Chronic hepatitis B: New potential therapeutic drugs target

Overrange dilution for improvement of hepatitis B core related antigen as a biomarker: protocol validation and examples for application

BACKGROUND

Hepatitis B core related antigen (HBcrAg) measurement predicts treatment outcomes and reflects intrahepatic HBV replication. The commercially available automated assay for HBcrAg has a linear range of 3.0 - 7.0 logU/mL, with higher levels requiring dilution. However, using different diluents across studies may impact comparability and cross-reactivity, which has not been thoroughly investigated. This study aims to validate a dilution method for specimens above the upper limit of quantification (7.0 logU/mL) to improve comparability.

METHODS

The dilution procedure was two-site tested with three matrices for practicability, accuracy and repeatability using samples from HBV-infected patients with high HBcrAg levels. Samples were tested undiluted or diluted when overrange using Fujirebio's specific dilution reagent (SD1) with reflex testing of pre-treated samples, or manually diluted with fetal calf serum (FCS) or human serum (HS) of samples before restarting pre-treatment. Overrange dilution was further validated in three patient cohorts: untreated HBV-infected patients (n = 157) and patients treated with nucleos(t)ide analogues (NA, n = 19), or pegylated interferon-2alpha (PEG-IFN, n = 80) RESULTS: On-board dilution with SD1 showed higher background signals compared to HS or FCS. The dilution process was reproducible across sites, but SD1 underestimated HBcrAg levels. Dilution with FCS showed an early decrease in HBcrAg levels in patients with HBeAg SC during NA treatment (after 3 months, p = 0.022) and PEG-IFN treatment, whereas no change in HBcrAg levels was found without overrange dilution.

CONCLUSION

Validation showed high background and underestimating levels of HBcrAg with SD1, while FCS-based overrange dilution resulted in significant early HBcrAg decreases and better correlation with treatment response.

A hepatitis B virus-free cccDNA-producing stable cell for antiviral screening

The covalently closed circular DNA (cccDNA) of the Hepatitis B virus (HBV) serves as a template for producing progeny viruses in virally infected hepatocytes. Promising cccDNA-targeting antiviral agents remain unavailable and unpredictable in the research and development pipelines, making sterile HBV elimination challenging at the current stage. The major challenge of discriminating trace amounts of cccDNA from the abundant HBV relaxed circular DNA (rcDNA), which is nearly identical to cccDNA in sequence, substantially discourages efforts to discover and directly screen cccDNA-targeting drugs. Therefore, an easy cccDNA cell culture system is required for high-throughput drug screening. In this study, we designed an HBV cccDNA self-generating stable cell culture system using a functional complementary concept and successfully generated an HBV cccDNA Gaussia luciferase reporter cell line in HepG2 and Huh7 cells. This design ensures that the Gluc signal is exclusively expressed upon cccDNA formation, allowing for the accurate and easy measurement of cccDNA levels via luminescent signals. Using this system, in conjunction with a firefly luciferase reporter to monitor cell activity, we screened 2074 drugs in the HepG2-HBV-cccDNA/Firefly cell line. Four compounds were selected for further experimentation and their anti-HBV effects were confirmed. Thus, this virus-free hepatitis B cccDNA cell culture system provides a valuable and convenient platform for the high-throughput screening of anti-HBV drugs.

The association between Clonorchis sinensis seropositivity and hepatocellular carcinoma in an endemic area: a study in Guangxi, China

BACKGROUND

Chronic infection with Clonorchis sinensis (C.sinensis) has been associated swith the development of intrahepatic cholangiocarcinoma (ICC); however, the relationship between C.sinensis and hepatocellular carcinoma (HCC) remains uncertain.

METHODS

This study examined 120 patients with liver cancer in the clonorchiasis endemic area of Hengzhou, Guangxi, China. The type of cancer, the differentiation grade according to Edmondson Steiner's classification, and the pathological characteristics of HCC were determined through postoperative tissue biopsy. C.sinensis infection was detected by measuring serum specific IgG antibody, and hepatitis B virus (HBV) infection was determined by detecting serum HBsAg and HBV DNA in HCC tissues. The C.sinensis infection rates in control groups were drawn from the local general population based on previous surveys. The association between C.sinensis infection and HCC was analyzed by comparing the differences in C.sinensis infection rates between the two groups.

