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

Long-Term Treatment with Bulevirtide in Patients with Chronic Hepatitis D and Advanced Chronic Liver Disease

Bulevirtide (BLV) is approved for the treatment of chronic hepatitis D (CHD). Because only limited long-term experience has been reported, we aimed to evaluate the efficacy and safety of BLV treatment in patients with advanced chronic liver disease (ACLD). We performed a retrospective analysis of patients with CHD who received BLV 2 mg/day for >12 months at a tertiary center. Virological response (VR) was defined as a reduction in hepatitis delta virus-ribonucleic acid (HDV-RNA) ≥2 log10 from baseline or HDV-RNA negativity and biochemical response (BR) as gender-specific normalization of transaminases. We identified 14 patients (9 men, 5 women; median age of 48 years; interquartile range (IQR) of 37-55), of whom 12 (86%) had suggested or assumed ACLD according to Baveno VI criteria. The median duration of BLV treatment was 26 months (IQR 17-27). During treatment, the mean HDV-RNA level decreased from log10 5.58 IU/ml to levels between log10 2.19 IU/ml and log10 3.19 IU/ml. HDV-RNA negativity was achieved in up to 63% after 24 months. VR and BR were 86% and 43% after 12 months, 90% and 60% after 18 months, 75% and 75% after 24 months, and 100% and 50% after 30 months, respectively. Two nonpersisting viral breakthroughs were observed after 24 months of treatment. The Child Pugh score and model of end-stage liver disease (MELD) scores remained stable or improved in 12 patients (86%). Only one patient developed hepatic decompensation after 24 months of treatment with ascites requiring large-volume paracentesis which was not associated with viral breakthrough, portal vein thrombosis, or hepatocellular carcinoma. Treatment with BLV beyond one year is effective and safe for patients with CHD and ACLD. Liver function remained stable or improved during treatment in the vast majority of patients, and only one case of hepatic decompensation occurred during a median follow-up of 26 months.

Assessment of performance and comparison of three commercial HDV RNA detection assays: implications for diagnosis and treatment monitoring

Objectives

Precise HDV-RNA detection and quantification are pivotal for diagnosis and monitoring of response to newly approved treatment. We evaluate the performance of three HDV RNA detection and quantification assays.

Methods

Hepatitis Delta RT-PCR system kit, EurobioPlex HDV assay, and RoboGene HDV RNA Quantification kit 2.0 were used for testing 151 HBsAg-positive samples, 90 HDV-RNA negative and 61 HDV-RNA positive. We also evaluated serial dilutions of the WHO international standard for HDV, PEI 7657/12. All HDV-RNA positive samples were genotyped using a next-generation sequencing strategy.

Results

Qualitative results indicated a 100% concordance between tests. Quantitative results correlated well, r2 = 0.703 (Vircell-vs-Eurobio), r2 = 0.833 (Vircell-vs-RoboGene), r2 = 0.835 (Robogene-vs-Eurobio). Bias index was 2.083 (Vircell-vs-Eurobio), -1.283 (Vircell-vs-RoboGene), and -3.36 (Robogene-vs-Eurobio). Using the WHO IS, Vircell overestimated the viral load by 0.98 log IU/mL, Eurobio by 1.46 log IU/mL, and RoboGene underestimated it by 0.98 log IU/mL. Fifty-nine samples were successfully genotyped (Genotype 1, n=52; Genotype 5, n=7; Genotype 6, n=1), with similar results for correlation and bias.

Conclusion

This study underscores the necessity of using reliable HDV-RNA detection and quantification assays, as evidenced by the high concordance rates in qualitative detection and the observed variability in quantitative results. These findings highlight the importance of consistent assay use in clinical practice to ensure accurate diagnosis and effective treatment monitoring of HDV infection.

Quantification of serum HDV RNA by Robogene 2.0 in HDV patients is significantly influenced by the extraction methods

BACKGROUND AND AIM

Management of chronic hepatitis delta (CHD) requires reliable tests for HDV RNA quantification. The aim of the study was to compare two extraction methods for the quantification of HDV RNA in untreated and bulevirtide (BLV)-treated CHD patients.

METHODS

Frozen sera from untreated and BLV-treated CHD patients were tested in a single-centre study for HDV RNA levels (Robogene 2.0, Roboscreen GmbH, Leipzig, Germany; LOD 6 IU/mL) with two extraction methods: manual (INSTANT Virus RNA/DNA kit; Roboscreen GmbH, Leipzig, Germany) versus automated (EZ1 DSP Virus Kit; Qiagen, Hilden, Germany). BLV-treated patients were sampled at baseline and during therapy.

RESULTS

Two hundred sixty-four sera collected from 157 CHD (139 untreated, 18 BLV-treated) patients were analysed: age 51 (28-78), 59% males, 90% of European origin, 60% cirrhotics, ALT 85 (17-889) U/L, HBsAg 3.8 (1.7-4.6) Log IU/mL, 81% HBV DNA undetectable, 98% HDV genotype 1. Median HDV RNA was 4.53 (.70-8.10) versus 3.77 (.70-6.93) Log IU/mL by manual versus automated extraction (p < .0001). Manual extraction reported similar HDV RNA levels in 31 (20%) patients, higher in 119 (76%) [+.5 and +1 log10 in 60; > +1 log10 in 59] and lower in 7 (4%). Among 18 BLV-treated patients, rates of HDV RNA < LOD significantly differed between the two assays at Weeks 16 and 24 (0% vs. 22%, p = .02; 11% vs. 44%, p = .03), but not at later timepoints. By contrast, virological response rates were similar.

CONCLUSIONS

Quantification of HDV RNA by Robogene 2.0 is influenced by the extraction method, the manual extraction being 1 Log more sensitive.

Management of chronic HBV-HDV patients chronic HBV-HDV infection: A review on new management options

Hepatitis D virus was first described by Mario Rizzeto in 1977, and it is considered chronic viral hepatitis with the poorest prognosis. Despite its discovery almost 50 years ago, progress in its diagnosis and treatment has been scarce until recent years. The approval of bulevirtide has shed some light for patients with Chronic Hepatitis D, although important gaps regarding its use in therapy as well as about the epidemiology and diagnosis of the disease need to be addressed.

Understanding the Natural History of Chronic Hepatitis D: Proposal of a Model for Cost-Effectiveness Studies

BACKGROUND

As new therapeutic options become available, better understanding the potential impact of emerging therapies on clinical outcomes of hepatits D virus (HDV) is critical.

OBJECTIVE

The aim of this study was to develop a natural history model for patients with hepatitis D virus.

METHODS

We developed a model (decision tree followed by a Markov cohort model) in adults with chronic HDV infection to assess the natural history and impact of novel treatments on disease progression versus best supportive care (BSC). The model time horizon was over a lifetime (up to 100 years of age); state transitions and health states were defined by responder status. Patients in fibrosis stages 0 through 4 received treatment; decompensated patients were not treated. Response was defined as the combined response endpoint of achievement of HDV-RNA undetectability/≥2-log10 decline and alanine aminotransferase normalization; response rates of 50% and 75% were explored. Health events associated with advanced liver disease were modeled as the number of events per 10,000 patients. Scenario analyses of early treatment, alternate treatment response, and no fibrosis regression for treatment responders were also explored.

RESULTS

The model was able to reflect disease progression similarly to published natural history studies for patients with HBV/HDV infection. In a hypothetical cohort of patients reflecting a population enrolled in a recent clinical trial, fewer advanced liver disease events were observed with a novel HDV treatment versus BSC. Fewer liver-related deaths were observed under 50% and 75% response (900 and 1,358 fewer deaths, respectively, per 10,000 patients). Scenario analyses showed consistently fewer advanced liver disease events with HDV treatment compared with BSC, with greater reductions observed with earlier treatment.

CONCLUSION

This HDV disease progression model replicated findings from natural history studies. Furthermore, it found that a hypothetical HDV treatment results in better clinical outcomes for patients versus BSC, with greater benefit observed when starting treatment early. This validated natural history model for HBV/HDV infection can serve as a foundation for future clinical and economic analyses of novel HDV treatments that can support healthcare stakeholders in the management of patients with chronic HDV.

