utilize the appropriate viral biomarkers to evaluate target engagement as an interim response [101]. Core protein allosteric modulator (CpAM) inhibits the formation of functional capsids and encapsidation, thereby reducing the amount of circulating encapsidated pgRNA. In patients who received vebicorvir (CpAM), significant reductions in serum HBV DNA and pgRNA were observed at week 12 and 24 even though no change in serum qHBsAg was seen [102]. The inhibition of pgRNA synthesis could be observed as early as day 15 in patients receiving ABI-H2158 (CpAM), with mean decline of >2 log from baseline compared to 0.03 log in the placebo group [103]. Other viral markers such as HBeAg and HBcrAg levels were evaluated in some of the trials involving CpAM [104,105].
According to a recent study with treatment-naïve cohorts receiving 4 8 week s of NUC s+RO70 49389 (CpAM) or NUCs+RO7049389+PEG-IFNa, the mean declines of HBeAg were 1.48 and 2.10 log IU/mL and for HBcrAg 1.23 and 1.76 log U/mL respectively [106]. However, the long-term durability of the viral kinetic changes during novel therapies, as well as predictive factors for a durable suppression of various viral biomarkers, remains largely unclear and should be evaluated in future clinical trials.
Table 2 summarizes the potential applications of the viral biomarkers discussed in various settings.

CONCLUSION

Viral biomarker assessment is indispensable in clinical management and through the journey of novel drug discovery in the field of CHB. In the current era with highly effective NUC therapy as the mainstay of treatment, HBV DNA will be expectedly undetectable and novel transcriptional (HBV RNA) and translational markers (qHBsAg and HBcrAg) can provide further insights into treatment efficacy. Emerging data suggests these viral biomarkers can aid treatment decision, risk stratification for HCC and risk prediction for partial cure/functional cure. As the primary outcome of phase III trials is set on functional cure, viral biomarkers can potentially inform the efficacy of novel compounds or treatment approaches in the early course of treatment, and help with prioritization of subjects into clinical trials. Importantly, standardization and validation studies are necessary before viral biomarkers can be broadly implemented in clinical use. The role of viral biomarkers needs to be further explored to pave the way into elimination of viral hepatitis B.

FOOTNOTES

Authors’ contribution
LYM was responsible literature search, critical appraisal and drafting of the manuscript. RWHH, JF and WKS were responsible for critical revision of the article. MFY was responsible for conception of the work and critical approval of the article.
Conflicts of Interest
LY Mak is an advisory board member for Gilead Sciences. WK Seto received speaker’s fees from AstraZeneca and Mylan, is an advisory board member of CSL Behring, is an advisory board member and received speaker’s fees from AbbVie, and is an advisory board member, received speaker’s fees and researching funding from Gilead Sciences. MF Yuen serves as advisor/consultant for AbbVie, Assembly Biosciences, Aligos Therapeutics, Arbutus Biopharma, Bristol Myer Squibb, Clear B Therapeutics, Dicerna Pharmaceuticals, Finch Therapeutics, GlaxoSmithKline, Gilead Sciences, Immunocore, Janssen, Merck Sharp and Dohme, Hoffmann-La Roche and Springbank Pharmaceuticals, Vir Biotechnology and receives grant/research support from Assembly Biosciences, Aligos Therapeutics, Arrowhead Pharmaceuticals, Bristol Myer Squibb, Fujirebio Incorporation, Gilead Sciences, Immunocore, Merck Sharp and Dohme, Hoffmann-La Roche, Springbank Pharmaceuticals and Sysmex Corporation. The remaining authors have no conflict of interests.

Figure 1.
Viral cycle of hepatitis B virus. Those highlighted in asterisks are detectable in the bloodstream and can be used as viral biomarkers. These include HBsAg, HBeAg, HBcrAg, HBV DNA and pgRNA. cccDNA, covalently closed circular DNA; dslDNA, double-stranded linear DNA; HBV, hepatitis B virus; HBcAg, hepatitis core antigen; HBcrAg, hepatitis B core related antigen; HBeAg, hepatitis B e antigen; HBsAg, hepatitis B surface antigen; mRNA, messenger RNA; NTCP, sodium taurocholate co-transporting polypeptide; pgRNA, pre-genomic RNA; rcDNA, relaxed circular DNA. *Detectable in the bloodstream.

cmh-2022-0448f1.jpg
Figure 2.
Treatment endpoints in the cascade of cure in chronic hepatitis B infection. cccDNA, covalently closed circular DNA; HBsAg, hepatitis B surface antigen; mRNA, messenger RNA; pgRNA, pre-genomic RNA; rcDNA, relaxed circular DNA; HBV, hepatitis B virus; DNA, double-stranded deoxy-ribonucleic acid.