RESULTS

Of the patients evaluated, 98 (81.7%) had HCC, 21 (17.5%) had ICC, and 1 (0.8%) had comorbidity of HCC/ICC. Among the HCC patients, 24 (24.5%) were solely infected with HBV, 71 (72.4%) were C. sinensis seropositive, and 3 (3.1%) showed no evidence of infection. C. sinensis seropositive rates in HCC patients are much higher than in general outpatient and non-liver cancer inpatients (χ2 = 141.92, p < 0.001), as well as in the local residents (χ2 = 82.61/21.38, p < 0.001). There were no significant differences in the pathological type, differentiation grade, and lesion composition between the tumor associated with C.sinensis/HBV mono- and co-infection (p > 0.05). Among the patients with C.sinensis-related HCC, 8 (8.2%) were solely C.sinensis seropositive, while 63 (64.3%) were co-infected with HBV. Infection with C. sinensis and HBV has a significant impact on the pathological types of liver cancer (χ2 = 22.86, p < 0.001).

CONCLUSIONS

These findings indicate that HCC still accounts for the majority of liver cancer in this region. In addition to being most commonly related with HBV infection, HCC may also be related to C. sinensis infection. Co-infection of C. sinensis and HBV may enhance the development of HCC in this area.

CLINICAL TRIAL

Not applicable.

Safety, Pharmacokinetics and Antiviral Efficacy of Capsid Assembly Modulator Freethiadine in Healthy Volunteers and Chronic Hepatitis B Patients

BACKGROUND AND AIMS

Freethiadine is a novel hepatitis B virus capsid assembly modulator. Herein, we report the safety, tolerability, pharmacokinetics and 28-day antiviral activities of freethiadine.

METHODS

The study consisted of two parts. Part 1 involved a single-ascending-dose, a multiple-ascending-dose and a food effect study. Part 2 was a double-blind, double-dummy, randomised, entecavir-controlled, multi-dose escalation study in chronic hepatitis B (CHB) patients.

RESULTS

A total of 88 healthy subjects and 40 patients with CHB were enrolled in this study. Freethiadine was well tolerated by both healthy subjects and patients. Among freethiadine-treated patients with CHB, the most common drug-related adverse event was alanine aminotransferase elevation (28.1%) (mostly grade 1 or 2). Both HEC160208 and its active metabolite, HEC142106, were rapidly absorbed and eliminated in plasma. Food intake did not significantly influence the exposure of either analyte. Following 28 days of treatment, the mean maximum HBV DNA declines from baseline were -2.76, -3.47, -3.56, -2.89 and -2.55 log10 IU/mL for the 100 mg BID, 200 mg QD, 200 mg BID and 300 mg QD of freethiadine or entecavir control cohorts, respectively; simultaneously, the mean maximum pregenomic RNA (pgRNA) declines from baseline were -1.69, -2.26, -2.07, -1.47 and -0.06 log10 copies/mL, respectively.

CONCLUSIONS

Freethiadine has an acceptable safety profile and favourable antiviral activity in patients with CHB. These results support further investigations of freethiadine for the treatment of chronic HBV infection.

TRIAL REGISTRATION

www.

CLINICALTRIALS

gov identifier NCT05391360; www.chinadrugtrials.org.cn identifier CTR20212114.

TCR-like bispecific antibodies toward eliminating infected hepatocytes in HBV mouse models

Therapeutics for eradicating hepatitis B virus (HBV) infection are still limited and current nucleos(t)ide analogs (NAs) and interferon are effective in controlling viral replication and improving liver health, but they cannot completely eradicate the hepatitis B virus and only a very small number of patients are cured of it. The TCR-like antibodies recognizing viral peptides presented on human leukocyte antigens (HLA) provide possible tools for targeting and eliminating HBV-infected hepatocytes. Here, we generated three TCR-like antibodies targeting three different HLA-A2.1-presented peptides derived from HBV core and surface proteins. Bispecific antibodies (BsAbs) were developed by fuzing variable fragments of these TCR-like mAbs with an anti-CD3ϵ antibody. Our data demonstrate that the BsAbs could act as T cell engagers, effectively redirecting and activating T cells to target HBV-infected hepatocytes in vitro and in vivo. In HBV-persistent mice expressing human HLA-A2.1, two infusions of BsAbs induced marked and sustained suppression in serum HBsAg levels and also reduced the numbers of HBV-positive hepatocytes. These findings highlighted the therapeutic potential of TCR-like BsAbs as a new strategy to cure hepatitis B.