Advances and Challenges in Managing Hepatitis D Virus: Evolving Strategies

Purpose of Review

Hepatitis D Virus (HDV), although a small defective virus, poses a substantial public health challenge due to lack of awareness, underrecognized prevalence, and limited treatment options. Universal HDV screening within hepatitis B virus (HBV) cohorts is essential to address this issue. Despite its aggressive nature, effective HDV therapies have remained elusive for over four decades.

Recent Findings

Advances in understanding HDV's biology and clinical behavior offer potential therapeutic breakthroughs, fostering optimism. As insights grow, effective and targeted therapies are being developed to improve HDV management.

Summary

This review delves into HDV's intricate structure and biology, highlighting formidable hurdles in antiviral development. It emphasizes the importance of widespread screening, exploring noninvasive diagnostics, and examining current and emerging innovative therapeutic strategies. Moreover, the review explores models for monitoring treatment response. In essence, this review simplifies the complexities of effectively combating HDV.

Modelling HDV kinetics under the entry inhibitor bulevirtide suggests the existence of two HDV-infected cell populations

Background & Aims

Bulevirtide (BLV) was approved for the treatment of compensated chronic hepatitis D virus (HDV) infection in Europe in 2020. However, research into the effects of the entry inhibitor BLV on HDV-host dynamics is in its infancy.

Methods

Eighteen patients with HDV under nucleos(t)ide analogue treatment for hepatitis B, with compensated cirrhosis and clinically significant portal hypertension, received BLV 2 mg/day. HDV RNA, alanine aminotransferase (ALT), and hepatitis B surface antigen (HBsAg) were measured at baseline, weeks 4, 8 and every 8 weeks thereafter. A mathematical model was developed to account for HDV, HBsAg and ALT dynamics during BLV treatment.

Results

Median baseline HDV RNA, HBsAg, and ALT were 4.9 log IU/ml [IQR: 4.4-5.8], 3.7 log IU/ml [IQR: 3.4-3.9] and 106 U/L [IQR: 81-142], respectively. During therapy, patients fit into four main HDV kinetic patterns: monophasic (n = 2), biphasic (n = 10), flat-partial response (n = 4), and non-responder (n = 2). ALT normalization was achieved in 14 (78%) patients at a median of 8 weeks (range: 4-16). HBsAg remained at pre-treatment levels. Assuming that BLV completely (∼100%) blocks HDV entry, modeling indicated that two HDV-infected cell populations exist: fast HDV clearing (median t1/2 = 13 days) and slow HDV clearing (median t1/2 = 44 days), where the slow HDV-clearing population consisted of ∼1% of total HDV-infected cells, which could explain why most patients exhibited a non-monophasic pattern of HDV decline. Moreover, modeling explained ALT normalization without a change in HBsAg based on a non-cytolytic loss of HDV from infected cells, resulting in HDV-free HBsAg-producing cells that release ALT upon death at a substantially lower rate compared to HDV-infected cells.

Conclusion

The entry inhibitor BLV provides a unique opportunity to understand HDV, HBsAg, ALT, and host dynamics.

Impact and implications

Mathematical modeling of hepatitis D virus (HDV) treatment with the entry inhibitor bulevirtide (BLV) provides a novel window into the dynamics of HDV RNA and alanine aminotransferase. Kinetic data from patients treated with BLV monotherapy can be explained by hepatocyte populations with different basal HDV clearance rates and non-cytolytic clearance of infected cells. While further studies are needed to test and refine the kinetic characterization described here, this study provides a new perspective on viral dynamics, which could inform evolving treatment strategies for HDV.

Determinants of worse liver-related outcome according to HDV infection among HBsAg positive persons living with HIV: Data from the ICONA cohort

OBJECTIVES

We aimed to study hepatitis D virus (HDV) prevalence and risk of progression to severe liver-related events (SLRE) in HBsAg positive people living with HIV (PLWH) in Italy; role of HDV-RNA copy levels, HCV coinfection and nadir CD4 counts were also investigated.

METHODS

People living with HIV (PLWH) from Italian Foundation cohort Naïve antiretrovirals (ICONA) with available HBsAg and HDV Ab were enrolled. HBsAg, HDV Ab, HDV-RNA and HDV genotypes were tested.

PRIMARY END-POINT

time from first HDV screening to Severe Liver Related Events (SLRE: decompensated cirrhosis, liver transplantation, HCC). Fine-grey regression models were used to evaluate the association of HDV Ab, HDV-RNA, HDV/HCV coinfection, CD4 nadir and outcome. Secondary end-points: time to SLRE or death; HDV Ab and HDV-RNA prevalence.

RESULTS

A total of 152/809 (18.8%) HBsAg positive PLWH showed HDV Ab reactivity; 63/93 (67.7%) were HDV-RNA positive. Being male, persons who inject drugs (PWID), HCV Ab positive, with FIB-4 > 3.25 were independent factors of HDV Ab positivity. In a median follow-up of 5 years, 37 PLWH (4.1% at 5-year) developed SLRE and 97 (12.0%) reached the SLRE or death end-point. HDV-RNA positive (independently from HDV-RNA copy level) PLWH had a 4.6-fold (95%CI 2.0-10.5) higher risk of SLRE than HDV negatives. PLWH positive for both HCV Ab and HDV Ab showed the highest independent risk of SLRE (ASHR: 11.9, 95%CI: 4.6-30.9 vs. HCV neg/HDV neg). Nadir CD4 < 200/mL was associated with SLRE (ASHR: 3.9, 95% 1.0-14.5).

CONCLUSIONS

One-fifth of the HBsAg positive PLWH harbour HDV infection, and are at high risk of progression to advanced liver disease. HCV contributes to worse outcomes. This population needs urgently effective treatments.

State of the Art: Test all for Anti-Hepatitis D Virus and Reflex to Hepatitis D Virus RNA Polymerase Chain Reaction Quantification

Diagnosis of HDV exposure is based on clinical assays of anti-hepatitis D antibody and current infection with hepatitis D RNA PCR. The role of hepatitis D antigen testing is not yet defined. RT-qPCR is the gold standard for measuring HDV RNA viral load, which is used to assess response to the treatment of HDV infection. Gaps in testing include poor sensitivity of antigen testing and quantitative HDV RNA accuracy can be affected by the genotypic variability of the virus and variation in laboratory techniques. There is also a limitation in HDV testing due to access, cost, and limited knowledge of testing indications. Droplet digital PCR promises to be a more accurate method to quantify HDV RNA. Also, the recent development of a rapid HDV detection test could prove useful in resource-limited areas.

Guidance on treatment endpoints and study design for clinical trials aiming to achieve cure in chronic hepatitis B and D: Report from the 2022 AASLD-EASL HBV-HDV Treatment Endpoints Conference

Representatives from academia, industry, regulatory agencies, and patient advocacy groups convened under the American Association for the Study of Liver Diseases (AASLD) and the European Association for the Study of the Liver (EASL) in June 2022 with the primary goal of achieving consensus on chronic HBV and HDV treatment endpoints to guide clinical trials aiming to "cure" HBV and HDV. Conference participants reached an agreement on some key points. The preferred primary endpoint for phase II/III trials evaluating finite treatments for chronic hepatitis B (CHB) is a "functional" cure, defined as sustained HBsAg loss and HBV DNA less than the lower limit of quantitation (LLOQ) 24 weeks off-treatment. An alternate endpoint would be "partial cure" defined as sustained HBsAg level <100 IU/mL and HBV DNA Collapse

Key Words

• HBV
• HDV
• diagnosis

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MESH Headings

• Humans
• Hepatitis B, Chronic/drug therapy
• Hepatitis B, Chronic/virology
• Hepatitis B, Chronic/therapy
• Antiviral Agents/therapeutic use
• Hepatitis D, Chronic/drug therapy
• Hepatitis Delta Virus/genetics
• Research Design
• Clinical Trials as Topic/methods
• DNA, Viral/blood
• DNA, Viral/analysis
• Hepatitis B virus/genetics
• Hepatitis B Surface Antigens/blood
• Endpoint Determination/methods
• Treatment Outcome
• Clinical Trials, Phase II as Topic/methods

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Grants

• 001 World Health Organization

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Affiliation(s)

