Treatment of hepatitis B virus with combination therapy now and in the future

A Landscape of CRISPR/Cas Technique for Emerging Viral Disease Diagnostics and Therapeutics: Progress and Prospects

Viral diseases have emerged as a serious threat to humanity and as a leading cause of morbidity worldwide. Many viral diagnostic methods and antiviral therapies have been developed over time, but we are still a long way from treating certain infections caused by viruses. Acquired immunodeficiency syndrome (AIDS) is one of the challenges where current medical science advancements fall short. As a result, new diagnostic and treatment options are desperately needed. The CRISPR/Cas9 system has recently been proposed as a potential therapeutic approach for viral disease treatment. CRISPR/Cas9 is a specialised, effective, and adaptive gene-editing technique that can be used to modify, delete, or correct specific DNA sequences. It has evolved into an advanced, configurable nuclease-based single or multiple gene-editing tool with a wide range of applications. It is widely preferred simply because its operational procedures are simple, inexpensive, and extremely efficient. Exploration of infectious virus genomes is required for a comprehensive study of infectious viruses. Herein, we have discussed the historical timeline-based advancement of CRISPR, CRISPR/Cas9 as a gene-editing technology, the structure of CRISPR, and CRISPR as a diagnostic tool for studying emerging viral infections. Additionally, utilizing CRISPR/Cas9 technology to fight viral infections in plants, CRISPR-based diagnostics of viruses, pros, and cons, and bioethical issues of CRISPR/Cas9-based genomic modification are discussed.

Efficacy and Safety of Bepirovirsen in Chronic Hepatitis B Infection

BACKGROUND

Bepirovirsen is an antisense oligonucleotide that targets all hepatitis B virus (HBV) messenger RNAs and acts to decrease levels of viral proteins.

METHODS

We conducted a phase 2b, randomized, investigator-unblinded trial involving participants with chronic HBV infection who were receiving or not receiving nucleoside or nucleotide analogue (NA) therapy. Participants were randomly assigned (in a 3:3:3:1 ratio) to receive weekly subcutaneous injections of bepirovirsen at a dose of 300 mg for 24 weeks (group 1), bepirovirsen at a dose of 300 mg for 12 weeks then 150 mg for 12 weeks (group 2), bepirovirsen at a dose of 300 mg for 12 weeks then placebo for 12 weeks (group 3), or placebo for 12 weeks then bepirovirsen at a dose of 300 mg for 12 weeks (group 4). Groups 1, 2, and 3 received loading doses of bepirovirsen. The composite primary outcome was a hepatitis B surface antigen (HBsAg) level below the limit of detection and an HBV DNA level below the limit of quantification maintained for 24 weeks after the planned end of bepirovirsen treatment, without newly initiated antiviral medication.

RESULTS

The intention-to-treat population comprised 457 participants (227 receiving NA therapy and 230 not receiving NA therapy). Among those receiving NA therapy, a primary-outcome event occurred in 6 participants (9%; 95% credible interval, 0 to 31) in group 1, in 6 (9%; 95% credible interval, 0 to 43) in group 2, in 2 (3%; 95% credible interval, 0 to 16) in group 3, and 0 (0%; post hoc credible interval, 0 to 8) in group 4. Among participants not receiving NA therapy, a primary-outcome event occurred in 7 participants (10%; 95% credible interval, 0 to 38), 4 (6%; 95% credible interval, 0 to 25), 1 (1%; post hoc credible interval, 0 to 6), and 0 (0%; post hoc credible interval, 0 to 8), respectively. During weeks 1 through 12, adverse events, including injection-site reactions, pyrexia, fatigue, and increased alanine aminotransferase levels, were more common with bepirovirsen (groups 1, 2, and 3) than with placebo (group 4).

CONCLUSIONS

In this phase 2b trial, bepirovirsen at a dose of 300 mg per week for 24 weeks resulted in sustained HBsAg and HBV DNA loss in 9 to 10% of participants with chronic HBV infection. Larger and longer trials are required to assess the efficacy and safety of bepirovirsen. (Funded by GSK; B-Clear ClinicalTrials.gov number, NCT04449029.).

