Long-term hepatitis B surface antigen (HBsAg) kinetics during nucleoside/nucleotide analogue therapy: finite treatment duration unlikely

T cell--associated immunoregulation and antiviral effect of oxymatrine in hydrodynamic injection HBV mouse model

Although oxymatrine (OMT) has been shown to directly inhibit the replication of hepatitis B virus (HBV) in vitro, limited research has been done with this drug in vivo. In the present study, the antiviral effect of OMT was investigated in an immunocompetent mouse model of chronic HBV infection. The infection was achieved by tail vein injection of a large volume of DNA solution. OMT (2.2, 6.7 and 20 mg/kg) was administered by daily intraperitoneal injection for 6 weeks. The efficacy of OMT was evaluated by the levels of HBV DNA, hepatitis B surface antigen (HBsAg), hepatitis B e antigen (HBeAg) and hepatitis B core antigen (HBcAg). The immunoregulatory activity of OMT was evaluated by serum ELISA and flow cytometry. Results shows that OMT at 20 mg/kg inhibited HBV replication, and it was more efficient than entecavir (ETV) in the elimination of serum HBsAg and intrahepatic HBcAg. In addition, OMT accelerated the production of interferon-γ (IFN-γ) in a dose-dependent manner in CD4⁺ T cells. Our findings demonstrate the beneficial effects of OMT on the enhancement of immunological function and in the control of HBV antigens. The findings suggest this drug to be a good antiviral therapeutic candidate for the treatment of HBV infection.

Complete and Incomplete Hepatitis B Virus Particles: Formation, Function, and Application

Hepatitis B virus (HBV) is a para-retrovirus or retroid virus that contains a double-stranded DNA genome and replicates this DNA via reverse transcription of a RNA pregenome. Viral reverse transcription takes place within a capsid upon packaging of the RNA and the viral reverse transcriptase. A major characteristic of HBV replication is the selection of capsids containing the double-stranded DNA, but not those containing the RNA or the single-stranded DNA replication intermediate, for envelopment during virion secretion. The complete HBV virion particles thus contain an outer envelope, studded with viral envelope proteins, that encloses the capsid, which, in turn, encapsidates the double-stranded DNA genome. Furthermore, HBV morphogenesis is characterized by the release of subviral particles that are several orders of magnitude more abundant than the complete virions. One class of subviral particles are the classical surface antigen particles (Australian antigen) that contain only the viral envelope proteins, whereas the more recently discovered genome-free (empty) virions contain both the envelope and capsid but no genome. In addition, recent evidence suggests that low levels of RNA-containing particles may be released, after all. We will summarize what is currently known about how the complete and incomplete HBV particles are assembled. We will discuss briefly the functions of the subviral particles, which remain largely unknown. Finally, we will explore the utility of the subviral particles, particularly, the potential of empty virions and putative RNA virions as diagnostic markers and the potential of empty virons as a vaccine candidate.

Management of Antiviral Resistance in Chronic Hepatitis B

The primary goal of therapy for chronic hepatitis B (CHB) is to prevent liver disease progression. Hepatitis B surface antigen (HBsAg) seroclearance or seroconversion is regarded as an optimal endpoint to discontinue treatment. However, HBsAg seroclearance occurs very rarely with nucleos(t)ide analog (NUC) treatment, and long-term, almost indefinite, NUC treatment is required for the majority of patients. In patients with drug-resistant hepatitis B virus (HBV), a combination of tenofovir disoproxil fumarate (TDF) and entecavir (ETV), which is currently regarded as the strongest combination therapy against HBV, would be potentially safe to prevent the emergence of additional HBV resistance mutations. However, long-term tolerance data are lacking, and cost may be an issue for combination therapies. Several recent, well-designed, randomized controlled trials have shown that TDF monotherapy provides similar antiviral efficacy compared with the combination of TDF and ETV. Furthermore, no additional HBV resistance mutations emerged during TDF monotherapy for up to 96 weeks. Considering a comparable antiviral efficacy, extremely low risk of TDF-resistance, lower cost, and better safety potential, TDF monotherapy would be a reasonable choice for the treatment of drug-resistant patients with CHB.

Reduction of covalently closed circular DNA with long-term nucleos(t)ide analogue treatment in chronic hepatitis B

BACKGROUND AND AIMS

Hepatitis B virus (HBV) covalently closed circular DNA (cccDNA), a mini-chromosome essential for HBV replication, is supposed to be resistant to nucleos(t)ide analogue treatment. We investigated the effect of long-term nucleos(t)ide analogue treatment on cccDNA.

METHODS

Among 129 patients who had been enrolled in previous international nucleos(t)ide analogue clinical trials and had liver biopsies at baseline and one year after treatment, we recruited 43 patients on long-term continuous treatment for 72 to 145months for a third liver biopsy. Serum HBV DNA, hepatitis B surface antigen (HBsAg) levels, total intrahepatic HBV DNA (ihHBV DNA), cccDNA, HBV pregenomic RNA (pgRNA) as well as histologic changes were examined.

RESULTS

At the time of the third biopsy, serum HBV DNA levels were undetectable in all but one patient. The median levels of HBsAg, ihHBV DNA, and cccDNA were 2.88logIU/ml, 0.03copies/cell, and 0.01copies/cell, respectively. Compared to baseline levels, there was reduction of HBsAg levels by 0.54log (71.46%), ihHBV DNA levels by 2.81log (99.84%), and cccDNA levels by 2.94log (99.89%), with 49% having cccDNA levels below the detection limit. One patient had undetectable HBsAg. The median pgRNA level, measured only in the third biopsy, was 0.021copies/cell, with 40% of patients having undetectable pgRNA.

CONCLUSIONS

Long-term nucleos(t)ide analogue treatment induced marked depletion of cccDNA in the majority of patients while serum HBsAg levels, though reduced, were detectable in all but one patient. Whether cccDNA depletion is sustained and associated with better patient outcome requires further study.

LAY SUMMARY

It is generally presumed that a form of hepatitis B virus DNA, called covalently closed circular DNA (cccDNA), which hides inside the nuclei of liver cells of patients with chronic hepatitis B, cannot be reduced by antiviral treatment. The present study showed that with prolonged treatment (median period 126months), cccDNA can be markedly reduced, with 49% of liver biopsies having undetectable cccDNA. This suggests that viral replication capacity would be very low after prolonged antiviral treatment.

The role of quantitative hepatitis B surface antigen revisited

In the past 10years, there has been a lot of enthusiasm surrounding the use of serum hepatitis B surface antigen (HBsAg) quantification to predict disease activity and monitor treatment response in chronic hepatitis B. The measurement of HBsAg levels have been standardized in IU/ml, and nowadays it is almost a mandatory measurement due to the development of new antiviral treatments aiming at HBsAg seroclearance, i.e., functional cure of hepatitis B. Recently, there has been an improved understanding of the molecular virology of HBsAg, and particularly the relative roles of covalently closed circular DNA and integrated hepatitis B virus (HBV) DNA. This has shed new light on the interpretation of HBsAg levels in different phases of chronic hepatitis B. HBsAg level can assist the differentiation of immune tolerance and immune clearance in hepatitis B e antigen (HBeAg)-positive patients, and it can predict inactive disease and spontaneous HBsAg seroclearance in HBeAg-negative patients. The determination of HBsAg level is pivotal to individualize pegylated interferon (PegIFN) treatment; it is the key investigation to decide early termination of PegIFN among non-responders. Among patients treated by nucleos(t)ide analogues, responders tend to have dramatic reduction of HBsAg to low levels, which may be followed by HBsAg seroclearance. With newer data on combination treatment of PegIFN and nucleos(t)ide analogues as well as emerging new antiviral agents, HBsAg quantification is expected to become increasingly important to monitor and guide antiviral therapy for chronic hepatitis B.

Telbivudine versus entecavir in patients with undetectable hepatitis B virus DNA: a randomized trial

BACKGROUND

Telbivudine has been suggested to induce hepatitis B surface antigen (HBsAg) decline to the similar degree as pegylated interferon. We aimed to investigate whether telbivudine could further decrease HBsAg titer in patients who maintain undetectable serum hepatitis B virus (HBV) DNA after initial entecavir treatment.

