The scientific basis of combination therapy for chronic hepatitis B functional cure

Epidemiology of liver diseases: global disease burden and forecasted research trends

We assessed the global incidence, mortality, and disability-adjusted life years (DALYs) associated with various liver diseases, including alcohol-related liver disease (ALD), hepatitis B/C virus infections (HBV or HCV), liver cancer, metabolic dysfunction-associated steatotic liver disease (MASLD), and other chronic liver diseases, from the 2019 Global Burden of Disease study. Additionally, we analyzed the global trends in hepatology research and drug development. From 2000 to 2019, prevalence rates increased for ALD, MASLD and other liver diseases, while they decreased for HBV, HCV, and liver cancer. Countries with a high socio-demographic index (SDI) exhibited the lowest mortality rates and DALYs. The burden of liver diseases varied due to factors like sex and region. In nine representative countries, MASLD, along with hepatobiliary cancer, showed highest increase in funding in hepatology research. Globally, the major research categories in hepatology papers from 2000 to 2019 were cancer, pathobiology, and MASLD. The United States (U.S.) was at the forefront of hepatology research, with China gradually increasing its influence over time. Hepatologists worldwide are increasingly focusing on studying the communication between the liver and other organs, while underestimating the research on ALD. Cancer, HCV, and MASLD were the primary diseases targeted for therapeutic development in clinical trials. However, the proportion of new drugs approved for the treatment of liver diseases was relatively low among all newly approved drugs in the U.S., China, Japan, and the European Union. Notably, there were no approved drug for the treatment of ALD in the world.

Differential T-cell profiles determined by Hepatitis B surface antigen decrease among people with Human Immunodeficiency Virus /Hepatitis B Virus coinfection on treatment

BACKGROUND

Several studies have reported that combination antiretroviral therapy (cART) enhances the hepatitis B surface antigen (HBsAg) clearance rate in Human Immunodeficiency Virus-1/Hepatitis B Virus (HIV/HBV) coinfected patients, yet the associated immunological characteristics remain unclear.

METHODS

Global and specific immune phenotypic profiles were examined in 48 patients with HIV/HBV coinfection before cART and at 1-year, and 3-year after cART using flow cytometry. In addition, 61 patients with HBV monoinfection were included for comparison.

RESULTS

HBsAg response (sAg-R) was defined as > 0.5 log decrease within six months of cART initiation, and 16 patients achieved it. Patients with sAg-R (the sAg-R group) exhibited distinct immune phenotypes compared to those of HBsAg-retained patients (the sAg-NR group). Notably, patients with sAg-R had lower CD4+ T cell counts and a higher number of HBcAg-specific T cells. Further, the sAg-R group exhibited upregulation of HLA-DR, Ki67, and PD-1 in CD4+ T cells and heightened HLA-DR and T-bet in CD8+ T cells. However, the sAg-R group had fewer TEMRA cells but more TEM and Th17 cells than those in the sAg-NR group. Expression of various markers, including HLA-DR+CD4+, Ki67+CD4+, PD-1+CD4+, CD38+CD8+, HLA-DR+CD8+, TIM-3+CD8+, HBV-specific CD4+ T cell secreting IFN-γ and IL-2, and specific CD8+ T cell secreting IFN-γ and IL-2, correlated with HBsAg decrease.

CONCLUSION

The decline in HBsAg levels during cART in HIV/HBV coinfection involves significant alterations in CD4+ and CD8+ T cells phenotypes, offering a novel perspective on a functional HBV cure.

Applications of CRISPR/Cas as a Toolbox for Hepatitis B Virus Detection and Therapeutics

Hepatitis B virus (HBV) infection remains a significant global health challenge, leading to chronic hepatitis, liver cirrhosis, and hepatocellular carcinoma (HCC). Covalently closed circular DNA (cccDNA) and integrated HBV DNA are pivotal in maintaining viral persistence. Recent advances in CRISPR/Cas technology offer innovative strategies to inhibit HBV by directly targeting both cccDNA and integrated HBV DNA or indirectly by degrading HBV RNAs or targeting host proteins. This review provides a comprehensive overview of the latest advancements in using CRISPR/Cas to inhibit HBV, with a special highlight on newer non-double-strand (non-DSB) break approaches. Beyond the canonical use of CRISPR/Cas for target inhibition, we discuss additional applications, including HBV diagnosis and developing models to understand cccDNA biology, highlighting the diverse use of this technology in the HBV field.

A molecular standard for circulating HBV RNA detection and quantification assays in patients with chronic hepatitis B

Background & Aims

Circulating HBV RNAs have been proposed as a biomarker that reflects the transcriptional activity of covalently closed circular DNA (cccDNA) and may help to evaluate HBV treatment activity. Different research assays have been proposed and, although two PCR-based research use only investigational assays have been developed, the lack of standardized protocols represents an important limitation. Here we have designed and generated a stable clonal cell line producing an RNA-based standard for the calibration of PCR-based circulating HBV RNA assays.

Methods

HBV RNA-producing Huh7-derived stable cell lines were generated by transfecting pTriEX plasmids containing 1.1 unit length HBV DNA genomes carrying mutations in the catalytic site (YMAA mutation) and the TP domain (Y63F) of the polymerase, and the ε-loop of the pregenomic (pg)RNA (mutation A1G).

Results

The clonal cell line (Huh7-3D29), carrying a double YMAA and Y63F mutation, displayed, and maintained over several passages in culture, a high RNA secretion phenotype with negligible residual secreted HBV DNA. Density gradient centrifugation showed that most of the secreted HBV RNA from Huh7-3D29 cells was detected in naked capsid and virion-like particles and only a minority in small extracellular vescicles. Nanopore sequencing of 5'RACE products shows that the majority of the Huh7-3D29-secreted HBV RNAs start at the 5' end of pgRNA and pgRNA-derived spliced RNAs. Finally, Huh7-3D29 cells showed a high and up-scalable secreted RNA yield allowing 1,300 standard curves in 9 days from one flask.

Conclusion

We generated a clonal cell line that produces high quantities of HBV RNAs with very low quantities of contaminating HBV DNAs, representing a stable source of RNA standard for HBV RNA assay calibration.

Impact and implications

Several investigational assays and two research use only assays have been developed to detect and quantify circulating HBV RNAs, an emerging biomarker of covalently closed circular DNA transcriptional activity and target engagement by new HBV treatments. The lack of a unique molecular standard for circulating HBV RNA quantification represents an important limitation. Here we describe the generation of a stable clonal cell line producing and secreting an RNA-based standard containing all the HBV RNA species found in HBV patients' sera (e.g. pgRNA, HBx transcripts). This new RNA standard can be used to calibrate all PCR-based assays for circulating HBV RNA quantification to evaluate, in a non-invasive manner, the size of the transcriptionally active cccDNA pool and the activity of novel strategies aimed at curing HBV infection.

CAM-A-dependent HBV core aggregation induces apoptosis through ANXA1

Background & Aims

Chronic HBV infection is the leading cause of liver disease and of hepatocellular carcinoma. The improvement of antiviral therapy remains an unmet medical need. Capsid assembly modulators (CAMs) target the HBV core antigen (HBc) and inhibit HBV replication. Although CAM-A compounds are well-known inducers of aberrant viral capsid aggregates, their mechanisms of action in HBV-hepatocyte interactions are poorly understood. Recently, we demonstrated that CAM-A molecules lead to a sustained reduction of HBsAg in the serum of HBV replicating mice and induce HBc aggregation in the nucleus of HBc-expressing cells leading to cell death.