Feasibility of hepatitis B elimination in high-income countries with ongoing immigration

BACKGROUND & AIMS

Addressing HBV is vital to meeting the World Health Organization (WHO)'s viral hepatitis elimination goals, as 47% of viral hepatitis complications can be attributed to HBV. The objective of this study is to develop an agent-based model determining which integrated strategies involving vaccination, screening, and treatment would achieve the WHO's goals.

METHODS

We developed an agent-based model to characterize the HBV epidemic in a high-income country with ongoing immigration. The spread of HBV was simulated through sexual networks and perinatal transmission. Model parameters were estimated from the literature and calibrated against historical HBV data. Sensitivity analyses were performed to assess the uncertainty.

RESULTS

We predict that under the current strategies, the incidence of acute hepatitis B, and HBV-attributable decompensated cirrhosis and hepatocellular carcinoma would decrease by 64.5%, 9.4%, and 10.5% between 2015-2030, respectively. However, the incidence of chronic hepatitis B and liver-related deaths would increase by 26.6% and 1.0% between 2015-2030, respectively. Results were sensitive to the number of immigrants and HBV prevalence in immigrants.

CONCLUSIONS

The results suggest that the current vaccination, screening, and treatment strategies will be inadequate to achieve WHO elimination goals. Even with extensive integrated scale-up in vaccination, screening, and treatment, the morbidity and mortality targets may not be reachable, highlighting the need for a re-evaluation of the global strategy for HBV, the importance of developing curative therapy for HBV, and of establishing tailored strategies to prevent long-term sequelae and improve health in immigrants.

LAY SUMMARY

We have developed a model that reflects the dynamics of hepatitis B virus (HBV) transmission in a high-income country with ongoing immigration, which enabled us to forecast the epidemiology of HBV for policy-level decision making. Our analysis suggests that current vaccination, screening, and treatment strategies are inadequate to achieve the WHO goals of eliminating chronic hepatitis B. Even with extensive integrated scale-up in vaccination, screening, and treatment, the morbidity and mortality targets may not be reachable.

The State-of-the-Art of Gene Editing and its Application to Viral Infections and Diseases Including COVID-19

Gene therapy delivers a promising hope to cure many diseases and defects. The discovery of gene-editing technology fueled the world with valuable tools that have been employed in various domains of science, medicine, and biotechnology. Multiple means of gene editing have been established, including CRISPR/Cas, ZFNs, and TALENs. These strategies are believed to help understand the biological mechanisms of disease progression. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has been designated the causative virus for coronavirus disease 2019 (COVID-19) that emerged at the end of 2019. This viral infection is a highly pathogenic and transmissible disease that caused a public health pandemic. As gene editing tools have shown great success in multiple scientific and medical areas, they could eventually contribute to discovering novel therapeutic and diagnostic strategies to battle the COVID-19 pandemic disease. This review aims to briefly highlight the history and some of the recent advancements of gene editing technologies. After that, we will describe various biological features of the CRISPR-Cas9 system and its diverse implications in treating different infectious diseases, both viral and non-viral. Finally, we will present current and future advancements in combating COVID-19 with a potential contribution of the CRISPR system as an antiviral modality in this battle.

Prevalence of Viral Hepatitis B, C, and D in Kazakhstan

Background

Viral hepatitis is a major burden for the healthcare system worldwide. Up to date, a comprehensive analysis of the prevalence of viral hepatitis in Kazakhstan and Central Asia has not been carried out yet. Our epidemiological study aimed at investigating the frequency and spread of viral hepatitis B, C, and D depending on age and sex in Kazakhstan (5-year period).

Materials and Methods

We utilized the data from the primary registration of the incidence of hepatitis B, C, and D in 18 regions of Kazakhstan (period: from 2015 to 2020). Age indicators, gender, and territorial characteristics of registered cases were determined and analysed. The data were obtained from the state information system “Electronic Register of Dispensary Patients”, based on the International Classification of Diseases-10 for coding diseases.

