Aiming for cure in HBV and HDV infection

Liver organoids as a primary human model to study HBV-mediated Hepatocellular carcinoma. A review

Hepatitis B Virus (HBV) is the prevailing cause of chronic liver disease, which progresses to Hepatocellular carcinoma (HCC) in 75% of cases. It represents a serious health concern being the fourth leading cause of cancer-related mortality worldwide. Treatments available to date fail to provide a complete cure with high chances of recurrence and related side effects. The lack of reliable, reproducible, and scalable in vitro modeling systems that could recapitulate the viral life cycle and represent virus-host interactions has hindered the development of effective treatments so far. The present review provides insights into the current in-vivo and in-vitro models used for studying HBV and their major limitations. We highlight the use of three-dimensional liver organoids as a novel and suitable platform for modeling HBV infection and HBV-mediated HCC. HBV organoids can be expanded, genetically altered, patient-derived, tested for drug discovery, and biobanked. This review also provides the general guidelines for culturing HBV organoids and highlights their several prospects for HBV drug discovery and screening.

Overview of the development of HBV small molecule inhibitors

Like tuberculosis and Acquired Immune Deficiency Syndrome (AIDS), hepatitis B is a globally recognized major public health threat. Although there are many small-molecule drugs for the treatment of hepatitis B, the approved drugs cannot eradicate the pathogenic culprit covalently closed circular DNA in patients, so the patients need long-term medication to control HBV amplification. Driven by a high unmet medical need, many pharmaceutical companies and research institutions have been engaged in the development of anti-HBV drugs to achieve a functional cure for chronic hepatitis B as soon as possible. This review summarizes the pathogenesis of hepatitis B virus and the research progress in the development of anti-HBV small molecule drugs, and introduces the cccDNA formation and transcription inhibitors and core inhibitors in detail, especially emphasizes the role of chinese herbal medicine in the treatment of chronic hepatitis B. Furthermore, this review proposes three potential strategies for cccDNA eradication in the future. We believe this review will provide meaningful guidance to achieve a functional cure for viral hepatitis B in the future.

Design and Synthesis of (3-Phenylisoxazol-5-yl)methanimine Derivatives as Hepatitis B Virus Inhibitors

Series of (3-phenylisoxazol-5-yl)methanimine derivatives were synthesized, and evaluated for anti-hepatitis B virus (HBV) activity in vitro. Half of them more effectively inhibited HBsAg than 3TC, and more favor to inhibit secretion of HBeAg than to HBsAg. Part of the compounds with significant inhibition on HBeAg were also effectively inhibit replication of HBV DNA. Compound (E)-3-(4-fluorophenyl)-5-((2-phenylhydrazineylidene)methyl)isoxazole inhibited excellently HBeAg with IC₅₀ in 0.65 μM (3TC(Lamivudine) in 189.90 μM), inhibited HBV DNA in 20.52 μM (3TC in 26.23 μM). Structures of compounds were determined by NMR and HRMS methods, and chlorination on phenyl ring of phenylisoxazol-5-yl was confirmed by X-ray diffraction analysis, and the structure-activity relationships (SARs) of the derivatives was discussed. This work provided a new class of potent non-nucleoside anti-HBV agents.

Characteristics of HBV Novel Serum Markers across Distinct Phases in Treatment-Naïve Chronic HBV-Infected Patients

Background and aims. To investigate the clinical implications of serum HBV RNA, serum hepatitis B core-related antigen (HBcrAg), and quantitative anti-HBc in treatment-naïve patients with chronic HBV infection. Methods. A total of 111 patients in total from different disease phases were recruited, including 21 in immune-tolerant (IT) phase, 49 in immune-clearance (IC) phases, 29 in immune-control or low replicative (LR) phase, and 12 in reactivation phases. Serum HBV RNA, anti-HBc, HBcrAg, and intrahepatic covalently closed circular DNA (cccDNA) were quantified and each of these indicator’s correlation with liver inflammation was analyzed. Results. HBeAg-positive individuals had significant higher serum levels of HBV RNA and HBcrAg than those who were HBeAg negative, similar to that of serum HBV DNA. Comparatively, HBV RNA ( $r$  =0.79, $P<0.01$ ) and HBcrAg ( $r$  =0.78, $P<0.01$ ) had almost same higher overall correlation with the cccDNA, as that of HBV DNA ( $r$  =0.81, $P<0.01$ ). Serum anti-HBc level ( $r$  = -0.52, $P<0.05$ ) is negatively correlated with cccDNA level at IT phase rather than the other three phases. When set the cutoff value at 4.00 log10 IU/mL, serum anti-HBc showed potential to indicate liver inflammation, with AUC as 0.79 and the specificities as 78.85% for HBeAg positive, and with AUC as 0.72 and the specificities as 62.16% for HBeAg-negative patients, respectively. Conclusions. In treatment-naïve patients, levels of serological markers HBV RNA and HBcrAg could mirror intrahepatic cccDNA level, but were not superior to HBV DNA level. Serum anti-HBc level had certain potential to be used as a predicting marker for liver inflammation.

Novel chimeric vectors harboring hepatitis B viral promoter and reporter gene demonstrated liver-specific significance

Aim: Expression of EGFP was investigated to ascertain the strength and specificity of CMV, U6 and hepatitis B virus (HBV) core promoters in hepatic and non-hepatic cells. Materials and methods: pSilencer-2.1 plasmid vector is known for siRNA-based inhibition. To achieve target-specific correction of disease-causing genes, pSilencer-GFP was constructed. For liver specific expression of therapeutic genes, endogenous U6 promoter of pSilencer-2.1 was replaced with HBV core promoter and ubiquitously active CMV promoter. Results: Transfection results showed that GFP expression under the control of HBV core promoter was higher in hepatic Hep3B than non-hepatic HEK293T cells. Conclusion: HBV core promoter could lead to specific expression in hepatocytes, which might be used in gene therapy of liver diseases as well as for siRNA-based therapeutic strategies.

CRISPR/Cas9 delivery by NIR-responsive biomimetic nanoparticles for targeted HBV therapy

Background

Currently, there are no curative drugs for hepatitis B virus (HBV). Complete elimination of HBV covalently closed circular DNA (cccDNA) is key to the complete cure of hepatitis B virus infection. The CRISPR/Cas9 system can directly destroy HBV cccDNA. However, a CRISPR/Cas9 delivery system with low immunogenicity and high efficiency has not yet been established. Moreover, effective implementation of precise remote spatiotemporal operations in CRISPR/Cas9 is a major limitation.

Results

In this work, we designed NIR-responsive biomimetic nanoparticles (UCNPs-Cas9@CM), which could effectively deliver Cas9 RNP to achieve effective genome editing for HBV therapy. HBsAg, HBeAg, HBV pgRNA and HBV DNA along with cccDNA in HBV-infected cells were found to be inhibited. These findings were confirmed in HBV-Tg mice, which did not exhibit significant cytotoxicity and minimal off-target DNA damage.

Conclusions

The UCNPs-based biomimetic nanoplatforms achieved the inhibition of HBV replication via CRISPR therapy and it is a potential system for efficient treatment of human HBV diseases.

Graphical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s12951-021-01233-4.

Innate immunity in hepatitis B and D virus infection: consequences for viral persistence, inflammation, and T cell recognition

Chronic infections with human hepatitis viruses continue to be a major health burden worldwide. Despite the availability of an effective prophylactic vaccine against the hepatitis B virus (HBV) and of antiviral agents efficiently suppressing HBV replication, more than 250 million people are currently chronically infected with this hepatotropic DNA virus, and resolution of chronic hepatitis B (CHB) is rarely achieved. Moreover, coinfection with the hepatitis D virus (HDV), a human RNA satellite virus requiring the envelope proteins of HBV for productive viral spreading, substantially aggravates the disease course of CHB. The molecular mechanisms by which these viruses interact with each other and with the intrinsic innate responses of the hepatocytes are not fully understood. While HBV appears to avoid innate immune recognition, HDV elicits a strong enhancement of innate responses. Notwithstanding, such induction does not hamper HDV replication but contributes to liver inflammation and pathogenesis. Intriguingly, HDV appears to influence the ability of T cells to recognize infected hepatocytes by boosting antigen presentation. This review focuses on current knowledge regarding how these viruses can shape and counteract the intrinsic innate responses of the hepatocytes, thus affecting the immune system and pathogenesis. Understanding the distinct strategies of persistence that HBV and HDV have evolved is central for advancing the development of curative therapies.