Methods

The mechanism of action by which CAM-A compounds induce cell death was investigated using an HBV infection model, HBc-overexpressing HepG2-NTCP cells, primary human hepatocytes, and HBV replicating HepAD38 cells.

Results

We first confirmed the decrease in HBsAg levels associated with CAM-A treatment and the induction of cell toxicity in HBV-infected differentiated HepaRG cells. Next, we showed that CAM-A-mediated nuclear aggregation of HBc was associated with cell death through the activation of apoptosis. Transcriptomic analysis was used to investigate the mechanism of action driving this phenotype. CAM-A-induced HBc nuclear aggregation led to the upregulation of ANXA1 expression, a documented driver of apoptosis. Finally, silencing of ANXA1 expression delayed cell death and apoptosis in CAM-A-treated cells, confirming its direct involvement in CAM-A-induced cell death.

Conclusions

Our results unravel a previously undiscovered mechanism of action involving CAM-As and open the door to new therapeutic strategies involving CAM to achieve a functional cure in patients with chronic infections.

Impact and implications

Chronic HBV infection is a global health threat. To date, no treatment achieves viral clearance in chronically infected patients. In this study, we characterized a new mechanism of action of an antiviral molecule targeting the assembly of the viral capsid (CAM). The study demonstrated that a CAM subtype, CAM-A-induced formation of aberrant structures from HBV core protein aggregates in the nucleus leading to cell death by ANXA1-driven apoptosis. Thus, CAM-A treatment may lead to the specific elimination of HBV-infected cells by apoptosis, paving the way to novel therapeutic strategies for viral cure.

Liver mechanosignaling as a natural anti-hepatitis B virus mechanism

The mechanisms underlying the natural control of hepatitis B virus (HBV) infection have long been an intriguing question. Given the wide physiological range of liver stiffness and the growing attention to the role of mechanical microenvironment in homeostasis and diseases, we investigated how physical matrix cues impact HBV replication. High matrix stiffness significantly inhibited HBV replication and activated YAP in primary hepatocyte culture system, a key molecule in mechanosignaling. YAP activation notably suppressed HBV transcription and antigen expression. Several YAP-induced genes exhibited strong anti-HBV effects. Single-cell analysis of liver tissue from male individuals with active HBV replication revealed a strong significant negative correlation between YAP signature activation and HBV transcript levels. Intraperitoneal administration of YAP small molecule agonist potently controls HBV in male mouse models. These findings unveil a mechanism that involves the mechanical environment of hepatocytes and YAP to clear hepatotropic viral infection in the liver, providing new perspectives for HBV cure studies and antiviral development.

Efficacy of short-term Peg-IFN α-2b treatment in chronic hepatitis B patients with ultra-low HBsAg levels: a retrospective cohort study

PURPOSE

Peginterferon alfa-2b (Peg-IFN α-2b) has demonstrated superior efficacy over nucleos(t)ide analogs (NAs) in the treatment of chronic hepatitis B (CHB), particularly among patients with low levels of hepatitis B surface antigen (HBsAg). This study aims to determine whether patients with ultra-low HBsAg levels (< 200 IU/mL) can achieve significantly higher clinical cure rates with abbreviated courses of Peg-IFN α-2b therapy.

METHODS

In this retrospective analysis, CHB patients with HBsAg levels below 200 IU/mL were categorized into a Peg-IFN α-2b group and a control group. The Peg-IFN α-2b group received Peg-IFN α-2b for a minimum of 24 weeks, with the possibility of early discontinuation upon achieving HBsAg clearance, and were followed through week 48. The control group remained untreated for hepatitis B virus (HBV), and was observed for 24 weeks. HBsAg clearance rates were compared between groups. Univariate and multivariate logistic regression analyses were employed to identify factors associated with HBsAg clearance .

RESULTS

By week 24, the HBsAg clearance rate in the Peg-IFN α-2b group was notably 52.1% (38/73), contrasting sharply with the mere 1.3% (1/77) observed in the control group. Within the Peg-IFN α-2b group, a substantial 97.3% (71/73) of patients noted a reduction in HBsAg levels. Besides, the decision to continue or discontinue treatment after the 24-week mark had no significant impact on the HBsAg clearance rate at week 48. Multivariable analysis pinpointed baseline HBsAg levels (OR = 0.984, p = 0.001) and the presence of fatty liver (OR = 5.960, p = 0.033) as independent predictors of HBsAg clearance.

CONCLUSION

Our findings confirm that a 24-week course of Peg-IFN α-2b yields robust efficacy in CHB patients with ultra-low HBsAg levels. Prolonging treatment beyond the 24-week threshold is deemed unnecessary. Both baseline HBsAg level and the presence of fatty liver emerged as significant predictors for HBsAg clearance.

An Experimental Animal Study: Electroacupuncture Facilitates Antiviral Immunity Against Hepatitis B Virus Through the IFN-γ/JAK/STAT Axis

Background

Chronic hepatitis B (CHB) remains a global health challenge, necessitating innovative therapeutic strategies. Enhancing the body's immune response against the hepatitis B virus (HBV) emerges as a fundamental strategy for achieving a functional cure. While acupuncture has shown potential in immune modulation, its specific anti-HBV effects are not well understood. This study evaluates the potential of electroacupuncture (EA) in HBV infection and explores its underlying immunological mechanisms using a mouse model.

Methods

HBV-infected mice were established using the high-pressure hydrodynamic method and divided into four groups: normal saline (NS), EA, sham EA (SE), and tenofovir disoproxil fumarate (TF), with n = 6 per group. During treatment, blood was collected every Sunday via the orbital sinus to monitor HBV DNA, HBsAg, and HBeAg levels. Transcriptomics and metabolomics analyses were employed to unearth clues regarding EA's anti-HBV mechanism. Validation of these mechanisms included splenic T-cell flow analysis, Western blotting, RT-qPCR, immunofluorescence, and ELISA.

Results

Serum HBV DNA levels decreased by 1.10, 0.19, and 1.98 log10 IU/mL in the EA, SE, and TF-treated mice, respectively, compared to the NS. Concurrently, the hepatic HBV DNA levels decreased by 1.09, 0.24, and 2.03 log10 IU/mL. EA also demonstrated superior inhibition of HBV antigens, with serum HBeAg levels decreasing by 43.86%, 8.74%, and 8.03%, and serum HBsAg levels decreasing by 28.01%, 0.26%, and 9.39% in the EA, SE, and TF groups, respectively. Further analysis through transcriptomics and metabolomics revealed that EA's anti-HBV effects primarily hinge on immune modulation, particularly the IFN-γ/JAK/STAT pathway and taurine metabolism. EA also increased the ratio of splenic CD8+ CD69+ and CD8+ IFN-γ+ T-cells while upregulating key proteins in the JAK/STAT pathway and cytokines associated with antiviral immunity.

Conclusion

EA manifests inhibitory effects on HBV, particularly in antigen suppression, with its mode of action intricately linked to the regulation of IFN-γ/JAK/STAT.