cmh-2022-0448f2.jpg
Table 1.
Summary of treatment effects on hepatitis B viral biomarkers at 48 or 52 weeks according to treatment type
Assessment criteria First-line NUCs PEG-IFNα
HBV DNA undetectability HBeAg-positive: 64–76% HBeAg-positive: 14%
HBeAg-negative: 90–94% HBeAg-negative: 19%
HBV RNA -1.46 log HBeAg-positive: -7.73 to -4.66 log
HBeAg-negative: -1.72 log
HBeAg seroclearance HBeAg-positive: 10–21% HBeAg-positive: 32%
HBsAg seroclearance <1% 4%
qHBsAg -0.107 log (average rate per year) -0.71 log
HBcrAg -1.37 log -1.37 log

HBcrAg, hepatitis B core-related antigen; HBeAg, hepatitis B e antigen; HBV, hepatitis B virus; NUCs, nucleos(t)ide analogues; PEG-IFNα, pegylated interferon alpha; qHBsAg, quantitative hepatitis B surface antigen.

Table 2.
Potential application of serum-based hepatitis B viral biomarkers in various settings
Biomarker Decision on treatment candidacy Dose adjustment or regimen modification Risk stratification for HCC Prediction of partial cure or functional cure Evaluation of target engagement for novel compounds
HBV DNA Highly viremic: indicated for treatment NUC viral resistance: switch to another class of NUC Residual viraemia increases risk of HCC Undetectable HBV DNA for a period of consolidation is pre-requisite for NUC cessation RNAi-based therapy/CpAM
Prevention of MTCT
HBV RNA - - Residual viraemia increases risk of HCC Lower levels predict partial cure and functional cure RNAi-based therapy/CpAM
HBeAg (qualitative) Prevention of MTCT PEG-IFNα: HBeAg seroclearance is the treatment endpoint for HBeAg-positive patients - HBeAg seroclearance is pre-requisite for NUC cessation RNAi-based therapy
HBsAg (qualitative) - HBsAg seroclearance is associated with reduced risk of HCC Defines functional cure Undetectable serum HBsAg is the primary endpoint for phase III trials
qHBsAg Prevention of MTCT PEG-IFNa: stopping rule Predict risk of HCC in low viremic patients Lower levels predict partial cure and functional cure RNAi-based therapy
Predict inactive carrier state in HBeAg(-) patients
HBcrAg RDT point of care test for identifying highly viremic patients - Higher on-treatment levels increase risk of HCC Lower levels predict partial cure and functional cure RNAi-based therapy/CpAM
Predict immune tolerance in HBeAg(+) patients Predict response to NA or PEG-IFN

CpAM, core protein allosteric modulator; HBcrAg, hepatitis B core-related antigen; HBeAg, hepatitis B e antigen; HBV, hepatitis B virus; HBsAg, hepatitis B surface antigen; HCC, hepatocellular carcinoma; MTCT, mother-to-child-transmission; NUCs, nucleos(t)ide analogues; PEG-IFNα, pegylated interferon alpha; qHBsAg, quantitative hepatitis B surface antigen; RDT, rapid diagnostic test; RNAi, RNA interference.

Abbreviations

CHB
chronic hepatitis B
HCC
hepatocellular carcinoma
WHO
World Health Organization
HBV
hepatitis B virus
DNA
double-stranded deoxy-ribonucleic acid
rcDNA
relaxed circular DNA
NTCP
sodium taurocholate co-transporting polypeptide
cccDNA
covalently closed circular DNA
pgRNA
pre-genomic RNA
HBsAg
hepatitis B surface antigen
HBeAg
hepatitis B e antigen
HBcAg
hepatitis core antigen
HBx
x protein
dslDNA
double-stranded linear DNA
NUCs
nucleos(t) ide analogues
PEG-IFNa
pegylated interferon alpha
ETV
entecavir
TDF
tenofovir disoproxil fumarate
TAF
tenofovir alafenamide
RACE
rapid amplification of complimentary DNA ends
SVP
subviral particles
qHBsAg
quantitative hepatitis B surface antigen
HBcrAg
hepatitis B core related antigen
P22Cr
precore protein
RDT
rapid diagnostic test
EOT
end-of-therapy
RNAi
RNA interference
siRNAs
small interfering RNAs
ASO
antisense oligonucleotide
CpAM
core protein allosteric modulator

REFERENCES

1. Polaris Observatory Collaborators. Global prevalence, treatment, and prevention of hepatitis B virus infection in 2016: a modelling study. Lancet Gastroenterol Hepatol 2018;3:383-403.
pmid
2. Global Hepatitis Report 2017. Geneva: World Health Organization; 2017.

3. Razavi-Shearer D, Gamkrelidze I, Blach S, Estes C, Mooneyhan E, Razavi-Shearer K, et al. The incidence of chronic HBV by age at the global and regional level, 2022. Hepatology Vol. 76. Wiley. 2022:S29.

