High rates of cirrhosis and severe clinical events in patients with HBV/HDV co-infection: longitudinal analysis of a German cohort

Prevalence and characteristics of hepatitis delta virus infection in patients with hepatitis B in the United States: An analysis of the All-Payer Claims Database

BACKGROUND AND AIMS

HDV leads to the most severe form of viral hepatitis; however, the prevalence of HDV is not well understood. Using real-world data from the All-Payer Claims Database, this study estimates the prevalence of HBV/HDV infection among the chronic HBV population and describes patient/clinical characteristics for adults with HBV/HDV infection in the United States.

APPROACH AND RESULTS

Adults (≥18 years) with ≥1 inpatient claim or ≥2 outpatient claims for HDV infection or HBV in the All-Payer Claims Database from January 1, 2014, to December 31, 2020, were identified. HDV prevalence was calculated as the proportion of patients with HBV/HDV infection among total patients with HBV infection. Patient characteristics, socioeconomic status, advanced liver complications (eg, cirrhosis, HCC), and comorbidities were assessed. A total of 6719 patients were diagnosed with HBV/HDV among 144,975 with HBV and 12 months of continuous data, for a prevalence of 4.6%. At diagnosis, 31.7% of patients with HBV/HDV had advanced liver complications, including compensated cirrhosis (16.3%) and decompensated cirrhosis (10.4%). Diabetes (50.5%), hypertension (49.8%), and HIV infection (30.9%) were the top 3 comorbidities.

CONCLUSIONS

In a large database capturing approximately 80% of the US-insured population, HBV/HDV infection prevalence was 4.6% among adults infected with HBV. Patients infected with HDV had high rates of baseline liver complications and other comorbidities at the time of diagnosis, suggesting potentially delayed diagnosis and/or treatment. Earlier identification of HBV/HDV infection among the population with HBV may provide opportunities to improve linkage to care and treatment, thereby reducing the risk of liver-related morbidity and mortality.

Association of hepatitis delta virus with liver morbidity and mortality: A systematic literature review and meta-analysis

BACKGROUND AND AIMS

Studies have suggested that patients with chronic hepatitis B, either co- or superinfected, have more aggressive liver disease progression than those with the HDV. This systematic literature review and meta-analysis examined whether HDV RNA status is associated with increased risk of advanced liver disease events in patients who are HBsAg and HDV antibody positive.

APPROACH AND RESULTS

A total of 12 publications were included. Relative rates of progression to advanced liver disease event for HDV RNA+/detectable versus HDV RNA-/undetectable were extracted for analysis. Reported OR and HRs with 95% CI were pooled using the Hartung-Knapp-Sidik-Jonkman method for random-effects models. The presence of HDV RNA+ was associated with an increased risk of any advanced liver disease event [random effect (95% CI): risk ratio: 1.48 (0.93, 2.33); HR: 2.62 (1.55, 4.44)]. When compared to the patients with HDV RNA- status, HDV RNA+ was associated with a significantly higher risk of progressing to compensated cirrhosis [risk ratio: 1.74 (1.24, 2.45)] decompensated cirrhosis [HR: 3.82 (1.60, 9.10)], HCC [HR: 2.97 (1.87, 4.70)], liver transplantation [HR: 7.07 (1.61, 30.99)], and liver-related mortality [HR: 3.78 (2.18, 6.56)].

CONCLUSIONS

The patients with HDV RNA+ status have a significantly greater risk of liver disease progression than the patients who are HDV RNA-. These findings highlight the need for improved HDV screening and linkage to treatment to reduce the risk of liver-related morbidity and mortality.

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.

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.

Hepatitis D infection induces IFN-β-mediated NK cell activation and TRAIL-dependent cytotoxicity

Background and aims

The co-infection of hepatitis B (HBV) patients with the hepatitis D virus (HDV) causes the most severe form of viral hepatitis and thus drastically worsens the course of the disease. Therapy options for HBV/HDV patients are still limited. Here, we investigated the potential of natural killer (NK) cells that are crucial drivers of the innate immune response against viruses to target HDV-infected hepatocytes.