The Mechanisms of HBV-Induced Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is a common malignancy, and the hepatitis B virus (HBV) is its major pathogenic factor. Over the past decades, it has been confirmed that HBV infection could promote disease progression through a variety of mechanisms, ultimately leading to the malignant transformation of liver cells. Many factors have been identified in the pathogenesis of HBV-associated HCC (HBV-HCC), including HBV gene integration, genomic instability caused by mutation, and activation of cancer-promoting signaling pathways. As research in the progression of HBV-HCC progresses, the role of many new mechanisms, such as epigenetics, exosomes, autophagy, metabolic regulation, and immune suppression, is also being continuously explored. The occurrence of HBV-HCC is a complex process caused by interactions across multiple genes and multiple steps, where the synergistic effects of various cancer-promoting mechanisms accelerate the process of disease evolution from inflammation to tumorigenesis. In this review, we aim to provide a brief overview of the mechanisms involved in the occurrence and development of HBV-HCC, which may contribute to a better understanding of the role of HBV in the occurrence and development of HCC.

Role of hepatitis D virus infection in development of hepatocellular carcinoma among chronic hepatitis B patients treated with nucleotide/nucleoside analogues

Hepatitis D virus (HDV) infection increases the risk of hepatocellular carcinoma (HCC) in the natural course of chronic hepatitis B (CHB) patients. Its role in patients treated with nucleotide/nucleoside analogues (NAs) is unclear. We aimed to study the role of hepatitis D in the development of HCC in CHB patients treated with NAs. Altogether, 1349 CHB patients treated with NAs were tested for anti-HDV antibody and RNA. The incidence and risk factors of HCC development were analyzed. Rates of anti-HDV and HDV RNA positivity were 2.3% and 1.0%, respectively. The annual incidence of HCC was 1.4 per 100 person-years after a follow-up period of over 5409.5 person-years. The strongest factor association with HCC development was liver cirrhosis (hazard ratio [HR]/95% confidence interval [CI] 9.98/5.11-19.46, P < 0.001), followed by HDV RNA positivity (HR/ CI 5.73/1.35-24.29, P = 0.02), age > 50 years old (HR/CI 3.64/2.03-6.54, P < 0.001), male gender (HR/CI 2.69/1.29-5.60, P: 0.01), and body mass index (BMI, HR/CI 1.11/1.03-1.18, P = 0.004). The 5-year cumulative incidence of HCC was 7.3% for patients with HDV RNA negativity compared to that of 22.2% for patients with HDV RNA positivity (P = 0.01). In the subgroup of cirrhotic patients, the factors associated with HCC development were HDV RNA positivity (HR/CI 4.45/1.04-19.09, P = 0.04) and BMI (HR/CI 1.11/1.03-1.19, P = 0.01). HDV viremia played a crucial role in HCC development in CHB patients who underwent NA therapy.

Persistent Control of Hepatitis B Virus and Hepatitis Delta Virus Infection Following REP 2139-Ca and Pegylated Interferon Therapy in Chronic Hepatitis B Virus/Hepatitis Delta Virus Coinfection

The nucleic acid polymer REP 2139 inhibits assembly/secretion of hepatitis B virus (HBV) subviral particles. Previously, REP 2139-Ca and pegylated interferon (pegIFN) in HBV/hepatitis delta virus (HDV) coinfection achieved high rates of HDV RNA and hepatitis B surface antigen (HBsAg) loss/seroconversion in the REP 301 study (NCT02233075). The REP 301-LTF study (NCT02876419) examined safety and efficacy during 3.5 years of follow-up. In the current study, participants completing therapy in the REP 301 study were followed for 3.5 years. Primary outcomes were safety and tolerability, and secondary outcomes were HDV functional cure (HDV RNA target not detected [TND], normal alanine aminotransferase [ALT]), HBV virologic control (HBV DNA ≤2,000 IU/mL, normal ALT), HBV functional cure (HBV DNA TND; HBsAg <0.05 IU/mL, normal ALT), and HBsAg seroconversion. Supplemental analysis included high-sensitivity HBsAg (Abbott ARCHITECT HBsAg NEXT), HBV pregenomic RNA (pgRNA), HBsAg/hepatitis B surface antibody (anti-HBs) immune complexes (HBsAg ICs), and hepatitis B core-related antigen (HBcrAg). Asymptomatic grade 1-2 ALT elevations occurred in 2 participants accompanying viral rebound; no other safety or tolerability issues were observed. During therapy and follow-up, HBsAg reductions to <0.05 IU/mL were also <0.005 IU/mL. HBsAg ICs declined in 7 of 11 participants during REP 2139-Ca monotherapy and in 10 of 11 participants during follow-up. HDV functional cure persisted in 7 of 11 participants; HBV virologic control persisted in 3 and functional cure (with HBsAg seroconversion) persisted in 4 of these participants. Functional cure of HBV was accompanied by HBV pgRNA TND and HBcrAg <lower limit of quantitation. Conclusion: REP 2139-Ca + pegIFN is not associated with long-term safety or tolerability issues. The establishment of HDV functional cure and HBV virologic control/functional cure and HBsAg seroconversion are durable over 3.5 years and may reflect removal of integrated HBV DNA from the liver. Further investigation is warranted in larger studies.

Effectiveness of pegylated interferon monotherapy in the treatment of chronic hepatitis D virus infection: A meta-analysis

Chronic HDV infection often is associated with aggressive form of liver disease, compared to chronic HBV mono-infection. However, chronic HDV treatment is challenging because currently there is no approved regimen for affected patients. While standard interferon with/without nucleos(t)ide analogues were reported to be inferior to pegylated interferon (peginterferon) as HDV treatment according to few randomized clinical trials. This meta-analysis will summarize the results of studies on the effectiveness of peginterferon as HDV treatment regimen. An electronic search was performed using PubMed, Cochrane Library, Research Gate, and Medline databases. Studies involving patients who received peginterferon therapy for at least 48 weeks and followed up for 24 weeks post-therapy were included. All analyses were conducted using Review Manager 5.3 designed for Cochrane Reviews. The primary efficacy endpoint was virological response (VR) or HDV-RNA negativity at the end of the follow-up period, whereas secondary efficacy endpoints were biochemical response (BR) or ALT normalization and HBsAg clearance with seroconversion to anti-HBs at the end of follow-up period. Data were abstracted from 13 relevant studies with a total of 475 patients who were treated with peginterferon alpha-2a or -2b. At the end of 24-week post-treatment the pooled VR was achieved in 29% of patients with 95% CI [24%; 34%], BR was reached in 33% of patients [95% CI 27%; 40%] and HBsAg clearance with seroconversion to anti-HBs was achieved in 1% of patients with 95% CI [-0.02; 0.05]. In conclusion, this study showed that peginterferon has limited effectiveness in HDV treatment, since only one-third of chronic HDV patients achieved viral clearance and normalized ALT levels. Morever, HBsAg clearance with seroconversion to anti-HBs has been rarely observed among chronic HDV patients.

Effect of combination treatment based on interferon and nucleos(t)ide analogues on functional cure of chronic hepatitis B: a systematic review and meta-analysis

BACKGROUND

Priority of antiviral treatment for patients with chronic hepatitis B (CHB) is to increase the probability of functional cure. We aimed to synthesize evidence regarding the efficacy of different combination strategies of antiviral treatment based on interferon (IFN) and nucleos(t)ide analogues (NAs) in adults with CHB.

METHODS

PubMed, Web of Science and Embase databases were searched from inception to May 26, 2019. Three types of combination strategies were studied: initial combination (IFN or NAs monotherapy as control), add-on (I: IFN add-on NAs vs. NAs; II: NAs add-on IFN vs. IFN), switch-to (I: IFN switch-to NAs vs. IFN; II: NAs switch-to IFN vs. NAs).

RESULTS

Compared to NAs monotherapy, initial combination strategy improved the probability of HBeAg loss (RR: 1.62, 95% CI 1.33-1.97) and HBsAg loss (RR: 15.59, 95% CI 3.22-75.49), while compared to IFN monotherapy, no higher rates in the loss of HBsAg or HBeAg for initial combination. Compared to NAs monotherapy, IFN add-on NAs strategy had a higher rate of HBsAg loss (RR: 4.52, 95% CI 1.95-10.47), while compared to IFN monotherapy, NAs add-on IFN had a similar outcome. Compared to NAs monotherapy, NAs switch-to IFN strategy improved HBsAg loss (RR: 12.15, 95% CI 3.99-37.01); while compared to IFN monotherapy, IFN switch-to NAs had no improved rate of HBsAg clearance but higher rates in undetectable HBV DNA, and HBeAg loss.

CONCLUSION

IFN add-on NAs, or NAs switched to IFN could significantly improve the probability of HBsAg loss compared to NAs monotherapy.

Role of hepatitis D virus in persistent alanine aminotransferase abnormality among chronic hepatitis B patients treated with nucleotide/nucleoside analogues

BACKGROUND

The biochemical response is a crucial indicator of prognosis in chronic hepatitis B (CHB) patients treated with nucleotide/nucleoside analogues (NAs). The impact of hepatitis D virus (HDV) infection on alanine aminotransferase normalization is elusive.