4. Ni Y, Lempp FA, Mehrle S, Nkongolo S, Kaufman C, Fälth M, et al. Hepatitis B and D viruses exploit sodium taurocholate cotransporting polypeptide for species-specific entry into hepatocytes. Gastroenterology 2014;146:1070-1083.
crossref pmid
5. Rabe B, Vlachou A, Panté N, Helenius A, Kann M. Nuclear import of hepatitis B virus capsids and release of the viral genome. Proc Natl Acad Sci U S A 2003;100:9849-9854.
crossref pmid pmc
6. Wei L, Ploss A. Core components of DNA lagging strand synthesis machinery are essential for hepatitis B virus cccDNA formation. Nat Microbiol 2020;5:715-726.
crossref pmid pmc pdf
7. Königer C, Wingert I, Marsmann M, Rösler C, Beck J, Nassal M. Involvement of the host DNA-repair enzyme TDP2 in formation of the covalently closed circular DNA persistence reservoir of hepatitis B viruses. Proc Natl Acad Sci U S A 2014;111:E4244-4253.
pmid pmc
8. Seeger C, Mason WS. Molecular biology of hepatitis B virus infection. Virology 2015;479-480:672-686.
crossref pmid
9. Tuttleman JS, Pourcel C, Summers J. Formation of the pool of covalently closed circular viral DNA in hepadnavirus-infected cells. Cell 1986;47:451-460.
crossref pmid
10. Ko C, Chakraborty A, Chou WM, Hasreiter J, Wettengel JM, Stadler D, et al. Hepatitis B virus genome recycling and de novo secondary infection events maintain stable cccDNA levels. J Hepatol 2018;69:1231-1241.
crossref pmid pmc
11. Tu T, Budzinska MA, Shackel NA, Urban S. HBV DNA integration: molecular mechanisms and clinical implications. Viruses 2017;9:75.
crossref pmid pmc
12. Jang JW, Kim JS, Kim HS, Tak KY, Nam H, Sung PS, et al. Persistence of intrahepatic hepatitis B virus DNA integration in patients developing hepatocellular carcinoma after hepatitis B surface antigen seroclearance. Clin Mol Hepatol 2021;27:207-218.
crossref pmid pdf
13. Schmid J, Langhorst J, Gaß F, Theysohn N, Benson S, Engler H, et al. Placebo analgesia in patients with functional and organic abdominal pain: a fMRI study in IBS, UC and healthy volunteers. Gut 2015;64:418-427.
crossref pmid
14. Berg T, Simon KG, Mauss S, Schott E, Heyne R, Klass DM, et al.; FINITE CHB study investigators. Long-term response after stopping tenofovir disoproxil fumarate in non-cirrhotic HBeAg-negative patients - FINITE study. J Hepatol 2017;67:918-924.
crossref pmid
15. Bonvin M, Achermann F, Greeve I, Stroka D, Keogh A, Inderbitzin D, et al. Interferon-inducible expression of APOBEC3 editing enzymes in human hepatocytes and inhibition of hepatitis B virus replication. Hepatology 2006;43:1364-1374.
crossref pmid
16. Lucifora J, Xia Y, Reisinger F, Zhang K, Stadler D, Cheng X, et al. Specific and nonhepatotoxic degradation of nuclear hepatitis B virus cccDNA. Science 2014;343:1221-1228.
crossref pmid pmc
17. Belloni L, Allweiss L, Guerrieri F, Pediconi N, Volz T, Pollicino T, et al. IFN-α inhibits HBV transcription and replication in cell culture and in humanized mice by targeting the epigenetic regulation of the nuclear cccDNA minichromosome. J Clin Invest 2012;122:529-537.
crossref pmid pmc
18. Cornberg M, Lok AS, Terrault NA, Zoulim F; 2019 EASL-AASLD HBV Treatment Endpoints Conference Faculty. Guidance for design and endpoints of clinical trials in chronic hepatitis B -Report from the 2019 EASL-AASLD HBV Treatment Endpoints Conference. Hepatology 2019 Nov 12;doi: 10.1002/hep.31030.
crossref pdf
19. Neuberger J, Patel J, Caldwell H, Davies S, Hebditch V, Hollywood C, et al. Guidelines on the use of liver biopsy in clinical practice from the British Society of Gastroenterology, the Royal College of Radiologists and the Royal College of Pathology. Gut 2020;69:1382-1403.
crossref pmid
20. Mani H, Kleiner DE. Liver biopsy findings in chronic hepatitis B. Hepatology 2009;49(5 Suppl):S61-71.
crossref pmid
21. Zhao XL, Yang JR, Lin SZ, Ma H, Guo F, Yang RF, et al. Serum viral duplex-linear DNA proportion increases with the progression of liver disease in patients infected with HBV. Gut 2016;65:502-511.
crossref pmid
22. Wong DK, Yuen MF, Yuan H, Sum SS, Hui CK, Hall J, et al. Quantitation of covalently closed circular hepatitis B virus DNA in chronic hepatitis B patients. Hepatology 2004;40:727-737.
crossref pmid
23. Lin LY, Wong VW, Zhou HJ, Chan HY, Gui HL, Guo SM, et al. Relationship between serum hepatitis B virus DNA and surface antigen with covalently closed circular DNA in HBeAg-negative patients. J Med Virol 2010;82:1494-1500.
crossref pmid
24. Guner R, Karahocagil M, Buyukberber M, Kandemir O, Ural O, Usluer G, et al. Correlation between intrahepatic hepatitis B virus cccDNA levels and other activity markers in patients with HBeAg-negative chronic hepatitis B infection. Eur J Gastroenterol Hepatol 2011;23:1185-1191.
crossref pmid
25. Gao Y, Li Y, Meng Q, Zhang Z, Zhao P, Shang Q, et al. Serum Hepatitis B Virus DNA, RNA, and HBsAg: Which Correlated Better with Intrahepatic Covalently Closed Circular DNA before and after Nucleos(t)ide Analogue Treatment? J Clin Microbiol 2017;55:2972-2982.
crossref pmid pmc pdf
26. European Association for the Study of the Liver. EASL 2017 Clinical Practice Guidelines on the management of hepatitis B virus infection. J Hepatol 2017;67:370-398.
crossref pmid
27. Wang J, Shen T, Huang X, Kumar GR, Chen X, Zeng Z, et al. Serum hepatitis B virus RNA is encapsidated pregenome RNA that may be associated with persistence of viral infection and rebound. J Hepatol 2016;65:700-710.
crossref pmid
28. Giersch K, Allweiss L, Volz T, Dandri M, Lütgehetmann M. Serum HBV pgRNA as a clinical marker for cccDNA activity. J Hepatol 2017;66:460-462.
crossref pmid
29. Wang Y, Liu Y, Liao H, Deng Z, Bian D, Ren Y, et al. Serum HBV DNA plus RNA reflecting cccDNA level before and during NAs treatment in HBeAg positive CHB patients. Int J Med Sci 2022;19:858-866.
crossref pmid pmc
30. Wang J, Yu Y, Li G, Shen C, Li J, Chen S, et al. Natural history of serum HBV-RNA in chronic HBV infection. J Viral Hepat 2018;25:1038-1047.
crossref pmid pdf
31. van Bömmel F, Bartens A, Mysickova A, Hofmann J, Krüger DH, Berg T, et al. Serum hepatitis B virus RNA levels as an early predictor of hepatitis B envelope antigen seroconversion during treatment with polymerase inhibitors. Hepatology 2015;61:66-76. Erratum in: Hepatology 2016;63:349.