METHODS

In this open-label trial, patients who had serum HBsAg and HBV DNA levels ≥1,000 IU/mL and <60 IU/mL, respectively, following entecavir (0.5 mg/day) treatment for HBeAg-positive chronic hepatitis B were randomized to either switch treatment to telbivudine (600 mg/day, n = 47) or continue entecavir (n = 50) for 48 weeks.

RESULTS

The baseline characteristics were comparable between groups including HBsAg levels (median, 3.41 log₁₀ IU/mL). All patients had undetectable HBV DNA and normal alanine aminotransferase level. At week 48, the mean change in serum HBsAg levels was not significantly different between the telbivudine and entecavir groups (-0.03 log₁₀ IU/mL vs. -0.05 log₁₀ IU/mL; P = 0.57). No patient experienced HBsAg seroclearance or HBsAg decline >0.5 log₁₀ IU/mL. Eleven patients (23.4%) in the telbivudine group, but none in the entecavir group, experienced virologic breakthrough (P < 0.001). Seven patients (14.9%) exhibited genotypic resistance mutations (M204I +/- L180M) during the virologic breakthrough.

CONCLUSION

Sequential therapy with entecavir followed by telbivudine resulted in a high rate of virologic breakthrough and drug-resistance without any beneficial effect on HBsAg decline. These results do not support the use of low genetic barrier drugs as a switch treatment strategy in patients who achieve virologic response with high genetic barrier drugs.

TRIAL REGISTRATION

NCT01595685 (date of trial registration: May 8, 2012).

Baseline HBsAg and HBcrAg titres allow peginterferon-based 'precision medicine' in HBeAg-negative chronic hepatitis B patients

Quantitative hepatitis B core-related antigen (qHBcrAg) has been proposed as an additional marker to quantitative HBsAg (qHBsAg), for management of chronic hepatitis B. Evaluate baseline combination of qHBsAg and qHBcrAg for identification of patients that could benefit from pegylated interferon-alpha-2a (PegIFN)-based therapy. Sixty-two HBeAg-negative patients treated with PegIFN or PegIFN plus tenofovir disoproxil fumarate (PegIFN+TDF). HBsAg and HBcrAg titres were evaluated at baseline. Thirty patients received PegIFN and 32 PegIFN+TDF. SR was 10 of 30 and 17 of 32 in PegIFN and PegIFN+TDF patients, respectively. Cut-offs determined by maximized Youden's index for identifying patients likely to respond to therapy were as follows: 3.141 log₁₀ IU/mL and 3.450 log₁₀ U/mL for HBsAg and HBcrAg, respectively. At the end of 3 years post-treatment follow-up, HBsAg loss was observed in 7 of 30 and 6 of 32 in PegIFN and PegIFN+TDF patients, respectively. The AUC was estimated to be 0.716 (95% CI [0.578, 0.855]) for HBsAg and 0.668 (95% CI [0.524, 0.811]) for HBcrAg (P=.5541). PPVs for AUCs(95%CI) were 0.762(0.590-0.947), 0.714(0.533-1.000) and 0.800(0.611-1.000), and NPVs for AUCs(95%CI) were 0.756(0.660-0.899), 0.718(0.630-0.857) and 0.765(0.675-0.889) for qHBsAg, qHBcrAg and the combination of both markers, respectively. Baseline qHBsAg 3.141 log₁₀ IU/mL and qHBcrAg 3.450 log₁₀ U/mL thresholds used separately or in combination allow prediction of response, prior to PegIFN-based therapy, with a PPV of 80.3% and NPV of 76.5%. Baseline qHBsAg is predictive of HBsAg loss. Both markers could be used, separately or in combination, for PegIFN-based 'precision therapy'. Our results emphasize that the combination of PegIFN alpha-2a plus TDF with 53% of SR might be an alternative to finite therapy.

Suppression of hepatitis B virus antigen production and replication by wild-type HBV dependently replicating HBV shRNA vectors in vitro and in vivo

Chronic infection with hepatitis B virus (HBV), a small DNA virus that replicates by reverse transcription of a pregenomic (pg) RNA precursor, greatly increases the risk for terminal liver disease. RNA interference (RNAi) based therapy approaches have shown potential to overcome the limited efficacy of current treatments. However, synthetic siRNAs as well as small hairpin (sh) RNAs expressed from non-integrating vectors require repeated applications; integrating vectors suffer from safety concerns. We pursue a new concept by which HBV itself is engineered into a conditionally replicating, wild-type HBV dependent anti-HBV shRNA vector. Beyond sharing HBV's hepatocyte tropism, such a vector would be self-renewing, but only as long as wild-type HBV is present. Here, we realized several important aspects of this concept. We identified two distinct regions in the 3.2 kb HBV genome which tolerate replacement by shRNA expression cassettes without compromising reverse transcription when complemented in vitro by HBV helper constructs or by wild-type HBV; a representative HBV shRNA vector was infectious in cell culture. The vector-encoded shRNAs were active, including on HBV as target. A dual anti-HBV shRNA vector delivered into HBV transgenic mice, which are not susceptible to HBV infection, by a chimeric adenovirus-HBV shuttle reduced serum hepatitis B surface antigen (HBsAg) up to ∼4-fold, and virus particles up to ∼20-fold. Importantly, a fraction of the circulating particles contained vector-derived DNA, indicating successful complementation in vivo. These data encourage further investigations to prove antiviral efficacy and the predicted self-limiting vector spread in a small animal HBV infection model.

Association Between Serum Level of Hepatitis B Surface Antigen at End of Entecavir Therapy and Risk of Relapse in E Antigen-Negative Patients

BACKGROUND & AIMS

This study investigated whether serum level of hepatitis B surface antigen (HBsAg) at the end of entecavir treatment was associated with risk of relapse.

METHODS

We performed a prospective multicenter study of 161 consecutive patients with chronic hepatitis B in whom the hepatitis B virus was no longer detected after 3 years or more of entecavir therapy. Treatment ended between July 1, 2011 and July 1, 2015. Patients were monitored for clinical relapse (hepatitis B virus DNA >2000 IU/mL and level of alanine aminotransferase more than 2-fold the upper limit of normal) and virologic relapse (hepatitis B virus DNA >2000 IU/mL). Outcomes were calculated using the Kaplan-Meier method and risk factors were identified by Cox proportional hazards modeling.

RESULTS

Two years after therapy ended, 49.2% of patients in the entire cohort had a clinical relapse (95% confidence interval [CI], 40.9%-58.1%) and 81.7% had a virologic relapse (95% CI, 74.3%-88.0%). Among patients who were hepatitis B e antigen-negative at the end of therapy, 39.2% had a clinical relapse (95% CI, 30.3%-49.6%) and 77.4% had a virologic relapse (95% CI, 68.6%-85.2%). Serum level of HBsAg was associated with relapse in the hepatitis B e antigen-negative patients (Ptrend = .006 for clinical relapse; Ptrend = .0001 for virologic relapse). In multivariate Cox regression analysis, the hazard ratio (per log IU/mL increment) for clinical relapse was 2.47 (95% CI, 1.45-4.23) and for virologic relapse was 1.80 (95% CI, 1.33-2.45). The 11 (9%) patients with levels of HBsAg <10 IU/mL did not relapse.

CONCLUSIONS

Serum level of HBsAg is associated with risk of relapse in patients who are hepatitis B e antigen-negative after treatment with entecavir. A low titer of HBsAg might be used to identify patients at low risk for relapse after treatment.

Recent advances in understanding and diagnosing hepatitis B virus infection

Hepatitis B virus (HBV) infects approximately 240 million individuals worldwide. Recent advances in the virology, immunopathogenesis, and diagnosis of HBV infection are summarized in this review article. The identification of a hepatocyte-specific cellular receptor for HBV, the sodium taurocholate co-transporting polypeptide (NTCP), made it possible to develop reliable cell culture systems and better understand the early steps of the viral lifecycle. Viral and host factors involved in covalently closed circular DNA synthesis, stability, and transcriptional regulation have also been identified and provide potential targets for new drugs. Based on recent evidence showing trained immunity in immune-tolerant patients, the immune tolerance and immune clearance phases have been renamed the non-inflammatory and inflammatory phases, respectively. New diagnostic and monitoring tools are now available, including rapid diagnostic tests for hepatitis B surface antigen (HBsAg) detection, HBsAg quantification assays, anti-HBc antibody quantification assays, an HBV core-related antigen (HBcrAg) quantification test, new HBV DNA detection and quantification assays, and an HBV RNA quantification test. Their clinical utility is under study. Finally, new antiviral and immune modulation approaches are in the preclinical or early clinical developmental stages, with the goal to achieve functional cure or ideally (if possible) eradication of HBV infection.

