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

Validation of Baveno VII criteria and other non-invasive diagnostic algorithms for clinically significant portal hypertension in hepatitis delta

BACKGROUND & AIMS

Non-invasive tests (NITs) for clinically significant portal hypertension (CSPH) require validation in patients with hepatitis D virus (HDV)-related compensated advanced chronic liver disease (cACLD). Therefore, we aimed to validate existing NIT algorithms for CSPH in this context.

METHODS

Patients with HDV-cACLD (LSM ≥10 kPa or histological METAVIR F3/F4 fibrosis) who underwent paired HVPG and NIT assessment at Medical University of Vienna or Hannover Medical School between 2013 and 2023 were retrospectively included. Liver stiffness measurement (LSM), von Willebrand factor to platelet count ratio (VITRO), and spleen stiffness measurement (SSM) were assessed. Individual CSPH risk was calculated according to previously published models (ANTICIPATE, 3P/5P). The diagnostic performance of Baveno VII criteria and refined algorithms (Baveno VII-VITRO, Baveno VII-SSM) was evaluated. The prognostic utility of NITs was investigated in the main cohort and an independent, multicenter, validation cohort.

RESULTS

Fifty-one patients (HVPG ≥10 mmHg/CSPH prevalence: 62.7%, varices: 42.2%) were included. Patients with CSPH had significantly higher LSM (25.8 [17.2-31.0] vs. 14.0 [10.5-19.8] kPa; p <0.001), VITRO (n = 31, 3.5 [2.7-4.5] vs. 1.3 [0.6-2.0] %/[G/L]; p <0.001), and SSM (n = 20, 53.8 [41.7-75.5] vs. 24.0 [17.0-33.9] kPa; p <0.001). Composite CSPH risk models yielded excellent AUROCs (ANTICIPATE: 0.885, 3P: 0.903, 5P: 0.912). Baveno VII criteria ruled out CSPH with 100% sensitivity and ruled in CSPH with 84.2% specificity. The Baveno VII 'grey zone' (41.1%) was significantly reduced by Baveno VII-VITRO or Baveno VII-SSM algorithms, which maintained diagnostic accuracy. Hepatic decompensation within 2 years only occurred in patients who had CSPH or met Baveno VII rule-in criteria. The prognostic value of NITs was confirmed in the validation cohort comprising 92 patients.

CONCLUSIONS

Standalone and composite NIT/diagnostic algorithms are useful for CSPH diagnosis in patients with HDV-cACLD. Thus, NITs may be applied to identify and prioritize patients with CSPH for novel antiviral treatments against chronic hepatitis D.

IMPACT AND IMPLICATIONS

Non-invasive tests (NITs) for clinically significant portal hypertension (CSPH) have been developed to identify patients with compensated advanced chronic liver disease (cACLD) at risk of decompensation, but conflicting data has been published regarding the accuracy of liver stiffness measurement (LSM) for the staging of fibrosis in patients infected with hepatitis D virus (HDV). In our study, including 51 patients with HDV-cACLD, LSM- and lab-based NITs yielded high AUROCs for CSPH. Moreover, only patients with CSPH or high non-invasively assessed CSPH risk were at risk of decompensation within 2 years, with the prognostic value of NITs confirmed in a validation cohort. Thus, NITs should be applied and updated in yearly intervals in clinical routine to identify patients with HDV-cACLD at short-term risk of clinical events; NITs may also guide prioritization for novel antiviral treatment options.

Treatment with bulevirtide in HIV-infected patients with chronic hepatitis D: ANRS HD EP01 BuleDelta and compassionate cohort

Background & Aims

In France, bulevirtide (BLV) became available in September 2019 through an early access program to treat patients with HDV. The aim of this analysis was to evaluate the efficacy and safety of BLV in patients with HIV and HDV coinfection.

Methods

Patients received BLV 2 mg ± pegylated interferon-α (pegIFNα) according to the physician's decision. The primary endpoint (per-protocol analysis) was the virological response rate at Week 48, defined as the proportion of patients with undetectable serum HDV RNA or a HDV RNA decline >2 log10 IU/ml from baseline.