32. Butler EK, Gersch J, McNamara A, Luk KC, Holzmayer V, de Medina M, et al. Hepatitis B virus serum DNA and RNA levels in Nucleos(t)ide analog-treated or untreated patients during chronic and acute infection. Hepatology 2018;68:2106-2117.
crossref pmid pdf
33. Mak LY, Cloherty G, Wong DK, Gersch J, Seto WK, Fung J, et al. HBV RNA profiles in patients with chronic hepatitis B under different disease phases and antiviral therapy. Hepatology 2021;73:2167-2179. Erratum in: Hepatology 2021;74:3561.

34. Wang X, Chi X, Wu R, Xu H, Gao X, Yu L, et al. Serum HBV RNA correlated with intrahepatic cccDNA more strongly than other HBV markers during peg-interferon treatment. Virol J 2021;18:4.
crossref pmid pmc pdf
35. Farag MS, van Campenhout MJH, Pfefferkorn M, Fischer J, Deichsel D, Boonstra A, et al. Hepatitis B virus RNA as early predictor for response to pegylated interferon alpha in HBeAg-negative chronic hepatitis B. Clin Infect Dis 2021;72:202-211.
crossref pmid pdf
36. Ma H, Yang RF, Wei L. Quantitative serum HBsAg and HBeAg are strong predictors of sustained HBeAg seroconversion to pegylated interferon alfa-2b in HBeAg-positive patients. J Gastroenterol Hepatol 2010;25:1498-1506.
crossref pmid
37. Geng M, Li Y, Gao F, Sun L, Yang X, Wang R, et al. A scoring model predicts hepatitis B e antigen seroconversion in chronic hepatitis B patients treated with nucleos(t)ide analogs: real-world clinical practice. Int J Infect Dis 2017;62:18-25.
crossref pmid
38. Yuen MF, Chen DS, Dusheiko GM, Janssen HLA, Lau DTY, Locarnini SA, et al. Hepatitis B virus infection. Nat Rev Dis Primers 2018;4:18035.
crossref pmid pdf
39. Wooddell CI, Yuen MF, Chan HL, Gish RG, Locarnini SA, Chavez D, et al. RNAi-based treatment of chronically infected patients and chimpanzees reveals that integrated hepatitis B virus DNA is a source of HBsAg. Sci Transl Med 2017;9:eaan0241.
crossref pmid pmc
40. Roche. Elecsys® HBsAg II: Immunoassay for the qualitative determination of hepatitis B surface antigen (HBsAg).