Lamivudine Monotherapy-Based cART Is Efficacious for HBV Treatment in HIV/HBV Coinfection When Baseline HBV DNA <20,000 IU/mL

BACKGROUND

Although combination antiretroviral therapy (cART) including tenofovir (TDF)+lamivudine (3TC) or emtricitabine (FTC) is recommended for treatment of HIV/HBV coinfected patients, TDF is unavailable in some resource-limited areas. Some data suggest that 3TC monotherapy-based cART may be effective in patients with low pretreatment HBV DNA.

METHODS

Prospective study of 151 Chinese HIV/HBV coinfected subjects of whom 60 received 3TC-based cART and 91 received TDF+3TC-based cART. Factors associated with HBV DNA suppression at 24 and 48 weeks, including anti-HBV drugs, baseline HBV DNA, and baseline CD4 cell count, were evaluated overall and stratified by baseline HBV DNA using Poisson regression with a robust error variance.

RESULTS

Baseline HBV DNA ≥20,000 IU/mL was present in 48.3% and 44.0% of subjects in the 3TC and TDF groups, respectively (P = 0.60). After 48 weeks of treatment, HBV DNA suppression rates were similar between these 2 groups (96.8% vs. 98.0% for 3TC and TDF+3TC, P > 0.999) in subjects with baseline HBV DNA <20,000 IU/mL; whereas in those with baseline HBV DNA ≥20,000 IU/mL, TDF+3TC was associated with higher suppression rates (34.5% vs. 72.5% in 3TC and TDF+3TC groups, respectively, P = 0.002). In stratified multivariate regression, TDF use (RR 1.98, P = 0.010) and baseline HBV DNA (per 1 log increase in International Units Per Milliliter, RR 0.74, P < 0.001) were associated with HBV DNA suppression only when baseline HBV DNA ≥20,000 IU/mL.

CONCLUSION

This study suggests that 3TC monotherapy-based cART is efficacious for HBV treatment through 48 weeks in HIV/HBV coinfection when baseline HBV DNA <20,000 IU/mL. Studies with long-term follow-up are warranted to determine if this finding persists.

Improved antiviral efficacy using TALEN-mediated homology directed recombination to introduce artificial primary miRNAs into DNA of hepatitis B virus

Chronic infection with hepatitis B virus (HBV) remains an important global health problem. Currently licensed therapies have modest curative efficacy, which is as a result of their transient effects and limited action on the viral replication intermediate comprising covalently closed circular DNA (cccDNA). Gene editing with artificial HBV-specific endonucleases and use of artificial activators of the RNA interference pathway have shown anti-HBV therapeutic promise. Although results from these gene therapies are encouraging, maximizing durable antiviral effects is important. To address this goal, a strategy that entails combining gene editing with homology-directed DNA recombination (HDR), to introduce HBV-silencing artificial primary microRNAs (pri-miRs) into HBV DNA targets, is reported here. Previously described transcription activator-like effector nucleases (TALENs) that target the core and surface sequences of HBV were used to introduce double stranded breaks in the viral DNA. Simultaneous administration of donor sequences encoding artificial promoterless anti-HBV pri-miRs, with flanking arms that were homologous to sequences adjoining the TALENs' targets, augmented antiviral efficacy. Analysis showed targeted integration and the length of the flanking homologous arms of donor DNA had a minimal effect on antiviral efficiency. These results support the notion that gene editing and silencing may be combined to effect improved inhibition of HBV gene expression.

Hepatitis B surface antigen seroclearance during nucleoside analogue therapy: surface antigen kinetics, outcomes, and durability

BACKGROUND

Hepatitis B surface antigen (HBsAg) seroclearance is the recommended treatment end point for nucleoside analogue (NA) therapy in chronic hepatitis B, yet the underlying kinetics and durability of HBsAg seroclearance in NA-treated patients have not been well described.

METHODS

We compared the HBsAg kinetics and long-term serologic outcomes of 51 chronic hepatitis B patients achieving HBsAg seroclearance during NA therapy with those of 51 HBsAg-positive controls, matched for age, sex, hepatitis B e antigen status, NA type, and treatment duration. Viral profiles before and after HBsAg seroclearance during and after NA treatment cessation were determined.

RESULTS

The median time to HBsAg seroclearance and the median follow-up duration after HBsAg seroclearance were 61.2 and 51.6 months respectively. Patients achieving HBsAg seroclearance maintained high median rates of HBsAg reduction throughout therapy (first 6 months, 0.40 IU/mL/year; after year 1, 0.39 IU/mL/year; p = 0.809). For controls, the median rate of HBsAg reduction was significantly slower with time (first 6 months and after year 1, 0.19 and 0.05 IU/mL/year; p = 0.006). The difference in the median HBsAg reduction rates after year 1 between the two groups was significant (p < 0.001). The cumulative rates of antibody to HBsAg development and HBsAg seroreversion 72 months after HBsAg seroclearance were 68.9 and 8.3% (one patient receiving immunosuppressive therapy; one patient with pre-S/S variant), respectively. Among 22 patients who discontinued therapy after HBsAg seroclearance, 21 remained HBsAg negative with undetectable hepatitis B virus DNA and one patient with reactivation had the pre-S/S variant.

CONCLUSION

NA-treated patients achieving HBsAg seroclearance uniquely maintained high rates of HBsAg reduction throughout treatment, with HBsAg seroclearance durable in most of the patients after treatment cessation.

Tenofovir monotherapy versus tenofovir and entecavir combination therapy in patients with entecavir-resistant chronic hepatitis B with multiple drug failure: results of a randomised trial

OBJECTIVE

Little clinical data are available regarding the optimal treatment of patients who harbour entecavir (ETV)-resistant HBV.

DESIGN

In this multicentre randomised trial, patients who had HBV with ETV resistance-associated mutations and serum HBV DNA concentrations >60 IU/mL were randomised to receive tenofovir disoproxil fumarate (TDF, 300 mg/day) monotherapy (n=45) or TDF and ETV (1 mg/day) combination therapy (n=45) for 48 weeks.

RESULTS

Baseline characteristics were comparable between groups, including HBV DNA levels (median, 4.02 log10 IU/mL) and hepatitis B e antigen-positivity (89%). All patients had at least one ETV-resistance mutation: rtT184A/C/F/G/I/L/S (n=49), rtS202G (n=43) and rtM250L/V (n=7), in addition to rtM204V/I (n=90). All except one patient in the TDF group completed 48 weeks of treatment. At week 48, the proportion of patients with HBV DNA <15 IU/mL, the primary efficacy endpoint, was not significantly different between the TDF and TDF+ETV groups (71% vs. 73%; p>0.99). The mean change in HBV DNA levels from baseline was not significantly different between groups (-3.66 vs. -3.74 log10 IU/mL; p=0.81). Virological breakthrough occurred in one patient on TDF, which was attributed to poor drug adherence. At week 48, six and three patients in the TDF and TDF+ETV groups, respectively, retained their baseline resistance mutations (p>0.99). None developed additional resistance mutations. Safety profiles were comparable in the two groups.

CONCLUSIONS

TDF monotherapy for 48 weeks provided a virological response comparable to that of TDF and ETV combination therapy in patients infected with ETV-resistant HBV.

TRIAL REGISTRATION NUMBER

ClinicalTrials.gov ID NCT01639092.

Role of covalently closed circular DNA in treatment of chronic hepatitis B

During hepatitis B virus (HBV) infection, covalently closed circular DNA (cccDNA) acts as the template for the synthesis of viral RNA and new virions. Current therapies rarely achieve an elimination of cccDNA. Biosynthesis of relaxed circular (RC) DNA by reverse transcription of the viral pregenomic RNA is now understood quite well, yet conversion of RC-DNA to cccDNA is still obscure. Conceptual and recent experimental data link cccDNA formation to cellular DNA repair, which is increasingly appreciated as a critical interface between cells and viruses. This review aims to summarize current knowledge on cccDNA molecular biology, to highlight the experimental restrictions that have hitherto hampered faster progress and to discuss cccDNA as a target for potentially curative therapies for chronic hepatitis B.