Results

The characteristics of the 38 patients were as follows: 28 male, mean age 47.7 years, and mean baseline HDV RNA viral load 5.7 ± 1.2 log10 IU/ml. Median HIV viral load and mean CD4 count were 32 (30-65) copies/ml and 566 ± 307/mm3, respectively. Eight patients stopped treatment before Week 48. At Week 48, 10 of 19 patients (52.6%) in the 2 mg BLV group and five of seven patients (71.4%) in the 2 mg BLV + pegIFNɑ group had reached virological response (no HDV RNA available in four patients). At Week 48, seven of 19 patients in the 2 mg BLV group and three of six patients in the 2 mg BLV + pegIFNɑ group had a combined response (virological response and normal alanine aminotransferase level).

Conclusions

Adults living with HIV coinfected with HDV can be treated by BLV with a virological response in more than 50% of patients. The combination of BLV and pegIFNɑ showed a strong virological response.

Impact and implications

Bulevirtide is the only EMA-approved drug for HDV treatment, and we showed that it can be used in adults living with HIV, with an overall good tolerability. Bulevirtide induces a virological response in more than 50% of patients, suggesting that bulevirtide should be considered as a first-line therapy in this specific population. Bulevirtide in combination with pegIFNα could be used in patients without pegIFNα contraindication. No specific drug-drug interaction is reported. Bulevirtide is the only EMA-approved drug for HDV treatment, and we showed that it can be used in adults living with HIV, with an overall good tolerability. Bulevirtide induces a virological response in more than 50% of patients, suggesting that bulevirtide should be considered as a first-line therapy in this specific population. Bulevirtide in combination with pegIFNα could be used in patients without pegIFNα contraindication. No specific drug-drug interaction is reported. Bulevirtide is the only EMA-approved drug for HDV treatment, and we showed that it can be used in adults living with HIV, with an overall good tolerability. Bulevirtide induces a virological response in more than 50% of patients, suggesting that bulevirtide should be considered as a first-line therapy in this specific population. Bulevirtide in combination with pegIFNα could be used in patients without pegIFNα contraindication. No specific drug-drug interaction is reported.

Advances in hepatitis delta research: emerging insights and future directions

OBJECTIVES

Hepatitis delta virus (HDV) is a defective virus needing the envelope provided by hepatitis B virus (HBV) in order to enter liver cells and propagate. Chronic HDV infection is considered the most severe viral hepatitis, resulting in accelerated fibrosis progression until cirrhosis and its complications (hepatocellular carcinoma, liver decompensation) compared with HBV mono-infected patients. Off-label treatment with interferon has represented the only treatment option in the last 40 years, resulting in suboptimal virological response rates and being limited by safety issues especially in patients with advanced cirrhosis. Recently, the first HBV-HDV entry inhibitor Bulevirtide (BLV) has been approved by the European Medicines Agency (EMA) for treatment of chronic compensated HDV.

METHODS

This review summarises most recent updates on HDV epidemiology, diagnosis and treatment, with a special focus both on clinical trials and real-life studies about BLV. An overview on new HDV compounds under development is also provided.

RESULTS

BLV, the HBV-HDV entry inhibitor, has shown promising safety and efficacy data in clinical trials and in real-life studies, also in patients with advanced cirrhosis and portal hypertension. However, according to EMA label treatment is currently intended long-term until clinical benefit and predictors of responses are still undefined. The potential combination with PegIFNα seems to increase virological and clinical responses. New compounds are under development or in pipeline for treatment of HDV.

CONCLUSION

After more than 40 years since HDV discovery, new treatment options are currently available to provide efficient strategies for chronic hepatitis Delta.

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.

Sodium taurocholate cotransporting polypeptide (NTCP) polymorphisms may influence HDV RNA load and early response to bulevirtide

BACKGROUND & AIMS

Genetic polymorphisms in the sodium taurocholate cotransporting peptide (NTCP encoded by SLC10A1) have been described, but their role in untreated and treated patients with chronic hepatitis delta (CHD) remains unknown. Virological response (VR) to the NTCP inhibitor bulevirtide (BLV) was achieved at week 48 by >70% of patients with CHD, but nearly 15% experienced virological non-response (VNR) or partial response (PR). This study aimed to evaluate whether NTCP genetic polymorphisms affect baseline HDV RNA load and response to BLV in patients with CHD.

METHODS

BLV-untreated and -treated patients were enrolled in a retrospective cross-sectional and longitudinal study. Clinical and virological characteristics were collected at baseline and up to 96 weeks in the BLV-treated patients. NTCP genetic polymorphisms were identified by Sanger sequencing.