41. Maylin S, Boyd A, Delaugerre C, Zoulim F, Lavocat F, Simon F, et al. Comparison between Elecsys HBsAg II and architect HBsAg QT assays for quantification of hepatitis B surface antigen among patients coinfected with HIV and hepatitis B virus. Clin Vaccine Immunol 2012;19:242-248.
crossref pmid pmc pdf
42. Wursthorn K, Jaroszewicz J, Zacher BJ, Darnedde M, Raupach R, Mederacke I, et al. Correlation between the Elecsys HBsAg II assay and the Architect assay for the quantification of hepatitis B surface antigen (HBsAg) in the serum. J Clin Virol 2011;50:292-296.
crossref pmid
43. Lou S, Taylor R, Pearce S, Kuhns M, Leary T. An ultra-sensitive Abbott ARCHITECT® assay for the detection of hepatitis B virus surface antigen (HBsAg). J Clin Virol 2018;105:18-25.
crossref pmid
44. Matsumoto A, Imaizumi M, Tanaka Y, Nishiguchi S, Yatsuhashi H, Ishida T, et al. Novel and highly sensitive immunoassay for total hepatitis B surface antigen, including that complexed with hepatitis B surface antibody. J Gastroenterol 2017;52:376-384.
crossref pmid pdf
45. Shinkai N, Matsuura K, Sugauchi F, Watanabe T, Murakami S, Iio E, et al. Application of a newly developed high-sensitivity HBsAg chemiluminescent enzyme immunoassay for hepatitis B patients with HBsAg seroclearance. J Clin Microbiol 2013;51:3484-3491.
crossref pmid pmc pdf
46. Wong DK, Chen C, Mak LY, Fung J, Seto WK, Yuen MF. Detection of the hepatitis B surface antigen in patients with occult hepatitis B by use of an assay with enhanced sensitivity. J Clin Microbiol 2022;60:e0220421.
crossref pmid pdf
47. Thompson AJ, Nguyen T, Iser D, Ayres A, Jackson K, Littlejohn M, et al. Serum hepatitis B surface antigen and hepatitis B e antigen titers: disease phase influences correlation with viral load and intrahepatic hepatitis B virus markers. Hepatology 2010;51:1933-1944.
crossref pmid
48. Chan HL, Fung S, Seto WK, Chuang WL, Chen CY, Kim HJ, et al.; GS-US-320-0110 Investigators. Tenofovir alafenamide versus tenofovir disoproxil fumarate for the treatment of HBeAg-positive chronic hepatitis B virus infection: a randomised, double-blind, phase 3, non-inferiority trial. Lancet Gastroenterol Hepatol 2016;1:185-195. Erratum in: Lancet Gastroenterol Hepatol 2016;1:e2.

49. Hara T, Suzuki F, Kawamura Y, Sezaki H, Hosaka T, Akuta N, et al. Long-term entecavir therapy results in falls in serum hepatitis B surface antigen levels and seroclearance in nucleos(t)idenaïve chronic hepatitis B patients. J Viral Hepat 2014;21:802-808.
crossref pmid pdf
50. Ko KL, To WP, Mak LY, Seto WK, Ning Q, Fung J, et al. A large real-world cohort study examining the effects of long-term entecavir on hepatocellular carcinoma and HBsAg seroclearance. J Viral Hepat 2020;27:397-406.
crossref pmid pdf
51. Lam YF, Seto WK, Wong D, Cheung KS, Fung J, Mak LY, et al. Seven-year treatment outcome of entecavir in a real-world cohort: effects on clinical parameters, HBsAg and HBcrAg levels. Clin Transl Gastroenterol 2017;8:e125.
crossref pmid pmc
52. Buti M, Tsai N, Petersen J, Flisiak R, Gurel S, Krastev Z, et al. Seven-year efficacy and safety of treatment with tenofovir disoproxil fumarate for chronic hepatitis B virus infection. Dig Dis Sci 2015;60:1457-1464.
crossref pmid pdf
53. Buti M, Gane E, Seto WK, Chan HL, Chuang WL, Stepanova T, et al.; GS-US-320-0108 Investigators. Tenofovir alafenamide versus tenofovir disoproxil fumarate for the treatment of patients with HBeAg-negative chronic hepatitis B virus infection: a randomised, double-blind, phase 3, non-inferiority trial. Lancet Gastroenterol Hepatol 2016;1:196-206. Erratum in: Lancet Gastroenterol Hepatol 2016;1:e2.