METHODS

The longitudinal study recruited 1185 CHB patients who received NAs. These patients were tested for anti-HDV antibody and HDV RNA at the initiation of anti-hepatitis B virus (HBV) therapy and annually for patients who were HDV-seropositive. ALT levels were examined at the first and second year of anti-HBV therapy. ALT abnormality was defined as ALT levels above 40 IU/mL in both male and female, and the risk factors associated with ALT abnormality were analysed.

RESULTS

Rates of seropositivity for anti-HDV and HDV RNA were 2.0% and 0.8% among 1185 NA-treated CHB patients, respectively. The strongest factor associated with ALT abnormality (>40 IU/mL) after first year treatment with NAs was HDV RNA seropositivity at year 1 (odds ratio [OR]/95% confidence interval [CI]: 31.44/3.49-283.56, P = 0.002), followed by liver cirrhosis (2.18/1.51-3.15, P < 0.001), detectable HBV DNA at year 1 (OR/CI: 1.99/1.36-2.92, P < 0.001), diabetes (OR/CI: 1.75/1.10-2.78, P = 0.02), body mass index (BMI) (OR/CI: 1.13/1.09-1.18, P < 0.001) and age (OR/CI: 0.97/0.96-0.98, P < 0.001). Among patients who were seronegative for HBV DNA at year 1, the strongest factor associated with ALT abnormality was HDV RNA seropositivity at year 1 (OR/CI: 30.00/3.28-274.05, P = 0.003), followed by liver cirrhosis (OR/CI: 1.83/1.21-2.75, P = 0.004), BMI (OR/CI: 1.16/1.11-1.21, P < 0.001) and age (OR/CI: 0.97/0.96-0.99, P < 0.001). Similarly, the impact of HDV RNA seropositivity on ALT abnormality was noted in patients without detectable HBV DNA but not in those with hepatitis B viremia at treatment year 2 (OR/CI: 10.16/1.33-77.74, P = 0.03).

CONCLUSION

HDV infection played an important role in ALT abnormality in CHB patients receiving 1-year and 2-year NAs. The impact was particularly noted in patients who had successfully suppressed HBV DNA.

Monitoring of serum HBV RNA, HBcrAg, HBsAg and anti-HBc levels in patients during long-term nucleoside/nucleotide analogue therapy

BACKGROUND

This study was aimed at evaluating the clinical significance of serum HBV RNA, hepatitis B core-related antigen (HBcrAg) and hepatitis B core antibody (anti-HBc) levels in chronic hepatitis B patients with undetectable HBV DNA during nucleoside/nucleotide analogue (NA) treatment.

METHODS

Fifty-seven patients who received long-term NA treatment of median 5.83 (25%, 75% percentiles 4.67, 7.75) years were enrolled, and 285 serum samples at five time points for each patient were quantitatively analysed for the three serum markers together with serum HBV DNA and hepatitis B surface antigen (HBsAg) levels.

RESULTS

The HBV RNA level significantly correlated with HBcrAg (r=0.629; P<0.001) but not HBsAg levels (P=0.1460). Nonetheless, the HBcrAg level significantly correlated with the HBsAg level (r=0.469; P<0.001). Hepatitis B e antigen (HBeAg)-positive samples showed higher HBV RNA, HBcrAg and HBsAg levels than HBeAg-negative samples did (all P<0.05). Nine patients with HBeAg loss manifested a significantly greater decline in HBV RNA and HBcrAg levels (median 1.84 [25%, 75% percentiles 1.02, 2.12] log₁₀ copies/ml, 1.14 [0.62, 2.21] log₁₀ U/ml, respectively) compared with those in seven patients without HBeAg loss (0.74 [0.10, 1.08] log₁₀ copies/ml and 0.41 [0.21, 0.69] log₁₀ U/ml, respectively). Overall, serum HBV RNA, HBcrAg, HBsAg and anti-HBc levels gradually decreased with time during NA treatment. At the end of observation, HBV RNA and HBcrAg reached an undetectable level in 26 and 6 (46% and 11%) patients, respectively.

CONCLUSIONS

Monitoring of HBV RNA and HBcrAg levels is useful for NA-treated patients with undetectable HBV DNA. The attainment of HBV RNA undetectability usually occurs prior to HBcrAg undetectability.

Advances in Targeting the Innate and Adaptive Immune Systems to Cure Chronic Hepatitis B Virus Infection

“Functional cure” is being pursued as the ultimate endpoint of antiviral treatment in chronic hepatitis B (CHB), which is characterized by loss of HBsAg whether or not anti-HBs antibodies are present. “Functional cure” can be achieved in <10% of CHB patients with currently available therapeutic agents. The dysfunction of specific immune responses to hepatitis B virus (HBV) is considered the major cause of persistent HBV infection. Thus, modulating the host immune system to strengthen specific cellular immune reactions might help eliminate HBV. Strategies are needed to restore/enhance innate immunity and induce HBV-specific adaptive immune responses in a coordinated way. Immune and resident cells express pattern recognition receptors like TLRs and RIG I/MDA5, which play important roles in the induction of innate immunity through sensing of pathogen-associated molecular patterns (PAMPs) and bridging to adaptive immunity for pathogen-specific immune control. TLR/RIG I agonists activate innate immune responses and suppress HBV replication in vitro and in vivo, and are being investigated in clinical trials. On the other hand, HBV-specific immune responses could be induced by therapeutic vaccines, including protein (HBsAg/preS and HBcAg), DNA, and viral vector-based vaccines. More than 50 clinical trials have been performed to assess therapeutic vaccines in CHB treatment, some of which display potential effects. Most recently, using genetic editing technology to generate CAR-T or TCR-T, HBV-specific T cells have been produced to efficiently clear HBV. This review summarizes the progress in basic and clinical research investigating immunomodulatory strategies for curing chronic HBV infection, and critically discusses the rather disappointing results of current clinical trials and future strategies.

Diagnostic Value of Detection of Pregenomic RNA in Sera of Hepatitis B Virus-Infected Patients with Different Clinical Outcomes

Pregenomic RNA (pgRNA) is a direct transcription product of hepatitis B virus (HBV) covalently closed circular DNA (cccDNA), and it plays important roles in viral genome amplification and replication. This study was designed to investigate whether serum pgRNA is a strong alternative marker for reflecting HBV cccDNA levels and to analyze the correlation between serum pgRNA, serum HBV DNA, and hepatitis B surface antigen (HBsAg). A total of 400 HBV-infected patients who received nucleos(t)ide analog (NA) therapy with different clinical outcomes were involved in this research. Case groups included asymptomatic hepatitis B virus carrier (ASC), chronic hepatitis B (CHB), liver cirrhosis (LC), and hepatocellular carcinoma (HCC) patients, with 100 patients in each group. The results showed that the levels of HBV pgRNA had significant differences between these 4 groups. Serum pgRNA levels correlated well with serum HBV DNA and HBsAg levels (HBV pgRNA levels versus HBV DNA levels, r = 0.58, P < 0.001; HBV pgRNA levels versus HBsAg levels, r = 0.47, P < 0.001). In addition, we focused on the 108 HBV-infected patients with HBV DNA levels of <500 IU/ml; it was surprising to find that in 17.57% (13/74) of cases, HBV pgRNA could be detected even when the HBV DNA level was below 20 IU/ml. In conclusion, HBV pgRNA levels in serum can be a surrogate marker for intrahepatic HBV cccDNA compared with serum HBV DNA and HBsAg. The detection of serum HBV pgRNA levels may provide a reference for clinical monitoring of cccDNA levels and the selection of appropriate timing for discontinuing antiviral therapy, especially when HBV DNA levels are below the detection limit.

Preferences of Patients with Chronic Hepatitis B - A Discrete Choice Experiment on the Acceptability of Functional Cure

BACKGROUND

Current antiviral therapies for chronic hepatitis B (CHB) rarely achieve functional cure, thus often requiring lifelong therapy. A therapy achieving functional cure in a significant percentage of patients could change the treatment landscape substantially. However, the acceptability of functional cure by patients is unknown, especially if associated with additional treatment burden.

METHODS

A Discrete Choice Experiment (DCE) including patients with CHB was performed between 2018 and 2019 in Germany. Patient inclusion criteria were confirmed CHB; age of at least 18 years; no history of hepatocellular carcinoma; no HIV or HCV/HDV co-infection. The final DCE included the following attributes: route of administration (oral administration by tablets; subcutaneous injection + tablets; intramuscular electroporation + tablets), side effect frequency (0/1/3 days per month), functional cure (1%/30%/50% of patients), frequency of physician visits (monthly, half-yearly) and travel time to treating physician (15/45 min).