Real-world study on the efficacy and safety of different treatment regimens in treatment-naïve CHB patients with high viral load

Evaluate the real-world effectiveness and safety of different treatment regimens for treatment-naïve high viral load chronic hepatitis B (CHB) patients. Between January 2021 and August 2022, CHB patients with HBV DNA ≥ 107 IU/mL were collected from four medical centers in Shenzhen. Patients treated with mono or combine antiviral therapy. The primary endpoint was the cumulative incidence of virological response at 48 weeks, and other endpoints included changes in HBsAg, HBeAg, ALT, and eGFR at 48 weeks. We used propensity score-based inverse probability of treatment weighting (IPTW) to balance the bias. Weighted logistics regression was used to estimate the factors affecting virological response. A total of 391 patients were included in the study, with 296 patients undergoing statistical analysis after IPTW. The patients were distributed into four groups: ETV (n = 62), TDF (n = 89), TAF (n = 36), TDF + LdT/ETV (n = 109). The 48-week cumulative incidence of virological response was significantly lower in ETV group (52.3%) compared to TDF (71.7%), TAF (74.2%), and TDF + LdT/ETV groups (77.9%) (P < 0.05). There were no significant differences in HBsAg loss among the four groups, but the HBeAg seroconversion rate was significantly higher in the TAF group. The ALT normalization rate was significantly higher in the TAF group (72.2%) compared to the others at 48 weeks (P < 0.05). In treatment-naïve CHB patients with high viral load, combination therapy was not superior to TDF or TAF monotherapy in virological response. Patients treated with TDF or TAF showed superior virological response compared to those treated with ETV. The TAF group demonstrated superiority in terms of ALT normalization and HBeAg seroconversion.

Mice Engrafted with Human Liver Cells

Rodents are commonly employed to model human liver conditions, although species differences can restrict their translational relevance. To overcome some of these limitations, researchers have long pursued human hepatocyte transplantation into rodents. More than 20 years ago, the first primary human hepatocyte transplantations into immunodeficient mice with liver injury were able to support hepatitis B and C virus infections, as these viruses cannot replicate in murine hepatocytes. Since then, hepatocyte chimeric mouse models have transitioned into mainstream preclinical research and are now employed in a diverse array of liver conditions beyond viral hepatitis, including malaria, drug metabolism, liver-targeting gene therapy, metabolic dysfunction-associated steatotic liver disease, lipoprotein and bile acid biology, and others. Concurrently, endeavors to cotransplant other cell types and humanize immune and other nonparenchymal compartments have seen growing success. Looking ahead, several challenges remain. These include enhancing immune functionality in mice doubly humanized with hepatocytes and immune systems, efficiently creating mice with genetically altered grafts and reliably humanizing chimeric mice with renewable cell sources such as patient-specific induced pluripotent stem cells. In conclusion, hepatocyte chimeric mice have evolved into vital preclinical models that address many limitations of traditional rodent models. Continued improvements may further expand their applications.

High accuracy model for HBsAg loss based on longitudinal trajectories of serum qHBsAg throughout long-term antiviral therapy

OBJECTIVE

Hepatitis B surface antigen (HBsAg) loss is the optimal outcome for patients with chronic hepatitis B (CHB) but this rarely occurs with currently approved therapies. We aimed to develop and validate a prognostic model for HBsAg loss on treatment using longitudinal data from a large, prospectively followed, nationwide cohort.

DESIGN

CHB patients receiving nucleos(t)ide analogues as antiviral treatment were enrolled from 50 centres in China. Quantitative HBsAg (qHBsAg) testing was prospectively performed biannually per protocol. Longitudinal discriminant analysis algorithm was used to estimate the incidence of HBsAg loss, by integrating clinical data of each patient collected during follow-up.

RESULTS

In total, 6792 CHB patients who had initiated antiviral treatment 41.3 (IQR 7.6-107.6) months before enrolment and had median qHBsAg 2.9 (IQR 2.3-3.3) log10IU/mL at entry were analysed. With a median follow-up of 65.6 (IQR 51.5-84.7) months, the 5-year cumulative incidence of HBsAg loss was 2.4%. A prediction model integrating all qHBsAg values of each patient during follow-up, designated GOLDEN model, was developed and validated. The AUCs of GOLDEN model were 0.981 (95% CI 0.974 to 0.987) and 0.979 (95% CI 0.974 to 0.983) in the training and external validation sets, respectively, and were significantly better than those of a single qHBsAg measurement. GOLDEN model identified 8.5%-10.4% of patients with a high probability of HBsAg loss (5-year cumulative incidence: 17.0%-29.1%) and was able to exclude 89.6%-91.5% of patients whose incidence of HBsAg loss is 0. Moreover, the GOLDEN model consistently showed excellent performance among various subgroups.

CONCLUSION

The novel GOLDEN model, based on longitudinal qHBsAg data, accurately predicts HBsAg clearance, provides reliable estimates of functional hepatitis B virus (HBV) cure and may have the potential to stratify different subsets of patients for novel anti-HBV therapies.

HBcrAg values may predict virological and immunological responses to pegIFN-α in NUC-suppressed HBeAg-negative chronic hepatitis B

OBJECTIVE

Selected populations of patients with chronic hepatitis B (CHB) may benefit from a combined use of pegylated interferon-alpha (pegIFN-α) and nucleos(t)ides (NUCs). The aim of our study was to assess the immunomodulatory effect of pegIFN-α on T and natural killer (NK) cell responses in NUC-suppressed patients to identify cellular and/or serological parameters to predict better T cell-restoring effect and better control of infection in response to pegIFN-α for a tailored application of IFN-α add-on.

DESIGN

53 HBeAg-negative NUC-treated patients with CHB were randomised at a 1:1 ratio to receive pegIFN-α-2a for 48 weeks, or to continue NUC therapy and then followed up for at least 6 months maintaining NUCs. Serum hepatitis B surface antigen (HBsAg) and hepatitis B core-related antigen (HBcrAg) levels as well as peripheral blood NK cell phenotype and function and HBV-specific T cell responses upon in vitro stimulation with overlapping HBV peptides were measured longitudinally before, during and after pegIFN-α therapy.

RESULTS

Two cohorts of pegIFN-α treated patients were identified according to HBsAg decline greater or less than 0.5 log at week 24 post-treatment. PegIFN-α add-on did not significantly improve HBV-specific T cell responses during therapy but elicited a significant multispecific and polyfunctional T cell improvement at week 24 post-pegIFN-α treatment compared with baseline. This improvement was maximal in patients who had a higher drop in serum HBsAg levels and a lower basal HBcrAg values.

CONCLUSIONS

PegIFN-α treatment can induce greater functional T cell improvement and HBsAg decline in patients with lower baseline HBcrAg levels. Thus, HBcrAg may represent an easily and reliably applicable parameter to select patients who are more likely to achieve better response to pegIFN-α add-on to virally suppressed patients.

Exploration of 1-(indolin-1-yl)-2-(thiazol-2-yl)ethan-1-one derivatives as novel anti-HBV agent with potential TLR7-agonistic effect

Hepatitis B virus (HBV) infection, as a serious global public health issue, is closely related to the immune dysfunction. Herein, thirty-seven 1-(indolin-1-yl)-2-(thiazol-4-yl)ethan-1-one derivatives were prepared as potential immunomodulatory anti-HBV agents. Anti-HBV activity evaluation confirmed compound 11a could significantly suppress the HBV DNA replication in both wild and resistant HBV stains, with IC50 values of 0.13 μM and 0.36 μM, respectively. Preliminary action mechanism studies showed that 11a had an inhibitory effect on cellular HBsAg secretion and could effectively activate TLR7, thereby inducing the secretion of TLR7-regulated cytokines IL-12, TNF-α and IFN-α in human PBMC cells. SPR analysis confirmed that 11a could bind to TLR7 protein with an affinity of 7.06 μM. MD simulation predicted that 11a could form tight interactions with residues in the binding pocket of TLR7. Physicochemical parameters perdition and pharmacokinetic analysis indicated that 11a displayed relatively favorable drug-like properties. Considering all the results, compound 11a might be a promising lead for developing novel immunomodulatory anti-HBV agents.