RESULTS

Of the six NTCP polymorphisms studied in 209 untreated patients with CHD, carriers of the rs17556915 TT/CC (n = 142) compared to CT (n = 67) genotype presented with higher median HDV RNA levels (5.39 vs. 4.75 log10 IU/ml, p = 0.004). Of 209 patients receiving BLV monotherapy at 2 mg/day, 76 were evaluated at week 24 and 40 up to week 96. Higher mean baseline HDV RNA levels were confirmed in TT/CC (n = 43) compared to CT (n = 33) carriers (5.38 vs. 4.72 log10 IU/ml, p = 0.010). Although 24-week VR was comparable between TT/CC and CT carriers (25/43 vs. 17/33, p = 0.565), the former group presented VNR more often than PR (9/11 vs. 9/23, p = 0.02) at week 24. 7/9 TT/CC genotype carriers remained VNR at week 48 of BLV treatment.

CONCLUSIONS

The NTCP rs17556915 C>T genetic polymorphisms may influence baseline HDV RNA load both in BLV-untreated and -treated patients with CHD and may contribute to identifying patients with different early virological responses to BLV.

IMPACT AND IMPLICATIONS

Although several sodium taurocholate cotransporting polypeptide (NTCP) genetic polymorphisms have been described, no data are available on their potential role in modifying HDV RNA load or treatment response to bulevirtide (BLV) in patients with chronic hepatitis delta (CHD). In this study, we demonstrated that patients with CHD, either treated or untreated, carrying NTCP rs17556915 TT/CC, presented higher baseline HDV RNA levels compared to those with the CT genotype. Higher HDV RNA levels in TT/CC carriers compared to CT carriers were also confirmed in patients with CHD treated with BLV monotherapy up to 96 weeks. Furthermore, carriers of TT/CC, compared to CT genotype, more frequently showed viral non-response (VNR) than partial response (PR) at week 24 of BLV treatment, and 7/9 TT/CC genotype carriers remained VNR at week 48 of BLV treatment. This is the first study demonstrating a potential role of NTCP genetic polymorphisms in influencing HDV viral load and early virological response to BLV monotherapy. Since no direct HDV resistance to BLV has been described so far, if confirmed in larger studies, the genetic polymorphisms in NTCP may help identify patients with different patterns of early virological response to BLV.

Risk factors associated with hepatitis D virus infection and preventive strategies in Mongolia

BACKGROUND

Hepatitis D virus (HDV) infection is highly prevalent in Mongolia. We aimed to identify the risk factors associated with HDV infection, propose preventive strategies, and evaluate the outcomes of a 3-year collaborative project between Taiwan and Mongolia.

METHODS

In 2016 and 2018, we conducted onsite visits to Mongolia. Mongolian investigators collected questionnaires focusing on risk factors, demographic characteristics, and serum samples for acute HDV infections. Furthermore, 19 Mongolian seed teachers participated in a 1-week workshop on infection control in Taiwan. Subsequently, these seed teachers trained more than 400 medical personnel in Mongolia. To assess secular changes in acute HDV infection, we reviewed the registration data from the National Center for Communicable Disease (NCCD) in Mongolia between 2011 and 2021.

RESULTS

Among the 194 Mongolian patients, 108 had dual infection with hepatitis B virus (HBV) and HDV, while 86 had acute hepatitis B (AHB). Patients with HBV/HDV dual infections were older (28.6 vs 25.5 years, p = 0.030) and had lower rates of positive hepatitis B e antigen in their sera, lower rates of serum HBV DNA exceeding 2000 IU/mL, and higher rates of having received dental treatment (59.4% vs 40.5%, p = 0.014) and injection therapy (64.2% vs 44.0%, p = 0.009) compared with those with AHB. Analysis of NCCD data revealed that new HDV infection cases were more prevalent between 2011 and 2015 (111.20 ± 29.79 cases/y) and decreased to 54.67 ± 27.34 cases/y between 2016 and 2021 ( p = 0.010).

CONCLUSION

Dental treatment and injections were associated with a higher risk of acute HDV infections in Mongolia. Through collaborative efforts, the incidence rate of HDV infection has declined in recent years.