Marc G Ghany Liver Diseases Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland, USA.
Maria Buti Liver Unit, Vall d'Hebron University Hospital and CIBEREHD del Instituto Carlos III, Barcelona, Spain
Pietro Lampertico Division of Gastroenterology and Hepatology, Milan, Italy; CRC "A. M. and A. Migliavacca" Center for Liver Disease, Milan, Italy
Hannah M Lee Department of Gastroenterology, Hepatology and Nutrition, Stravitz Sanyal Institute for Liver Disease and Metabolic Health, Virginia Commonwealth University, Richmond, Virginia, USA

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Hepatitis delta: Epidemiology to recent advances in therapeutic agents

Hepatitis D virus (HDV) was first described in 1977 and is dependent on the presence of hepatitis B surface antigen (HBsAg) for its entry into cells and on the human host for replication. Due to the envelopment with the hepatitis B virus (HBV) envelope, early phases of HDV entry resemble HBV infection. Unlike HBV, HDV activates innate immune responses. The global prevalence of HDV is estimated to be about 5% of HBsAg positive individuals. However, recent studies have described a wide range of prevalence between 12 to 72 million individuals. Infection can occur as super-infection or co-infection. The diagnosis of active HDV infection involves screening with anti HDV antibodies followed by quantitative PCR testing for HDV RNA in those who are HBsAg positive. The diagnostic studies have evolved over the years improving the validity and reliability of the tests performed. HDV infection is considered the most severe form of viral hepatitis and the HDV genotype may influence the disease course. There are eight major HDV genotypes with prevalence varying by geographic region. HDV treatment has been challenging as HDV strongly depends on the host cell for replication and provides few, if any viral targets. Better understanding of HDV virology has led to the development of several therapeutic agents currently being studied in different phase II and III clinical trials. There is increasing promise of effective therapies that will ameliorate the course of this devastating disease.

HDV RNA assays: Performance characteristics, clinical utility, and challenges

Coinfection with HBV and HDV results in hepatitis D, the most severe form of chronic viral hepatitis, frequently leading to liver decompensation and HCC. Pegylated interferon alpha, the only treatment option for chronic hepatitis D for many years, has limited efficacy. New treatments are in advanced clinical development, with one recent approval. Diagnosis and antiviral treatment response monitoring are based on detection and quantification of HDV RNA. However, the development of reliable HDV RNA assays is challenged by viral heterogeneity (at least 8 different genotypes and several subgenotypes), intrahost viral diversity, rapid viral evolution, and distinct secondary structure features of HDV RNA. Different RNA extraction methodologies, primer/probe design for nucleic acid tests, lack of automation, and overall dearth of standardization across testing laboratories contribute to substantial variability in performance characteristics of research-based and commercial HDV RNA assays. A World Health Organization (WHO) standard for HDV RNA, available for about 10 years, has been used by many laboratories to determine the limit of detection of their assays and facilitates comparisons of RNA levels across study centers. Here we review challenges for robust pan genotype HDV RNA quantification, discuss particular clinical needs and the importance of reliable HDV RNA quantification in the context of drug development and patient monitoring. We summarize distinct technical features and performance characteristics of available HDV RNA assays. Finally, we provide considerations for the use of HDV RNA assays in the context of drug development and patient monitoring.

Diagnosis and Management of Hepatitis Delta Virus Infection

Hepatitis D virus (HDV) depends on hepatitis B virus (HBV) to enter and exit hepatocytes and to replicate. Despite this dependency, HDV can cause severe liver disease. HDV accelerates liver fibrosis, increases the risk of hepatocellular carcinoma, and hastens hepatic decompensation compared to chronic HBV monoinfection. The Chronic Liver Disease Foundation (CLDF) formed an expert panel to publish updated guidelines on the testing, diagnosis, and management of hepatitis delta virus. The panel group performed network data review on the transmission, epidemiology, natural history, and disease sequelae of acute and chronic HDV infection. Based on current available evidence, we provide recommendations for screening, testing, diagnosis, and treatment of hepatitis D infection and review upcoming novel agents that may expand treatment options. The CLDF recommends universal HDV screening for all patients who are Hepatitis B surface antigen-positive. Initial screening should be with an assay to detect antibodies generated against HDV (anti-HDV). Patients who are positive for anti-HDV IgG antibodies should then undergo quantitative HDV RNA testing. We also provide an algorithm that describes CLDF recommendations on the screening, diagnosis, testing, and initial management of Hepatitis D infection.

Treatment endpoints for chronic hepatitis D

Management of chronic hepatitis D (CHD) has entered a new era. In this new era, the virus entry inhibitor bulevirtide has received conditional approval as a treatment for compensated CHD. Three phase 3 studies with two new compounds are ongoing for the treatment of CHD. In this context, surrogate markers of treatment efficacy have been well defined for chronic hepatitis B (CHB) (7) and chronic hepatitis C (8) but not for CHD. The aim of this review is to give a perspective on treatment endpoints in CHD. For this, we took guidance from CHB studies and tried to make suggestions which differed according to finite versus prolonged treatment durations and also took into account the different characteristics of the new compounds.

Hepatitis Delta Infection: A Clinical Review

First discovered over 40 years ago, the hepatitis delta virus (HDV) is a unique RNA virus, requiring hepatitis B virus (HBV) antigens for its assembly, replication, and transmission. HBV and HDV can be acquired at the same time (coinfection) or HDV infection can occur in persons with chronic HBV (superinfection). Screening guidelines for HDV are inconsistent. While some guidelines recommend universal screening for all people with HBV, others recommend risk-based screening. Estimates of the global HDV prevalence range from 4.5 to 14.6% among persons with HBV; thus, there may be up to 72 million individuals with HDV worldwide. HDV is the most severe form of viral hepatitis. Compared to HBV monoinfection, HDV coinfection increases the risk of cirrhosis, hepatocellular carcinoma, hepatic decompensation, mortality, and necessity for liver transplant. Despite the severity of HDV, there are few treatment options. Pegylated interferon (off-label use) has long been the only available treatment, although bulevirtide is conditionally approved in some European countries. There are many potential treatments in development, but as yet, there are few effective and safe therapies for HDV infection. In conclusion, given the severity of HDV disease and the paucity of treatments, there is a great unmet need for HDV therapies.

EASL Clinical Practice Guidelines on hepatitis delta virus

Hepatitis D virus (HDV) is a defective virus that requires the hepatitis B virus to complete its life cycle and cause liver damage in humans. HDV is responsible for rare acute and chronic liver diseases and is considered the most aggressive hepatitis virus. Acute infection can cause acute liver failure, while persistent infection typically causes a severe form of chronic hepatitis which is associated with rapid and frequent progression to cirrhosis and its end-stage complications, hepatic decompensation and hepatocellular carcinoma. Major diagnostic and therapeutic innovations prompted the EASL Governing Board to commission specific Clinical Practice Guidelines on the identification, virologic and clinical characterisation, prognostic assessment, and appropriate clinical and therapeutic management of HDV-infected individuals.

Natural history of untreated HDV patients: Always a progressive disease?

A severe course has been described in early studies on chronic hepatitis D (CHD), with faster pace towards liver cirrhosis with subsequent high liver-related morbidity and mortality in the majority of patients. Earlier studies have included risk groups as people using intravenous drugs (PWID) or those with multiple co-morbidities. During the last decade, the epidemiological landscape of CHD has changed with domestic cases decreasing while increasing cases of CHD consisting of younger persons immigrating from endemic regions to low-endemic regions. Recently, further insights into the spectrum of the disease with an indolent disease course in a substantial proportion of persons with CHD have been gained. At diagnosis, ≥30%-50% had already established liver cirrhosis. Older age, liver cirrhosis, co-infection with HIV and lack of interferon (IFN) therapy are the main predictors of worse clinical outcome. The newly introduced and upcoming antivirals against CHD are highly anticipated, considering the historically low virological response rates to antiviral therapy. Further knowledge is needed to fully comprehend the natural course and the spectrum of this severe form of viral hepatitis. This is also to be able to evaluate the long-term effects of the new antivirals on disease progression.

Hepatitis delta virus infection prevalence, diagnosis and treatment in the Middle East: A scoping review

Hepatitis D virus (HDV) infection is a global public health concern, especially because of its unique existence in the presence of hepatitis B virus infection. HDV infection is estimated to affect 12 million people globally. Having a clearer understanding of its prevalence in all regions of the world is essential for helping direct preventive and early interventional treatment. This mini-review assessed the literature over the last 10 years to determine the prevalence, diagnostic means and treatment guidelines available for HDV in the Middle East. The search found limited data available in 21 articles, of which 18 were studies focused on Iran. Prevalence rates ranged dramatically among the countries, and none of the 12 countries included in the search had specific HDV guidelines. This review highlights the urgent need for more precise data for the Middle East region to help establish early diagnosis and treatment options for HDV.