Activating adaptive immunity by bispecific, T-cell engager antibodies bridging infected and immune-effector cells is a promising novel therapy for chronic hepatitis B

Bispecific antibodies (bsAbs) are engineered immunoglobulins that combine two different antigen-binding sites in one molecule. BsAbs can be divided into two molecular formats: IgG-like and non-IgG-like antibodies. Structural elements of each format have implications for engaging the immune system. T cell engager antibodies (TCEs) are bsAbs designed to engage T cells with target cells. TCEs can be applied not only in cancer but also in infectious disease therapy to activate T-cell responses. In this review, we focus on current literature on the design and use of bsAbs as an innovative strategy to enhance adaptive antiviral immune responses. We summarized the novel T cell-related immunotherapies with a focus on TCEs, that are developed for the treatment of chronic hepatitis B. Chronic infection with the hepatitis B virus (HBV) had a death toll of 1.1 million humans in 2022, mainly due to liver cirrhosis and hepatocellular carcinoma developing in the more than 250 million humans chronically infected. A curative treatment approach for chronic hepatitis B is lacking. Combining antiviral therapy with immune therapies activating T-cell responses is regarded as the most promising therapeutic approach to curing HBV and preventing the sequelae of chronic infection. Attracting functionally intact T cells that are not HBV-specific and, therefore, have not yet been exposed to regulatory mechanisms and activating those at the target site in the liver is a very interesting therapeutic approach that could be achieved by TCEs. Thus, TCEs redirecting T cells toward HBV-positive cells represent a promising strategy for treating chronic hepatitis B and HBV-associated hepatocellular carcinoma.

Improved preclinical drug metabolism and pharmacokinetics of pibothiadine (HEC121210), a novel hepatitis B virus capsid assembly modulator

Pibothiadine (PBD; HEC121120) is a novel hepatitis B virus capsid assembly modulator based on GLS4 (morphothiadine) and has inhibitory activities against resistant strains.To assess the overall preclinical drug metabolism and pharmacokinetics (DMPK) properties of PBD, in vivo pharmacokinetics studies in rats and dogs have been performed along with a series of in vitro metabolism assays.The oral bioavailability of PBD in rats and dogs might be related to its medium permeability in Caco-2 cells and largely be impacted by the pH-dependent solubility. PBD was highly distributed to the liver where the local exposure was 16.4 fold of the system exposure. PBD showed relatively low metabolic rate in recombinant human cytochrome P450 enzymes, whereas low to moderate in vitro clearance in liver microsomes and low (dog) to moderate (rat) in vivo clearance. Furthermore, β-oxidation and dehydrogenation were proposed as the primary metabolic pathways of PBD in rats.Compared to GLS4, the higher systemic exposure of PBD might be attributed to its improved oral absorption and metabolic stability. In addition, the enhanced liver/plasma exposure ratio could further increase the local exposure around the target. These improved DMPK properties might indicate better development of PBD in the clinical phase.

Characterisation of HBV and co-infection with HDV and HIV through spatial transcriptomics

Background and aims

The intrahepatic processes associated with chronic hepatitis B (CHB), especially in the context of hepatitis delta virus (HDV) and HIV co-infection, require a better understanding. Spatial transcriptomics can provide new insights into the complex intrahepatic biological processes, guiding new personalised treatments. Our aim is to evaluate this method characterising the intrahepatic transcriptional landscape, cellular composition and biological pathways in liver biopsy samples from patients with hepatitis B virus (HBV) and HDV or HIV co-infection.

Method

The NanoString GeoMx digital spatial profiling platform was employed to assess expression of HBV surface antigen and CD45 in formalin-fixed paraffin-embedded (FFPE) biopsies from three treatment-naïve patients with chronic HBV and HDV or HIV co-infection. The GeoMx Human Whole Transcriptome Atlas assay quantified the expression of genes enriched in specific regions of interest (ROIs). Cell type proportions within ROIs were deconvoluted using a training matrix from the human liver cell atlas. A weighted gene correlation network analysis evaluated transcriptomic signatures across sampled regions.

Results

Spatially discrete transcriptomic signatures and distinct biological pathways were associated with HBV infection/disease status and immune responses. Shared features including 'cytotoxicity' and 'B cell receptor signalling' were consistent across patients, suggesting common elements alongside individual traits. HDV/HBV co-infection exhibited upregulated genes linked to apoptosis and immune cell recruitment, whereas HIV/HBV co-infection featured genes related to interferon response regulation. Varied cellular characteristics and immune cell populations, with an abundance of γδT cells in the HDV/HBV sample, were observed within analysed regions. Transcriptional differences in hepatocyte function suggest disrupted metabolic processes in HDV/HBV co-infection potentially impacting disease progression.

Conclusion

This proof-of-principle study shows the value of this platform in investigating the complex immune landscape, highlighting relevant host pathways to disease pathogenesis.

Toward a Functional Cure for Hepatitis B

Current treatment of chronic hepatitis B virus (HBV) infection, pegylated interferon-α (pegIFN-α) and nucleos(t)ide analogue (NA), can suppress HBV replication, reverse liver inflammation and fibrosis, and decrease risks of cirrhosis and hepatocellular carcinoma, but hepatitis B surface antigen (HBsAg) loss is rare. Functional HBV cure is defined as undetectable HBsAg and unquantifiable serum HBV DNA for at least 24 weeks after a finite course of therapy. This requires suppression of HBV replication and viral protein production as well as restoration of immune response to HBV. Direct-acting antivirals targeting virus entry, capsid assembly, viral protein production and secretion are in clinical trials. In parallel, immune modulatory therapies to stimulate HBV-specific immune response and to remove immune blockade are being tested. Clinical trials of direct-acting antivirals alone or immune modulatory therapies alone have not been successful in achieving HBV cure. Recent combinations of direct-acting antivirals and immune modulatory therapies have shown promising results particularly with combinations that included pegIFN-α. These results need to be confirmed in larger studies with longer follow-up, and further work is needed to develop simpler regimens with fewer drugs that can be administered orally and safely. While there is a strong desire to develop finite therapies that can achieve HBV cure, safety is paramount and new therapies must provide incremental value compared to standard of care, which is predominantly long-term NA therapy.

Furanocoumarins promote proteasomal degradation of viral HBx protein and down-regulate cccDNA transcription and replication of hepatitis B virus

Nucleot(s)ide analogues, the current antiviral treatments against chronic hepatitis B (CHB) infection, are non-curative due to their inability to eliminate covalently closed circular DNA (cccDNA) from the infected hepatocytes. Preclinical studies have shown that coumarin derivatives can effectively reduce the HBV DNA replication. We evaluated the antiviral efficacy of thirty new coumarin derivatives in cell culture models for studying HBV. Furanocoumarins Fc-20 and Fc-31 suppressed the levels of pre-genomic RNA as well as cccDNA, and reduced the secretion of virions, HBsAg and HBeAg. The antiviral efficacies of Fc-20 and Fc31 improved further when used in combination with the hepatitis B antiviral drug Entecavir. There was a marked reduction in the intracellular HBx level in the presence of these furanocoumarins due to proteasomal degradation resulting in the down-regulation of HBx-dependent viral genes. Importantly, both Fc-20 and Fc-31 were non-cytotoxic to cells even at high concentrations. Further, our molecular docking studies confirmed a moderate to high affinity interaction between furanocoumarins and viral HBx via residues Ala3, Arg26 and Lys140. These data suggest that furanocoumarins could be developed as a new therapeutic for CHB infection.