[Diagnosis and treatment of viral hepatitis B and D in 2024]

Despite the availability of vaccines, hepatitis B remains a significant cause of fulminant hepatitis, liver cirrhosis and hepatocellular carcinoma worldwide. The increase in reported hepatitis B cases in Germany is attributed to factors such as immigration and the hepatitis B surface antigen (HBsAg) screening introduced in 2020 as part of health check-ups. The indication for treatment depends on various factors, including the level of hepatitis B virus (HBV) DNA and inflammatory activity. Nucleos(t)ide analogues are the preferred treatment option, but functional cure, defined as HBsAg loss, is rare. In principle, treatment with nucleos(t)ide analogues should usually be discontinued after loss of HBsAg, but can be stopped earlier under certain conditions and is currently the subject of ongoing research. Pregnancy and immunosuppression in the context of hepatitis B require special attention. In addition, a possible hepatitis D virus co-infection must always be taken into account, which is why every HBsAg-positive person should be tested for anti-HDV. Since 2020, the entry inhibitor bulevirtide has become a new treatment option alongside pegylated interferon alfa, which represents a significant advance in the treatment landscape.

Efficacy of Newer Nucleos(t)ide Analogs After Hepatitis B Immunoglobulin Discontinuation Against Hepatitis B and D Recurrence in Liver Transplant Recipients

BACKGROUND

The use of nucleos(t)ide analogs (NAs) with a high genetic barrier to resistance, namely entecavir and tenofovir, has improved the efficacy of antiviral prophylaxis against hepatitis B virus (HBV) recurrence after liver transplantation (LT). However, the optimal duration and dosage of hepatitis B immunoglobulin (HBIG) administration, particularly in patients transplanted for HBV and hepatitis D virus (HDV) coinfection, remains controversial.

METHODS

We evaluated 28 patients transplanted for HBV/HDV cirrhosis. After LT, each patient received a fixed scheme of low-dose HBIG plus NA for 6 mo post-LT and then continued with long-term NA prophylaxis (entecavir: 8, tenofovir: 20 patients).

RESULTS

During 72 mo of follow-up, reappearance of hepatitis B surface antigen at low titers was observed in 1 (3.6%) patient at 33 mo after HBIG discontinuation, which became negative after a single dose of HBIG 1000 IU/L, whereas both serum HBV DNA and HDV RNA remained persistently undetectable and without any clinical or biochemical evidence of HBV/HDV recurrence.

CONCLUSIONS

We showed for the first time the efficacy of a short, fixed scheme of low-dose HBIG plus NA followed by long-term NA monoprophylaxis against HBV/HDV recurrence after LT, although careful follow-up is needed after HBIG discontinuation, whereas further larger studies are needed to confirm these findings.

Safety and efficacy of off-label bulevirtide monotherapy in patients with HDV with decompensated Child-B cirrhosis-A real-world case series

BACKGROUND AND AIMS

Chronic hepatitis D is the most debilitating form of viral hepatitis frequently progressing to cirrhosis and subsequent decompensation. However, the HDV entry inhibitor bulevirtide is only approved for antiviral treatment of patients with compensated disease. We aimed for the analysis of real-world data on the off-label use of bulevirtide in the setting of decompensated liver cirrhosis.

APPROACH AND RESULTS

We conducted a retrospective study in patients with HDV with decompensated liver disease at German, Austrian, and Italian centers. We included 19 patients (47% male, mean age: 51 years) with liver cirrhosis Child-Pugh B. The median MELD score was 12 (range 9-17) at treatment initiation. The median observation period was 41 weeks. Virologic response was achieved in 74% and normal alanine aminotransferase was observed in 74%. The combined response was achieved by 42%. The most relevant adverse events included self-limited alanine aminotransferase flares, an asymptomatic increase in bile acids, and the need for liver transplantation. Despite bile acid increases, adverse events were considered unrelated. Clinical and laboratory improvement from Child-Pugh B to A occurred in 47% (n = 9/19). Improvements in the amount of ascites were observed in 58% of the patients initially presenting with ascites (n = 7/12).

CONCLUSIONS

This report on off-label bulevirtide treatment in patients with decompensated HDV cirrhosis shows similar virologic and biochemical response rates as observed in compensated liver disease. Significant improvements were observed in surrogates of hepatic function and portal hypertension. However, this improvement was not seen in all patients. Controlled trials are needed to confirm the safety and efficacy of bulevirtide in decompensated HDV cirrhosis.

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.

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.

Dynamics of Virological and Clinical Response Parameters of Bulevirtide Treatment for Hepatitis D: Real-World Data

Background and Aims

The entry inhibitor bulevirtide represents the first specific treatment for hepatitis-D virus (HDV)-infected patients. In clinical trials, around 80% of patients achieve normalization of alanine aminotransferase (ALT) with about 60% virological response after 1 year, but little is known about the dynamics of responses and clinical predictors of treatment outcomes. We report our single-center data from 15 patients and describe response dynamics, clinical outcomes, and predictive factors for treatment response.