N-Hydroxypiridinedione: A Privileged Heterocycle for Targeting the HBV RNase H

Hepatitis B virus (HBV) remains a global health threat. Ribonuclease H (RNase H), part of the virus polymerase protein, cleaves the pgRNA template during viral genome replication. Inhibition of RNase H activity prevents (+) DNA strand synthesis and results in the accumulation of non-functional genomes, terminating the viral replication cycle. RNase H, though promising, remains an under-explored drug target against HBV. We previously reported the identification of a series of N-hydroxypyridinedione (HPD) imines that effectively inhibit the HBV RNase H. In our effort to further explore the HPD scaffold, we designed, synthesized, and evaluated 18 novel HPD oximes, as well as 4 structurally related minoxidil derivatives and 2 barbituric acid counterparts. The new analogs were docked on the RNase H active site and all proved able to coordinate the two Mg2+ ions in the catalytic site. All of the new HPDs effectively inhibited the viral replication in cell assays exhibiting EC50 values in the low μM range (1.1-7.7 μM) with low cytotoxicity, resulting in selectivity indexes (SI) of up to 92, one of the highest reported to date among HBV RNase H inhibitors. Our findings expand the structure-activity relationships on the HPD scaffold, facilitating the development of even more potent anti-HBV agents.

Managing HBV and HCV Infection Pre- and Post-liver Transplant

Hepatitis B and C are common causes of end-stage liver disease and etiologies of liver transplantation. It is important to prevent recurrence in cases of hepatitis B. Nucleos(t)ide analogs are the mainstay of HBV treatment before (in patients with decompensated cirrhosis) and after liver transplantation. After the introduction of direct-acting antivirals, the treatment of HCV has become considerably easy. In patients with advanced HCV-related cirrhosis, it is better to do transplantation first and treat them after liver transplantation. The sustained virological response rates have improved from 8 to 50% in the interferon era to 90% in the direct-acting antivirals era. In the current review, we discuss the treatment of HBV and HCV before and after liver transplantation.

First-in-human randomized study of RNAi therapeutic RG6346 for chronic hepatitis B virus infection

BACKGROUND & AIMS

RG6346 is an N-acetyl-D-galactosamine (GalNAc)-conjugated, double-stranded RNA interference agent targeting the HBV genome S-region. We investigated the safety, tolerability, pharmacokinetics, and pharmacodynamics of RG6346 in healthy volunteers and patients with chronic HBV infection (CHB).

METHODS

This first-in-human, adaptive, randomized, double-blinded, phase I study recruited three groups of participants: Group A, 30 healthy volunteers received single-dose RG6346 at 0.1, 1.5, 3.0, 6.0, or 12.0 mg/kg, or placebo; Group B, nucleos(t)ide analogue-naïve participants with CHB received single-dose RG6346 at 3.0 mg/kg (n = 6) or placebo (n = 3); Group C, participants with nucleos(t)ide-suppressed CHB received four doses (every 28 days) of RG6346 at 1.5, 3.0, or 6.0 mg/kg (n = 4 in each cohort) or placebo (n = 6).

RESULTS

RG6346 treatment for up to 4 months was safe and well tolerated. The most common adverse event was a mild injection site reaction. Several nucleos(t)ide-naïve participants exhibited self-resolving transaminase elevations with preserved liver function. By the end of RG6346 treatment in Group C (Day 112), the mean reduction from baseline in hepatitis B surface antigen (HBsAg) was 1.39, 1.80, and 1.64 log10 IU/ml in the 1.5, 3.0, and 6.0 mg/kg cohorts, respectively. Of the 12 participants in Group C, 11 (91.7%) achieved a ≥1 log10 IU/ml reduction in HBsAg (3 of 11 [27.3%] had the response sustained at conditional follow-up Day 448). No dose-response relationship was apparent between RG6346 and serum HBsAg levels. The RG6346-induced HBsAg response was independent of hepatitis B e antigen status. Moderate-to-marked sustained reductions of hepatitis B core-related antigen, HBV RNA, HBV DNA (in nucleos[t]ide analogue-naïve participants), and hepatitis B e antigen levels were observed.

CONCLUSIONS

These favorable safety and pharmacodynamic data support the clinical development of RG6346 as the backbone of a finite antiviral treatment regimen, with the goal of sustained HBsAg loss (functional cure) in patients with CHB.

CLINICAL TRIAL NUMBER

ClinicalTrials.gov NCT03772249.

IMPACT AND IMPLICATIONS

Currently available therapies for chronic HBV infection are associated with low rates of functional cure and new, more efficacious treatments are needed. This first-in-human study of RG6346, an RNA interference therapy, showed a favorable safety profile as well as marked and durable reductions in hepatitis B surface antigen levels. These results support the continued development of RG6346 as the backbone of a finite treatment regimen targeting high functional cure rates and are important for HBV researchers and physicians.