Major open questions in the hepatitis B and D field - Proceedings of the inaugural International emerging hepatitis B and hepatitis D researchers workshop

The early and mid-career researchers (EMCRs) of scientific communities represent the forefront of research and the future direction in which a field takes. The opinions of this key demographic are not commonly aggregated to audit fields and precisely demonstrate where challenges lie for the future. To address this, we initiated the inaugural International Emerging Researchers Workshop for the global Hepatitis B and Hepatitis D scientific community (75 individuals). The cohort was split into small discussion groups and the significant problems, challenges, and future directions were assessed. Here, we summarise the outcome of these discussions and outline the future directions suggested by the EMCR community. We show an effective approach to gauging and accumulating the ideas of EMCRs and provide a succinct summary of the significant gaps remaining in the Hepatitis B and Hepatitis D field.

Modulation of monocyte activity by hepatocellular MicroRNA delivery through HBsAg particles: Implications for pathobiology of chronic hepatitis B

BACKGROUND AND AIMS

HBsAg serves as an important immune-modulatory factor in chronic hepatitis B. One aspect of such modulation may act through monocytes, which are the major Ag-presenting cells taking up HBsAg. There is evidence for the encapsulation of hepatocellular microRNAs (miRNAs) by HBsAg particles, while its pathobiological significance is unclear. Here, we characterized the miRNA profile in patients with chronic hepatitis B and probed their association with liver inflammation.

APPROACHES AND RESULTS

We collected plasma from patients that are treatment-naive with chronic hepatitis B (n = 110) and quantified total/HBsAg-enveloped miRNAs by qRT-PCR and plasma cytokines by ELISA. The biological effects of HBsAg-delivered miRNAs in monocytes were evaluated using multiple approaches. The clinical significance of candidate miRNAs and cytokines was corroborated in patients with HBV-associated advanced liver diseases. The plasma miRNA profile showed 2 major clusters, one significantly associated with HBsAg titer and the other correlated with liver inflammation. Among HBsAg-carried miRNAs, miR-939 displayed the most significant correlation with IL-8. Mechanistically, miR-939 in subviral particles enters monocytes and significantly augments IL-8 production through the mitogen-activated protein kinase (MAPK) p38 signaling pathway. Finally, the findings that miR-939 positively correlated with IL-8 level and inflammation/fibrosis stage in the cohort of HBV-associated advanced liver diseases support its causative role in the progression of liver diseases.

CONCLUSIONS

HBsAg particles carry hepatocellular miRNAs, including miR-939, which enter monocytes and alter their functional status, such as IL-8 secretion. Our findings demonstrate that the HBsAg-miR-939-IL-8 axis may play a crucial role in HBV-induced hepatic necro-inflammation and the progression of advanced liver diseases.

Stopping Nucleos(t)ide Analogues in Chronic Hepatitis B Using HBsAg Thresholds: A Meta-Analysis and Meta-Regression

BACKGROUND AND AIMS

Recommendations for stopping nucleoside analogue (NA) therapy in hepatitis B e antigen-negative chronic hepatitis B (CHB) are unclear. End-of-treatment quantitative hepatitis B serum antigen (EOTqHBsAg) thresholds <100 IU/mL or <1000 IU/mL have been proposed as stopping criteria, which we assessed by meta-analysis and meta-regression.

METHODS

We searched PubMed, EMBASE, and conference abstracts for studies of hepatitis B e antigen-negative CHB NA discontinuation. Extracted studies were analyzed for risk of bias, pooled risk of hepatitis B serum antigen (HBsAg) loss, virological relapse (VR), and biochemical relapse (BR). Significant heterogeneity (I2) was addressed by subgroup analysis and random-effects meta-regression with known important covariates, including EOTqHBsAg thresholds, ethnicity, duration of therapy, and follow-up.

RESULTS

We found 24 articles (3732 subjects); 16 had low and 8 had moderate risk of bias. The pooled risks of HBsAg loss, VR, and BR for stopping therapy at EOTqHBsAg <100 IU/mL were 41.8%, 33.4%, and 17.3%, respectively, vs 4.6%, 72.1%, and 34.6%, respectively, for EOTqHBsAg ≥100 IU/mL. The pooled risks of HBsAg loss, VR, and BR for stopping therapy at EOTqHBsAg <1000 IU/mL were 22.0%, 52.7%, and 15.9%, respectively, vs 3.4%, 63.8%, and 26.4%, respectively, for EOTqHBsAg ≥1000 IU/mL. Multivariable analysis for HBsAg loss showed that ethnicity, follow-up duration, and EOTqHBsAg <100 IU/mL and ≥100 IU/mL explained 85% of the variance in heterogeneity; Asians with EOTqHBsAg <100 IU/mL had 28.2%, while non-Asians with EOTqHBsAg <1000 IU/mL had 38.4% HBsAg loss. Multivariable analysis showed EOTqHBsAg <100 IU/mL and ≥100 IU/mL and other covariates only explained 43% and 63% of the variance in heterogeneity for VR and BR, respectively, suggesting that other factors are also important for relapse.

CONCLUSIONS

While EOTqHBsAg thresholds, ethnicity, and follow-up duration strongly predict HBsAg loss, this is not true for VR and BR, hence stopping NA therapy should be considered cautiously.

A nucleosome switch primes Hepatitis B Virus infection

Chronic hepatitis B virus (HBV) infection is an incurable global health threat responsible for causing liver disease and hepatocellular carcinoma. During the genesis of infection, HBV establishes an independent minichromosome consisting of the viral covalently closed circular DNA (cccDNA) genome and host histones. The viral X gene must be expressed immediately upon infection to induce degradation of the host silencing factor, Smc5/6. However, the relationship between cccDNA chromatinization and X gene transcription remains poorly understood. Establishing a reconstituted viral minichromosome platform, we found that nucleosome occupancy in cccDNA drives X transcription. We corroborated these findings in cells and further showed that the chromatin destabilizing molecule CBL137 inhibits X transcription and HBV infection in hepatocytes. Our results shed light on a long-standing paradox and represent a potential new therapeutic avenue for the treatment of chronic HBV infection.

The lack of HBsAg secretion does neither facilitate induction of antiviral T cell responses nor Hepatitis B Virus clearance in mice

Immune tolerance to the hepatitis B virus (HBV) is crucial for developing chronic hepatitis B, and the HBV surface antigen (HBsAg) produced and secreted in high amounts is regarded as a key contributor. HBsAg is expressed in HBV-infected hepatocytes and those carrying an HBV integration. Whether either HBsAg secretion or the high antigen amount expressed in the liver determines its immunomodulatory properties, however, remains unclear. We, therefore, developed a novel HBV animal model that allowed us to study the role of secreted HBsAg. We introduced a previously described HBs mutation, C65S, abolishing HBsAg secretion into a replication-competent 1.3-overlength HBV genome and used adeno-associated virus vectors to deliver it to the mouse liver. The AAV-HBV established a carrier state of wildtype and C65S mutant HBV, respectively. We investigated antiviral B- and T-cell immunity in the HBV-carrier mice after therapeutic vaccination. Moreover, we compared the effect of a lacking HBsAg secretion with that of an antiviral siRNA. While missing HBsAg secretion allowed for higher levels of detectable anti-HBs antibodies after therapeutic vaccination, it did neither affect antiviral T-cell responses nor intrahepatic HBV gene expression, irrespective of the starting level. A treatment with HBV siRNA restricting viral antigen expression within hepatocytes, however, improved the antiviral efficacy of therapeutic vaccination, irrespective of the ability of HBV to secrete HBsAg. Our data indicate that clearing HBsAg from blood cannot significantly impact HBV persistence or T-cell immunity. This indicates that a restriction of hepatic viral antigen expression will be required to break HBV immunotolerance.