Global strategies are required to cure and eliminate HBV infection

Chronic HBV infection results in >1 million deaths per year from cirrhosis and liver cancer. No known cure for chronic HBV exists, due in part to the continued presence of transcriptionally active DNA in the nucleus that is not directly targeted by current antiviral therapies. A coordinated approach is urgently needed to advance an HBV cure worldwide, such as those established in the HIV field. We propose the establishment of an International Coalition to Eliminate Hepatitis B Virus (ICE-HBV) to facilitate the formation of international working groups on HBV virology, immunology, innovative tools and clinical trials: to promote awareness and education as well as to drive changes in government policy and ensure funds are channelled to HBV cure research and drug development. With the ICE-HBV in place, it should be possible to enable a HBV cure within the next decade.

In vivo reduction of hepatitis B virus antigenemia and viremia by antisense oligonucleotides

BACKGROUND & AIMS

Current treatment of chronic hepatitis B virus infection (CHB) includes interferon and nucleos(t)ide analogues, which generally do not reduce HBV surface antigen (HBsAg) production, a constellation that is associated with poor prognosis of CHB. Here we evaluated the efficacy of an antisense approach using antisense oligonucleotide (ASO) technology already in clinical use for liver targeted therapy to specifically inhibit HBsAg production and viremia in a preclinical setting.

METHODS

A lead ASO was identified and characterized in vitro and subsequently tested for efficacy in vivo and in vitro using HBV transgenic and hydrodynamic transfection mouse and a cell culture HBV infection model, respectively.

RESULTS

ASO treatment decreased serum HBsAg levels ⩾2 logs in a dose and time-dependent manner; HBsAg decreased 2 logs in a week and returned to baseline 4 weeks after a single ASO injection. ASO treatment effectively reduced HBsAg in combination with entecavir, while the nucleoside analogue alone did not. ASO treatment has pan-genotypic antiviral activity in the hydrodynamic transfection system. Finally, cccDNA-driven HBV gene expression is ASO sensitive in HBV infected cells in vitro.

CONCLUSION

Our results demonstrate in a preclinical setting the efficacy of an antisense approach against HBV by efficiently reducing serum HBsAg (as well as viremia) across different genotypes alone or in combination with standard nucleoside therapy. Since the applied antisense technology is already in clinical use, a lead compound can be rapidly validated in a clinical setting and thus, constitutes a novel therapeutic approach targeting chronic HBV infection.

Progress With Developing Use of Gene Editing To Cure Chronic Infection With Hepatitis B Virus

Chronic infection with hepatitis B virus (HBV) occurs in approximately 6% of the world's population. Carriers of the virus are at risk for life-threatening complications, and developing curative treatment remains a priority. The main shortcoming of licensed therapies is that they do not affect viral covalently closed circular DNA (cccDNA), a stable intermediate of replication. Harnessing gene editing to mutate cccDNA provides the means to inactivate HBV gene expression permanently. Reports have described use of engineered zinc finger nucleases (ZFNs), transcription activator-like effector nucleases (TALENs), and clustered regularly interspaced short palindromic repeats (CRISPR) with CRISPR-associated (Cas) nucleases. Although inhibition of viral replication has been demonstrated, reliably detecting mutations in cccDNA has been difficult. Also, the dearth of murine models that mimic cccDNA formation has hampered analysis in vivo. To reach a stage of clinical use, efficient delivery of the editors to HBV-infected hepatocytes and limiting unintended off-target effects will be important. Investigating therapeutic efficacy in combination with other treatment strategies, such as immunotherapies, may be useful to augment antiviral effects. Advancing gene editing as a mode of treating HBV infection is now at an interesting stage and significant progress is likely to be made in the immediate future.

Hepatocellular carcinoma and hepatitis B surface protein

The tumorigenesis of hepatitis B virus (HBV)-associated hepatocellular carcinoma (HCC) has been widely studied. HBV envelope proteins are important for the structure and life cycle of HBV, and these proteins are useful for judging the natural disease course and guiding treatment. Truncated and mutated preS/S are produced by integrated viral sequences that are defective for replication. The preS/S mutants are considered “precursor lesions” of HCC. Different preS/S mutants induce various mechanisms of tumorigenesis, such as transactivation of transcription factors and an immune inflammatory response, thereby contributing to HCC. The preS2 mutants and type II “Ground Glass” hepatocytes represent novel biomarkers of HBV-associated HCC. The preS mutants may induce the unfolded protein response and endoplasmic reticulum stress-dependent and stress-independent pathways. Treatments to inhibit hepatitis B surface antigen (HBsAg) and damage secondary to HBsAg or the preS/S mutants include antivirals and antioxidants, such as silymarin, resveratrol, and glycyrrhizin acid. Methods for the prevention and treatment of HCC should be comprehensive.

An ultrasensitive sandwich-type electrochemical immunosensor based on δ-MnO2 and palladium nanoparticles covered natural halloysite nanotubes for the detection of hepatitis B surface antigen

An ultrasensitive sandwich-type immunosensor for the detection of HBsAg based on the multifunctional natural halloysite nanotube nanocomposites (Pd/δ-MnO₂/HNTs).

Hepatitis B: 50 years after the discovery of Australia antigen

It is an honour to be invited to recount the progress in our understanding and management of hepatitis B 50 years after the discovery of Australia antigen (Au Ag). During this half century, we have gone from identifying the causative agent--hepatitis B virus (HBV), understanding its biology and the disease it causes, to having vaccines that can prevent HBV infection and antiviral therapy that can suppress HBV replication and prevent progression of HBV-related liver disease. As a result of the progress, prevalence of HBV infection and morbidity and mortality from chronic HBV infection has declined.

Stable Human Hepatoma Cell Lines for Efficient Regulated Expression of Nucleoside/Nucleotide Analog Resistant and Vaccine Escape Hepatitis B Virus Variants and Woolly Monkey Hepatitis B Virus

Hepatitis B virus (HBV) causes acute and chronic hepatitis B (CHB). Due to its error-prone replication via reverse transcription, HBV can rapidly evolve variants that escape vaccination and/or become resistant to CHB treatment with nucleoside/nucleotide analogs (NAs). This is particularly problematic for the first generation NAs lamivudine and adefovir. Though now superseded by more potent NAs, both are still widely used. Furthermore, resistance against the older NAs can contribute to cross-resistance against more advanced NAs. For lack of feasible HBV infection systems, the biology of such variants is not well understood. From the recent discovery of Na⁺-taurocholate cotransporting polypeptide (NTCP) as an HBV receptor new in vitro infection systems are emerging, yet access to the required large amounts of virions, in particular variants, remains a limiting factor. Stably HBV producing cell lines address both issues by allowing to study intracellular viral replication and as a permanent source of defined virions. Accordingly, we generated a panel of new tetracycline regulated TetOFF HepG2 hepatoma cell lines which produce six lamivudine and adefovir resistance-associated and two vaccine escape variants of HBV as well as the model virus woolly monkey HBV (WMHBV). The cell line-borne viruses reproduced the expected NA resistance profiles and all were equally sensitive against a non-NA drug. The new cell lines should be valuable to investigate under standardized conditions HBV resistance and cross-resistance. With titers of secreted virions reaching >3x10⁷ viral genome equivalents per ml they should also facilitate exploitation of the new in vitro infection systems.

Serum HBsAg kinetics and usefulness of interferon-inducible protein 10 serum in HBeAg-negative chronic hepatitis B patients treated with tenofovir disoproxil fumarate

The kinetics of serum HBsAg and interferon-inducible protein 10 (IP10) levels in patients with chronic hepatitis B infection treated with tenofovir are unclear. We evaluated the changes of HBsAg levels and the predictability of IP10 for HBsAg decline in 160 HBeAg-negative patients receiving tenofovir for ≥12 months. Serum samples taken before and at 6, 12, 24, 36 and 48 months after tenofovir were tested for HBsAg levels. In 104 patients, serum samples before tenofovir were tested for IP10 levels. Compared to before tenofovir, HBsAg levels decreased by a median of 0.08, 0.11, 0.24, 0.33 and 0.38 log10 IU/mL at 6, 12, 24, 36 and 48 months, respectively (P < 0.001). HBsAg kinetics did not differ between nucleos(t)ide analogue(s) naive and experienced patients. The 12-, 24-, 36- and 48-month cumulative rates of ≥0.5 log10 HBsAg decline were 8%, 16%, 24% and 41% and of HBsAg ≤100 IU/mL were 9%, 12%, 14% and 18%, respectively. The only factor associated with HBsAg ≤100 IU/mL was lower HBsAg levels before tenofovir (P < 0.001), while HBsAg decline ≥0.5 log10 was associated with higher IP10 levels (P = 0.002) and particularly with IP10 > 350 pg/mL (P < 0.001). In conclusion, tenofovir decreases serum HBsAg levels in both nucleos(t)ide analogue(s) naive and experienced patients with HBeAg-negative chronic hepatitis B infection. After 4 years of therapy, HBsAg ≤100 IU/mL can be achieved in approximately 20% of patients, particularly in those with low baseline HBsAg levels. HBsAg decline is slow (≥0.5 log10 in 40% of patients after 4 years) and is associated only with higher baseline serum IP10 levels.