Methods

We established in vitro co-culture models using HDV-infected hepatoma cell lines and human peripheral blood NK cells. We determined NK cell activation by flow cytometry, transcriptome analysis, bead-based cytokine immunoassays, and NK cell-mediated effects on T cells by flow cytometry. We validated the mechanisms using CRISPR/Cas9-mediated gene deletions. Moreover, we assessed the frequencies and phenotype of NK cells in peripheral blood of HBV and HDV superinfected patients.

Results

Upon co-culture with HDV-infected hepatic cell lines, NK cells upregulated activation markers, interferon-stimulated genes (ISGs) including the death receptor ligand tumor necrosis factor-related apoptosis-inducing ligand (TRAIL), produced interferon (IFN)-γ and eliminated HDV-infected cells via the TRAIL-TRAIL-R2 axis. We identified IFN-β released by HDV-infected cells as an important enhancer of NK cell activity. In line with our in vitro data, we observed activation of peripheral blood NK cells from HBV/HDV co-infected, but not HBV mono-infected patients.

Conclusion

Our data demonstrate NK cell activation in HDV infection and their potential to eliminate HDV-infected hepatoma cells via the TRAIL/TRAIL-R2 axis which implies a high relevance of NK cells for the design of novel anti-viral therapies.

Clinical long-term outcome of hepatitis D compared to hepatitis B monoinfection

BACKGROUND AND AIMS

Hepatitis D virus (HDV) infection causes the most severe form of chronic viral hepatitis. However, it is still unclear to what extent the underlying cirrhosis may contribute to disease progression. The aim of this study was to compare the long-term outcome of HDV infection with HBV monoinfection in a single-center cohort of both non-cirrhotic and cirrhotic patients.

METHOD

We retrospectively studied 175 patients with chronic hepatitis D (CHD) who were followed for at least 6 months (median of 6.3 (0.6-23.6) years). In addition, we selected 175 patients with HBV monoinfection (CHB) who were matched for gender, age, region of origin, HBeAg status, and bilirubin. Liver-related clinical end points were defined as hepatic decompensation (ascites, encephalopathy, variceal bleeding), liver transplantation, HCC, or liver-related death.

RESULTS

Clinical complications developed earlier (4.6 vs. 6.2 years) and more frequently (35.4% vs. 12.6%, p < 0.01) in CHD patients. In a multivariate Cox regression, HDV infection was independently associated with the development of end points (p < 0.01; HR: 3.0; 95% CI 1.4-6.4). However, in cirrhotic patients there were no significant differences between HBV and HDV in the development of end points. Besides, CHB patients with cirrhosis developed more frequently HCC (35.5%) than CHD patients with cirrhosis (18.5%).

CONCLUSION

Our results confirmed that HDV leads to a faster progression to cirrhosis compared to HBV. However, once cirrhosis is present, not HDV but the underlying cirrhosis is the dominate intrinsic risk factor for the development of liver-related end points and for the progression to HCC.

Non-Invasive Prediction Scores for Hepatitis B Virus- and Hepatitis D Virus-Infected Patients-A Cohort from the North-Eastern Part of Romania

Approximately 62-72 million people are infected worldwide with HDV. Patients with chronic hepatitis D (CHD) have a higher risk of developing cirrhosis or hepatocellular carcinoma (HCC) and an increased mortality rate compared to those with chronic hepatitis B (CHB). The stage of liver fibrosis or the risk of developing HCC can also be estimated by non-invasive scores, which are cost effective, easier to apply, and reproducible. In this study, we aimed to evaluate the predictive value of four non-invasive scores (FIB-4, APRI, AST/ALT ratio, and aMAP) in assessing severe fibrosis/cirrhosis and the presence of HCC in patients with HBV/HDV superinfection, as compared with HBV mono-infection. Our 8-year retrospective analysis revealed that HDV-infected patients had a 2-3 times higher risk of developing cirrhosis and HCC than HBV-mono-infected subjects. High AST and ALT baseline levels qualified as independent predictors for cirrhosis development in both groups. The following fibrosis scores, FIB-4, APRI score, and AAR, were significantly increased when cirrhosis was present at baseline and showed a good prediction for developing cirrhosis in the CHD group. The aMAP score, a risk predictor for HCC, showed significantly higher values in patients with HCC in both groups. Nonetheless, non-invasive scores should always be considered for monitoring patients with CHB and CHD, but only when associated with other diagnosis methods.