Self-assembly of peptides in living cells for disease theranostics

The past few decades have witnessed substantial progress in biomedical materials for addressing health concerns and improving disease therapeutic and diagnostic efficacy. Conventional biomedical materials are typically created through an ex vivo approach and are usually utilized under physiological environments via transfer from preparative media. This transfer potentially gives rise to challenges for the efficient preservation of the bioactivity and implementation of theranostic goals on site. To overcome these issues, the in situ synthesis of biomedical materials on site has attracted great attention in the past few years. Peptides, which exhibit remarkable biocompability and reliable noncovalent interactions, can be tailored via tunable assembly to precisely create biomedical materials. In this review, we summarize the progress in the self-assembly of peptides in living cells for disease diagnosis and therapy. After a brief introduction to the basic design principles of peptide assembly systems in living cells, the applications of peptide assemblies for bioimaging and disease treatment are highlighted. The challenges in the field of peptide self-assembly in living cells and the prospects for novel peptide assembly systems towards next-generation biomaterials are also discussed, which will hopefully help elucidate the great potential of peptide assembly in living cells for future healthcare applications.

TLR8 agonist selgantolimod regulates Kupffer cell differentiation status and impairs HBV entry into hepatocytes via an IL-6-dependent mechanism

OBJECTIVE

Achieving HBV cure will require novel combination therapies of direct-acting antivirals and immunomodulatory agents. In this context, the toll-like receptor 8 (TLR8) agonist selgantolimod (SLGN) has been investigated in preclinical models and clinical trials for chronic hepatitis B (CHB). However, little is known regarding its action on immune effectors within the liver. Our aim was to characterise the transcriptomic changes and intercellular communication events induced by SLGN in the hepatic microenvironment.

DESIGN

We identified TLR8-expressing cell types in the human liver using publicly available single-cell RNA-seq data and established a method to isolate Kupffer cells (KCs). We characterised transcriptomic and cytokine KC profiles in response to SLGN. SLGN's indirect effect was evaluated by RNA-seq in hepatocytes treated with SLGN-conditioned media (CM) and quantification of HBV parameters following infection. Pathways mediating SLGN's effect were validated using transcriptomic data from HBV-infected patients.

RESULTS

Hepatic TLR8 expression takes place in the myeloid compartment. SLGN treatment of KCs upregulated monocyte markers (eg, S100A12) and downregulated genes associated with the KC identity (eg, SPIC). Treatment of hepatocytes with SLGN-CM downregulated NTCP and impaired HBV entry. Cotreatment with an interleukin 6-neutralising antibody reverted the HBV entry inhibition.

CONCLUSION

Our transcriptomic characterisation of SLGN sheds light into the programmes regulating KC activation. Furthermore, in addition to its previously described effect on established HBV infection and adaptive immunity, we show that SLGN impairs HBV entry. Altogether, SLGN may contribute through KCs to remodelling the intrahepatic immune microenvironment and may thus represent an important component of future combinations to cure HBV infection.

Highlights from the 2023 International Meeting on the Molecular Biology of Hepatitis B virus

Since its discovery in 1965, our understanding of the hepatitis B virus (HBV) replication cycle and host immune responses has increased markedly. In contrast, our knowledge of the molecular biology of hepatitis delta virus (HDV), which is associated with more severe liver disease, is less well understood. Despite the progress made, critical gaps remain in our knowledge of HBV and HDV replication and the mechanisms underlying viral persistence and evasion of host immunity. The International HBV Meeting is the leading annual scientific meeting for presenting the latest advances in HBV and HDV molecular virology, immunology, and epidemiology. In 2023, the annual scientific meeting was held in Kobe, Japan and this review summarises some of the advances presented at the Meeting and lists gaps in our knowledge that may facilitate the development of new therapies.

ISG12a promotes immunotherapy of HBV-associated hepatocellular carcinoma through blocking TRIM21/AKT/β-catenin/PD-L1 axis

Hepatitis B virus (HBV) infection generally elicits weak type-I interferon (IFN) immune response in hepatocytes, covering the regulatory effect of IFN-stimulated genes. In this study, low level of IFN-stimulated gene 12a (ISG12a) predicted malignant transformation and poor prognosis of HBV-associated hepatocellular carcinoma (HCC), whereas high level of ISG12a indicated active NK cell phenotypes. ISG12a interacts with TRIM21 to inhibit the phosphorylation activation of protein kinase B (PKB, also known as AKT) and β-catenin, suppressing PD-L1 expression to block PD-1/PD-L1 signaling, thereby enhancing the anticancer effect of NK cells. The suppression of PD-1-deficient NK-92 cells on HBV-associated tumors was independent of ISG12a expression, whereas the anticancer effect of PD-1-expressed NK-92 cells on HBV-associated tumors was enhanced by ISG12a and treatments of atezolizumab and nivolumab. Thus, tumor intrinsic ISG12a promotes the anticancer effect of NK cells by regulating PD-1/PD-L1 signaling, presenting the significant role of innate immunity in defending against HBV-associated HCC.

Discovery of Hepatitis B Virus Surface Antigen Suppressor GS-8873

Chronic hepatitis B (CHB) virus infection afflicts hundreds of millions of people and causes nearly one million deaths annually. The high levels of circulating viral surface antigen (HBsAg) that characterize CHB may lead to T-cell exhaustion, resulting in an impaired antiviral immune response in the host. Agents that suppress HBsAg could help invigorate immunity toward infected hepatocytes and facilitate a functional cure. A series of dihydropyridoisoquinolizinone (DHQ) inhibitors of human poly(A) polymerases PAPD5/7 were reported to suppress HBsAg in vitro. An example from this class, RG7834, briefly entered the clinic. We set out to identify a potent, orally bioavailable, and safe PAPD5/7 inhibitor as a potential component of a functional cure regimen. Our efforts led to the identification of a dihydropyridophthalazinone (DPP) core with improved pharmacokinetic properties. A conformational restriction strategy and optimization of core substitution led to GS-8873, which was projected to provide deep HBsAg suppression with once-daily dosing.

Hypermethylation of the glutathione peroxidase 4 gene promoter is associated with the occurrence of immune tolerance phase in chronic hepatitis B

BACKGROUND

Hepatitis B virus (HBV) infection is a public health problem that seriously threatens human health. This study aimed to investigate the clinical significance of glutathione peroxidase 4(GPX4) in the occurrence and development of chronic hepatitis B (CHB).

METHODS

A total of 169 participants including 137 patients with CHB and 32 healthy controls (HCs) were recruited. We detected the expression of GPX4 and stimulator of interferon genes (STING) in peripheral blood mononuclear cells (PBMCs) by real-time quantitative polymerase chain reaction (RT-qPCR). The methylation level of GPX4 gene promoter in PBMCs was detected by TaqMan probe-based quantitative methylation-specific PCR (MethyLight). Enzyme-linked immunosorbent assay (ELISA) was performed to detect the serum levels of GPX4, IFN-β, oxidative stress (OS) related molecules, and pro-inflammatory cytokines.