Methods

Retrospective data from 15 patients have been analyzed at our department who started treatment with bulevirtide between 10/2020 and 08/2022. According to our standard procedures, laboratory parameters were controlled monthly; transient elastography was performed every 3 months, and the treatment duration was 12 months.

Results

Treatment response rates after 1 year of treatment were similar to published data from clinical trials. ALT normalization usually occurs between months 2-6 of treatment, followed by a virological response after ≥6 months. Patients with more severe hepatitis at the start of treatment were less likely to respond in the first year of treatment. Loss of HDV-RNA was observed in one-third of patients after ≥1 year of treatment. Low body mass index and high alpha-fetoprotein at baseline were possible predictors of a delayed treatment response.

Conclusion

Bulevirtide is a safe treatment option for HDV, leading to a fast hepatological response. Of note, decrease in transaminases precedes virological response. Patients with high viral load and ALT levels respond slower, but nonresponders (as classified by Food and Drug Administration criteria) still show a reduction in viremia. Longer observation periods are required to determine the optimal duration of bulevirtide monotherapy.

Hepatitis D: A Review

Importance

Hepatitis D virus (HDV) infection occurs in association with hepatitis B virus (HBV) infection and affects approximately 12 million to 72 million people worldwide. HDV causes more rapid progression to cirrhosis and higher rates of hepatocellular carcinoma than HBV alone or hepatitis C virus.

Observations

HDV requires HBV to enter hepatocytes and to assemble and secrete new virions. Acute HDV-HBV coinfection is followed by clearance of both viruses in approximately 95% of people, whereas HDV superinfection in an HBV-infected person results in chronic HDV-HBV infection in more than 90% of infected patients. Chronic hepatitis D causes more rapidly progressive liver disease than HBV alone. Approximately 30% to 70% of patients with chronic hepatitis D have cirrhosis at diagnosis and more than 50% die of liver disease within 10 years of diagnosis. However, recent studies suggested that progression is variable and that more than 50% of people may have an indolent course. Only approximately 20% to 50% of people infected by hepatitis D have been diagnosed due to lack of awareness and limited access to reliable diagnostic tests for the HDV antibody and HDV RNA. The HBV vaccine prevents HDV infection by preventing HBV infection, but no vaccines are available to protect those with established HBV infection against HDV. Interferon alfa inhibits HDV replication and reduces the incidence of liver-related events such as liver decompensation, hepatocellular carcinoma, liver transplant, or mortality from 8.5% per year to 3.3% per year. Adverse effects from interferon alfa such as fatigue, depression, and bone marrow suppression are common. HBV nucleos(t)ide analogues, such as entecavir or tenofovir, are ineffective against HDV. Phase 3 randomized clinical trials of bulevirtide, which blocks entry of HDV into hepatocytes, and lonafarnib, which interferes with HDV assembly, showed that compared with placebo or observation, these therapies attained virological and biochemical response in up to 56% of patients after 96 weeks of bulevirtide monotherapy and 19% after 48 weeks of lonafarnib, ritonavir, and pegylated interferon alfa treatment.

Conclusions and Relevance

HDV infection affects approximately 12 million to 72 million people worldwide and is associated with more rapid progression to cirrhosis and liver failure and higher rates of hepatocellular carcinoma than infection with HBV alone. Bulevirtide was recently approved for HDV in Europe, whereas pegylated interferon alfa is the only treatment available in most countries.

Hepatitis D Virus and HBsAg Dynamics in the era of new Antiviral Treatments

PURPOSE OF REVIEW

Hepatitis D virus (HDV) infection is the most severe form of chronic viral hepatitis, with no FDA-approved therapy. Progress in the development of effective HDV treatments is accelerating. This review highlights how mathematical modeling is improving understanding of HDV-HBsAg-host dynamics during antiviral therapy and generating insights into the efficacy and modes of action (MOA) of new antiviral agents.

RECENT FINDINGS

Clinical trials with pegylated-interferon-λ, bulevertide, nucleic acid polymers, and/or lonafarnib against various steps of the HDV-life cycle have revealed new viral-kinetic patterns that were not observed under standard treatment with pegylated-interferon-α. Modeling indicated that the half-lives of circulating HDV and HBsAg are ~ 1.7 d and ~ 1.3 d, respectively, estimated the relative response of HDV and HBsAg during different antiviral therapies, and provided insights into the efficacy and MOA of drugs in development for treating HDV, which can inform response-guided therapy to individualize treatment duration. Mathematical modeling of HDV and HBsAg kinetics provides a window into the HDV virus lifecycle, HDV-HBsAg-host dynamics during antiviral therapy, and the MOA of new drugs for HDV.