Liver disease progression in patients with alpha-1 antitrypsin deficiency and protease inhibitor ZZ genotype with or without lung disease

BACKGROUND

Alpha-1 antitrypsin deficiency (AATD) is caused by mutations in SERPINA1, which encodes alpha-1 antitrypsin, a protease inhibitor (Pi). Individuals with AATD and the homozygous Pi*ZZ genotype have variable risk of progressive liver disease but the influence of comorbid lung disease is poorly understood.

AIMS

To characterise patients with AATD Pi*ZZ and liver disease (AATD-LD-Pi*ZZ) with or without lung disease and describe liver disease-related clinical events longitudinally.

METHODS

This was an observational cohort study of patients in the Mayo Clinic Healthcare System (January 2000-September 2021). Patients were identified using diagnosis codes and natural language processing. Fibrosis stage (F0-F4) was assessed using a hierarchical approach at baseline (90 days before or after the index date) and follow-up. Clinical events associated with liver disease progression were assessed.

RESULTS

AATD-LD-Pi*ZZ patients with lung disease had a longer median time from AATD diagnosis to liver disease diagnosis versus those without lung disease (2.2 vs. 0.2 years, respectively). Compared to those without lung disease, patients with lung disease had a longer time to liver disease-related clinical events (8.5 years and not reached, respectively). AATD-LD-Pi*ZZ patients without lung disease were more likely to undergo liver transplantation compared with those with lung disease.

CONCLUSION

In patients with AATD and lung disease, there is a delay in the diagnosis of comorbid liver disease. Our findings suggest that liver disease may progress more rapidly in patients without comorbid lung disease.

An Insight Into the Factors Affecting the Prevalence and Natural History of Hepatitis D

Epidemiological studies and recent metanalyses addressing hepatitis D have reported a wide variation in the prevalence of the disease. Between 4.5% to 15% of all hepatitis B surface antigen (HBsAg) positive patients are thought to harbor the hepatitis D virus. The emergent variation in prevalence can be attributed to several factors. Unsurprisingly, published literature shows that the prevalence of the disease is higher in areas where aggregate viral hepatitis infections are endemic and amongst groups with high-risk practices facilitating the horizontal transfer. Meanwhile, the natural history of the disease is influenced by the genotype of the virus, the hepatitis D virus (HDV) RNA levels, HBV-HDV codominance, HBsAg titers, HBV genotype, nutritional status, HIV co-infection, and prior treatment. Together these factors contribute to the accelerated development of fibrosis and the increased risk of hepatocellular carcinoma. Superinfection with genotype 1 results in rapid progression to cirrhosis with lower rates of remission. Genotype 3 follows an aggressive course but shows a good response to interferon therapy. Other genotypes have better outcomes. The course of the disease leading to these outcomes can be tracked by HDV-specific models integrating clinical surrogate markers and epidemiological factors such as age, region, alanine aminotransferase (ALT), gamma-glutamyl transferase, albumin, platelets and cholinesterase, and liver stiffness.

Non-organ-specific autoantibodies with unspecific patterns are a frequent para-infectious feature of chronic hepatitis D

Infections with hepatotropic viruses are associated with various immune phenomena. Hepatitis D virus (HDV) causes the most severe form of viral hepatitis. However, few recent data are available on non-disease-specific and non-organ-specific antibody (NOSA) titers and immunoglobulin G (IgG) levels in chronic hepatitis D (CHD) patients. Here, we examined the NOSA titers and IgG levels of 40 patients with CHD and different disease courses and compared them to 70 patients with chronic hepatitis B (CHB) infection. 43% of CHD patients had previously undergone treatment with pegylated interferon-α (IFN-α). The antibody display of 46 untreated patients diagnosed with autoimmune hepatitis (AIH) was used as a reference. The frequency of elevated NOSA titers (CHD 69% vs. CHB 43%, p < 0.01), and the median IgG levels (CHD 16.9 g/L vs. CHB 12.7 g/L, p < 0.01) were significantly higher in CHD patients than in patients with CHB, and highest in patients with AIH (96%, 19.5 g/L). Also, the antinuclear antibody pattern was homogeneous in many patients with AIH and unspecific in patients with viral hepatitis. Additionally, f-actin autoantibodies were only detectable in patients with AIH (39% of SMA). In CHD patients, IgG levels correlated with higher HDV viral loads, transaminases, and liver stiffness values. IgG levels and NOSA were similar in CHD patients irrespective of a previous IFN-α treatment. In summary, autoantibodies with an unspecific pattern are frequently detected in CHD patients with unclear clinical relevance.