Results

During the period studied, 268 975 cases of hepatitis B, C, and D were detected in Kazakhstan. Hepatitis B was registered in n = 109 734 cases. In women, the incidence rate was 40.6% of all cases (n = 44545), and in men it was 59.4% (n = 65189) of all cases (p ≤ 0.01). Hepatitis D was detected in 8 656 cases, of which 58.3% (n = 5049) were in men and 41.7% (n = 3607) in women (p ≤ 0.01). Hepatitis C was registered in n = 159 585 cases. The rate was higher in the male population (54.6%; n = 82 203) compared to women 45.4% (n = 68382) (p ≤ 0.01). In 2020 (in comparison with 2015), there was a significant increase in the incidence of hepatitis D by 68.3%, hepatitis B by 49.8%, and hepatitis C by 46.4%. The largest prevalence of hepatitis D was recorded in 2016 which is 22.3% higher compared to 2020. A significant increase in hepatitis C was recorded in 2019 compared to 2015, where indicators were 49.2% higher.

Conclusion

An analysis of the prevalence of hepatitis B, C, and D showed an increase in new cases in Kazakhstan. These findings indicate the need to develop effective preventive measures and screening strategies among people in a high-risk group. The results of the study can be used for the development of a national program to combat the spread of viral hepatitis.

The Use of CRISPR/Cas9 as a Tool to Study Human Infectious Viruses

Clustered regularly interspaced short palindromic repeats (CRISPR) systems are a set of versatile gene-editing toolkit that perform diverse revolutionary functions in various fields of application such as agricultural practices, food industry, biotechnology, biomedicine, and clinical research. Specially, as a novel antiviral method of choice, CRISPR/Cas9 system has been extensively and effectively exploited to fight against human infectious viruses. Infectious diseases including human immunodeficiency virus (HIV), hepatitis B virus (HBV), human papillomavirus (HPV), and other viruses are still global threats with persistent potential to probably cause pandemics. To facilitate virus removals, the CRISPR/Cas9 system has already been customized to confer new antiviral capabilities into host animals either by modifying host genome or by directly targeting viral inherent factors in the form of DNA. Although several limitations and difficulties still need to be conquered, this technology holds great promises in the treatment of human viral infectious diseases. In this review, we will first present a brief biological feature of CRISPR/Cas9 systems, which includes a description of CRISPR/Cas9 structure and composition; thereafter, we will focus on the investigations and applications that employ CRISPR/Cas9 system to combat several human infectious viruses and discuss challenges and future perspectives of using this new platform in the preclinical and clinical settings as an antiviral strategy.

Treatments for HBV: A Glimpse into the Future

The hepatitis B virus is responsible for most of the chronic liver disease and liver cancer worldwide. As actual therapeutic strategies have had little success in eradicating the virus from hepatocytes, and as lifelong treatment is often required, new drugs targeting the various phases of the hepatitis B virus (HBV) lifecycle are currently under investigation. In this review, we provide an overview of potential future treatments for HBV.

De novo combination antiviral therapy in e antigen-negative chronic hepatitis B virus-infected paediatric patients with advanced fibrosis

To date, studies that focus on treatment of e antigen-negative chronic hepatitis B virus-infected children with advanced fibrosis are extremely limited. This puts these patients at risk of rapid disease progression. Our study aimed to investigate the efficacy of combination antiviral therapy in this population. We prospectively enrolled treatment-naı̈ve paediatric patients between 1 year and 12 years of age who had e antigen-negative chronic hepatitis B and histologically proven advanced fibrosis. All patients received de novo combination therapy with lamivudine (LAM) and interferon-α (IFN) for 12 months and then were clinically followed up. The main outcome measure was rate of serum hepatitis B surface antigen (HBsAg) loss at month 12 of treatment. A total of 14 paediatric patients were enrolled, including 9 boys and 5 girls. All patients achieved undetectable HBV DNA levels at month 9 of treatment. A total of 5 patients (35.7%) achieved HBsAg loss at month 12 and finally developed HBsAg seroconversion. Four patients who did not clear HBsAg underwent second liver biopsy, and histological evaluation revealed significant improvements in all of them. As a serum fibrosis marker, aspartate aminotransferase-to-platelet ratio index after 12-month treatment in the 14 patients showed a significant improvement compared with that at baseline (P = .0021). No serious adverse events were observed during the study. Combination antiviral therapy is beneficial to e antigen-negative chronic hepatitis B virus-infected paediatric patients with advanced fibrosis. Further studies with larger cohorts are required.