Evaluation of reverse transcription-polymerase chain reaction and simultaneous amplification and testing for quantitative detection of serum hepatitis B virus RNA

BACKGROUND

Chronic hepatitis B virus (HBV) infection is one of the common infectious diseases in the world. HBV covalently closed circular DNA (cccDNA) is the initial template of HBV replication, which can exist in human hepatocytes for a long time and is difficult to be completely removed. It has been shown that HBV RNA can directly respond to the levels and transcriptional activity of cccDNA in hepatocytes and can be used as a surrogate marker of cccDNA transcriptional activity. At present, the detection techniques used for quantitative HBV RNA mainly include reverse transcription quantitative polymerase chain reaction (RT-qPCR) and simultaneous amplification and testing (SAT).

METHODS

In this study, we verified the performance of the SAT method for detecting HBV RNA and the clinical effectiveness of SAT and RT-qPCR, and compared the correlation and consistency of the two detection methods for HBV RNA detection.

RESULTS

The results showed that the limit of detection for HBV RNA by SAT method was 50 copies/mL, with a linear range of 1 × 102-1 × 108 copies/mL. There was no difference in HBV RNA levels detected by the two methods. The correlation and consistency of the results were good, with the coefficient of determination of 0.7787 in HBeAg positive group and 0.8235 in HBeAg negative group.

CONCLUSIONS

Therefore, this study confirmed that the SAT method and RT-qPCR for detecting HBV RNA have good agreement, which are both reliable methods to detect HBV RNA and can replace each other.

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.

The progress of molecules and strategies for the treatment of HBV infection

Hepatitis B virus infections have always been associated with high levels of mortality. In 2019, hepatitis B virus (HBV)-related diseases resulted in approximately 555,000 deaths globally. In view of its high lethality, the treatment of HBV infections has always presented a huge challenge. The World Health Organization (WHO) came up with ambitious targets for the elimination of hepatitis B as a major public health threat by 2030. To accomplish this goal, one of the WHO's strategies is to develop curative treatments for HBV infections. Current treatments in a clinical setting included 1 year of pegylated interferon alpha (PEG-IFNα) and long-term nucleoside analogues (NAs). Although both treatments have demonstrated outstanding antiviral effects, it has been difficult to develop a cure for HBV. The reason for this is that covalently closed circular DNA (cccDNA), integrated HBV DNA, the high viral burden, and the impaired host immune responses all hinder the development of a cure for HBV. To overcome these problems, there are clinical trials on a number of antiviral molecules being carried out, all -showing promising results so far. In this review, we summarize the functions and mechanisms of action of various synthetic molecules, natural products, traditional Chinese herbal medicines, as clustered regularly interspaced short palindromic repeats and their associated proteins (CRISPR/Cas)-based systems, zinc finger nucleases (ZFNs), and transcription activator-like effector nucleases (TALENs), all of which could destroy the stability of the HBV life cycle. In addition, we discuss the functions of immune modulators, which can enhance or activate the host immune system, as well some representative natural products with anti-HBV effects.

Potential antiviral activities of chrysin against hepatitis B virus

BACKGROUND

Interferon and nucleos(t)ide analogues are current therapeutic treatments for chronic Hepatitis B virus (HBV) infection with the limitations of a functional cure. Chrysin (5, 7-dihydroxyflavone) is a natural flavonoid, known for its antiviral and hepatoprotective activities. However, its anti-HBV activity is unexplored.

METHODS

In the present study, the anti-hepatitis B activity of chrysin was investigated using the in vitro experimental cell culture model, HepG2 cells. In silico studies were performed where chrysin and lamivudine (used here as a positive control) were docked with high mobility group box 1 protein (HMGB1). For the in vitro studies, wild type HBV genome construct (pHBV 1.3X) was transiently transfected in HepG2. In culture supernatant samples, HBV surface antigen (HBsAg) and Hepatitis B e antigen (HBeAg) were measured by enzyme-linked immunosorbent assay (ELISA). Secreted HBV DNA and intracellular covalently closed circular DNA (cccDNA) were measured by SYBR green real-time PCR. The 3D crystal structure of HMGB1 (1AAB) protein was developed and docked with the chrysin and lamivudine. In silico drug-likeness, Absorption, Distribution, Metabolism, Excretion and Toxicity (ADMET) properties of finest ligands were performed by using SwissADME and admetSAR web servers.