RESULTS

The main analysis sample consisted of 108 patients with CHB (mean age: 49.1 years, female: 37.0%, average time since CHB diagnosis: 14.0 years, 52.8% with Hepatitis B surface antigen (HBsAg) chronic HBV infection). High efficacy was found to be the main driver of decisions for/against the presented treatment options (impacted 57% of patients' decisions), followed by therapy regimen (17%), safety profile (12%) and number of physician visits (11%). Latent class analysis revealed first insights into different decision patterns, with age, gender and previous side-effect experience affecting patients' decisions.

CONCLUSION

In comparison to all other treatment-related attributes such as therapy regimen or safety profile, patients with CHB showed a strong preference towards a scenario where a substantial number of patients benefit from sustained disease remission, which mimics functional cure.

Hepatitis B Surface Antigen Seroconversion by Interferon-α2b Combined with Granulocyte-Macrophage Colony-Stimulating Factor and Hepatitis B Vaccine: A Case Report

Hepatitis B surface antigen (HBsAg) loss and/or seroconversion is the ideal endpoint for the treatment of patients with chronic hepatitis B (CHB), whereas the "functional cure" of hepatitis B virus (HBV) infection is hard to obtain with routine therapeutics. Thus, potential new strategies are explored to cure HBV infection. A combination immunomodulatory therapeutic regime was used in a 43-year-old female patient with hepatitis B e antigen (HBeAg)-negative CHB; the regimen included consecutive combination therapy with recombinant human granulocyte-macrophage colony-stimulating factor (rhGM-CSF) plus HBV vaccine, in addition to ongoing normal interferon (IFN)-α2b treatment. The serum levels of alanine aminotransferase (ALT), HBV DNA, HBsAg, and hepatitis B surface antibody (HBsAb) were monitored every 6 months. The ALT level normalized and HBV DNA decreased to a level below the limit of detection within 3 months after the initiation of IFN-α2b therapy. After an entire year of IFN treatment, serum HBsAg decreased to a very low level (3.16 IU/mL), and HBsAb was still negative (0.78 mIU/mL). Then, rhGM-CSF and the HBV vaccine were applied, in addition to continuous IFN therapy. A steady decline in HBsAg was observed, and HBsAg loss with HBsAb seroconversion was achieved 12 months after initiation of the combination treatment with rhGM-CSF and HBV vaccine; the IFN-α2b was discontinued for the later 6 months. A therapeutic regimen with GM-CSF plus HBV vaccine could keep the immune system actively stimulated and trigger an HBV-specific immune response to control, or even clear the virus; this regimen may be helpful in the "cure" of HBV infection when combined with IFN-α.

Poly I:C-based rHBVvac therapeutic vaccine eliminates HBV via generation of HBV-specific CD8+ effector memory T cells

OBJECTIVE

Chronic hepatitis B (CHB) virus infection is a global health problem. Finding a cure for CHB remains a challenging task.

DESIGN

In this study, poly I:C was employed as an adjuvant for HBV therapeutic vaccine (referred to as pHBV-vaccine) and the feasibility and efficiency of pHBV-vaccine in CHB treatment were evaluated in HBV-carrier mice.

RESULTS

We found that pHBV-vaccine decreased HBsAg and HBV DNA efficiently and safely in HBV-carrier mice. Further investigation showed that pHBV-vaccine promoted maturation and antigen presentation ability of dendritic cells in vivo and in vitro. This vaccine successfully restored the exhaustion of antigen-specific CD8⁺ T cells and partly broke the immune tolerance established in HBV-carrier mice. pHBV-vaccine also enhanced the proliferation and polyfunctionality of HBV-specific CD11a^hi CD8α^lo cells. Importantly, we observed that T cell activation molecule KLRG1 was only expressed on HBV specific CD11a^hi CD8α^lo cells. Furthermore, pHBV-vaccine reduced the expression of Eomes and increased the serum IL-12 levels, which in turn promoted the generation of effector memory short-lived effector cells (SLECs) to exhibit a critical role in HBV clearance. SLECs induced by pHBV-vaccine might play a crucial role in protecting from HBV reinfection.

CONCLUSIONS

Findings from this study provide a new basis for the development of therapeutic pHBV-vaccine, which might be a potential candidate for clinical CHB therapy.

Roadmap to functional cure of chronic hepatitis B: An expert consensus

Hepatitis B virus (HBV) infection continues to be a major public health issue worldwide. HBsAg loss is associated with functional remission and improved long-term outcome, and is considered to be a 'functional cure' (also referred to as clinical or immunologic cure) for chronic hepatitis B. This ideal goal of therapy can be achieved using optimized combination regimens with direct-acting antivirals [eg nucleos(t)ide analogues (NAs)] and immunomodulators [eg pegylated interferon alpha2a (Peg-IFN)] in selected patients with chronic hepatitis B. Among different combination therapies currently available, those with NA lead-in followed by Peg-IFN in virally suppressed patients has been demonstrated to be effective. This review provides an updated overview of the evidence supporting the use of combination therapies and summarizes expert consensus on the roadmap to attain functional cure for chronic hepatitis B patients.

New treatment options for delta virus: Is a cure in sight?

Current treatment of chronic hepatitis D viral infection with interferons is poorly tolerated and effective only in a minority of patients. Despite delta virus causing the most severe form of chronic viral hepatitis, no other treatments are available. After many years of inactivity, there is now hope for new treatment approaches for delta virus and some are likely to enter clinical practice in the near future. Four new treatment approaches are currently being evaluated in phase 2 studies. These involve the hepatocyte entry inhibitor myrcludex B, the farnesyl transferase inhibitor lonafarnib, the nucleic acid inhibitor REP 2139 Ca and pegylated interferon lambda. Results obtained so far are promising, and phase 3 studies are expected shortly. This review summarizes the available data on the efficacy and safety of these new drugs.

Treating chronic hepatitis delta: The need for surrogate markers of treatment efficacy

Chronic hepatitis delta represents the most severe form of chronic viral hepatitis. The current treatment of hepatitis delta virus (HDV) infection consists of the use of interferons and is largely unsatisfactory. Several new compounds are currently in development for the treatment of HDV infection. However, surrogate markers that can be used to develop clinical endpoints in HDV infection are not well defined. In the current manuscript, we aimed to evaluate the existing data on treatment of HDV infection and to suggest treatment goals (possible "trial endpoints") that could be used across different clinical trials.

Serum HBV RNA quantification: useful for monitoring natural history of chronic hepatitis B infection

BACKGROUND

As an alternative biomarker of intrahepatic covalently closed circular DNA (cccDNA) transcriptional activity, hepatitis B virus (HBV) RNA may evolve during long-lasting virus-host interactions during chronic hepatitis B viral infection. The distribution pattern of serum HBV RNA levels in the natural course of chronic HBV infection remains unclear. The aim of this study was to evaluate the levels of HBV RNA during the natural course of CHB and the role in distinguishing the natural history of HBV infection.

METHODS

A total of 291 treatment-naïve chronic HBV carriers were enrolled. Based on the clinical, biochemical, serological, and histological data as well as HBV DNA levels, patients were classified into the following four categories: the immune-tolerant phase (IT,n = 35), HBeAg-positive immune-active phase (EPIA,n = 121), inactive chronic hepatitis B(ICH,n = 77) and HBeAg-negative immune reactive hepatitis (ENH,n = 58) [corrected]. The parameters and distribution patterns of serum HBV RNA were evaluated in relation to viral replication status, immune phase, disease category and Child-Pugh class. The relationships between serum HBV RNA and other serum hepatitis B viral markers were also analyzed.

RESULTS

Serum HBV RNA levels were significantly lower in the HBeAg-negative patients compared to those in the HBeAg-positive patients, with the lowest levels seen in inactive carriers. In HBeAg-negative patients, serum HBV RNA levels increased if there is reactivation to active hepatitis and showed obvious superiority for the combination of serum HBV DNA (cutoff>3.39 Log copies/mL) and HBsAg (cutoff>2.74 Log IU/mL) in discriminating between 'HBeAg-negative immune reactive' phase and inactive chronic hepatitis B phases of HBeAg-negative chronic HBV infection. Serum HBV RNA levels were positively correlated with serum HBV DNA and HBsAg levels in all chronic HBV-infected patients. A stratified analysis revealed that a correlation between serum HBV RNA and HBV DNA or HBsAg was present in HBeAg-positive patients; however, in HBeAg-negative patients, serum HBV RNA was positively correlated with HBV DNA only.

CONCLUSION

During the natural course of chronic HBV infection, serum HBV RNA levels vary. Serum HBV RNA can act as a biomarker to predict the natural history of disease in chronic hepatitis B patients. In treatment-naïve HBeAg-negative chronic HBV-infected individuals, serum HBV RNA shows superiority in differentiating the 'HBeAg-negative reactive' phase.