New paradigms in hepatitis B management: only diamonds are forever

INTRODUCTION

The hepatitis B virus (HBV) causes chronic hepatitis B (CHB) in ∼350 million people worldwide who have an increased risk of end-stage liver disease and/or hepatocellular carcinoma.

SOURCES OF DATA

Several peer-reviewed papers featuring new approaches to anti-HBV management. Additionally, we also reviewed recent abstract presentations at international congresses.

AREAS OF AGREEMENT

There has been great progress in CHB therapy with the development of standard and pegylated interferon (i.e. PEG-IFN) as well as nucleos/tide analogs (NAs). IFN has both antiviral and immunomodulatory effects and through immune-mediated destruction of infected hepatocytes offers the possibility of finite therapy. However, this 'killing for a cure' antiviral strategy may not be tolerated in many, especially in cirrhotic patients. NAs inhibit viral reverse transcriptase, have few side effects and prevent liver disease progression, but cannot offer a cure as they have little effect on the resilient HBV covalently closed circular DNA (cccDNA) intermediate. Moreover, NAs such as tenofovir and entecavir offer a high genetic barrier to resistance, but are expensive and not readily available in many global regions.

GROWING POINTS

Despite significant treatment advances, there is increased recognition of the need for improved anti-HBV treatments, and new virologic tests for monitoring treatment response.

AREAS OF CONTROVERSY

The role of quantitative hepatitis B surface antigen, intrahepatic cccDNA levels and viral genotype in selecting treatment candidates and refining NA stopping rules.

AREAS TIMELY FOR DEVELOPING NEW RESEARCH

Potential new therapies include viral entry inhibitors, RNA interference technologies (i.e. RNAi) and small molecules that modulate cccDNA transcription, as well as novel immunomodulatory therapies to boost HBV-specific T cell responses. The ultimate goal of new tests and anti-HBV therapies is to reduce the burden and expense of life-long CHB treatment, as 'only diamonds are forever'.

Systematic review: cessation of long-term nucleos(t)ide analogue therapy in patients with hepatitis B e antigen-negative chronic hepatitis B

BACKGROUND

It has been debated whether finite nucleos(t)ide analogue therapy is feasible in HBeAg-negative chronic hepatitis B.

AIM

To review this issue systematically.

METHODS

Using text terms HBsAg and various nucleos(t)ide analogues, PubMed was searched between 1995 and 2014 to find studies on therapy >6 months in adult HBeAg-negative chronic hepatitis B patients with off-therapy follow-up >6 months.

RESULTS

Twenty-two studies with a total of 1732 patients were identified and included. The median duration of therapy, consolidation therapy and off-therapy follow-up ranged from 6 months to 8 years, 4 to 96 weeks and 6 to 80 months respectively. Patients were monitored with serum ALT and HBV DNA monthly in the first 1-3 months and every 3-6 months afterwards in most studies. The 1-year off-therapy 'virological relapse' (HBV DNA >2000 IU/mL) and 'clinical relapse' (HBV DNA > 2000 IU/mL + ALT elevation) occurred in <70% and <50% of the patients, respectively, and <40% of the patients received re-treatment. These rates were higher in patients with shorter treatment, shorter consolidation therapy and those treated with less potent nucleos(t)ide analogues. Off-therapy severe flares were rare and hepatic decompensation was reported in only one patient with cirrhosis. Biochemical relapse reflecting enhanced immune-mediated hepatocyte killing may lead to a higher chance for off-therapy HBsAg seroclearance and be possibly desirable.

CONCLUSION

With an appropriate stopping rule and a proper off-therapy monitoring plan, cessation of long-term nucleos(t)ide analogue therapy prior to HBsAg seroclearance in HBeAg-negative chronic hepatitis B is a feasible alternative to indefinite treatment.

Durability of Nucleos(t)ide Analogues Treatment in Patients With Chronic Hepatitis B

Long-term nucleos(t)ide analogues (NUCs) treatment is usually required for patients with chronic hepatitis B (CHB). However, whether discontinuation of NUCs is possible in selected patients remains debated. The aim of this study was to assess the durability of NUCs and predictors of sustained response after cessation of NUCs.Ninety-three CHB patients (29 HBeAg-positive and 64 HBeAg-negative) from 2 medical centers in Taiwan with discontinuation of NUCs after a median of 3 years' treatment were retrospectively reviewed. Fifteen (51.7%) HBeAg-positive and 57 (89.1%) HBeAg-negative patients achieved APASL treatment endpoints. Virological relapse (VR) and clinical relapse (CR) were defined according to APASL guidelines.Achieving APASL endpoint was associated with longer median time to CR in HBeAg-positive patients, but not in HBeAg-negative cases. The cumulative 1-year VR and CR rates were 55.3% and 14.4% in HBeAg-positive patients, and 77.7% and 41.9% in HBeAg-negative patients, respectively. In HBeAg-negative patients, baseline HBV DNA >10 IU/mL was the only predictor of VR (hazard ratio [HR] = 2.277, P = 0.019) and CR (HR = 3.378, P = 0.014). HBsAg >200 IU/mL at the end of treatment (EOT) was associated with CR (HR = 3.573, P = 0.023) in patients developing VR. HBeAg-negative patients with low baseline viral loads and low HBsAg levels at EOT had minimal risk of CR after achieving APASL treatment endpoint (P = 0.016).The VR rate is high, but the risk of CR is low within 1 year with consolidation treatment after HBeAg seroconversion. Longer consolidation treatment to reduce the risk of VR should be considered in HBeAg-positive patients. As high risk of VR and CR, cessation of NUCs therapy could be considered only in selected HBeAg-negative patients.

Hepatitis B Virus Pregenomic RNA Is Present in Virions in Plasma and Is Associated With a Response to Pegylated Interferon Alfa-2a and Nucleos(t)ide Analogues

BACKGROUND

Treatment of patients with chronic hepatitis B (CHB) with nucleos(t)ide analogues (NAs) suppresses hepatitis B virus (HBV) DNA production but does not affect the synthesis of the RNA pregenome or HBV messenger RNA. Whether HBV RNA-containing particles continue to be secreted into the bloodstream remains controversial.

METHODS

We developed a sensitive polymerase chain reaction (PCR) assay to quantify the HBV RNA load in a supernatant of NA-treated HepG2-2.2.15 cells and in plasma specimens from 20 patients with CHB who were receiving NA therapy and 86 patients treated with pegylated interferon alfa (Peg-IFN) and adefovir.

RESULTS

Treatment of HepG2-2.2.15 cells with NAs for 9 days reduced HBV DNA levels (by 1.98 log10 copies/mL), whereas HBV RNA levels increased (by 0.47 log10 copies/mL; P < .05). During long-term NA treatment of patients with CHB, HBV RNA levels remained higher than HBV DNA levels. Peg-IFN-based treatment induced a stronger decrease in the HBV RNA load than NA monotherapy, and this decline was more pronounced in responders than in nonresponders. In HBV e antigen-negative patients, a lower baseline plasma HBV RNA level was independently associated with response to Peg-IFN and adefovir (odds ratio, 0.44; P = .019). Immunoprecipitation with HBV core antigen-specific antibodies after removal of the HBV surface antigen envelope demonstrated the association of plasma HBV RNA with virions.

CONCLUSIONS

HBV RNA is present in virions in plasma specimens from patients with CHB. HBV RNA levels vary significantly from those of established viral markers during antiviral treatment, which highlights its potential as an independent marker in the evaluation of patients with CHB.