A Phase 3, Randomized Trial of Bulevirtide in Chronic Hepatitis D

BACKGROUND

Coinfection with hepatitis D virus (HDV) accelerates the progression of liver disease associated with chronic hepatitis B. Bulevirtide inhibits the entry of HDV into hepatocytes.

METHODS

In this ongoing phase 3 trial, patients with chronic hepatitis D, with or without compensated cirrhosis, were randomly assigned, in a 1:1:1 ratio, to receive bulevirtide subcutaneously at 2 mg per day (2-mg group) or 10 mg per day (10-mg group) for 144 weeks or to receive no treatment for 48 weeks followed by bulevirtide subcutaneously at 10 mg per day for 96 weeks (control group). Patients will complete 96 weeks of additional follow-up after the end of treatment. The primary end point was a combined response at week 48 of an undetectable HDV RNA level, or a level that decreased by at least 2 log10 IU per milliliter from baseline, and normalization of the alanine aminotransferase (ALT) level. The key secondary end point was an undetectable HDV RNA level at week 48, in a comparison between the 2-mg group and the 10-mg group.

RESULTS

A total of 49 patients were assigned to the 2-mg group, 50 to the 10-mg group, and 51 to the control group. A primary end-point response occurred in 45% of patients in the 2-mg group, 48% in the 10-mg group, and 2% in the control group (P<0.001 for the comparison of each dose group with the control group). The HDV RNA level at week 48 was undetectable in 12% of patients in the 2-mg group and in 20% in the 10-mg group (P = 0.41). The ALT level normalized in 12% of patients in the control group, 51% in the 2-mg group (difference from control, 39 percentage points [95% confidence interval {CI}, 20 to 56]), and 56% in the 10-mg group (difference from control, 44 percentage points [95% CI, 26 to 60]). Loss of hepatitis B virus surface antigen (HBsAg) or an HBsAg level that decreased by at least 1 log10 IU per milliliter did not occur in the bulevirtide groups by week 48. Headache, pruritus, fatigue, eosinophilia, injection-site reactions, upper abdominal pain, arthralgia, and asthenia were more common in the 2-mg and 10-mg groups combined than in the control group. No treatment-related serious adverse events occurred. Dose-dependent increases in bile acid levels were noted in the 2-mg and 10-mg groups.

CONCLUSIONS

After 48 weeks of bulevirtide treatment, HDV RNA and ALT levels were reduced in patients with chronic hepatitis D. (Funded by Gilead Sciences; MYR 301 ClinicalTrials.gov number, NCT03852719.).

Emerging drugs for hepatitis D

INTRODUCTION

Chronic hepatitis delta (CHD) is the most severe form of chronic viral hepatitis. Until recently, its treatment consisted of pegylated interferon alfa (pegIFN) use.

AREAS COVERED

Current and new drugs for treating CHD. Virus entry inhibitor bulevirtide has received conditional approval by the European Medicines Agency. Prenylation inhibitor lonafarnib and pegIFN lambda are in phase 3 and nucleic acid polymers in phase 2 of drug development.

EXPERT OPINION

Bulevirtide appears to be safe. Its antiviral efficacy increases with treatment duration. Combining bulevirtide with pegIFN has the highest antiviral efficacy short-term. The prenylation inhibitor lonafarnib prevents hepatitis D virus assembly. It is associated with dose dependent gastrointestinal toxicity and is better used with ritonavir which increases liver lonafarnib concentrations. Lonafarnib also possesses immune modulatory properties which explains some post-treatment beneficial flare cases. Combining lonafarnib/ritonavir with pegIFN has superior antiviral efficacy. Nucleic acid polymers are amphipathic oligonucleotides whose effect appears to be a consequence of phosphorothioate modification of internucleotide linkages. These compounds led to HBsAg clearance in a sizeable proportion of patients. PegIFN lambda is associated with less IFN typical side effects. In a phase 2 study it led to 6 months off treatment viral response in one third of patients.

Hepatitis delta coinfection in persons with HIV: misdiagnosis and disease burden in Italy

Hepatitis Delta virus (HDV) causes severe liver disease. Due to similarities in transmission routes, persons living with HIV (PLWH) are at risk of HDV infection. This analysis investigates the prevalence and the long-term clinical outcome of people with HDV in a large cohort of PLWH. We retrieved HBsAg ± anti-HDV positive PLWH enrolled from 1997 to 2015 in the multicentre, prospective ICONA study. The primary endpoint was a composite clinical outcome (CCO = having experienced ≥1 of the following: Fib4 score >3.25; diagnosis of cirrhosis; decompensation; hepatocellular carcinoma or liver-related death). Kaplan-Meier curves and unweighted and weighted Cox regression models were used for data analysis. Less than half of HBsAg positive patients had been tested for anti-HDV in clinical practice. After testing stored sera, among 617 HBV/HIV cases, 115 (19%) were anti-HDV positive; 405 (65%) HBV monoinfected; 99 (16%) undeterminate. The prevalence declined over the observation period. HDV patients were more often males, intravenous drug users, HCV coinfected. After a median of 26 months, 55/115 (48%) developed CCO among HDV+; 98/403 (24%) among HBV monoinfected; 18/99 (18%) in HDV unknown (p < 0.001). After controlling for geographical region, alcohol consumption, CD4 count, anti-HCV status and IFN-based therapies, the association with HDV retained statistical significance [HR = 1.67 (1.15, 2.95; p = 0.025)]. HDV infection among PLWH is underdiagnosed, although HDV entails an high risk of liver disease progression. Because effective drugs to treat HDV are now available, it is even more crucial to identify PLWH at an early stage of liver disease.

Bulevirtide in the Treatment of Hepatitis Delta: Drug Discovery, Clinical Development and Place in Therapy

It has been ten years since the identification of NTCP as the cell surface receptor for HBV and HDV entry into hepatocytes. The search for molecules interfering with the binding of NTCP and HBV/HDV led to design bulevirtide (BLV). This large polypeptide mimics a region of the pre-S1 HBsAg and blocks viral entry by inhibitory competition. BLV was initially tested in cell cultures, animal models and more recently in Phase I-III human trials (called 'MYRS'). As monotherapy or in combination with peginterferon, BLV is well tolerated and exhibits potent antiviral activity. Plasma viremia significantly declines and/or becomes undetectable in more than 75% of patients treated for >24 weeks. However, serum HBsAg concentrations remain unchanged. No selection of BLV resistance in HBV/HDV has been reported in vivo to date. BLV is administered subcutaneously once daily at doses between 2 and 10 mg. BLV received conditional approval in Europe in 2020 to treat chronic hepatitis delta. The advent of peginterferon lambda or new specific anti-HDV antivirals (lonafarnib, etc.) will open the door for combination therapies with BLV. Since there is no stable reservoir for HDV-RNA within infected hepatocytes, viral clearance might be achieved using antivirals for a minimum timeframe. This is what happens in hepatitis C combining several antivirals, curing nearly all patients treated for 3 months. Clearance of HDV-RNA genomes may occur despite HBV persistence as cccDNA or chromosome integrated HBV-DNA within hepatocytes. This is supported by cases of HDV elimination using BLV despite persistence of serum HBsAg. Another path for HDV cure will derive from achieving HBsAg clearance, the goal of new promising anti-HBV gene therapies (bepirovirsen, etc.). In summary, the advent of BLV has triggered a renovated interest for antiviral therapy in hepatitis delta. We envision combination therapies that will lead to HDV cure in the near future.