Prevalence and determinants of hepatitis delta virus infection among HIV/hepatitis B-coinfected adults in care in the United States

Hepatitis delta virus (HDV) infection increases the risk of liver complications compared to hepatitis B virus (HBV) alone, particularly among persons with human immunodeficiency virus (HIV). However, no studies have evaluated the prevalence or determinants of HDV infection among people with HIV/HBV in the US. We performed a cross-sectional study among adults with HIV/HBV coinfection receiving care at eight sites within the Center for AIDS Research Network of Integrated Clinical Systems (CNICS) between 1996 and 2019. Among patients with available serum/plasma specimens, we selected the first specimen on or after their initial HBV qualifying test. All samples were tested for HDV IgG antibody and HDV RNA. Multivariable log-binomial generalized linear models were used to estimate prevalence ratios (PRs) with 95% CIs of HDV IgG antibody-positivity associated with determinants of interest (age, injection drug use [IDU], high-risk sexual behaviour). Among 597 adults with HIV/HBV coinfection in CNICS and available serum/plasma samples (median age, 43 years; 89.9% male; 52.8% Black; 42.4% White), 24/597 (4.0%; 95% CI, 2.4%-5.6%) were HDV IgG antibody-positive, and 10/596 (1.7%; 95% CI, 0.6%-2.7%) had detectable HDV RNA. In multivariable analysis, IDU was associated with exposure to HDV infection (adjusted PR = 2.50; 95% CI, 1.09-5.74). In conclusion, among a sample of adults with HIV/HBV coinfection in care in the US, 4.0% were HDV IgG antibody-positive, among whom 41.7% had detectable HDV RNA. History of IDU was associated with exposure to HDV infection. These findings emphasize the importance of HDV testing among persons with HIV/HBV coinfection, especially those with a history of IDU.

No virologic resistance to bulevirtide monotherapy detected in patients through 24 weeks treatment in phase II and III clinical trials for chronic hepatitis delta

BACKGROUND & AIMS

Bulevirtide (BLV) is a HDV/HBV entry inhibitor that is associated with virologic response (responders, HDV-RNA undetectable or ≥2 log10 IU/ml decrease from baseline) in >50% of patients after a 24-week treatment. However, some patients only achieve a <1 log10 IU/ml decline in HDV-RNA after the 24-week treatment (non-responders). Here, we report a viral resistance analysis in participants receiving BLV monotherapy who were non-responders or experienced virologic breakthrough (VB, i.e., two consecutive increases in HDV-RNA of ≥1 log10 IU/ml from nadir or two consecutive HDV-RNA detectable results if previously undetectable) from the phase II MYR202 and phase III MYR301 study.

METHODS

Deep-sequencing of the BLV-corresponding region in HBV PreS1 and of the HDV HDAg gene, as well as in vitro phenotypic testing, were performed for the participant with VB (n = 1) and non-responders (n = 20) at baseline (BL) and Week 24 (WK24).

RESULTS

No amino acid exchanges associated with reduced susceptibility to BLV within the BLV-corresponding region or within HDAg were identified in isolates from any of the 21 participants at BL or at WK24. Although variants (HBV n = 1; HDV n = 13) were detected at BL in some non-responders or in the participant with VB, none were associated with reduced sensitivity to BLV in vitro. Furthermore, the same variant was detected in virologic responders. A comprehensive phenotypic analysis demonstrated that the BLV EC50 values from 116 BL samples were similar across non-responders, partial responders (HDV RNA decline ≥1 but <2 log10 IU/ml), and responders regardless of the presence of HBV and/or HDV polymorphisms.

CONCLUSIONS

No amino acid substitutions associated with reduced sensitivity to BLV monotherapy were detected at BL or WK24 in non-responders or the participant with VB after 24-week BLV treatment.

IMPACT AND IMPLICATIONS

This is the first study investigating the development of resistance in patients treated with BLV. Excluding resistance to BLV as an explanation for an insufficient decrease in HDV-RNA levels during BLV therapy is an important finding for patients, clinicians, and researchers. It demonstrates that BLV has a high barrier to resistance, indicating it is safe and suitable for long-term treatment, although long-term surveillance for resistance should be performed. Our results hint at other still unknown mechanisms as an explanation for the persistence of serum HDV-RNA during inhibition of viral entry.