Inhibition of HBV replication by N-hydroxyisoquinolinedione and N-hydroxypyridinedione ribonuclease H inhibitors

We recently developed a screening system capable of identifying and evaluating inhibitors of the Hepatitis B virus (HBV) ribonuclease H (RNaseH), which is the only HBV enzyme not targeted by current anti-HBV therapies. Inhibiting the HBV RNaseH blocks synthesis of the positive-polarity DNA strand, causing early termination of negative-polarity DNA synthesis and accumulation of RNA:DNA heteroduplexes. We previously reported inhibition of HBV replication by N-hydroxyisoquinolinediones (HID) and N-hydroxypyridinediones (HPD) in human hepatoma cells. Here, we report results from our ongoing efforts to develop more potent anti-HBV RNaseH inhibitors in the HID/HPD compound classes. We synthesized and screened additional HIDs and HPDs for preferential suppression of positive-polarity DNA in cells replicating HBV. Three of seven new HIDs inhibited HBV replication, however, the therapeutic indexes (TI = CC50/EC50) did not improve over what we previously reported. All nine of the HPDs inhibited HBV replication with EC50s ranging from 110 nM to 4 μM. Cellular cytotoxicity was evaluated by four assays and CC50s ranged from 15 to >100 μM. The best compounds have a calculated TI of >300, which is a 16-fold improvement over the primary HPD hit. These studies indicate that the HPD compound class holds potential for antiviral discovery.

Hepatitis B virus-specific effector CD8+ T cells are an important determinant of disease prognosis: A meta-analysis

BACKGROUND

Hepatitis B virus (HBV)-specific effector CD8⁺ T cells are critical for viral clearance. To determine the effects of HBV-specific effector CD8⁺ T cells on HBV infection, we performed a meta-analysis of the available literature.

METHODS

Electronic database searches identified appropriately designed studies that detected specific CD8⁺ T cells in HBV-infected patients. Our main endpoints were the course of infection, seroconversion of HBV "e" antigen (HBeAg), the level of HBVDNA, and alanine aminotransferase (ALT) activity. We used a fixed/random model for analysis, according to the results of a heterogeneity test (P value of Q-squared, I²).

RESULTS

Our searches found five eligible articles. Pooled estimation of the reported results showed that levels of specific CD8⁺ T cells were significantly higher in patients with acute hepatitis B than in patients with chronic hepatitis B (odds ratio [OR] = 76.30, 95% confidence interval [CI]: 15.37-378.70). With respect to chronic hepatitis B, patients with <10⁷ copies/ml HBVDNA had higher levels of specific CD8⁺ T cells relative to patients with >10⁷ copies/ml HBVDNA, but the difference had no statistics significance (OR: 3.89, 95% CI: 0.71-21.33). Patients with negative HBeAg or positive anti-HBeAg antibody (anti-HBe) results had significantly higher levels of specific CD8⁺ T cells versus patients with positive HBeAg results (OR: 5.82, 95% CI: 1.41-24.13). There were no significant associations between the levels of specific CD8⁺ T cells and serum ALT activity (OR = 0.86, 95% CI: 0.01-74.15).

CONCLUSION

HBV-specific effector CD8⁺ T cells influence the disease activity in HBV-infected patients in various ways and determine prognosis by eliminating the virus. Therefore, efforts of studying HBV-specific effector CD8⁺ T cells focused vaccine are potentially needed.

Applications of Virus Vector-Mediated Gene Therapy in China

Due to the increased safety and efficiency of virus vectors, virus vector-mediated gene therapy is now widely used for various diseases, including monogenic diseases, complex disorders, and infectious diseases. Recent gene therapy trials have shown significant therapeutic benefits, and Chinese researchers have contributed significantly to this progress. This review highlights disease applications and strategies for virus vector-mediated gene therapy in preclinical studies and clinical trials in China.

Low hepatitis B surface antigen and HBV DNA levels predict response to the addition of pegylated interferon to entecavir in hepatitis B e antigen positive chronic hepatitis B

BACKGROUND

Various treatment combinations of peginterferon (PEG-IFN) and nucleos(t)ide analogues have been evaluated for chronic hepatitis B (CHB), but the optimal regimen remains unclear.

AIMS

To study whether PEG-IFN add-on increases response compared to entecavir (ETV) monotherapy, and whether the duration of ETV pretreatment influences response.

METHODS

Response was evaluated in HBeAg positive patients previously treated in two randomized controlled trials. Patients received ETV pretreatment for at least 24 weeks and were then allocated to 24-48 weeks of ETV+PEG-IFN add-on, or continued ETV monotherapy. Response was defined as HBeAg loss combined with HBV DNA <200 IU/mL 48 weeks after discontinuing PEG-IFN.

RESULTS

Of 234 patients, 118 were assigned PEG-IFN add-on and 116 continued ETV monotherapy. Response was observed in 38/118 (33%) patients treated with add-on therapy and in 23/116 (20%) with monotherapy (P = 0.03). The highest response to add-on therapy compared to monotherapy was observed in PEG-IFN naive patients with HBsAg levels below 4000 IU/mL and HBV DNA levels below 50 IU/mL at randomization (70% vs 34%; P = 0.01). Above the cut-off levels, response was low and not significantly different between treatment groups. Duration of ETV pretreatment was associated with HBsAg and HBV DNA levels (both P < 0.005), but not with response (P = 0.82).

CONCLUSIONS

PEG-IFN add-on to ETV therapy was associated with higher response compared to ETV monotherapy in patients with HBeAg positive CHB. Response doubled in PEG-IFN naive patients with HBsAg below 4000 IU/mL and HBV DNA below 50 IU/mL, and therefore identifies them as the best candidates for PEG-IFN add-on (Identifiers: NCT00877760, NCT01532843).

Antiviral Therapy for AECHB and Severe Hepatitis B (Liver Failure)

This chapter describes the principles of antiviral therapy, treatment strategies, medications and recommendations for AECHB, HBV-ACLF, HBV-related liver cirrhosis, HBV-related HCC, and liver transplantation.

Severe exacerbation of chronic hepatitis B is closely related to continuous HBV replication. Therefore, inhibiting HBV replication to reduce viral load may block disease progression and improve the quality of life of these patients. ETV or TDF has been recommend first-line drug for the treatment of AECHB.

A hyperactive immune response due to continuous HBV replication is the main mechanism for development of severe hepatitis B. In addition to comprehensive treatment, early administration of potent nucleoside analogs can rapidly reduce HBV DNA concentration, relieve immune injury induced by HBV, and reduce liver inflammation and patient mortality. Antiviral agents have become important in the treatment of severe exacerbation of chronic hepatitis B.

Long-term antiviral treatment with nucleoside analogs can delay or reverse the progress of liver cirrhosis. Virologic response, viral resistance and adverse drug reactions should be closely monitored during treatment. The treatment should be optimized for maximum effect based on each patient’s responses.

Effective antiviral therapy can suppress HBV replication and reduce the incidence of HBV-related HCC. Patients with HBV-related HCC should receive individualized and optimal multidisciplinary comprehensive treatment. Anti-viral drugs with high efficacy, low resistance and low adverse drug reactions should be selected to improve the patient’s quality of life and prolong survival time.

Methods to prevent HBV reinfection after liver transplantation include passive immunization (HBIG), antiviral treatment (nucleoside analogs) and active immunization (hepatitis B vaccine).

Clinical trials involving sequential combination therapy with NUC and Peg-IFN have shown statistically significant decline in HBsAg levels on treatment and high rates of sustained post-treatment serologic response. Combination therapy with novel DAA and immunotherapeutic approach may hold promise to overcome both cccDNA persistence and immune escape, representing a critical step towards HBV cure.

Hepatitis delta virus persists during liver regeneration and is amplified through cell division both in vitro and in vivo

OBJECTIVE

Hepatitis delta virus (HDV) was shown to persist for weeks in the absence of HBV and for months after liver transplantation, demonstrating the ability of HDV to persevere in quiescent hepatocytes. The aim of the study was to evaluate the impact of cell proliferation on HDV persistence in vitro and in vivo.

DESIGN

Genetically labelled human sodium taurocholate cotransporting polypeptide (hNTCP)-transduced human hepatoma(HepG2) cells were infected with HBV/HDV and passaged every 7 days for 100 days in the presence of the entry inhibitor Myrcludex-B. In vivo, cell proliferation was triggered by transplanting primary human hepatocytes (PHHs) isolated from HBV/HDV-infected humanised mice into naïve recipients. Virological parameters were measured by quantitative real time polymerase chain reaction (qRT-PCR). Hepatitis delta antigen (HDAg), hepatitis B core antigen (HBcAg) and cell proliferation were determined by immunofluorescence.