Hepatitis D virus: Improving virological knowledge to develop new treatments

Hepatitis delta virus (HDV), a satellite of hepatitis B virus (HBV), possesses the smallest viral genome known to infect animals. HDV needs HBV surface protein for secretion and entry into target liver cells. However, HBV is dispensable for HDV genome amplification, as it relies almost exclusively on cellular host factors for replication. HBV/HDV co-infections affect over 12 million people worldwide and constitute the most severe form of viral hepatitis. Co-infected individuals are at higher risk of developing liver cirrhosis and hepatocellular carcinoma compared to HBV mono-infected patients. Bulevirtide, an entry inhibitor, was conditionally approved in July 2020 in the European Union for adult patients with chronic hepatitis delta (CHD) and compensated liver disease. There are several drugs in development, including lonafarnib and interferon lambda, with different modes of action. In this review, we detail our current fundamental knowledge of HDV lifecycle and review antiviral treatments under development against this virus, outlining their respective mechanisms-of-action. Finally, we describe the antiviral effect these compounds are showing in ongoing clinical trials, discussing their promise and potential pitfalls for managing HDV infected patients.

Safety and efficacy of bulevirtide in combination with tenofovir disoproxil fumarate in patients with hepatitis B virus and hepatitis D virus coinfection (MYR202): a multicentre, randomised, parallel-group, open-label, phase 2 trial

BACKGROUND

Bulevirtide is a first-in-class peptidic entry inhibitor for hepatitis B virus (HBV) and hepatitis D virus infection. In July, 2020, bulevirtide 2 mg received conditional marketing authorisation by the European Medical Agency for treatment of chronic hepatitis D virus infection. We investigated the antiviral activity of bulevirtide in patients chronically infected with HBV and hepatitis D virus.

METHODS

MYR202 (ClinicalTrials.gov, NCT03546621; EudraCT, 2016-000395-13) was a multicentre, parallel-group, randomised, open-label, phase 2 trial. Adults (aged 18-65 years) with chronic hepatitis D virus infection, including patients with cirrhosis and patients who had contraindications to PegIFNα treatment or for whom treatment did not work, were eligible and were enrolled from four hospitals in Germany and 12 hospitals in Russia. Patients were randomly assigned (1:1:1:1) to receive 2 mg (n=28), 5 mg (n=32), or 10 mg (n=30) subcutaneous bulevirtide once per day with tenofovir disoproxil fumarate (TDF; 245 mg once per day orally) or TDF alone (245 mg once per day orally; n=30) for 24 weeks. Randomisation was done using a digital block scheme with stratification, consisting of 480 randomisation numbers separated into 30 blocks. The primary endpoint was undetectable hepatitis D virus RNA or 2 log10 IU/mL or higher decline in hepatitis D virus RNA at week 24, which was analysed in the modified intention-to-treat population, including patients who received study medication at least once after randomisation. Hepatitis D virus RNA concentrations were monitored until week 48. Safety was assessed for all patients who received at least one dose of bulevirtide or TDF.

FINDINGS

Between Feb 16, 2016, and Dec 8, 2016, 171 patients with chronic hepatitis D virus infection were screened; 51 were ineligible based on the exclusion criteria and 120 patients (59 with cirrhosis) were enrolled. At week 24, 15 (54%, 95% CI 34-73) of 28 patients achieved undetectable hepatitis D virus RNA or a 2 log10 IU/mL or more decline in hepatitis D virus RNA (p<0·0001 vs TDF alone) with 2 mg bulevirtide, 16 (50%, 32-68) of 32 with 5 mg bulevirtide (p<0·0001), and 23 (77%, 58-90) of 30 with 10 mg bulevirtide (p<0·0001), versus one (4%, 0·1-18) of 28 with TDF alone. By week 48 (24 weeks after bulevirtide cessation), hepatitis D virus RNA concentrations had rebounded, with median changes from week 24 to week 48 of 1·923 log10 IU/mL (IQR 0·566-2·485) with 2 mg bulevirtide, 1·732 log10 (0·469-2·568) with 5 mg bulevirtide, and 2·030 log10 (1·262-2·903) with 10 mg bulevirtide. There were no deaths associated with treatment. Three (9%) patients in the bulevirtide 5 mg group, two (7%) patients in the bulevirtide 10 mg group, and one (4%) patient in the TDF group had serious adverse events. Common treatment-emergent adverse events included asymptomatic bile salt increases and increases in alanine aminotransferase and aspartate aminotransferase.

INTERPRETATION

Bulevirtide induced a significant decline in hepatitis D virus RNA over 24 weeks. After cessation of bulevirtide, hepatitis D virus RNA concentrations rebounded. Longer treatment durations and combination therapies should be investigated.

FUNDING

Hepatera LLC, MYR GmbH, and the German Centre for Infection Research, TTU Hepatitis.

Bulevirtide monotherapy for 48 weeks in patients with HDV-related compensated cirrhosis and clinically significant portal hypertension

BACKGROUND & AIMS

Bulevirtide (BLV) has recently been conditionally approved for the treatment of chronic hepatitis delta (CHD) in Europe, but its effectiveness and safety in patients with compensated cirrhosis and clinically significant portal hypertension (CSPH) are unknown.

METHODS

Consecutive patients with HDV-related compensated cirrhosis and CSPH who started BLV 2 mg/day were enrolled in this single-center study. Clinical/virological characteristics were collected at baseline, weeks 4, 8 and every 8 weeks thereafter. HDV RNA was quantified by Robogene 2.0 (lower limit of detection 6 IU/ml).

RESULTS

Eighteen Caucasian patients with compensated cirrhosis and CSPH under nucleos(t)ide analogue treatment were enrolled: median (IQR) age was 48 (29-77) years, and 67% were male. Median (IQR) platelet count was 70 (37-227) x10³/μl, liver stiffness measurement (LSM) 16.4 (7.8-57.8) kPa, alanine aminotransferase (ALT) 106 (32-222) U/L, HBsAg 3.7 (2.5-4.3) log IU/ml, HDV RNA 4.9 (3.3-6.6) log IU/ml. During 48 weeks of BLV monotherapy, HDV RNA declined by 3.1 (0.2-4.3) log IU/ml (p <0.001 vs. baseline), becoming undetectable in 5 patients (23%). A virological response was observed in 14 (78%) patients while a non-response was observed in 2 (11%). ALT decreased to 35 (15-86) U/L (p <0.001 vs. baseline), normalizing in 83% of patients. A combined response was observed in 67% of patients. Aspartate aminotransferase and gamma-glutamyltransferase levels significantly improved. Concerning liver function parameters, albumin values significantly increased and bilirubin remained stable. LSM significantly improved in patients with virological response, while platelet count was unchanged. None of the patients developed decompensating events or hepatocellular carcinoma. BLV was well tolerated, no patient discontinued treatment and the increase in bile acids was fully asymptomatic.

CONCLUSIONS

A 48-week course of BLV 2 mg/day monotherapy is safe and effective even for difficult-to treat patients with HDV-related compensated cirrhosis and CSPH.

LAY SUMMARY

Hepatitis delta virus (HDV) is associated with the most severe form of viral hepatitis. A new treatment for HDV called bulevirtide has recently received conditional approval for patients with chronic HDV infection. However, its safety and effectiveness in patients with more advanced liver disease is not known. Herein, we show that it is safe and effective in patients with HDV-related cirrhosis and clinically significant portal hypertension.

1H, 15N and 13C backbone and side chain solution NMR assignments of the truncated small hepatitis delta antigen Δ60-S-HDAg

Hepatitis D virus (HDV) is a defective virus that relies on hepatitis B virus envelope proteins to complete its replication cycle. The HDV genome contains two isoforms of hepatitis delta antigen: the small and the large hepatitis delta antigens (S- and L-HDAg). Here we report the ¹H, ¹³C and ¹⁵ N backbone and side chain resonance assignments of an N-terminally truncated form of S-HDAg (S^Δ60), which lacks the 1-60 oligomerization domain. We derived secondary structures based on NMR chemical shifts, which will be used in further structural and functional studies. We show that S^Δ60 is partially disordered, and that the central structured part contains two well-defined α-helices of 22 and 17 residues, respectively. A temperature titration allowed to identify the residues involved in hydrogen bonds.