RESULTS

The expression levels of GPX4 in PBMCs and serum of CHB patients were lower than those of HCs, but the methylation levels of GPX4 promoter were higher than those of HCs, especially in patients at the immune tolerance phase. STING mRNA expression levels in PBMCs and serum IFN-β levels of patients at the immune activation phase and reactivation phase of CHB were higher than those at other clinical phases of CHB and HCs. GPX4 mRNA expression level and methylation level in PBMCs from patients with CHB had a certain correlation with STING and IFN-β expression levels. In addition, the methylation level of the GPX4 promoter in PBMCs from patients with CHB was correlated with molecules associated with OS and inflammation.

CONCLUSIONS

GPX4 may play an important role in the pathogenesis and immune tolerance of CHB, which may provide new ideas for the functional cure of CHB.

Long-Term Outcomes after Switching to Tenofovir Alafenamide in Patients with Chronic Hepatitis B

We sought to determine the long-term outcomes of chronic hepatitis B (CHB) cases switching to tenofovir alafenamide (TAF, n = 104, median age = 63.5 years). Data at switching to TAF (baseline) and those at 1, 2, 3, 4, and 5 years from switching to TAF were compared. At baseline, HB envelop antigen (HBeAg) seropositivity was found in 20 patients (19.2%), and undetectable HBV-DNA in 77 patients (74.0%). Percentage of detectable HBV-DNA significantly reduced at any time point. HB surface antigen (HBsAg) levels significantly reduced at 3, 4, and 5 years. The percentage of HBeAg seropositivity significantly reduced at 5 years. HB core related antigen levels did not significantly change. In patients with baseline HbeAg seropositivity, HbsAg levels significantly reduced at any time point, and a similar trend was found in patients without HBeAg seropositivity. In patients with baseline FIB4 index >1.85, HBsAg levels significantly reduced at 3, 4, and 5 years, and in patients with baseline FIB4 index <1.85, HBsAg levels significantly reduced at any time point. The estimated glomerular filtration rate significantly reduced only at 5 years. The discontinuation rate owing to the side effects of TAF was 0%. In conclusion, switching to TAF therapy in patients with CHB may be effective and safe at least up to 5 years.

Classifying hepatitis B therapies with insights from covalently closed circular DNA dynamics

The achievement of a functional cure for chronic hepatitis B (CHB) remains limited to a minority of patients treated with currently approved drugs. The primary objective in developing new anti-HBV drugs is to enhance the functional cure rates for CHB. A critical prerequisite for the functional cure of CHB is a substantial reduction, or even eradication of covalently closed circular DNA (cccDNA). Within this context, the changes in cccDNA levels during treatment become as a pivotal concern. We have previously analyzed the factors influencing cccDNA dynamics and introduced a preliminary classification of hepatitis B treatment strategies based on these dynamics. In this review, we employ a systems thinking perspective to elucidate the fundamental aspects of the HBV replication cycle and to rationalize the classification of treatment strategies according to their impact on the dynamic equilibrium of cccDNA. Building upon this foundation, we categorize current anti-HBV strategies into two distinct groups and advocate for their combined use to significantly reduce cccDNA levels within a well-defined timeframe.

miR-26a exerts broad-spectrum antiviral effects via the enhancement of RIG-I-mediated type I interferon response by targeting USP15

IMPORTANCE

miR-26a serves as a potent positive regulator of type I interferon (IFN) responses. By inhibiting USP15 expression, miR-26a promotes RIG-I K63-ubiquitination to enhance type I IFN responses, resulting in an active antiviral state against viruses. Being an intricate regulatory network, the activation of type I IFN responses could in turn suppress miR-26a expression to avoid the disordered activation that might result in the so-called "type I interferonopathy." The knowledge gained would be essential for the development of novel antiviral strategies against viral infection.

Patient acceptability of, and attitudes towards, hepatitis B cure research - A scoping review and identification of knowledge gaps

Functional cure, defined as durable loss of hepatitis B surface antigen (HBsAg) and hepatitis B virus (HBV) DNA suppression off therapy, is an increasingly important goal in the treatment of chronic hepatitis B. Although novel treatments aimed at achieving functional cure are being developed and tested in clinical trials, it is important to assess the perspectives of people living with HBV towards these potential treatments and their participation in HBV functional cure research. We have performed a scoping review that revealed that there is limited knowledge regarding patient perspectives of HBV functional cure research and then identified gaps in knowledge for further investigation. Our work highlights the need for further studies in patient perspectives in HBV functional cure research.

What Is the Current Status of Hepatitis B Virus Viro-Immunology?

The natural history of hepatitis B virus (HBV) infection is closely dependent on the dynamic interplay between the host immune response and viral replication. Spontaneous HBV clearance in acute self-limited infection is the result of an adequate and efficient antiviral immune response. Instead, it is widely recognized that in chronic HBV infection, immunologic dysfunction contributes to viral persistence. Long-lasting exposure to high viral antigens, upregulation of multiple co-inhibitory receptors, dysfunctional intracellular signaling pathways and metabolic alterations, and intrahepatic regulatory mechanisms have been described as features ultimately leading to a hierarchical loss of effector functions up to full T-cell exhaustion.

Design, Synthesis, and Biological Evaluation of Novel Thioureidobenzamide (TBA) Derivatives as HBV Capsid Assembly Modulators

Hepatitis B virus (HBV) capsid assembly modulators (CAMs) represent a promising therapeutic approach for the treatment of HBV infection. In this study, we designed and synthesized five series of benzamide derivatives based on a multisite-binding strategy at the tolerant region and diversity modification in the solvent-exposed region. Among them, thioureidobenzamide compound 17i exhibited significantly increased anti-HBV activity in HepAD38 (EC50 = 0.012 μM) and HBV-infected HLCZ01 cells (EC50 = 0.033 μM). Moreover, 17i displayed a better inhibitory effect on the assembly of HBV capsid protein compared with NVR 3-778 and a inhibitory effect similar to the clinical drug GLS4. In addition, 17i showed moderate metabolic stability in human microsomes, had excellent oral bioavailability in Sprague-Dawley (SD) rats, and inhibited HBV replication in the HBV carrier mice model, which could be considered as a promising candidate drug for further development.

Interspecies comparison of the early transcriptomic changes associated with hepatitis B virus exposure in human and macaque immune cell populations

Background and aims

Hepatitis B virus (HBV) infection affects 300 million individuals worldwide, representing a major factor for the development of hepatic complications. Although existing antivirals are effective in suppressing replication, eradication of HBV is not achieved. Therefore, a multi-faceted approach involving antivirals and immunomodulatory agents is required. Non-human primates are widely used in pre-clinical studies due to their close evolutionary relationship to humans. Nonetheless, it is fundamental to identify the differences in immune response between humans and these models. Thus, we performed a transcriptomic characterization and interspecies comparison of the early immune responses to HBV in human and cynomolgus macaques.

Methods

We characterized early transcriptomic changes in human and cynomolgus B cells, T cells, myeloid and plasmacytoid dendritic cells (pDC) exposed to HBV ex vivo for 2 hours. Differentially-expressed genes were further compared to the profiles of HBV-infected patients using publicly-available single-cell data.

Results

HBV induced a wide variety of transcriptional changes in all cell types, with common genes between species representing only a small proportion. In particular, interferon gamma signaling was repressed in human pDCs. At the gene level, interferon gamma inducible protein 16 (IFI16) was upregulated in macaque pDCs, while downregulated in humans. Moreover, IFI16 expression in pDCs from chronic HBV-infected patients anti-paralleled serum HBsAg levels.