Guidance for design and endpoints of clinical trials in chronic hepatitis B - Report from the 2019 EASL-AASLD HBV Treatment Endpoints Conference‡

Representatives from academia, industry, regulatory agencies, and patient groups convened in March 2019 with the primary goal of developing agreement on chronic HBV treatment endpoints to guide clinical trials aiming to 'cure' HBV. Agreement among the conference participants was reached on some key points. 'Functional' but not sterilising cure is achievable and should be defined as sustained HBsAg loss in addition to undetectable HBV DNA 6 months post-treatment. The primary endpoint of phase III trials should be functional cure; HBsAg loss in ≥30% of patients was suggested as an acceptable rate of response in these trials. Sustained virologic suppression (undetectable serum HBV DNA) without HBsAg loss 6 months after discontinuation of treatment would be an intermediate goal. Demonstrated validity for the prediction of sustained HBsAg loss was considered the most appropriate criterion for the approval of new HBV assays to determine efficacy endpoints. Clinical trials aimed at HBV functional cure should initially focus on patients with HBeAg-positive or negative chronic hepatitis, who are treatment-naïve or virally suppressed on nucleos(t)ide analogues. A hepatitis flare associated with an increase in bilirubin or international normalised ratio should prompt temporary or permanent cessation of an investigational treatment. New treatments must be as safe as existing nucleos(t)ide analogues. The primary endpoint for phase III trials for HDV coinfection should be undetectable serum HDV RNA 6 months after stopping treatment. On treatment HDV RNA suppression associated with normalisation of alanine aminotransferase is considered an intermediate goal. In conclusion, regarding HBV 'functional cure', the primary goal is sustained HBsAg loss with undetectable HBV DNA after completion of treatment and the intermediate goal is sustained undetectable HBV DNA without HBsAg loss after stopping treatment.

Guidance for design and endpoints of clinical trials in chronic hepatitis B - Report from the 2019 EASL-AASLD HBV Treatment Endpoints Conference

Representatives from academia, industry, regulatory agencies, and patient groups convened in March 2019 with the primary goal of developing agreement on chronic hepatitis B virus (HBV) treatment endpoints to guide clinical trials aiming to 'cure' HBV. Agreement among the conference participants was reached on some key points. 'Functional' but not sterilizing cure is achievable and should be defined as sustained HBsAg loss in addition to undetectable HBV DNA 6 months post-treatment. The primary endpoint of phase 3 trials should be functional cure; HBsAg loss in ≥30% of patients was suggested as an acceptable rate of response in these trials. Sustained virologic suppression (undetectable serum HBV DNA) without HBsAg loss, 6 months after discontinuation of treatment would be an intermediate goal. Demonstrated validity in predicting sustained HBsAg loss was considered the most appropriate criterion for the approval of new HBV assays to determine efficacy endpoints. Clinical trials aimed at HBV functional cure should initially focus on patients with HBeAg-positive and HBeAg-negative chronic hepatitis, treatment-naïve or virally suppressed on nucleos(t)ide analogues. A hepatitis flare associated with increase in bilirubin or INR should prompt temporary or permanent cessation of investigational treatment. New treatments must be as safe as existing nucleos(t)ide analogues. The primary endpoint for phase 3 trials for hepatitis D virus (HDV) co-infection should be undetectable serum HDV RNA 6 months after stopping treatment. On treatment HDV RNA suppression associated with normalization of ALT is considered an intermediate goal. CONCLUSION: For HBV 'functional cure', sustained HBsAg loss with undetectable HBV DNA after completion of treatment is the primary goal and sustained undetectable HBV DNA without HBsAg loss after stopping treatment an intermediate goal.