Clinical trials in hepatitis D virus: Measuring success

Chronic hepatitis D infection results in the most severe form of chronic viral hepatitis but currently lacks effective treatment options. Therapy with pegylated interferon alpha is recommended for finite treatment duration by major liver societies. Still, it is plagued by low rates of sustained virologic response (SVR) and frequent relapses even if SVR is achieved. Recently, a wave of investigational therapies has come under evaluation, including bulevirtide, lonafarnib, pegylated interferon lambda, and REP-2139 creating excitement with this viral infection. However, there has been significant variability in the endpoints used to evaluate these therapeutics. One of the recently introduced endpoints is characterized by a decline in HDV RNA by 2 logs, with or without achieving an undetectable serum hepatitis D virus (HDV) RNA, as a marker of virologic response. Furthermore, this measure has been combined with alanine aminotransferase normalization, also known as a biochemical response, to formulate the primary endpoint of several late-stage studies. Per recent guidance by the US Food and Drug Administration, these should be surrogate endpoints that will ultimately portend long-term clinical benefits. These clinical benefits may include reducing the risk of progression to cirrhosis, hepatic decompensation, hepatocellular carcinoma, liver transplantation, and mortality. However, the optimal way to measure success in HDV clinical trials remains unknown and will continue to evolve.

A Review of HDV Infection

Hepatitis D is the most severe viral hepatitis. Hepatitis D virus (HDV) has a very small RNA genome with unique biological properties. It requires for infection the presence of hepatitis B virus (HBV) and is transmitted parenterally, mainly by superinfection of HBsAg carriers who then develop chronic hepatitis D. HDV has been brought under control in high-income countries by the implementation of HBV vaccination, and the clinical pattern has changed to a chronic hepatitis D seen in ageing patients with advanced fibrotic disease; the disease remains a major health concern in developing countries of Africa and Asia. Every HBsAg-positive subject should be tested for HDV serum markers by reflex testing, independently of clinical status. Vaccination against HBV provides the best prophylaxis against hepatitis D. The only therapy available so far has been the poorly performing Interferon alfa; however, several new and promising therapeutic approaches are under study.

Future anti-HDV treatment strategies, including those aimed at HBV functional cure

HDV is a defective virus that uses the HBV surface antigen to enter hepatocytes. It is associated with an accelerated course of liver fibrosis progression and an increased risk of hepatocellular carcinoma. Negative HDV RNA 24 weeks after the end of therapy has been proposed as an endpoint but late relapses make this endpoint suboptimal, hence HBsAg loss appears to be more appropriate. Current HBV antiviral agents have poor activity against HDV hence the search for improved therapy. Drugs only active against HDV, such as lonafarnib, have shown efficacy in combination with nucleoside analogues and peginterferon, but do not lead to HBsAg loss. HBsAg loss sustained 24 weeks after the end of therapy with negative HBV DNA is termed functional cure. Agents that are being investigated for functional cure include those that inhibit replication such as entry inhibitors, polymerase inhibitors and capsid assembly modulators but seldom lead to functional cure. Agents that reduce HBV antigen load such as RNA interference and inhibitors of HBsAg secretion are promising. Immunomodulators on their own seldom achieve functional cure, hence these agents in combination to assess the optimal combination are being investigated. Consequently, agents leading to functional cure of HBV are ideal for both HBV and HDV.

A phase 2 dose-finding study of lonafarnib and ritonavir with or without interferon alpha for chronic delta hepatitis

BACKGROUND AND AIMS

Proof-of-concept studies demonstrated lonafarnib (LNF), a first-in-class oral prenylation inhibitor, efficacy in patients infected with HDV. The lonafarnib with ritonavir for HDV-2 (LOWR-2) study's aim was to identify optimal combination regimens of LNF + ritonavir (RTV) ± pegylated interferon alpha (PEG-IFNα) with efficacy and tolerability for longer-term dosing. Here we report the safety and efficacy at end of treatment for up to 24 weeks.

APPROACH AND RESULTS

Fifty-five patients with chronic HDV were consecutively enrolled in an open-label, single-center, phase 2 dose-finding study. There were three main treatment groups: high-dose LNF (LNF ≥ 75 mg by mouth [po] twice daily [bid] + RTV) (n = 19, 12 weeks); all-oral low-dose LNF (LNF 25 or 50 mg po bid + RTV) (n = 24, 24 weeks), and combination low-dose LNF with PEG-IFNα (LNF 25 or 50 mg po bid + RTV + PEG-IFNα) (n = 12, 24 weeks). The primary endpoint, ≥2 log10 decline or < lower limit of quantification of HDV-RNA from baseline at end of treatment, was reached in 46% (6 of 13) and 89% (8 of 9) of patients receiving the all-oral regimen of LNF 50 mg bid + RTV, and combination regimens of LNF (25 or 50 mg bid) + RTV + PEG-IFNα, respectively. In addition, multiple patients experienced well-tolerated transient posttreatment alanine aminotransferase increases, resulting in HDV-RNA negativity and alanine aminotransferase normalization. The proportions of grade 2 and 3 gastrointestinal adverse events in the high-dose versus low-dose groups were 49% (37 of 76) and only 22% (18 of 81), respectively.

CONCLUSIONS

LNF, boosted with low-dose RTV, is a promising all-oral therapy, and maximal efficacy is achieved with PEG-IFNα addition. The identified optimal regimens support a phase 3 study of LNF for the treatment of HDV.

Therapeutic Advances in Viral Hepatitis A-E

Viral hepatitis remains a significant global health problem. All forms of viral hepatitis A through E (A-E) can lead to acute symptomatic infection, while hepatitis B and C can lead to chronic infection associated with significant morbidity and mortality related to progression to cirrhosis, end-stage-liver disease, and liver cancer. Viral hepatitis occurs worldwide, though certain regions are disproportionately affected. We now, remarkably, have highly effective curative regimens for hepatitis C, and safe and tolerable medications to suppress hepatitis B activity, and to prevent liver damage and slow disease progression. We have effective vaccines for hepatitis A and B which provide long-lasting immunity, while improved sanitation and awareness can curb outbreaks of hepatitis A and E. However, more effective and available preventive and curative strategies are needed to achieve global eradication of viral hepatitis. This review provides an overview of the epidemiology, transmission, diagnosis, and clinical features of each viral hepatitis with a primary focus on current and future therapeutic and curative options.

Management of Delta Hepatitis 45 Years after the Discovery of HDV

In 1977 the viral Delta agent was discovered and subsequently characterized as the hepatitis Delta virus (HDV). HDV infection is associated with HBV infection since the defective HDV needs HBV to infect and replicate in the liver. Even if not a frequent cause of chronic liver disease, HDV infection is responsible for an aggressive progression of hepatitis towards advanced liver disease. At present, no FDA approved treatment exists for this specific form of hepatitis. Interferon alfa has been recommended as off-label therapy by major scientific societies (AASLD, EASL and APASL) and has proved effective in about one quarter of patients. In recent years, new therapeutic approaches have been studied, and EMA has approved a new drug (bulevirtide) for Delta hepatitis. In this review, we encompass the 45-year journey of managing Delta hepatitis and address the most recent developments in treating this severe and aggressive liver disease.

HBcrAg Levels Are Associated With Virological Response to Treatment With Interferon in Patients With Hepatitis Delta

Standard treatment of hepatitis delta virus (HDV) infection remains pegylated-interferon alfa (peg-IFNα) in most centers, which is not only associated with rather low efficacy but several adverse events. Hepatitis B core-related antigen (HBcrAg) is linked to intrahepatic covalently closed circular DNA levels and has previously been suggested as response predictor in IFN-based treatment of hepatitis B virus (HBV) mono-infection. This study aimed to investigate the value of HBcrAg in the management of patients with HBV/HDV co-infection undergoing peg-IFNα treatment. The Hep-Net-International-Delta-Hepatitis-Intervention Trial-2 study included 120 patients co-infected with HBV/HDV. Patients were treated for 96 weeks with peg-IFNα and either tenofovir or placebo. Ninety-nine patients with HDV-RNA results 24 weeks after end of treatment (FU24) were included in this analysis, of whom 32 patients (32.3%) had undetectable HDV RNA at FU24. HBcrAg was measured at baseline, week 12, 24, 48, 96, and FU24. HBcrAg levels showed no significant correlation with HDV RNA but were significantly linked to treatment outcome. HBcrAg levels < 4.5 log IU/mL at baseline, week 24, and week 48 had high negative predictive value (NPV) for achieving undetectable HDV RNA at FU24 (81.8%, 87.1% and 95.0%, respectively). Similarly, HBcrAg levels at week 96 were significantly higher in patients with viral relapse until FU24 (3.0 vs. 3.63 log IU/mL; P = 0.0089). Baseline, week 24, and week 48 HBcrAg levels were also associated with the likelihood of achieving HBsAg level < 100 IU/mL at FU24 (HBcrAg < 3.0 log IU/mL: NPV 91.7%, 90.4% and 92.3%, respectively). Test statistics improved when combining HBcrAg with additional viral and clinical parameters. Conclusion: HBcrAg is linked to treatment response to peg-IFNα in patients with HBV/HDV co-infection and could be a promising marker to determine treatment futility.