Current and future directions for treating hepatitis B virus infection

Hepatitis B virus (HBV) persistently infects approximately 350 million people, and approximately 600000 liver-related deaths are observed per year worldwide. HBV infection is also one of the major risk factors for hepatocellular carcinoma (HCC). The persistence of serum hepatitis B e antigen (HBeAg) and high level of serum HBV DNA are thought to reflect a high HBV replication status in hepatocytes, causing cirrhosis, HCC and liver-related deaths. It has been reported that antiviral therapy, such as peginterferon and nucleos(t)ide analogues (NUCs), could suppress liver-related death by inhibiting the HBV DNA levels and inducing seroconversion from HBeAg to antibody to HBe antigen. Currently, peginterferon is widely used, but there are also several disadvantages in the use of peginterferon, such as various adverse events, the administration route and duration. It is difficult to predict the effects of treatment and interferon is contraindicated for the patients with advanced fibrosis of the liver and cirrhosis. With respect to NUCs, entecavir and tenofovir disoproxil fumarate are current the first-choice drugs. NUCs can be administered orally, and their anti-viral effects are stronger than that of peginterferon. However, because cessation of NUC administration leads to high levels of viral replication and causes severe hepatitis, they must be administered for a long time. On the other hand, the use of both interferon and NUCs cannot eliminate covalently closed circular DNA of HBV. In this review, we evaluate the natural course of chronic HBV infection and then provide an outline of these representative drugs, such as peginterferon, entecavir and tenofovir disoproxil fumarate.

Genome-free hepatitis B virion levels in patient sera as a potential marker to monitor response to antiviral therapy

Complete virions of hepatitis B virus (HBV) contain a DNA genome that is enclosed in a capsid composed of the HBV core antigen (HBcAg), which is in turn surrounded by a lipid envelope studded with viral surface antigens (HBsAg). In addition, HBV-infected cells release subviral particles composed of HBsAg only (HBsAg 'spheres' and 'filaments') or HBsAg enveloping HBcAg but devoid of viral DNA ('empty virions'). The hepatitis B e antigen (HBeAg), a soluble antigen related to HBcAg, is also secreted in some HBV-infected patients. The goals of this study were to explore the levels of empty virions in HBV-infected patients before and during therapy with the nucleotide analog tenofovir disoproxil fumarate (TDF) that inhibits HBV DNA synthesis and the relationships of empty virions to complete virions, HBsAg and HBeAg. HBV DNA, HBcAg and HBsAg levels were determined in serum samples from 21 patients chronically infected with HBV and enrolled in clinical TDF studies. Serum levels of empty virions were found to exceed levels of DNA-containing virions, often by ≥ 100-fold. Levels of both empty and complete virions varied and were related to the HBeAg status. When HBV DNA replication was suppressed by TDF, empty virion levels remained unchanged in most but were decreased (to the limit of detection) in some patients who also experienced significant decrease or loss of serum HBsAg. In conclusion, empty virions are present in the serum of chronic hepatitis B patients at high levels and may be useful in monitoring response to antiviral therapy.

Sequential combination therapy with pegylated interferon leads to loss of hepatitis B surface antigen and hepatitis B e antigen (HBeAg) seroconversion in HBeAg-positive chronic hepatitis B patients receiving long-term entecavir treatment

Nucleos(t)ide analogues rarely result in a durable off-treatment response in chronic hepatitis B infection, whereas pegylated interferon (Peg-IFN) induces a long-lasting response only in a subset of patients. We assessed the effect of sequential combination therapy with Peg-IFN-α2a and entecavir in hepatitis B e antigen (HBeAg)-positive patients with prior long-term entecavir therapy and investigated the predictors of response to treatment. HBeAg-positive individuals who did not achieve HBeAg seroconversion during previous long-term entecavir therapy, receiving Peg-IFN-α2a added to ongoing entecavir therapy (sequential combination [S-C] therapy; n = 81) for 48 weeks or remaining on entecavir monotherapy (n = 116), were retrospectively included. A matched pair was created at a 1:1 ratio from each treatment group. The primary endpoint was HBeAg seroconversion at week 48. Subgroup analysis of response prediction was conducted for 81 patients with S-C therapy. More patients in the S-C therapy group achieved HBeAg seroconversion than those in the entecavir group (44% versus 6%; P < 0.0001). An HBeAg level of <200 signal-to-cutoff ratio (S/CO) at baseline was a strong predictor for higher HBeAg seroconversion than that achieved when HBeAg was ≥200 S/CO (64.2% versus 17.9%; P < 0.0001). Hepatitis B surface antigen (HBsAg) levels at baseline and the decrease in HBsAg levels predicted HBsAg loss in the S-C therapy group. The combination of baseline HBeAg of <200 S/CO and HBsAg of <1,000 IU/ml and an HBsAg decline at week 12 of ≥0.5 log10 IU/ml provided the highest rate of HBeAg seroconversion (92.31%) and HBsAg loss (83.3%) at week 48. Patients receiving sequential combination therapy have a higher rate of HBeAg seroconversion and are more likely to experience HBsAg clearance than do those continuing entecavir monotherapy. Sequential combination therapy can be guided by baseline HBsAg/HBeAg levels and on-treatment HBsAg dynamics.

The FDA-approved drug irbesartan inhibits HBV-infection in HepG2 cells stably expressing sodium taurocholate co-transporting polypeptide

BACKGROUND

Little is known about the early steps of the HBV life cycle due to the lack of susceptible cells permissive for viral infection. Hence, viral entry has not been exploited for antiviral targets, but the recent seminal discovery of sodium taurocholate co-transporting polypeptide (NTCP) as the cellular receptor for HBV entry opened up many avenues of investigation, making HBV entry amenable to therapeutic intervention.

METHODS

In order to exploit HBV entry, we established a HepG2-NTCP cell line that supports HBV infection. Over 70% of cells were infected at a dose of 10(4) genome equivalents (GEq) per cell. Several FDA-approved drugs with NTCP-inhibiting activity were tested for their ability to inhibit HBV infection of the cell line.

RESULTS

Consistent with their NTCP inhibitory activities, our results showed that several of them inhibit HBV infection. In particular, irbesartan, a drug used for the treatment of hypertension, inhibits HBV infection at the 50% effective concentration value of 35 μM.

CONCLUSIONS

The observation that the pharmacological inhibitors of the NTCP transporter could block HBV entry suggests that NTCP represents an attractive molecular target for therapeutic intervention in HBV infection.

New insights in the management of chronic hepatitis B

Chronic hepatitis B (CHB) remains a global healthcare challenge, complicated by the development of cirrhosis and hepatocellular carcinoma, accounting for approximately 600,000 deaths per year. Hepatitis B is a DNA virus, which utilises a covalently closed circular (ccc) DNA to act as a transcriptional template for the virus. The persistence of cccDNA in the nucleus of infected hepatocytes accounts for HBV chronicity. Quantitative hepatitis B surface antigen (qHBsAg) acts as a surrogate for the level of cccDNA and therefore may provide useful information around treatment response and viral immune control. Current antiviral therapies are limited in their ability to achieve HBsAg loss, which is considered the 'gold-standard' treatment endpoint. This article focuses on the unmet needs in CHB today; a better definition of disease phase, the timing of therapeutic intervention, optimising treatment strategies with current therapies and the development of novel agents; all with HBsAg loss as the therapeutic goal.

Use of hepatitis B surface and "e" antigen quantification during extensive treatment with tenofovir in patients co-infected with HIV-HBV

BACKGROUND & AIMS

In patients infected with hepatitis B virus (HBV) and HIV, hepatitis B 'e' antigen (qHBeAg) and hepatitis B surface antigen quantification (qHBsAg) may be used to predict short-term HBeAg and HBsAg loss, respectively. To determine if these quantifiable markers also provide accurate prediction of antigen loss during long-term, extensive tenofovir (TDF) treatment and to further establish qHBsAg profiles associated with HBsAg seroconversion.

METHODS

Prospective study of 111 co-infected, antiretroviral-experienced patients undergoing a TDF-containing regimen for >12 months. HBV-DNA viral load, qHBeAg [Paul Ehrlich Institute Units (PEIU)/ml] and qHBsAg were quantified at baseline and every 6-12 months. Sensitivity (Se) and specificity (Sp) of qHBeAg criteria were calculated using a time-dependent receiver operator characteristic curve, and qHBsAg profiles were developed using a group-based trajectory model.