RESULTS

Data showed that chrysin significantly decreases HBeAg, HBsAg secretion, supernatant HBV DNA and cccDNA, in a dose dependent manner. The docking studies demonstrated HMGB1 as an important target for chrysin as compared to lamivudine. Chrysin revealed high binding affinity and formed a firm kissing complex with HMGB1 (∆G = - 5.7 kcal/mol), as compared to lamivudine (∆G = - 4.3 kcal/mol), which might be responsible for its antiviral activity.

CONCLUSIONS

The outcome of our study establishes chrysin as a new antiviral against HBV infection. However, using chrysin to treat chronic HBV disease needs further endorsement and optimization by in vivo studies in animal models.

Development and characterization of a chronic hepatitis B murine model with a mutation in the START codon of an HBV polymerase

Chronic hepatitis B (CHB) is caused by the Hepatitis B virus (HBV) and affects millions of people worldwide. Developing an effective CHB therapy requires using in vivo screening methods, such as mouse models reflecting CHB based on hydrodynamic delivery of plasmid vectors containing a replication-competent HBV genome. However, long-term expression of HBV proteins is accompanied by production of progeny virions, thereby requiring a Biosafety Level (BSL) 3 animal facility. In the present study, we introduced a point mutation in the START codon of the HBV polymerase to develop a mouse model reflecting chronic hepatitis B infection without formation of viral progeny. We induced the mouse model by hydrodynamic injection of adeno-associated virus plasmid vector (pAAV) and minicircle plasmid (pMC) constructs into C57Bl/6 and C3H/HeN mouse strains, monitoring HBV antigens and antibodies in blood by enzyme-linked immunosorbent assay and analyzing liver expression of HBV core antigen by immunohistology. Persisting expression of viral antigens over 140 days (study endpoint) was observed only in the C3H/HeN mouse strain when using pAAV/1.2HBV-A and pMC/1.0HBV-D with pre-C and pre-S recombination sites. In addition, pAAV/1.2HBV-A in C3H/HeN sustained HBV core antigen positivity up to the study endpoint in C3H/HeN mice. Moreover, introducing the point mutation in the START codon of polymerase effectively prevented the formation of viral progeny. Our study establishes an accessible and affordable experimental paradigm for developing a robust mouse model reflecting CHB suitable for preclinical testing of anti-HBV therapeutics in a BSL2 animal facility.

Resistant mutations within the hepatitis B virus reverse transcriptase sequence in treatment failure patients with chronic HBV infection in Vietnam

OBJECTIVES

We conducted this study to describe whether mutations in the gene coding for the enzyme reverse transcriptase (RT) were related to drugs used in the treatment of hepatitis B in Vietnam.

METHODS

Patients receiving antiretroviral therapy with evidence of treatment failure were included in the study. The RT fragment was cloned using the polymerase chain reaction technique after being extracted from patients' blood samples. The nucleotide sequences were analysed using Sanger method. The HBV drug resistance database contains mutations associated to resistance to existing HBV therapies. Medical records were accessed to collect information on patient parameters, such as treatment, viral load, biochemistry, and blood count.

RESULTS

Resistance mutations to lamivudine, telbivudine, and entecavir were found in the highest proportion (75-91.7%) of HBV samples from patients who had failed antiretroviral therapy. Only 20.8% of HBV strains had mutations exhibiting adefovir resistance, while none had mutations conferring tenofovir resistance. M204I/V, L180M, and L80I are frequent variants linked with resistance to lamivudine, telbivudine, and entecavir. In contrast, the A181L/T/V mutation was detected predominantly in tenofovir-resistant HBV strains. Following the drug resistance mutation test, patients achieved the greatest virological response after 24 weeks of therapy with tenofovir and entecavir at a daily dose of one tablet.

CONCLUSION

Lamivudine, telbivudine, and entecavir were all highly resistant to the RT enzyme modifications in 24 treatment failure patients, with M204I/V, L180M, and L80I being the most prevalent mutations. Tenofovir resistance mutations have not been found in Vietnam.

Cautious optimism in anticipation of hepatitis B curative therapies

Despite relative effectiveness of current hepatitis B therapies, there is still no curative agents available. The new emerging approaches hold promise to achieve cure and loss of hepatitis B surface antigen. Studies or clinical trials investigating new therapies remain small and either focus on patients with low viral load and without hepatotoxic injury or patients with hepatitis D co-infection, which makes it challenging to assess their effectiveness and side effect profile in hepatitis B population.