Therapy of Chronic Viral Hepatitis: The Light at the End of the Tunnel?

Chronic viral hepatitis determines significant morbidity and mortality globally and is caused by three main etiological actors (Hepatitis B Virus, Hepatitis C Virus, and Hepatitis D Virus) with different replicative cycles and biological behaviors. Thus, therapies change according to the different characteristics of the viruses. In chronic hepatitis B, long term suppressive treatments with nucleoside/nucleotide analogues have had a dramatic impact on the evolution of liver disease and liver-related complications. However, a conclusive clearance of the virus is difficult to obtain; new strategies that are able to eradicate the infection are currently objects of research. The therapy for Hepatitis D Virus infection is challenging due to the unique virology of the virus, which uses the synthetic machinery of the infected hepatocyte for its own replication and cannot be targeted by conventional antivirals that are active against virus-coded proteins. Recently introduced antivirals, such as bulevertide and lonafarnib, display definite but only partial efficacy in reducing serum HDV-RNA. However, in combination with pegylated interferon, they provide a synergistic therapeutic effect and appear to represent the current best therapy for HDV-positive patients. With the advent of Direct Acting Antiviral Agents (DAAs), a dramatic breakthrough has occurred in the therapeutic scenario of chronic hepatitis C. Cure of HCV infection is achieved in more than 95% of treated patients, irrespective of their baseline liver fibrosis status. Potentially, the goal of global HCV elimination by 2030 as endorsed by the World Health Organization can be obtained if more global subsidised supplies of DAAs are provided.

Safety and effectiveness of up to 3 years' bulevirtide monotherapy in patients with HDV-related cirrhosis

The entry inhibitor bulevirtide (BLV) received conditional approval from the EMA in July 2020 for the treatment of adult patients with compensated chronic hepatitis delta. However, the effectiveness and safety of BLV administered as monotherapy beyond 48 weeks in difficult-to-treat patients with HDV-related cirrhosis is presently unknown. Herein, we describe the first patients with HDV-related compensated cirrhosis who were treated with BLV (10 mg/day as a starting dose) for up to 3 years on a compassionate use program. Patients were also monitored for HBcrAg and HBV RNA levels, and HDV- and HBV-specific T-cell markers. In the patient who stopped BLV at week 48, after achieving a virological and biochemical response, the initial virological and biochemical rebound was followed by alanine aminotransferase normalization coupled with low HDV RNA and HBsAg levels. In the 2 patients treated continuously for 3 years, virological and biochemical responses were maintained throughout the treatment period even after dose reduction. In a patient with advanced compensated cirrhosis, liver function tests significantly improved, esophageal varices disappeared, and histological/laboratory features of autoimmune hepatitis resolved. Overall, no safety issues were recorded, as bile salt increase was asymptomatic. While serum HBV RNA levels remained undetectable in all patients, HBV core-related antigen levels showed a progressive, yet modest decline during long-term BLV treatment. No HDV-specific interferon-γ-producing T cells were detected, neither after HDV reactivation (after BLV withdrawn in Patient 1) nor during 3 years of BLV treatment. In conclusion, this report shows that continuous administration of BLV monotherapy for 3 years leads to excellent virological and clinical responses in patients with HDV-related cirrhosis who had contraindications to interferon-based therapies.

[Bulevirtide as the first specific agent against hepatitis D virus infections-mechanism and clinical effect]

Die Blockade des Zelleintritts von Krankheitserregern ist ein geeigneter Ansatz, um Neuinfektionen zu verhindern. Der therapeutische Einsatz von Eintrittsinhibitoren bei chronisch infizierten Patienten war jedoch bisher nur begrenzt erfolgreich. Zur Behandlung von chronischen Hepatitis-D-Virus-(HDV-)Infektionen wurde im Juli 2020 mit Bulevirtide (BLV) ein vielversprechender Wirkstoff bedingt zugelassen, der auf diesem Wirkprinzip beruht. Zuvor hatten für HDV keine gezielte Medikation zur Verfügung gestanden und die Behandlung beruhte auf dem Off-Label-Einsatz von Interferon-Alpha/Peginterferon-Alpha (IFNα/Peg-IFNα). In diesem Beitrag wird ein Überblick über die Grundlagen des Wirkmechanismus von BLV gegeben und bisher vorliegende klinische Daten werden zusammengefasst.

Eine HDV-Infektion manifestiert sich als Ko- oder Superinfektion bei Hepatitis-B-Virus-(HBV-)Infektionen und betrifft 4,5–15 % der HBV-Patienten weltweit. HDV nutzt die Hüllproteine von HBV zur Verbreitung. BLV wirkt, indem es den HBV/HDV-Rezeptor natriumtaurocholat-co-transportierendes Polypeptid (NTCP) blockiert und so den Eintritt von HBV/HDV in Hepatozyten verhindert. BLV senkt die HDV-Serum-RNA-Spiegel und führt bei HBV/HDV-infizierten Personen zur Normalisierung der Alanin-Aminotransferase-(ALT-)Werte. Es hat ein ausgezeichnetes Sicherheitsprofil, selbst wenn es über 48 Wochen in hohen Dosen (10 mg täglich) verabreicht wird. In Kombination mit Peg-IFNα zeigt BLV synergistische Effekte auf die Senkung der HDV-RNA im Serum, aber auch auf die Hepatitis-B-Oberflächenantigen-(HBsAg‑)Spiegel. Dies führte bei einer Untergruppe von Patienten zu einer funktionellen Heilung, wenn 2 mg BLV plus Peg-IFNα verabreicht wurden. Der Mechanismus dieser wahrscheinlich immunvermittelten Eliminierung wird in Folgestudien untersucht.

[Delta hepatitis: Epidemiology, diagnostic, natural history and treatment]

Hepatitis B virus is a small enveloped RNA virus, which replicates independently but requires the hepatitis B virus (HBV) to provide the envelope proteins necessary for the assembly of its own viral particles. Approximately 5% of chronic hepatitis B virus carriers are infected with HDV. HBV vaccination remains the best preventive treatment for HDV. All HBV patients should be screened for HDV (anti-HDV serology). In case of positive HDV serology, HDV replication (HDV RNA) should be investigated using a sensitive and specific technique. Hepatitis Delta is often complicated by cirrhosis and hepatocellular carcinoma (HCC). For this reason, every patient with Delta cirrhosis should be screened for HCC by abdominal ultrasound every 6 months. The historical treatment was based on PEG-IFN with many side effects. A new treatment has been approved, Bulevirtide (Hepcludex®) an HDV/HBV entry inhibitor, for any patient with chronic hepatitis Delta infection (CHD) with active replication (except in decompensated cirrhosis), at a dose of 2mg/day by subcutaneous injection. The exact duration on-treatment is unknown, thus treatment should be continued if clinical benefit is observed.

Efficacy and safety of bulevirtide in patients with chronic hepatitis D and compensated cirrhosis

Aim. To study the efficacy and safety of bulevirtide, the HBV and HDV entry inhibitor. Materials and methods. Analysis of the results of using bulevirtide in randomized controlled open-label comparative studies MYR202 and MYR203 in 56 patients with chronic hepatitis D and compensated cirrhosis, in monotherapy and combination with pegylated interferon alpha-2a (PEG-IFN). Results. Monotherapy with bulevirtide for 24 weeks in the MYR202 study in 46 patients with compensated liver cirrhosis demonstrated: 1) a high rate of virological (100%) and biochemical response (alanine aminotransferase normalization rate 45.7%), 2) superiority of bulevirtide in efficacy over the control group (tenofovir), 3) comparability of treatment efficacy in patients with and without cirrhosis, 4) no progression of liver fibrosis with elastometry in most patients. Treatment with bulevirtide in monotherapy and combination with PEG-IFN for 48 weeks in 10 patients with compensated liver cirrhosis in the MYR203 study was accompanied by a high rate of virological response (80%) and normalization of alanine aminotransferase (70%). Bulevirtide was well tolerated, there was no deterioration in tolerability compared with patients without cirrhosis, there were no serious adverse events and cases of treatment cancellation due to adverse events. Conclusion. Bulevirtide is recommended as the first line of treatment for chronic hepatitis D in patients with compensated cirrhosis in monotherapy and combination with PEG-IFN.