RESULTS

After a median 74.2 months (IQR: 33.1-94.7) of TDF treatment, four patients had HBsAg seroconversion. Among the 78 (70.3%) HBeAg-positive patients, cumulative proportion with HBeAg loss was 42.0% (n = 23) at month 96. Baseline qHBeAg ≤100 PEIU/ml was the only significant factor for HBeAg loss (adjusted-HR = 2.36, 95% CI: 1.02-5.46) in multivariable analysis. In terms of predicting HBeAg-loss until month 96, qHBeAg ≤10 PEIU/ml was more accurate when evaluated at month 24 (Se = 0.73, Sp = 0.80) than month 12 (Se = 0.48, Sp = 0.90). All four patients with HBsAg seroconversion had profiles with large decreases in qHBsAg (>2 log10 IU/ml), not necessarily occurring during the first 12 months, which was infrequent in patients without seroconversion (8.4%, P < 0.001).

CONCLUSIONS

Quantifying hepatitis 'e' antigen during the first 2 years of TDF treatment is a practical tool in predicting long-term HBeAg loss. Non time-specific declines in qHBsAg may be a useful indicator of HBsAg seroconversion.

[Is it possible to stop treatment with nucleos(t)ide analogs in patients with e-antigen negative chronic hepatitis B? Experience and new expectations]

BACKGROUND

Treatment of HBeAg-negative chronic hepatitis B (CHB) with nucleos(t)ide analogues (NA) is usually indefinite, since the loss of HBsAg, as a criterion for its discontinuation, is a rare event. Recent evidence suggests that discontinuing NA therapy may be feasible in selected patients.

OBJECTIVES

To analyze the rate of virological relapse in patients with HBeAg-negative CHB who discontinued treatment with NAs.

METHODS

We performed a single-center observational study that included 140 patients with HBsAg-negative CHB. Twenty-two patients, who received only NAs, discontinued treatment for different reasons and were subsequently monitored. All had normal ALT and AST, undetectable DNA and absence of cirrhosis or significant comorbidities before stopping treatment.

RESULTS

Twelve patients showed virologic relapse (54.54%). The mean interval between discontinuation and relapse was 6.38 months (± 1.9) (75% relapsed during the first 12 months after discontinuation). Five received adefovir, 1 lamivudine and adefovir, 1 tenofovir and 5 lamivudine alone. The mean treatment duration in this group was 38.5 months (± 4.5). The sustained response group had a higher mean age and longer treatment duration than patients with virologic relapse but these differences were not statistically significant.

CONCLUSIONS

The results suggest that NA treatment can be stopped in selected patients with CHB as long as they are not cirrhotic, have completed a minimum period of treatment, have normal ALT and sustained undetectable DNA. These patients should be closely monitored during the first year and then indefinitely.

Optimal therapy for chronic hepatitis B: hepatitis B virus combination therapy?

Currently available antiviral treatment for chronic hepatitis B can be divided into two classes of therapeutic agents: pegylated interferon alpha (PEG-IFN) and nucleos(t)ide analogues (NAs). The major advantages of NAs are good tolerance and potent antiviral activity associated with high rates of on-treatment response to therapy. The advantages of PEG-IFN include a finite course of treatment, the absence of drug resistance, and an opportunity to obtain a durable post-treatment response to therapy. The use of these two antiviral agents with different mechanisms of action in combination is theoretically an attractive approach for treatment, either simultaneously, as sequential combination therapy (add-on), or even as an immediate switch from one agent to the other. Different NAs have also been combined in certain clinical situations. At present, several studies have confirmed certain virological advantages to combination therapies, but pivotal prospective studies demonstrating long-term clinical benefit to patients are still missing. Therefore, combination treatment, especially with PEG-IFN plus NAs, is not indicated and was not recommended by the European Association for the Study of the Liver Clinical Practice Guidelines written in 2012, while the guidelines for the use of combination NAs is limited to very few clinical situations.

Quantification of HBsAg in nucleos(t)ide-naïve patients treated for chronic hepatitis B with entecavir with or without tenofovir in the BE-LOW study

BACKGROUND & AIMS

Serum hepatitis B surface antigen (HBsAg) levels may predict treatment response in chronic hepatitis B (CHB). We examined the association between changes in HBsAg levels and response to treatment in the BE-LOW study.

METHODS

In this open-label, multicentre study, 379 nucleos(t)ide-naïve patients with hepatitis B e antigen (HBeAg)-positive or -negative CHB were randomized and treated with daily entecavir 0.5mg alone (n = 182) or combined with tenofovir 300 mg (n = 197) for 100 weeks. HBsAg levels were quantified (Abbott Architect assay) at baseline and at Weeks 12, 48, and 96.

RESULTS

Mean baseline HBsAg levels were comparable across subgroups by baseline alanine aminotransferase (ALT), genotype, age, and treatment type, but were higher in HBeAg-positive than in HBeAg-negative patients. Mean HBsAg changes from baseline at Weeks 12, 48, and 96 were more pronounced in HBeAg-positive than in HBeAg-negative patients, in patients with genotype A than in those with genotypes C or D, and in patients with elevated baseline ALT, but were similar between treatment groups and between patients of different age categories. Mean HBsAg changes over 96 weeks were also comparable in patients with or without HBV DNA <50 IU/ml at Week 96, but among patients that were HBeAg-positive at baseline, changes were greater for those with Week 96 HBeAg loss than for those without.

CONCLUSIONS

In this population of HBeAg-positive and HBeAg-negative, nucleos(t)ide-naïve patients, a greater HBsAg decline through 96 treatment weeks was observed in HBeAg-positive patients, especially in those who achieved subsequent HBeAg loss.

HBsAg quantification to optimize treatment monitoring in chronic hepatitis B patients

Hepatitis B surface antigen (HBsAg) levels in serum have been shown to reflect active intrahepatic covalently closed circular DNA (cccDNA) and to have additional value as a marker of on-treatment efficacy. In the past few years, immunoassays to quantify HBsAg have been developed to monitor HBsAg kinetics during treatment. Although HBsAg quantification cannot replace HBV DNA measurement in clinical practice, the combined use of HBsAg quantification and HBV DNA measurements could help predict treatment outcome. One of the most important results of the studies in this new marker is that a decline in HBsAg titres during pegylated-interferon (PEG-IFN) treatment is a strong predictor of response so that a 'week 12 stopping rule' could be established for both Hepatitis B e antigen (HBeAg)-positive and HBeAg-negative patients. However, the positive predictive value (PPV) for a sustained viral response (SVR) remains low. The role of HBsAg measurements during nucloes(t)ides analogue (NAs) treatment is unclear. It may be a useful marker for stopping NAs by limiting the chance of relapse or for add-on strategies. Monitoring serum HBsAg levels in chronic hepatitis B (CHB) patients during treatment may provide significant complementary information to HBV DNA measurements.

Switching from entecavir to PegIFN alfa-2a in patients with HBeAg-positive chronic hepatitis B: a randomised open-label trial (OSST trial)

BACKGROUND & AIMS

Durable post-treatment response is uncommon in chronic hepatitis B (CHB) patients on nucleos(t)ide analogue therapy. Response, response predictors and safety were assessed in patients who switched from long-term entecavir (ETV) to peginterferon alfa-2a.

METHODS

Hepatitis B e antigen (HBeAg)-positive CHB patients who had received ETV for 9-36 months, with HBeAg <100 PEIU/ml and HBV DNA ⩽1000 copies/ml, were randomised 1:1 to receive peginterferon alfa-2a 180 μg/week or ETV 0.5mg/day for 48 weeks. The primary endpoint was HBeAg seroconversion at week 48 (ClinicalTrials.gov: NCT00940485).