54. Wong VW, Wong GL, Yan KK, Chim AM, Chan HY, Tse CH, et al. Durability of peginterferon alfa-2b treatment at 5 years in patients with hepatitis B e antigen-positive chronic hepatitis B. Hepatology 2010;51:1945-1953.
crossref pmid
55. Singh AK, Sharma MK, Hissar SS, Gupta E, Sarin SK. Relevance of hepatitis B surface antigen levels in patients with chronic hepatitis B during 5 year of tenofovir treatment. J Viral Hepat 2014;21:439-446.
crossref pmid pdf
56. Brunetto MR, Moriconi F, Bonino F, Lau GK, Farci P, Yurdaydin C, et al. Hepatitis B virus surface antigen levels: a guide to sustained response to peginterferon alfa-2a in HBeAg-negative chronic hepatitis B. Hepatology 2009;49:1141-1150.
crossref pmid
57. Mak LY, Wong DK, Cheung KS, Seto WK, Lai CL, Yuen MF. Review article: hepatitis B core-related antigen (HBcrAg): an emerging marker for chronic hepatitis B virus infection. Aliment Pharmacol Ther 2018;47:43-54.
crossref pmid pdf
58. Kimura T, Rokuhara A, Sakamoto Y, Yagi S, Tanaka E, Kiyosawa K, et al. Sensitive enzyme immunoassay for hepatitis B virus core-related antigens and their correlation to virus load. J Clin Microbiol 2002;40:439-445.
crossref pmid pmc pdf
59. Beudeker BJ, Groothuismink ZM, de Man RA, Janssen H, van der Eijk AA, Boonstra A, et al. Hepatitis B core-related antigen levels predict pegylated interferon-α therapy response in HBeAg-positive chronic hepatitis B. Antivir Ther 2020;25:217-222.
crossref pmid pdf
60. Chuaypen N, Posuwan N, Payungporn S, Tanaka Y, Shinkai N, Poovorawan Y, et al. Serum hepatitis B core-related antigen as a treatment predictor of pegylated interferon in patients with HBeAg-positive chronic hepatitis B. Liver Int 2016;36:827-836.
crossref pmid pdf
61. Inoue T, Kusumoto S, Iio E, Ogawa S, Suzuki T, Yagi S, et al. Clinical efficacy of a novel, high-sensitivity HBcrAg assay in the management of chronic hepatitis B and HBV reactivation. J Hepatol 2021;75:302-310.
crossref pmid
62. Terrault NA, Lok ASF, McMahon BJ, Chang KM, Hwang JP, Jonas MM, et al. Update on prevention, diagnosis, and treatment of chronic hepatitis B: AASLD 2018 hepatitis B guidance. Hepatology 2018;67:1560-1599.
crossref pdf
63. Sarin SK, Kumar M, Lau GK, Abbas Z, Chan HL, Chen CJ, et al. Asian-Pacific clinical practice guidelines on the management of hepatitis B: a 2015 update. Hepatol Int 2016;10:1-98.
crossref pdf
64. Lee HA, Lee HW, Park Y, Kim HS, Seo YS. Hepatitis B corerelated antigen is useful for predicting phase and prognosis of hepatitis B e antigen-positive patients. J Clin Med 2022;11:1729.
crossref pmid pmc
65. Ungtrakul T, Sriprayoon T, Kusuman P, Chunnuan P, Soonklang K, Sornsamdang G, et al. Role of quantitative hepatitis B surface antigen in predicting inactive carriers and HBsAg seroclearance in HBeAg-negative chronic hepatitis B patients. Medicine (Baltimore) 2017;96:e6554.
crossref pmid pmc
66. Chan HL, Thompson A, Martinot-Peignoux M, Piratvisuth T, Cornberg M, Brunetto MR, et al. Hepatitis B surface antigen quantification: why and how to use it in 2011 - a core group report. J Hepatol 2011;55:1121-1131.
crossref pmid
67. Martinot-Peignoux M, Lapalus M, Asselah T, Marcellin P. The role of HBsAg quantification for monitoring natural history and treatment outcome. Liver Int 2013;33 Suppl 1:125-132.
crossref pmid pdf
68. Tseng TC, Kao JH. Clinical utility of quantitative HBsAg in natural history and nucleos(t)ide analogue treatment of chronic hepatitis B: new trick of old dog. J Gastroenterol 2013;48:13-21.
crossref pmid pdf
69. Prevention of mother-to-child transmission of hepatitis B virus: guidelines on antiviral prophylaxis in pregnancy. Geneva: World Health Organization; 2020.