Divergent synthesis of a thiolate-based α-hydroxytropolone library with a dynamic bioactivity profile

Here we describe a rapid and divergent synthetic route toward structurally novel αHTs functionalized with either one or two thioether or sulfonyl appendages. Evaluation of this library against hepatitis B and herpes simplex virus, as well as the pathogenic fungus Cryptococcus neoformans, and a human hepatoblastoma (HepDES19) revealed complementary biological profiles and new lead compounds with sub-micromolar activity against each pathogen.

Antiviral treatment for treatment-naïve chronic hepatitis B: systematic review and network meta-analysis of randomized controlled trials

BACKGROUND

Chronic hepatitis B (CHB) infection poses a significant burden to public health worldwide. Most cases are clinically silent until late in the disease course. The main goal of current therapy is to improve survival and quality of life by preventing disease progression to cirrhosis and liver failure, and consequently hepatocellular carcinoma development. The objective of this review is to provide a contemporary and comprehensive evaluation of the effectiveness of treatment options.

METHODS

We performed a systematic review of peer-reviewed literature for randomized controlled trials involving treatment-naïve CHB adult population who received antiviral therapy. The endpoints were virologic response (VR), normalization of alanine aminotransferase (ALT norm), HBeAg loss, HBeAg seroconversion, and HBsAg loss for the HBeAg-positive population; and VR and ALT norm for the HBeAg-negative population. Network meta-analysis (NMA) was performed to synthesize evidence on the efficacy of treatment.

RESULTS

Forty-two publications were selected. Twenty-three evaluated HBeAg-positive population, 13 evaluated HBeAg-negative population, and six evaluated both. We applied NMA to the efficacy outcomes of the two populations separately. Treatment strategies were ranked by the probability of achieving outcomes, and pairwise comparisons calculated from NMA were reported in odds ratios (OR). For HBeAg-positive population, tenofovir disoproxil fumarate (TDF) and tenofovir alafenamide (TAF) were the best for VR; OR vs adefovir = 14.29, 95% CI 7.69-25 and 12.5, 95% CI 4.35-33.33 respectively. TAF was the best for achieving ALT norm (OR vs placebo = 12.5, 95% CI 4.55-33.33), HBeAg loss, and seroconversion (OR vs entecavir/TDF combination = 3.03, 95% CI 1.04-8.84 and 3.33, 95% CI 1.16-10 respectively). In the HBeAg-negative population, TDF and TAF were the best for VR (OR vs adefovir = 9.79, 95% CI 2.38-42.7 and 11.71, 95% CI 1.03-150.48 respectively). Telbivudine and TAF were the best for ALT norm. Certain nucleos(t)ide combinations also had high probability of achieving positive outcomes.

CONCLUSIONS

Our results are consonant with current clinical guidelines and other evidence reviews. For both HBeAg-positive and HBeAg-negative populations, TDF and TAF are the most effective agents for virologic suppression, and TAF is effective across all outcomes.

Incidence of hepatocellular carcinoma among older Americans attributable to hepatitis C and hepatitis B: 2001 through 2013

BACKGROUND

In the United States, incidence and mortality rates of hepatocellular carcinoma (HCC) are increasing in older individuals. Chronic infection with hepatitis C virus (HCV) and hepatitis B virus (HBV) are important causes of HCC; however, the contribution of viral hepatitis to recent trends in HCC incidence among older Americans is unclear.