RESULTS

200 patients were randomised; 197 received ⩾1 study drug dose. Five patients who were anti-HBe-positive at baseline were excluded from the modified intention-to-treat population (peginterferon alfa-2a, n = 94; ETV, n = 98). Patients who switched to peginterferon alfa-2a achieved higher week 48 HBeAg seroconversion rates vs. those who continued ETV (14.9% vs. 6.1%; p = 0.0467). Only patients receiving peginterferon alfa-2a achieved HBsAg loss (8.5%). Among peginterferon alfa-2a-treated patients with HBeAg loss and HBsAg <1500 IU/ml at randomisation, 33.3% and 22.2% achieved HBeAg seroconversion and HBsAg loss, respectively. Early on-treatment HBsAg decline predicted response at week 48; highest rates were observed in patients with week 12 HBsAg <200 IU/ml (HBeAg seroconversion, 66.7%; HBsAg loss, 77.8%). Alanine aminotransferase elevations were not associated with viral rebound (n = 38). Peginterferon alfa-2a was well-tolerated.

CONCLUSIONS

For patients who achieve virological suppression with ETV, switching to a finite course of peginterferon alfa-2a significantly increases rates of HBeAg seroconversion and HBsAg loss. A response-guided approach may identify patients with the greatest chance of success.

Involvement of the host DNA-repair enzyme TDP2 in formation of the covalently closed circular DNA persistence reservoir of hepatitis B viruses

Hepatitis B virus (HBV), the causative agent of chronic hepatitis B and prototypic hepadnavirus, is a small DNA virus that replicates by protein-primed reverse transcription. The product is a 3-kb relaxed circular DNA (RC-DNA) in which one strand is linked to the viral polymerase (P protein) through a tyrosyl-DNA phosphodiester bond. Upon infection, the incoming RC-DNA is converted into covalently closed circular (ccc) DNA, which serves as a viral persistence reservoir that is refractory to current anti-HBV treatments. The mechanism of cccDNA formation is unknown, but the release of P protein is one mandatory step. Structural similarities between RC-DNA and cellular topoisomerase-DNA adducts and their known repair by tyrosyl-DNA-phosphodiesterase (TDP) 1 or TDP2 suggested that HBV may usurp these enzymes for its own purpose. Here we demonstrate that human and chicken TDP2, but only the yeast ortholog of TDP1, can specifically cleave the Tyr-DNA bond in virus-adapted model substrates and release P protein from authentic HBV and duck HBV (DHBV) RC-DNA in vitro, without prior proteolysis of the large P proteins. Consistent with TPD2's having a physiological role in cccDNA formation, RNAi-mediated TDP2 depletion in human cells significantly slowed the conversion of RC-DNA to cccDNA. Ectopic TDP2 expression in the same cells restored faster conversion kinetics. These data strongly suggest that TDP2 is a first, although likely not the only, host DNA-repair factor involved in HBV cccDNA biogenesis. In addition to establishing a functional link between hepadnaviruses and DNA repair, our results open new prospects for directly targeting HBV persistence.

HBsAg seroclearance after nucleoside analogue therapy in patients with chronic hepatitis B: clinical outcomes and durability

OBJECTIVE

Little is known about the long-term clinical outcome and durability of HBsAg seroclearance following nucleos(t)ide analogue (NUC) therapy in patients with chronic hepatitis B (CHB).

DESIGN

During a median follow-up period of 6 years (33 567 patient-years) of 5409 CHB patients who were initially treated with lamivudine or entecavir, a total of 110 achieved HBsAg seroclearance (0.33% annual seroclearance rate) and were included in this study.

RESULTS

Baseline alanine aminotransferase (ALT) level >5 times of upper limit of normal was associated with higher probability of HBsAg seroclearance (HR 1.80, p<0.01), while HBeAg positivity (HR 0.46, p<0.01), high HBV DNA level (log(10) IU/mL; HR 0.61, p<0.01), and cirrhosis (HR 0.48, p<0.01) were inversely associated with the probability of HBsAg seroclearance by multivariable analysis. During follow-up for 287 patient-years after HBsAg seroclearance, only two patients with baseline cirrhosis developed hepatocellular carcinoma (HCC) or died (0.7% annual risk), which was of a significantly lower rate compared with propensity score-matched patients without HBsAg seroclearance (HR 0.09, p<0.01). HBsAg reversion and/or HBV DNA reversion occurred in 18 patients, most of which were transient with extremely low serum levels of HBsAg (0.05-1.00 IU/mL) and HBV DNA (17-1818 IU/mL). None required retreatment. The cumulative probability of anti-HBs seroconversion (detection of anti-HBs) at 4 years was 67.4% by Kaplan-Meier analysis. Selection for lamivudine-resistance HBV mutants during treatment was not associated with composite reversion (p=0.66).

CONCLUSIONS

HBsAg seroclearance achieved after NUC treatment was associated with favourable clinical outcomes and was durable in most cases during long-term follow-up.

Serum hepatitis B surface antigen levels predict treatment response to nucleos(t)ide analogues

Quantification of hepatitis B surface antigen (HBsAg) has been suggested to be helpful in the management of chronic hepatitis B (CHB) patients. Nucleos(t)ide analogs (NAs) are the therapy of choice for CHB and are used in the majority of CHB patients. NAs are able to induce hepatitis B virus (HBV) viral suppression, normalization of alanine aminotransferase (ALT) levels, and improvement in liver histology. Automated quantitative assays for serum HBsAg have recently become available, facilitating standardized quantification of serum HBsAg. This has led to increased interest in the clinical application of quantitative serum HBsAg for predicting therapeutic response to NAs. Recent studies have shown that a decline in serum HBsAg levels in patients receiving peginterferon may signal successful induction of immune control over HBV, and can therefore be used to predict therapeutic response. NA treatment typically induces a less rapid decline in HBsAg than interferon treatment; it has been estimated that full HBsAg clearance can require decades of NA treatment. However, a rapid HBsAg decline during NA therapy may identify patients who will show clearance of HBsAg. Currently, there is no consensus on the clinical utility of serum HBsAg monitoring for evaluating patient responses to NA therapy. This review focuses on recent findings regarding the potential application of HBsAg quantification in the management of CHB patients receiving NA therapy.

[Clinical significance of hepatitis B surface antigen quantification in chronic hepatitis B]

Since the discovery of HBsAg in the early 1960s, presence of HBsAg in serum has only served to diagnose hepatitis B. Recent development in the quantitative measurement of serum HBsAg has enabled us to improve our understanding on the management of chronic hepatitis B. The surface antigen (sAg) level is at its highest in immune tolerance phase and decreases to the lowest level in immune control/inactive phase when HBeAg is cleared from the serum. Combination of serum sAg titer less than 1,000 IU/mL and serum HBV DNA less than 2,000 IU/mL can identify true inactive carrier from e antigen (eAg) negative hepatitis with diagnostic accuracy of 95%. During the natural course of chronic hepatitis B, changes or absolute level of sAg less than certain level can predict spontaneous sero-clearance of HBsAg. Although the decline of sAg is very slow in interferon (IFN)/pegylated interferon (PEG-IFN) or oral nucleos(-t)ide treated patients, interferon based therapy results in a greater decrease of sAg level and sAg loss. Lack of any decline in sAg titer during PEG-IFN therapy could identify the group of patients who do not response to IFN/PEG-IFN therapy. With the aid of serum HBV DNA, quantitative measurement of serum HBsAg level can be used to optimize the management of chronic hepatitis B in our daily practice.

When to stop nucleos(t)ide analogues treatment for chronic hepatitis B? Durability of antiviral response

Introduction of nucleos(t)ide analogues (NAs) for oral antiviral therapy has dramatically improved the clinical outcome in patients with chronic hepatitis B (CHB). Although current international guidelines for the management of CHB provide information regarding when to begin the antiviral therapy with NAs, there is no clear consensus on when to stop the treatment, especially for those who respond to the therapy. Hepatitis B surface antigen loss has been regarded as an ideal endpoint of oral antiviral therapy with NAs, however since this is rarely achieved, practical endpoints have been suggested by the international guidelines. Despite the stopping rules recommended by the international guidelines, whether oral antiviral therapy with NAs can be safely discontinued is of major concern. While attention has been drawn to whether antiviral treatment with NAs can be a finite therapy, there is lack of sufficient data on off-treatment durability of highly potent NAs. Based on the available evidences, current guidelines for stopping NA therapy seems to be inadequate in terms of off-treatment durability, with relapse rates of more than 40% for both hepatitis Be antigen (HBeAg)-positive and HBeAg-negative patients. Therefore, further studies are required to accumulate data on off-treatment durability of highly potent NAs, and future studies are warranted to identify adequate predictive markers that could provide supplementary information to guide the timing of stopping NA therapy.