CLINICAL TRIAL NUMBERS

NCT03546621 and NCT03852719.

Diagnosis of HDV: From virology to non-invasive markers of fibrosis

Hepatitis D viral infection in humans is a disease that requires the establishment of hepatitis B, relying on hepatitis B surface Ag and host cellular machinery to replicate and propagate the infection. Since its discovery in 1977, substantial progress has been made to better understand the hepatitis D viral life cycle, pathogenesis and modes of transmission along with expanding on clinical knowledge related to prevention, diagnosis, monitoring and treatment. The availability of serologic diagnostic assays for hepatitis D infection has evolved over time with current widespread availability, improved detection and standardized reporting. With human migration, the epidemiology of hepatitis D infection has changed over time. Thus, the ability to use diagnostic assays remains essential to monitor the global impact of hepatitis D infection. Separately, while liver biopsy remains the gold standard for the staging of this rapidly progressive and severe form of chronic viral hepatitis, there is an unmet need for clinical monitoring of chronic hepatitis D infection for management of progressive disease. Thus, exploration of the utility of non-invasive fibrosis markers in hepatitis D is ongoing. In this review, we discuss the virology, the evolution of diagnostics and the development of non-invasive markers for the detection and monitoring of fibrosis in patients with hepatitis D infection.

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.

Recent treatment advances and practical management of hepatitis D virus

Hepatitis D virus (HDV), also referred to as hepatitis delta virus, is the smallest virus capable of causing human disease. It is unable to replicate on its own and can only propagate in the presence of hepatitis B virus (HBV). Infection with both HBV and HDV frequently results in more severe disease than HBV alone, with higher instances of cirrhosis, liver failure and hepatocellular carcinoma (HCC). Thus, there is a need for effective treatment for HDV; however, currently approved treatment options are very limited both in terms of their efficacy and availability. This makes the management of HDV a challenge for physicians. In this review, we look at the background, diagnosis and treatment of HDV, informed by our hospital data, to set out the optimal management of HDV; we also explore novel treatment options for this disease.

Bile acid increase during bulevirtide treatment of hepatitis D is not associated with a decline in HDV RNA

Bulevirtide (BLV) is an entry inhibitor blocking entry of HBsAg into hepatocytes by interfering with the bile acid transporter Na+-taurocholate co-transporting polypeptide. We here investigated if bile acid levels before or during BLV treatment would correlate with HDV RNA declines. We studied 20 patients with compensated HDV infection receiving a daily dose of 2 mg bulevirtide subcutaneously qd for at least 24 weeks. ALT levels improved in all patients including 13/20 patients showing normal ALT values at treatment Week 24. An HDV RNA drop of at least 50% was evident in 20/20 patients at Week 24 including 10 patients showing a ≥ 2 log HDV RNA decline. Elevated bile acid levels were detected already before treatment in 10 patients and further increased during BLV administration with different kinetics. Baseline bile acids were associated with higher transient elastography values (p = .0029) and evidence of portal hypertension (p = .0004). Bile acid levels before treatment were associated with HDV RNA declines throughout therapy, but not at Week 24 (rho = -0.577; p = .0078; rho = -0.635, p = .0026; rho = -0.577, p = .0077; rho = -0.519, p = .0191; rho = -0.564, p = .0119 and rho = -0.393, p = .087 at treatment Weeks 2, 8, 12, 16, 20 and 24, respectively). However, bile acid increases during treatment were not associated with HDV RNA or ALT declines at any of the time points. BLV-induced increases in bile salts do not correlate with HDV RNA declines suggesting that the inhibitory effects of BLV on NTCP differ between blocking bile acid transport and hindering HBsAg entry. If baseline bile salt levels could be useful to predict virological response remains to be confirmed.

The Role of Antiviral Prophylaxis in Preventing HBV and HDV Recurrence in the Setting of Liver Transplantation

Hepatitis B virus (HBV) is a prevalent underlying disease, leading to liver transplantation (LT) for both decompensated cirrhosis and hepatocellular carcinoma (HCC). The hepatitis delta virus (HDV) affects approximately 5-10% of HBsAg carriers, accelerating the progression of liver injury and HCC. The initial introduction of HBV immunoglobulins (HBIG), and then of nucleos(t)ide analogues (NUCs), considerably improved the survival of HBV/HDV patients post-transplantation, as they helped prevent re-infection of the graft and recurrence of liver disease. Combination therapy with HBIG and NUCs is the primary post-transplant prophylaxis strategy in patients transplanted for HBV- and HDV-related liver disease. However, monotherapy with high-barrier NUCs, such as entecavir and tenofovir, is safe and also effective in some individuals who are at low risk of HBV reactivation. To address the problems of organ shortage, last-generation NUCs have facilitated the use of anti-HBc and HBsAg-positive grafts to meet the ever-increasing demand for grafts.