Conclusion

Our characterization of early transcriptomic changes induced by HBV in humans and cynomolgus macaques represents a useful resource for the identification of shared and divergent host responses, as well as potential immune targets against HBV.

Fatal acute-on-chronic liver failure following camrelizumab for hepatocellular carcinoma with HBsAg seroclearance: a case report and literature review

In the last few years, immune checkpoint inhibitors (ICIs) have become major therapeutic agents for the treatment of advanced hepatocellular carcinoma (HCC). However, immunotherapy can activate hepatitis B virus (HBV), and immune clearance may lead to liver failure and even life-threatening conditions. Here we report a case of HCC with HBV-related cirrhosis that caused severe liver injury and rapidly progressed to fatal acute-on-chronic liver failure (ACLF) after only once application of camrelizumab; the patient underwent serological conversion of hepatitis B surface antigen (HBsAg) with liver injury. The patient's condition progressed rapidly. We added corticosteroids and applied plasma dialysis, along with tenofovir alafenamide (TAF) to control HBV. However, the patient eventually died of liver failure. To our knowledge, there are few reports of HBsAg clearance due to ICIs accompanied by fatal acute-on-chronic liver failure shortly after ICIs initiation. These results suggest that ICIs can cause fatal liver injury in a short term; in patients with chronic HBV infection, ICIs use may promote serological conversion of HBsAg.

Chronic Hepatitis B Infection: New Approaches towards Cure

Chronic hepatitis B virus (HBV) infection leads to the development of cirrhosis and hepatocellular carcinoma. Lifelong treatment with nucleotides/nucleoside antiviral agents is effective at suppressing HBV replication, however, adherence to daily therapy can be challenging. This review discusses recent advances in the development of long-acting formulations for HBV treatment and prevention, which could potentially improve adherence. Promising new compounds that target distinct steps of the virus life cycle are summarized. In addition to treatments that suppress viral replication, curative strategies are focused on the elimination of covalently closed circular DNA and the inactivation of the integrated viral DNA from infected hepatocytes. We highlight promising long-acting antivirals and genome editing strategies for the elimination or deactivation of persistent viral DNA products in development.

Development of Therapy Based on the Exploration of Biological Events Underlying the Pathogenetic Mechanisms of Chronic Hepatitis B Infection

According to the World Health Organization (WHO), an estimated 296 million people are chronically infected with hepatitis B virus (HBV). Approximately 15-25% of these people develop complications such as advanced chronic liver diseases (ACLDs). Mortality due to HBV-related complications accounted for an estimated 882,000 deaths in 2019. Potent preventive vaccines have already restricted new HBV infections, and several drugs are available to treat chronic HBV infections. However, the positive impacts of these drugs have been recorded in only a few patients with chronic HBV infection. These drugs do not show long-term efficacy and cannot halt the progression to complications. Thus, more effective and evidence-based therapeutic strategies need to be urgently developed for patients with chronic HBV infection. CHB is a pathological entity induced by HBV that progresses due to impaired host immunity. This indicates the inherent limitations of antiviral-drug-based monotherapy for treating patients with chronic HBV infection. Additionally, commercially available antiviral drugs are not available to patients in developing and resource-constrained countries, posing a challenge to achieving the following WHO goal: "Elimination of Hepatitis by 2030". As such, this review aimed to provide insights regarding evidence-based and effective management strategies for chronic HBV infection.

Past, present, and future of long-term treatment for hepatitis B virus

The estimated world prevalence of hepatitis B virus (HBV) infection is 316 million. HBV infection was identified in 1963 and nowadays is a major cause of cirrhosis and hepatocellular carcinoma (HCC) despite universal vaccination programs, and effective antiviral therapy. Long-term administration of nucleos(t)ide analogues (NA) has been the treatment of choice for chronic hepatitis B during the last decades. The NA has shown a good safety profile and high efficacy in controlling viral replication, improving histology, and decreasing the HCC incidence, decompensation, and mortality. However, the low probability of HBV surface antigen seroclearance made necessary an indefinite treatment. The knowledge, in recent years, about the different phases of the viral cycle, and the new insights into the role of the immune system have yielded an increase in new therapeutic approaches. Consequently, several clinical trials evaluating combinations of new drugs with different mechanisms of action are ongoing with promising results. This integrative literature review aims to assess the knowledge and major advances from the past of hepatitis B, the present of NA treatment and withdrawal, and the future perspectives with combined molecules to achieve a functional cure.

New Perspectives on Development of Curative Strategies for Chronic Hepatitis B

A functional cure of chronic hepatitis B defined as sustained hepatitis B surface antigen loss after finite course of therapy is rarely achieved with current therapy but is the goal of novel treatments. Understanding the virological and immunological mechanisms of hepatitis B virus persistence has enabled the identification of novel treatment targets, drug discovery, and the evaluation of novel agents in clinical trials. Lessons were learned from early phase 1 and phase 2 trials regarding the antiviral activity and safety profile of these agents. There is a strong rationale to combine agents to reduce viral replication, reduce viral antigen load, invigorate immune responses, and induce specific adaptive immune responses. Nucleos(t)ide analogs will likely remain an essential backbone of future combinations to control viral replication and prevent resistance to antiviral drugs. In this review, we discuss perspectives on approaches to achieving functional cure, with a review of virological and immunological strategies, highlighting challenges and unresolved questions with the various attempts to achieve cure, as well as exploring alternative endpoints such as partial cure and new noninvasive viral and immunological biomarkers to stratify patients and predict/monitor antiviral response.

Current and novel modalities for management of chronic hepatitis B infection

Over 296 million people are estimated to have chronic hepatitis B viral infection (CHB), and it poses unique challenges for elimination. CHB is the result of hepatitis B virus (HBV)-specific immune tolerance and the presence of covalently closed circular DNA as mini chromosome inside the nucleus and the integrated HBV. Serum hepatitis B core-related antigen is the best surrogate marker for intrahepatic covalently closed circular DNA. Functional HBV “cure” is the durable loss of hepatitis B surface antigen (HBsAg), with or without HBsAg seroconversion and undetectable serum HBV DNA after completing a course of treatment. The currently approved therapies are nucleos(t)ide analogues, interferon-alpha, and pegylated-interferon. With these therapies, functional cure can be achieved in < 10% of CHB patients. Any variation to HBV or the host immune system that disrupts the interaction between them can lead to reactivation of HBV. Novel therapies may allow efficient control of CHB. They include direct acting antivirals and immunomodulators. Reduction of the viral antigen load is a crucial factor for success of immune-based therapies. Immunomodulatory therapy may lead to modulation of the host immune system. It may enhance/restore innate immunity against HBV (as toll-like-receptors and cytosolic retinoic acid inducible gene I agonist). Others may induce adaptive immunity as checkpoint inhibitors, therapeutic HBV vaccines including protein (HBsAg/preS and hepatitis B core antigen), monoclonal or bispecific antibodies and genetically engineered T cells to generate chimeric antigen receptor-T or T-cell receptor-T cells and HBV-specific T cells to restore T cell function to efficiently clear HBV. Combined therapy may successfully overcome immune tolerance and lead to HBV control and cure. Immunotherapeutic approaches carry the risk of overshooting immune responses causing uncontrolled liver damage. The safety of any new curative therapies should be measured in relation to the excellent safety of currently approved nucleos(t)ide analogues. Development of novel antiviral and immune modulatory therapies should be associated with new diagnostic assays used to evaluate the effectiveness or to predict response.