RESULTS

Despite 15 in vitro cell passages and block of viral spreading by Myrcludex-B, clonal cell expansion permitted amplification of HDV infection. In vivo, expansion of PHHs isolated from HBV/HDV-infected humanised mice was confirmed 3 days, 2, 4 and 8 weeks after transplantation. While HBV markers rapidly dropped in proliferating PHHs, HDAg-positive hepatocytes were observed among dividing cells at all time points. Notably, HDAg-positive cells appeared in clusters, indicating that HDV was transmitted to daughter cells during liver regeneration even in the absence of de novo infection.

CONCLUSION

This study demonstrates that HDV persists during liver regeneration by transmitting HDV RNA to dividing cells even in the absence of HBV coinfection. The strong persistence capacities of HDV may also explain why HDV clearance is difficult to achieve in HBV/HDV chronically infected patients.

Upregulation of HBV transcription by sodium taurocholate cotransporting polypeptide at the postentry step is inhibited by the entry inhibitor Myrcludex B

Sodium taurocholate cotransporting polypeptide (NTCP) is a functional receptor for hepatitis B virus (HBV) entry. However, little is known regarding whether NTCP is involved in regulating the postentry steps of the HBV life cycle. Here, we found that NTCP expression upregulated HBV transcription at the postentry step and that the NTCP-targeting entry inhibitor Myrcludex B (MyrB) effectively suppressed HBV transcription both in an HBV in vitro infection system and in mice hydrodynamically injected with an HBV expression plasmid. Mechanistically, NTCP upregulated HBV transcription via farnesoid X receptor α (FxRα)-mediated activation of the HBV EN2/core promoter at the postentry step in a manner that was dependent on the bile acid (BA)-transport function of NTCP, which was blocked by MyrB. Our findings uncover a novel role for NTCP in the HBV life cycle and provide a reference for the use of novel NTCP-targeting entry inhibitors to suppress HBV infection and replication.

Hepatitis D virus replication is sensed by MDA5 and induces IFN-β/λ responses in hepatocytes

BACKGROUND & AIMS

Hepatitis B virus (HBV) and D virus (HDV) co-infections cause the most severe form of viral hepatitis. HDV induces an innate immune response, but it is unknown how the host cell senses HDV and if this defense affects HDV replication. We aim to characterize interferon (IFN) activation by HDV, identify the responsible sensor and evaluate the effect of IFN on HDV replication.

METHODS

HDV and HBV susceptible hepatoma cell lines and primary human hepatocytes (PHH) were used for infection studies. Viral markers and cellular gene expression were analyzed at different time points after infection. Pattern recognition receptors (PRRs) required for HDV-mediated IFN activation and the impact on HDV replication were studied using stable knock-down or overexpression of the PRRs.

RESULTS

Microarray analysis revealed that HDV but not HBV infection activated a broad range of interferon stimulated genes (ISGs) in HepG2^NTCP cells. HDV strongly activated IFN-β and IFN-λ in cell lines and PHH. HDV induced IFN levels remained unaltered upon RIG-I (DDX58) or TLR3 knock-down, but were almost completely abolished upon MDA5 (IFIH1) depletion. Conversely, overexpression of MDA5 but not RIG-I and TLR3 in HuH7.5^NTCP cells partially restored ISG induction. During long-term infection, IFN levels gradually diminished in both HepG2^NTCP and HepaRG^NTCP cell lines. MDA5 depletion had little effect on HDV replication despite dampening HDV-induced IFN response. Moreover, treatment with type I or type III IFNs did not abolish HDV replication.

CONCLUSION

Active replication of HDV induces an IFN-β/λ response, which is predominantly mediated by MDA5. This IFN response and exogenous IFN treatment have only a moderate effect on HDV replication in vitro indicating the adaption of HDV replication to an IFN-activated state.

LAY SUMMARY

In contrast to hepatitis B virus, infection with hepatitis D virus induces a strong IFN-β/λ response in innate immune competent cell lines. MDA5 is the key sensor for the recognition of hepatitis D virus replicative intermediates. An IFN-activated state did not prevent hepatitis D virus replication in vitro, indicating that hepatitis D virus is resistant to self-induced innate immune responses and therapeutic IFN treatment.

Drugs in Development for Hepatitis B

With high morbidity and mortality worldwide, there is great interest in effective therapies for chronic hepatitis B (CHB) virus. There are currently several dozen investigational agents being developed for treatment of CHB. They can be broadly divided into two categories: (1) direct-acting antivirals (DAAs) that interfere with a specific step in viral replication; and (2) host-targeting agents that inhibit viral replication by modifying host cell function, with the latter group further divided into the subcategories of immune modulators and agents that target other host functions. Included among the DAAs being developed are RNA interference therapies, covalently closed circular DNA (cccDNA) formation and transcription inhibitors, core/capsid inhibitors, reverse transcriptase inhibitors, hepatitis B surface antigen (HBsAg) release inhibitors, antisense oligonucleotides, and helioxanthin analogues. Included among the host-targeting agents are entry inhibitors, cyclophilin inhibitors, and multiple immunomodulatory agents, including Toll-like receptor agonists, immune checkpoint inhibitors, therapeutic vaccines, engineered T cells, and several cytokine agents, including recombinant human interleukin-7 (CYT107) and SB 9200, a novel therapy that is believed to both have direct antiviral properties and to induce endogenous interferon. In this review we discuss agents that are currently in the clinical stage of development for CHB treatment as well as strategies and agents currently at the evaluation and discovery phase and potential future targets. Effective approaches to CHB may require suppression of viral replication combined with one or more host-targeting agents. Some of the recent research advances have led to the hope that with such a combined approach we may have a functional cure for CHB in the not distant future.

TLR7 Agonist Increases Responses of Hepatitis B Virus-Specific T Cells and Natural Killer Cells in Patients With Chronic Hepatitis B Treated With Nucleos(T)Ide Analogues

BACKGROUND & AIMS

The oral Toll-like receptor (TLR) 7 agonist GS-9620 has antiviral effects in woodchuck and chimpanzee models of chronic hepatitis B virus (HBV) infection. We investigated, in a clinical trial, the capacity of this agent to reconstitute protective immunity in patients with chronic HBV infection.

METHODS

We performed a prospective study of 28 patients with suppression of HBV infection by nucleos(t)ide analogue therapy and who tested negative for hepatitis B e antigen at 4 medical centers in Italy. Patients were randomly assigned (1:3:3:3) to groups given placebo or different doses of GS-9620 (1, 2, and 4 mg, weekly for 12 weeks). We added data from 8 patients receiving nucleos(t)ide analogue therapy to the placebo group (controls); 13 treatment-naïve patients with chronic HBV infection and 15 subjects who spontaneously recovered from an acute HBV infection served as additional controls. Peripheral blood mononuclear cells were collected at baseline, during administration of GS-9620 or placebo, and 12 weeks afterward. Phenotype and function of natural killer (NK) and HBV-specific T cells were analyzed by flow cytometry. T cells were expanded by incubation with peptides from the entire HBV proteome and studied after overnight or 10 days culture. NK-cell inhibition of T-cell responses was measured by assessing cytokine production by T cells stimulated with peptides in the presence or absence of NK cells.

RESULTS

T cells collected at baseline before addition of GS-9620, when patients were receiving only nucleos(t)ide therapy, had greater responses to HBV than T cells from treatment-naïve patients, based on cytokine production in response to HBV peptides. However, during or after administration of GS-9620, T cells produced higher levels of cytokines compared to baseline. NK-cell activation and function increased after patients were given GS-9620, but the ability of NK cells to suppress T-cell responses was lower during GS-9620 therapy than before. Changes in T-cell or NK-cell function did not correlate with levels of hepatitis B surface antigen. Serum levels of hepatitis B surface antigen did not decrease significantly compared to baseline in patients given any dose of GS-9620.

CONCLUSIONS

Twelve weeks administration of GS-9620 had no significant effect on serum hepatitis B surface antigen levels, but did appear to increase T-cell and NK-cell responses and reduce the ability of NK to suppress T cells. GS-9620 might therefore be included in therapies to increase the immune response to HBV.