70. Boucheron P, Lu Y, Yoshida K, Zhao T, Funk AL, Lunel-Fabiani F, et al. Accuracy of HBeAg to identify pregnant women at risk of transmitting hepatitis B virus to their neonates: a systematic review and meta-analysis. Lancet Infect Dis 2021;21:85-96.
crossref pmid
71. Sun KX, Li J, Zhu FC, Liu JX, Li RC, Zhai XJ, et al. A predictive value of quantitative HBsAg for serum HBV DNA level among HBeAg-positive pregnant women. Vaccine 2012;30:5335-5340.
crossref pmid
72. Wen WH, Huang CW, Chie WC, Yeung CY, Zhao LL, Lin WT, et al. Quantitative maternal hepatitis B surface antigen predicts maternally transmitted hepatitis B virus infection. Hepatology 2016;64:1451-1461.
crossref pmid pdf
73. Jackson K, Tekoaua R, Li X, Locarnini S. Real-world application of the Xpert® HBV viral load assay on serum and dried blood spots. J Med Virol 2021;93:3707-3713.
crossref pmid pdf
74. Abravanel F, Lhomme S, Trémeaux P, Migueres M, Harter A, Haslé C, et al. Performance of the Xpert HBV Viral Load assay versus the Aptima Quant assay for quantifying hepatitis B virus DNA. Diagn Microbiol Infect Dis 2020;96:114946.
crossref pmid
75. Shimakawa Y, Ndow G, Kaneko A, Aoyagi K, Lemoine M, Tanaka Y; the PROLIFICA/HBcrAg-RDT Study Group. Rapid pointof-care test for hepatitis B core-related antigen to diagnose high viral load in resource-limited settings. Clin Gastroenterol Hepatol 2022 Jun 11;doi: 10.1016/j.cgh.2022.05.026.
crossref
76. Tseng TC, Liu CJ, Yang HC, Su TH, Wang CC, Chen CL, et al. High levels of hepatitis B surface antigen increase risk of hepatocellular carcinoma in patients with low HBV load. Gastroenterology 2012;142:1140-1149.e3 quiz e13-4.
crossref pmid
77. Yuen MF, Wong DK, Fung J, Ip P, But D, Hung I, et al. HBsAg Seroclearance in chronic hepatitis B in Asian patients: replicative level and risk of hepatocellular carcinoma. Gastroenterology 2008;135:1192-1199.
crossref pmid
78. Yip TC, Chan HL, Wong VW, Tse YK, Lam KL, Wong GL. Impact of age and gender on risk of hepatocellular carcinoma after hepatitis B surface antigen seroclearance. J Hepatol 2017;67:902-908.
crossref pmid
79. Chen CJ, Yang HI, Iloeje UH; REVEAL-HBV Study Group. Hepatitis B virus DNA levels and outcomes in chronic hepatitis B. Hepatology 2009;49(5 Suppl):S72-84.
crossref pmid
80. Su TH, Kao JH. Improving clinical outcomes of chronic hepatitis B virus infection. Expert Rev Gastroenterol Hepatol 2015;9:141-154.
crossref pmid
81. Wu JW, Kao JH, Tseng TC. Three heads are better than two: Hepatitis B core-related antigen as a new predictor of hepatitis B virus-related hepatocellular carcinoma. Clin Mol Hepatol 2021;27:524-534.
crossref pmid pmc pdf
82. Inoue T, Tanaka Y. Novel biomarkers for the management of chronic hepatitis B. Clin Mol Hepatol 2020;26:261-279.
crossref pmid pmc pdf
83. Mak LY, Ko KL, To WP, Wong DK, Seto WK, Fung J, et al. Entecavir reduced serum hepatitis B core-related antigen in chronic hepatitis B patients with hepatocellular carcinoma. Gut Liver 2020;14:665-668.
crossref pmid pmc
84. Cheung KS, Seto WK, Wong DK, Lai CL, Yuen MF. Relationship between HBsAg, HBcrAg and hepatocellular carcinoma in patients with undetectable HBV DNA under nucleos(t)ide therapy. J Viral Hepat 2017;24:654-661.
crossref pmid pdf
85. Mak LY, Huang Q, Wong DK, Stamm L, Cheung KS, Ko KL, et al. Residual HBV DNA and pgRNA viraemia is associated with hepatocellular carcinoma in chronic hepatitis B patients on antiviral therapy. J Gastroenterol 2021;56:479-488.
crossref pmid pdf
86. Liem KS, Fung S, Wong DK, Yim C, Noureldin S, Chen J, et al. Limited sustained response after stopping nucleos(t)ide analogues in patients with chronic hepatitis B: results from a randomised controlled trial (Toronto STOP study). Gut 2019;68:2206-2213.
crossref pmid
87. Chen CH, Hung CH, Hu TH, Wang JH, Lu SN, Su PF, et al. Association between level of hepatitis B surface antigen and relapse after entecavir therapy for chronic hepatitis B virus infection. Clin Gastroenterol Hepatol 2015;13:1984-1992.e1.
crossref pmid
88. Chen CH, Hung CH, Wang JH, Lu SN, Hu TH, Lee CM. Long-term incidence and predictors of hepatitis B surface antigen loss after discontinuing nucleoside analogues in noncirrhotic chronic hepatitis B patients. Clin Microbiol Infect 2018;24:997-1003.
crossref pmid