The global hepatitis delta virus (HDV) epidemic: what gaps to address in order to mount a public health response?

BACKGROUND

Co-infection between hepatitis B virus (HBV) and hepatitis delta virus (HDV) causes the severest chronic hepatitis and is associated with a high risk of cirrhosis and hepatocellular carcinoma (HCC). The Global Health Sector Strategy on Viral Hepatitis called for the elimination of hepatitis (- 65% mortality and - 90% incidence) by 2030. Our aims were to summarize key points of knowledge and to identify the gaps that need to be addressed to mount a public health response to HDV.

METHODS

We performed a current literature review in terms of epidemiology by WHO regions, genotypes distribution and their pathogenicity, factors associated with HDV infection, mortality due to HDV infection, testing strategies and treatment.

RESULTS

Prevalence of infection and genotypes are heterogeneous distributed, with highest prevalence in foci around the Mediterranean, in the Middle East, and in Central, Northern Asia and Eastern Asia. Persons who inject drugs (PWID) and migrants from highly endemic areas are highly affected. While antibody detection tests are available, HDV RNA tests of current infection are not standardized nor widely available. The few therapeutic options, including lofartinib, are not widely available; however several new and promising agents have entered clinical trials.

CONCLUSION

HDV infection is an poorly known cause of chronic liver disease. To mount a public health response, we need a better description of the HDV epidemic, standardized testing strategies and better treatment options.

The effect of twelve weeks of treatment with ezetimibe on HDV RNA level in patients with chronic hepatitis D

BACKGROUND/AIMS

Sodium taurocholate co-transporting polypeptide (NTCP) is the receptor for the hepatitis B virus (HBV) and hepatitis D virus (HDV) entry into hepatocytes. Ezetimibe is a cholesterol-lowering drug that possesses the pharmacophore features to inhibit NTCP. This study evaluates the efficacy of ezetimibe in patients with chronic HDV infection in a nonrandomized trial.

MATERIALS AND METHODS

This proof of concept phase 2 trial evaluated the efficacy and safety of ezetimibe 10 mg daily in (interferon treatment-experienced or interferon ineligible) patients with chronic hepatitis D (CHD). Forty-four patients with CHD were recruited, 38 male and 6 female patients, mean age 35.2±8.7 (range 19-64). Fifteen (34%) patients were on concomitant nucleoside therapy, and cirrhosis was present in 14 subjects. The primary therapeutic endpoint was a decline in HDV RNA at one log or more from the baseline at week 12.

RESULTS

The mean HDV RNA level was 5.4±1.3 log10 IU/mL. HBeAg was non-reactive in 43 (98%). HBV DNA was undetectable in 28 (64%). One patient stopped treatment at week 4, and one patient did not follow-up. One log or more reduction in the HDV RNA levels was observed in 18/44 (41%) patients. No log reduction occurred in 16 patients, and 8 experienced a log increase. No adverse effects from the concomitant nucleoside analogue use or clinical cirrhosis were observed. The drug exhibited a positive safety profile.

CONCLUSION

Treatment of CHD patients with ezetimibe resulted in a one log reduction of viral load in 43% (18/42) of the patients who completed the 12 weeks of therapy.

Hepatitis D virus (HDV): investigational therapeutic agents in clinical trials

INTRODUCTION

Chronic Hepatitis D virus (HDV) infection is a global disease leading to rapidly progressive liver disease with increased liver-related mortality and hepatocellular carcinoma. Therapies are minimally effective; however, an increased understanding of the HDV lifecycle has provided new potential drug targets. Thus, there is a growing number of investigational therapeutics under exploration for HDV with the potential for successful viral eradication.

AREAS COVERED

This review discusses the clinical impact of HDV infection and offers an in-depth look at the HDV life cycle. The authors examine current and new drug targets and the investigational therapies in clinical trials. The search strategy was based on PubMed database and clinicaltrials.gov which highlight the most up-to-date aspects of investigational therapies for chronic HDV infection.

HBV and HDV: New Treatments on the Horizon

Despite the accumulating knowledge, chronic hepatitis B (CHB) and HDV infection represent a global health problem, and there are still several critical issues, which frequently remain uncovered. In this paper, we provided an overview of the current therapeutic options and summarized the investigational therapies in the pipeline. Furthermore, we discussed some critical issues such as a “functional cure” approach, the futility of long-term NA therapy and the relevance of understanding drug actions and safety of antivirals, especially in special populations.

Hepatitis D virus in 2021: virology, immunology and new treatment approaches for a difficult-to-treat disease

Approximately 5% of individuals infected with hepatitis B virus (HBV) are coinfected with hepatitis D virus (HDV). Chronic HBV/HDV coinfection is associated with an unfavourable outcome, with many patients developing liver cirrhosis, liver failure and eventually hepatocellular carcinoma within 5-10 years. The identification of the HBV/HDV receptor and the development of novel in vitro and animal infection models allowed a more detailed study of the HDV life cycle in recent years, facilitating the development of specific antiviral drugs. The characterisation of HDV-specific CD4+ and CD8+T cell epitopes in untreated and treated patients also permitted a more precise understanding of HDV immunobiology and possibly paves the way for immunotherapeutic strategies to support upcoming specific therapies targeting viral or host factors. Pegylated interferon-α has been used for treating HDV patients for the last 30 years with only limited sustained responses. Here we describe novel treatment options with regard to their mode of action and their clinical effectiveness. Of those, the entry-inhibitor bulevirtide (formerly known as myrcludex B) received conditional marketing authorisation in the European Union (EU) in 2020 (Hepcludex). One additional drug, the prenylation inhibitor lonafarnib, is currently under investigation in phase III clinical trials. Other treatment strategies aim at targeting hepatitis B surface antigen, including the nucleic acid polymer REP2139Ca. These recent advances in HDV virology, immunology and treatment are important steps to make HDV a less difficult-to-treat virus and will be discussed.

One-quarter of chronic hepatitis D patients reach HDV-RNA decline or undetectability during the natural course of the disease

BACKGROUND

Spontaneous HDV-RNA fluctuations, assessed by nonstandardised in-house assays, have been reported during the course of chronic hepatitis delta (CHD).

AIMS

To evaluate changes in serum HDV-RNA concentrations in untreated CHD patients and correlate these changes with other HBV markers.

METHODS

A total of 323 consecutive serum samples from 56 CHD patients (detectable HDV-RNA) followed for >3 years were retested for HDV-RNA levels by a sensitive technique using the first WHO international HDV-RNA standard. Quantitative HBsAg, HBV-DNA, and HBV-RNA were also determined.

RESULTS

Most participants were male, middle-aged, white European, and HBeAg-negative (82%). Almost half had liver cirrhosis and 64% were receiving nucleos(t)ide analogues. At inclusion, median-HDV-RNA was 5.3 (4.2-6.5) log₁₀ IU/mL, HBsAg 4.0 (3.5-4.3) log₁₀ IU/mL, and HBV-DNA 1.6 (1.0-2.6) log₁₀ IU/mL; ALT values were normal in 13 (23%). During a mean follow-up of 5.6 (3-16) years, 14 (25%) showed ≥2log₁₀ HDV-RNA decline, including 11 (20%) who spontaneously achieved undetectable HDV-RNA. Four patients (7%) lost HBsAg, with undetectable HDV-RNA. The remaining 42 (75%) had persistently detectable HDV-RNA. During follow-up, patients with a ≥2log₁₀ HDV-RNA decline showed a greater HBsAg drop (-0.7 ± 1.1 vs -0.09 ± 0.9 log IU/mL; P = 0.039) than those with a <2 log₁₀ HDV-RNA decline. Overall, ALT and HBV-DNA levels decreased over time. There were no differences in clinical outcomes between groups.

CONCLUSIONS

One-quarter of untreated CHD patients showed a ≥2log₁₀ decline in HDV-RNA and 20% reached HDV-RNA undetectability during a mean follow-up of 5.6 years. The decline was associated with ALT decrease. These findings have implications for designing new therapies for CHD.