Bulevirtide-based treatment strategies for chronic hepatitis delta: A review

Chronic hepatitis Delta (CHD) is a rare and severe form of chronic viral hepatitis. Until recently, the only therapeutic approach has been the off-label use of a 48 weeks course of PegInterferon alpha (PegIFNα), that was characterized by suboptimal efficacy and burdened by significant side effects that limited treatment applicability in patients with advanced liver disease. In July 2020, European Medicines Agency (EMA) conditionally approved the entry inhibitor Bulevirtde (BLV) at the dose of 2 mg/day for the treatment of adult patients with compensated CHD. Efficacy and safety of BLV in CHD have been evaluated in clinical trials either as monotherapy or in combination with PegIFNα. These results were confirmed by real-life studies, which also evaluated long-term BLV monotherapy in patients with advanced compensated cirrhosis. Notwithstanding these promising results there are still several issues to be addressed, such as the optimal duration of the treatment, the rates of off-therapy responses, as well as the long-term clinical benefits. This review summarizes updated and current literature data about clinical trials and real-life studies with BLV monotherapy and/or in combination with PegIFNα.

Epidemiology, presentation, and therapeutic approaches for hepatitis D infections

INTRODUCTION

Chronic Hepatitis D virus (HDV) infection remains an important global public health problem, with a changing epidemiological landscape over the past decade along with widespread implementation of hepatitis B vaccination and human migration. The landscape of HDV treatments has been changing, with therapies that have been under development for the last decade now in late stage clinical trials. The anticipated availability of these new therapies will hopefully replace the current therapies which are minimally effective.

AREAS COVERED

This narrative review discusses the clinical course, screening and diagnosis, transmission risk factors, epidemiology, current and investigational therapies, and liver transplantation in HDV. Literature review was performed using PubMed and ClinicalTrials.gov and includes relevant articles from 1977 to 2022.

EXPERT OPINION

HDV infection is an important global public health issue with a true prevalence that is still unknown. The distribution of HDV infection has changed globally with the availability of HBV vaccination and patterns of human migration. As HDV infection is associated with accelerated disease courses and poor outcomes, the global community needs to agree upon a uniform HDV screening strategy to understand the truth of global prevalence such that new therapies can target appropriate individuals as they become available in the future.

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.

A 3-Year Course Of Bulevirtide Monotherapy May Cure Hdv Infection In Cirrhotics

Bulevirtide has been recently conditionally approved by the European Medicines Agency for the treatment of Chronic Hepatitis Delta, but the ideal duration of therapy is unknown. Here we describe the first case of cure of Hepatitis Delta following 3 years of Bulevirtide monotherapy in a patient with compensated cirrhosis and esophageal varices. During the 72-week off-Bulevirtide follow-up, virological and biochemical responses were maintained. In the off-therapy liver biopsy, intrahepatic HDV RNA and Hepatitis D antigen were undetectable, <1% hepatocytes were Hepatitis B surface antigen positive while hepatitis B core antigen was negative. Grading and staging improved compared to pre-treatment biopsy.

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.

Treatment of Chronic Hepatitis D with Bulevirtide-A Fight against Two Foes-An Update

HDV infection frequently causes progression to cirrhosis and hepatocellular carcinoma (HCC). In summer 2020, the first potentially effective drug Bulevirtide (BLV) has been approved for the treatment of HDV by the EMA. BLV is a synthetic N-acylated pre-S1 lipopeptide that blocks the binding of HBsAg-enveloped particles to the sodium taurocholate co-transporting polypeptide (NTCP), which is the cell entry receptor for both HBV and HDV. In this review, we discuss the available data from the ongoing clinical trials and from "real world series". Clinical trials and real-world experiences demonstrated that BLV 2 mg administered for 24 or 48 weeks as monotherapy or combined with pegIFNα reduces HDV viremia and normalizes ALT levels in a large proportion of patients. The combination of BLV and pegIFNα shows a synergistic on-treatment effect compared with either one of the monotherapies.