Interferon down-regulation of miR-1225-3p as an antiviral mechanism through modulating Grb2-associated binding protein 3 expression

Induction of interferons (IFNs) is a central event of antiviral innate immunity. As crucial posttranscriptional regulators, microRNAs (miRNAs) are important for IFN-mediated host defense. Although screening has indicated a substantial number of miRNAs to be differentially expressed after IFN stimulation, the detailed mechanisms of these miRNAs in the antiviral response are underexplored and of great significance. Here, we show that hsa-miR-1225-3p is specifically down-regulated by type I IFN through the IFN/JAK/STAT signaling pathway. Silencing endogenous miR-1225-3p inhibited infection by multiple IFN-susceptible viruses, including hepatitis C virus, Sendai virus, and Newcastle disease virus. In contrast, overexpression of miR-1225-3p impaired the antiviral effect of IFNs and facilitated viral infection. Regarding the mechanism, we identified growth factor receptor-bound protein 2-associated binding protein 3 (GAB3) as a direct target of miR-1225-3p. GAB3 expression was up-regulated by IFN, and overexpression of GAB3 demonstrated potent antiviral effects through enhancing IFN response and virus-triggered innate immune activation. Taken together, our findings reveal the biological function of miR-1225-3p for the first time and propose a novel antiviral regulation pathway in which miRNA and GAB3 participate. This study contributes to the understanding of host miRNA participation in antiviral processes of IFN.

Efficacy of NVR 3-778, Alone and In Combination With Pegylated Interferon, vs Entecavir In uPA/SCID Mice With Humanized Livers and HBV Infection

BACKGROUND & AIMS

NVR3-778 is a capsid assembly modulator in clinical development. We determined the in vivo antiviral efficacy and effects on innate and endoplasmic reticulum (ER) stress responses of NVR3-778 alone or in combination with pegylated interferon alpha (peg-IFN) and compared with entecavir.

METHODS

We performed 2 studies, with a total of 61 uPA/SCID mice with humanized livers. Mice were infected with a hepatitis B virus (HBV) genotype C preparation; we waited 8 weeks for persistent infection of the human hepatocytes in livers of mice. Mice were then randomly assigned to groups (5 or 6 per group) given vehicle (control), NVR3-778, entecavir, peg-IFN, NVR3-778 + entecavir, or NVR3-778 + peg-IFN for 6 weeks. We measured levels of HB surface antigen, HB e antigen, HBV RNA, alanine aminotransferase, and human serum albumin at different time points. Livers were collected and analyzed by immunohistochemistry; levels of HBV DNA, covalently closed circular DNA, and HBV RNA, along with markers of ER stress and IFN response, were quantified.

RESULTS

Mice given NVR3-778 or entecavir alone for 6 weeks had reduced serum levels of HBV DNA compared with controls or mice given peg-IFN. The largest reduction was observed in mice given NVR3-778 + peg-IFN; in all mice in this group, the serum level of HBV DNA was below the limit of quantification. NVR3-778 and peg-IFN, but not entecavir, also reduced serum level of HBV RNA. The largest effect was obtained in the NVR3-778 + peg-IFN group, in which serum level of HBV RNA was below the limit of quantification. Levels of HB surface antigen and HB e antigen were reduced significantly in only the groups that received peg-IFN. Levels of covalently closed circular DNA did not differ significantly among groups. NVR3-778 was not associated with any significant changes in level of alanine aminotransferase, the ER stress response, or IFN-stimulated genes.

CONCLUSIONS

NVR3-778 has high antiviral activity in mice with humanized livers and stable HBV infection, reducing levels of serum HBV DNA and HBV RNA. Entecavir reduced levels of serum HBV DNA, but had no effect on HBV RNA. The combination of NVR3-778 and peg-IFN prevented viral replication and HBV RNA particle production to a greater extent than each compound alone or entecavir.

Upcoming pharmacological developments in chronic hepatitis B: can we glimpse a cure on the horizon?

Background

Hepatitis B virus (HBV) chronic infection affects up to 240 million people in the world and it is a common cause of cirrhosis and hepatocellular carcinoma (HCC). HBV covalently closed circular DNA (cccDNA) plays an essential role in HBV persistence and replication. Current pharmacological treatment with nucleos(t)ide analogues (NA) may suppress HBV replication with little or no impact on cccDNA, hence lifelong treatment is required in the vast majority of patients. Clearances of intrahepatic cccDNA and/or HBsAg are critical endpoints for future antiviral therapy in chronic HBV. Recent promising developments targeting different molecular HBV life cycle steps are being pre-clinically tested or have moved forward in early clinical trials.

Methods

We review the current state of the art of these pharmacological developments, mainly focusing on efficacy and safety results, which are expected to lay the ground for future HBV eradication. An inclusive literature search on new treatments of HBV using the following electronic databases: Pubmed/MEDLINE, AMED, CINAHL and the Cochrane Central Register of Controlled Trials. Full-text manuscripts and abstracts published over the last 12 years, from 2005 to March 2011 were reviewed for relevance and reference lists were crosschecked for additional applicable studies regarding new HBV antiviral treatment.

Results

HBV entry inhibitors, HBV core inhibitors, HBV cccDNA transcripts RNA interference, HBV cell apoptosis inducers, HBV RNA, viral proteins and DNA knock down agents, HBV release inhibitors, anti-sense nucleosides, exogenous interferon stimulation, interferon response stimulation and HBV therapeutic vaccines were reviewed.

Conclusion

This review will provide readers with an updated vision of current and foreseeable therapeutic developments in chronic hepatitis B.

Potential use of serum HBV RNA in antiviral therapy for chronic hepatitis B in the era of nucleos(t)ide analogs

Although the efficacy of nucleos(t)ide analogue (NA) has been confirmed for treatment of chronic hepatitis B, long-term therapy has been recommended due to the high frequency of off-therapy viral DNA rebound and disease relapse. In this review, the RNA virion-like particles of hepatitis B virus (HBV) are integrated into the life cycle of HBV replication, and the potential significance of serum HBV RNA is systematically described. The production of HBV RNA virion-like particles should not be blocked by NA; in this regard, serum HBV RNA is found to be a suitable surrogate marker for the activity of intrahepatic covalently closed circular DNA (cccDNA), particularly among patients receiving NA therapy. Therefore, the concept of virological response is redefined as persistent loss of serum HBV DNA and HBV RNA. In contrast to hepatitis B surface antigen (HBsAg) that can originate from either the cccDNA or the integrated HBV DNA fragment, serum HBV RNA, with pregenomic RNA origination, can only be transcribed from cccDNA. Therefore, the loss of serum HBV RNA would likely be a promising predicator for safe drug discontinuation. The clinical status of consistent loss of serum HBV RNA accompanied with low serum HBsAg levels might be implicated as a "para-functional cure," a status nearly close to the functional cure of chronic hepatitis B, to distinguish the "functional cure" characterized as serum HBsAg loss with or without anti-HBs seroconversion.

Switching to PegIFNα-2b leads to HBsAg loss in patients with low HBsAg levels and HBV DNA suppressed by NAs

Patients with low hepatitis B surface antigen (HBsAg) levels and hepatitis B virus (HBV) DNA suppression by nucleos(t)ide analogues (NAs) achieve high rate of HBsAg loss through switching to PegIFNα in pre-registration study. The aim of this study was to achieve higher rate of HBsAg loss through extended PegIFN treatment. 98 patients with HBsAg < 2,000 IU/ml and HBV DNA < 20 IU/ml were randomized to receive PegIFNα-2b or continuing NA therapy for 60 weeks. At the end of treatment (EOT) and end of follow-up (EOF), only patients who switched to PegIFNα-2b achieved HBsAg loss (32.6%) and HBsAg seroconversion (27.9% and 25.6%). Patients who switched to PegIFNα-2b also achieved higher HBeAg seroconversion rates (65.1%) and HBeAg loss (81.4% and 90.7%) than those who continued NAs treatment. On-treatment HBsAg declines predicted the responses at EOT, and HBsAg declines at post-baseline times predicted the responses at EOF. The rates of responses were not increased through extended PegIFNα treatment. For patients with low HBsAg and HBV suppression with NAs, switching to PegIFNα-2b significantly increased the rates of HBsAg loss and HBsAg seroconversion. HBsAg decline can predict the response of switching to PegIFNα-2b following from NAs.

Substitutions of rtL228 and/or L229 are involved in the regulation of replication and HBsAg secretion in hepatitis B virus, and do not affect susceptibility to nucleos(t)ide analogs

Nucleos(t)ide analogs (NAs) are widely used in the treatment of hepatitis B virus (HBV) and human immunodeficiency virus (HIV). The mutation L210W of HIV‑1 reverse transcriptase (RT) is one of the six principal mutations which confer in vivo resistance to zidovudine. Due to the similar 3D‑structure and high conservation between HIV‑RT and HBV‑RT, the present study aimed to clarify whether corresponding mutations in HBV may decrease its susceptibility to relevant NAs. Mutations including rtL228C/W, rtL229W and rtL228W/L229W were introduced into a HBV replication competent plasmid by fusion polymerase chain reaction. Replication capacity, HBs/e antigen (Ag) levels and susceptibility to NAs were subsequently analyzed in vitro. Single or combination mutations of rtL228 and rtL229 impaired HBV replication. Decreased HBsAg secretion in the supernatant and production in the cell lysate wasobserved with single rtL229W or in combination with rtL228W, while there was no significant difference between wild‑type and mutant HBV with regard to the level of HBeAg in the supernatant and susceptibility to commonly‑used NAs. Substitution mutations of rtL228 and/or L229 in HBV did not alter the susceptibility of the virus to NAs, although replication and HBsAg secretion were affected.