89. Jeng WJ, Chen YC, Sheen IS, Lin CL, Hu TH, Chien RN, et al. Clinical relapse after cessation of tenofovir therapy in hepatitis B e antigen-negative patients. Clin Gastroenterol Hepatol 2016;14:1813-1820.e1.
crossref pmid
90. Sonneveld MJ, Park JY, Kaewdech A, Seto WK, Tanaka Y, Carey I, et al.; CREATE Study Group. Prediction of sustained response after nucleo(s)tide analogue cessation using HBsAg and HBcrAg levels: a multicenter study (CREATE). Clin Gastroenterol Hepatol 2022;20:e784-e793.
crossref pmid
91. Seto WK, Liu KS, Mak LY, Cloherty G, Wong DK, Gersch J, et al. Role of serum HBV RNA and hepatitis B surface antigen levels in identifying Asian patients with chronic hepatitis B suitable for entecavir cessation. Gut 2021;70:775-783.
crossref pmid
92. Fan R, Peng J, Xie Q, Tan D, Xu M, Niu J, et al.; Chronic Hepatitis B Study Consortium. Combining hepatitis B virus RNA and hepatitis B core-related antigen: guidance for safely stopping nucleos(t)ide analogues in hepatitis B e antigen-positive patients with chronic hepatitis B. J Infect Dis 2020;222:611-618.
crossref pmid pdf
93. Papatheodoridi M, Papachristou E, Moschidis Z, Hadziyannis E, Rigopoulou E, Zachou K, et al. Significance of serum HBV RNA in non-cirrhotic HBeAg-negative chronic hepatitis B patients who discontinue effective antiviral therapy. J Viral Hepat 2022;29:948-957.
pmid
94. Hirode G, Choi HSJ, Chen CH, Su TH, Seto WK, Van Hees S, et al.; RETRACT-B Study Group. Off-therapy response after nucleos(t) ide analogue withdrawal in patients with chronic hepatitis B: an international, multicenter, multiethnic cohort (RETRACT-B Study). Gastroenterology 2022;162:757-771.e4.
crossref pmid
95. Berg T, Lampertico P. The times they are a-changing - A refined proposal for finite HBV nucleos(t)ide analogue therapy. J Hepatol 2021;75:474-480.
crossref pmid
96. Mak LY, Wong D, Kuchta A, Hilfiker M, Hamilton A, Chow N, et al. Hepatitis B virus pre-genomic RNA and hepatitis B corerelated antigen reductions at week 4 predict favourable hepatitis B surface antigen response upon long-term nucleos(t)ide analogue in chronic hepatitis B. Clin Mol Hepatol 2023;29:146-162.
crossref pmid pdf
97. Kim SW, Yoon JS, Lee M, Cho Y. Toward a complete cure for chronic hepatitis B: Novel therapeutic targets for hepatitis B virus. Clin Mol Hepatol 2022;28:17-30.
crossref pmid pdf
98. Mak LY, Cheung KS, Fung J, Seto WK, Yuen MF. New strategies for the treatment of chronic hepatitis B. Trends Mol Med 2022;28:742-757.
crossref pmid
99. Yuen MF, Locarnini S, Lim TH, Strasser SI, Sievert W, Cheng W, et al. Combination treatments including the small-interfering RNA JNJ-3989 induce rapid and sometimes prolonged viral responses in patients with CHB. J Hepatol 2022;77:1287-1298.
crossref pmid
100. Yuen MF, Lim SG, Plesniak R, Tsuji K, Janssen HLA, Pojoga C, et al.; B-Clear Study Group. Efficacy and safety of bepirovirsen in chronic hepatitis B infection. N Engl J Med 2022;387:1957-1968.
crossref pmid
101. Lim YS. New biomarkers of hepatitis B virus (HBV) infection: HBV RNA and HBV core-related antigen, new kids on the block? Clin Mol Hepatol 2023;29:118-119.
crossref pmid pdf
102. Sulkowski MS, Agarwal K, Ma X, Nguyen TT, Schiff ER, Hann HL, et al. Safety and efficacy of vebicorvir administered with entecavir in treatment-naïve patients with chronic hepatitis B virus infection. J Hepatol 2022;77:1265-1275.
crossref pmid
103. Agarwal K, Xu J, Gane EJ, Nguyen TT, Ding Y, Knox SJ, et al. Safety, pharmacokinetics and antiviral activity of ABI-H2158, a hepatitis B virus core inhibitor: A randomized, placebocontrolled phase 1 study. J Viral Hepat 2023;30:209-222.
pmid
104. Zoulim F, Lenz O, Vandenbossche JJ, Talloen W, Verbinnen T, Moscalu I, et al. JNJ-56136379, an HBV capsid assembly modulator, is well-tolerated and has antiviral activity in a phase 1 study of patients with chronic infection. Gastroenterology 2020;159:521-533.e9.
crossref pmid
105. Yuen MF, Gane EJ, Kim DJ, Weilert F, Yuen Chan HL, Lalezari J, et al. Antiviral activity, safety, and pharmacokinetics of capsid assembly modulator NVR 3-778 in patients with chronic HBV infection. Gastroenterology 2019;156:1392-1403.e7.
crossref pmid
106. Hou J, Gane EJ, Zhang W, Zhang J, Yuen MF, Lim TH, et al. Hepatitis B virus antigen reduction effect of RO7049389 plus NUC with/without Peg-IFN in chronic hepatitis B patients. J Hepatol 2022;77:S299.
crossref

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