METHODS

Data from the Surveillance, Epidemiology, and End Results-Medicare linkage (SEER-Medicare) for the years 2001 through 2013 were used to identify HCC cases among individuals aged ≥66 years and Medicare files were used to assess the HCV and HBV status of these HCC cases. Age-standardized incidence rates of HCV-attributable, HBV-attributable, and HCV/HBV-unrelated HCC were estimated overall and by age group, sex, and race/ethnicity. The authors also calculated annual percent changes (APCs) in HCC incidence.

RESULTS

Between 2001 and 2013, a total of 15,300 HCC cases occurred in this population. Overall HCC rates increased 43% from 16.3 to 23.3 per 100,000 population (APC, 3.40% per year), whereas HCV-attributable HCC rates nearly doubled from 4.2 to 8.2 per 100,000 population (APC, 5.62% per year). HCC rates increased more slowly for HBV-attributable HCC (1.3 to 1.8 per 100,000 population; APC, 3.17% per year) and HCV/HBV-unrelated HCC (11.3 to 14.1 per 100,000 population; APC, 2.35% per year). The percentage of HCC cases with evidence of HCV infection increased from 25.7% in 2001 through 2004 to 32.3% in 2011 through 2013, whereas the percentage with HBV remained stable at 8%. In 2013, higher rates for both HCV-attributable and HBV-attributable HCC were noted among individuals aged 66 to 75 years, men, and individuals of Asian ancestry.

CONCLUSIONS

Among Americans aged ≥66 years, HCC rates increased rapidly between 2001 and 2013. Although HCV-attributable cases contributed substantially to this increase, rates of HBV-attributable and HCV/HBV-unrelated HCC also rose during this period.

Unconventional RNA-binding proteins step into the virus-host battlefront

The crucial participation of cellular RNA‐binding proteins (RBPs) in virtually all steps of virus infection has been known for decades. However, most of the studies characterizing this phenomenon have focused on well‐established RBPs harboring classical RNA‐binding domains (RBDs). Recent proteome‐wide approaches have greatly expanded the census of RBPs, discovering hundreds of proteins that interact with RNA through unconventional RBDs. These domains include protein–protein interaction platforms, enzymatic cores, and intrinsically disordered regions. Here, we compared the experimentally determined census of RBPs to gene ontology terms and literature, finding that 472 proteins have previous links with viruses. We discuss what these proteins are and what their roles in infection might be. We also review some of the pioneering examples of unorthodox RBPs whose RNA‐binding activity has been shown to be critical for virus infection. Finally, we highlight the potential of these proteins for host‐based therapies against viruses.

This article is categorized under:

RNA Interactions with Proteins and Other Molecules > Protein–RNA Interactions: Functional Implications

RNA in Disease and Development > RNA in Disease

RNA Interactions with Proteins and Other Molecules > RNA–Protein Complexes

Is it possible to stop nucleos(t)ide analogue treatment in chronic hepatitis B patients?

Chronic hepatitis B (CHB) remains a challenging global health problem, with nearly one million related deaths per year. Nucleos(t)ide analogue (NA) treatment suppresses viral replication but does not provide complete cure of the hepatitis B virus (HBV) infection. The accepted endpoint for therapy is the loss of hepatitis B surface antigen (HBsAg), but this is hardly ever achieved. Therefore, indefinite treatment is usually required. Many different studies have evaluated NA therapy discontinuation after several years of NA treatment and before HBsAg loss. The results have indicated that the majority of patients can remain off therapy, with some even reaching HBsAg seroconversion. Fortunately, this strategy has proved to be safe, but it is essential to consider the risk of liver damage and other comorbidities and to ensure a close follow-up of the candidates before considering this strategy. Unanswered questions remain, namely in which patients could this strategy be effective and what is the optimal time point at which to perform it. To solve this enigma, we should keep in mind that the outcome will ultimately depend on the equilibrium between HBV and the host’s immune system. Viral parameters that have been described as good predictors of response in HBeAg(+) cases, have proven useless in HBeAg(-) ones. Since antiviral immunity plays an essential role in the control of HBV infection, we sought to review and explain potential immunological biomarkers to predict safe NA discontinuation in both groups.