Host-directed therapies for bacterial and viral infections

Host-directed therapy (HDT) is a novel approach in the field of anti-infectives for overcoming antimicrobial resistance.

HDT aims to interfere with host cell factors that are required by a pathogen for replication or persistence, to enhance protective immune responses against a pathogen, to reduce exacerbated inflammation and to balance immune reactivity at sites of pathology.

HDTs encompassing the 'shock and kill' strategy or the delivery of recombinant interferons are possible approaches to treat HIV infections. HDTs that suppress the cytokine storm that is induced by some acute viral infections represent a promising concept.

In tuberculosis, HDT aims to enhance the antimicrobial activities of phagocytes through phagosomal maturation, autophagy and antimicrobial peptides. HDTs also curtail inflammation through interference with soluble (such as eicosanoids or cytokines) or cellular (co-stimulatory molecules) factors and modulate granulomas to allow the access of antimicrobials or to restrict tissue damage.

Numerous parallels between the immunological abnormalities that occur in sepsis and cancer indicate that the HDTs that are effective in oncology may also hold promise in sepsis.

Advances in immune phenotyping, genetic screening and biosignatures will help to guide drug therapy to optimize the host response. Combinations of canonical pathogen-directed drugs and novel HDTs will become indispensable in treating emerging infections and diseases caused by drug-resistant pathogens.

Host-directed therapy (HDT) aims to interfere with host cell factors that are required by a pathogen for replication or persistence. In this Review, Kaufmannet al. describe recent progress in the development of HDTs for the treatment of viral and bacterial infections and the challenges in bringing these approaches to the clinic.

Despite the recent increase in the development of antivirals and antibiotics, antimicrobial resistance and the lack of broad-spectrum virus-targeting drugs are still important issues and additional alternative approaches to treat infectious diseases are urgently needed. Host-directed therapy (HDT) is an emerging approach in the field of anti-infectives. The strategy behind HDT is to interfere with host cell factors that are required by a pathogen for replication or persistence, to enhance protective immune responses against a pathogen, to reduce exacerbated inflammation and to balance immune reactivity at sites of pathology. Although HDTs encompassing interferons are well established for the treatment of chronic viral hepatitis, novel strategies aimed at the functional cure of persistent viral infections and the development of broad-spectrum antivirals against emerging viruses seem to be crucial. In chronic bacterial infections, such as tuberculosis, HDT strategies aim to enhance the antimicrobial activities of phagocytes and to curtail inflammation through interference with soluble factors (such as eicosanoids and cytokines) or cellular factors (such as co-stimulatory molecules). This Review describes current progress in the development of HDTs for viral and bacterial infections, including sepsis, and the challenges in bringing these new approaches to the clinic.

Both interferon alpha and lambda can reduce all intrahepatic HDV infection markers in HBV/HDV infected humanized mice

Co-infection with hepatitis B (HBV) and D virus (HDV) is associated with the most severe course of liver disease. Interferon represents the only treatment currently approved. However, knowledge about the impact of interferons on HDV in human hepatocytes is scant. Aim was to assess the effect of pegylated interferon alpha (peg-IFNα) and lambda (peg-IFNλ), compared to the HBV-polymerase inhibitor entecavir (ETV) on all HDV infection markers using human liver chimeric mice and novel HDV strand-specific qRT-PCR and RNA in situ hybridization assays, which enable intrahepatic detection of HDV RNA species. Peg-IFNα and peg-IFNλ reduced HDV viremia (1.4 log and 1.2 log, respectively) and serum HBsAg levels (0.9-log and 0.4-log, respectively). Intrahepatic quantification of genomic and antigenomic HDV RNAs revealed a median ratio of 22:1 in untreated mice, resembling levels determined in HBV/HDV infected patients. Both IFNs greatly reduced intrahepatic levels of genomic and antigenomic HDV RNA, increasing the amounts of HDAg- and antigenomic RNA-negative hepatocytes. ETV-mediated suppression of HBV replication (2.1-log) did not significantly affect HBsAg levels, HDV productivity and/or release. In humanized mice lacking adaptive immunity, IFNs but not ETV suppressed HDV. Viremia decrease reflected the intrahepatic reduction of all HDV markers, including the antigenomic template, suggesting that intracellular HDV clearance is achievable.

Detection of HBV Covalently Closed Circular DNA

Chronic hepatitis B virus (HBV) infection affects approximately 240 million people worldwide and remains a serious public health concern because its complete cure is impossible with current treatments. Covalently closed circular DNA (cccDNA) in the nucleus of infected cells cannot be eliminated by present therapeutics and may result in persistence and relapse. Drug development targeting cccDNA formation and maintenance is hindered by the lack of efficient cccDNA models and reliable cccDNA detection methods. Southern blotting is regarded as the gold standard for quantitative cccDNA detection, but it is complicated and not suitable for high-throughput drug screening, so more sensitive and simple methods, including polymerase chain reaction (PCR)-based methods, Invader assays, in situ hybridization and surrogates, have been developed for cccDNA detection. However, most methods are not reliable enough, and there are no unified standards for these approaches. This review will summarize available methods for cccDNA detection. It is hoped that more robust methods for cccDNA monitoring will be developed and that standard operation procedures for routine cccDNA detection in scientific research and clinical monitoring will be established.

Animal models of HBV infection

The mechanisms determining hepatitis B virus (HBV) persistence and pathogenesis are not fully elucidated, but appear to be multi-factorial. Current medication to repress viral replication is available; however, the unique replication strategies employed by HBV enable the virus to persist within the infected hepatocytes. Consequently, cure is rarely achieved. Progresses in HBV research and preclinical testing of antiviral agents have been limited by the narrow species- and tissue-tropism of the virus, the paucity of infection models available and the restrictions imposed by the use of chimpanzees, the only animals fully susceptible to HBV infection. Mice are not HBV permissive but major efforts have focused on the development of mouse models of HBV replication and infection, such as the generation of humanized mice. By presenting the different animal models available, this review will highlight the most important and clinically relevant findings that have been retrieved from the respective systems.

Antibody-mediated immunotherapy against chronic hepatitis B virus infection

The currently available drugs to treat hepatitis B virus (HBV) infection include interferons and nucleos(t)ide analogs, which can only induce disease remission and are inefficient for the functional cure of patients with chronic HBV infection (CHB). Since high titers of circulating hepatitis B surface antigen (HBsAg) may be essential to exhaust the host anti-HBV immune response and they cannot be significantly reduced by current drugs, new antiviral strategies aiming to suppress serum hepatitis B surface antigen (HBsAg) could help restore virus-specific immune responses and promote the eradication of the virus. As an alternative strategy, immunotherapy with HBsAg-specific antibodies has shown some direct HBsAg suppression effects in several preclinical and clinical trial studies. However, most described previously HBsAg-specific antibodies only had very short-term HBsAg suppression effects in CHB patients and animal models mimicking persistent HBV infection. More-potent antibodies with long-lasting HBsAg clearance effects are required for the development of the clinical application of antibody-mediated immunotherapy for CHB treatment. Our recent study described a novel mAb E6F6 that targets a unique epitope on HBsAg. It could durably suppress the levels of HBsAg and HBV DNA via Fcγ receptor-dependent phagocytosis in vivo. In this commentary, we summarize the current research progress, including the therapeutic roles and mechanisms of antibody-mediated HBV clearance as well as the epitope-determined therapeutic potency of the antibody. These insights may provide some clues and guidance to facilitate the development of therapeutic antibodies against persistent viral infection.

Preclinical and Clinical Advances of GalNAc-Decorated Nucleic Acid Therapeutics

A main challenge in realizing the full potential of nucleic acid therapeutics is efficient delivery of them into targeted tissues and cells. N-acetylgalactosamine (GalNAc) is a well-defined liver-targeted moiety benefiting from its high affinity with asialoglycoprotein receptor (ASGPR). By conjugating it directly to the oligonucleotides or decorating it to a certain delivery system as a targeting moiety, GalNAc has achieved compelling successes in the development of nucleic acid therapeutics in recent years. Several oligonucleotide modalities are undergoing pivotal clinical studies, followed by a blooming pipeline in the preclinical stage. This review covers the progress of GalNAc-decorated oligonucleotide drugs, including siRNAs, anti-miRs, and ASOs, which provides a panorama for this field.