Treating hepatitis D with bulevirtide - Real-world experience from 114 patients

Background & Aims

Bulevirtide is a first-in-class entry inhibitor of hepatitis B surface antigen. In July 2020, bulevirtide was conditionally approved for the treatment of hepatitis D, the most severe form of viral hepatitis, which frequently causes end-stage liver disease and hepatocellular carcinoma. Herein, we report the first data from a large multicenter real-world cohort of patients with hepatitis D treated with bulevirtide at a daily dose of 2 mg without additional interferon.

Methods

In a joint effort with 16 hepatological centers, we collected anonymized retrospective data from patients treated with bulevirtide for chronic hepatitis D.

Results

Our analysis is based on data from 114 patients, including 59 (52%) with cirrhosis, receiving a total of 4,289 weeks of bulevirtide treatment. A virologic response defined as an HDV RNA decline of at least 2 log or undetectable HDV RNA was observed in 87/114 (76%) cases with a mean time to virologic response of 23 weeks. In 11 cases, a virologic breakthrough (>1 log-increase in HDV RNA after virologic response) was observed. After 24 weeks of treatment, 19/33 patients (58%) had a virologic response, while three patients (9%) did not achieve a 1 log HDV RNA decline. No patient lost hepatitis B surface antigen. Alanine aminotransferase levels improved even in patients not achieving a virologic response, including five patients who had decompensated cirrhosis at the start of treatment. Treatment was well tolerated and there were no reports of drug-related serious adverse events.

Conclusions

In conclusion, we confirm the safety and efficacy of bulevirtide monotherapy in a large real-world cohort of patients with hepatitis D treated in Germany. Future studies need to explore the long-term benefits and optimal duration of bulevirtide treatment.

Impact and implications

Clinical trials proved the efficacy of bulevirtide for chronic hepatitis D and led to conditional approval by the European Medical Agency. Now it is of great interest to investigate the effects of bulevirtide treatment in a real-world setting. In this work, we included data from 114 patients with chronic hepatitis D who were treated with bulevirtide at 16 German centers. A virologic response was seen in 87/114 cases. After 24 weeks of treatment, only a small proportion of patients did not respond to treatment. At the same time, signs of liver inflammation improved. This observation was independent from changes in hepatitis D viral load. The treatment was generally well tolerated. In the future, it will be of interest to investigate the long-term effects of this new treatment.

Strain-specific responsiveness of hepatitis D virus to interferon-alpha treatment

Background & Aims

Pegylated interferon alpha (pegIFNα) is commonly used for the treatment of people infected with HDV. However, its mode of action in HDV-infected cells remains elusive and only a minority of people respond to pegIFNα therapy. Herein, we aimed to assess the responsiveness of three different cloned HDV strains to pegIFNα. We used a previously cloned HDV genotype 1 strain (dubbed HDV-1a) that appeared insensitive to interferon-α in vitro, a new HDV strain (HDV-1p) we isolated from an individual achieving later sustained response to IFNα therapy, and one phylogenetically distant genotype 3 strain (HDV-3).

Methods

PegIFNα was administered to human liver chimeric mice infected with HBV and the different HDV strains or to HBV/HDV infected human hepatocytes isolated from chimeric mice. Virological parameters and host responses were analysed by qPCR, sequencing, immunoblotting, RNA in situ hybridisation and immunofluorescence staining.

Results

PegIFNα treatment efficiently reduced HDV RNA viraemia (∼2-log) and intrahepatic HDV markers both in mice infected with HBV/HDV-1p and HBV/HDV-3. In contrast, HDV parameters remained unaffected by pegIFNα treatment both in mice (up to 9 weeks) and in isolated cells infected with HBV/HDV-1a. Notably, HBV viraemia was efficiently lowered (∼2-log) and human interferon-stimulated genes similarly induced in all three HBV/HDV-infected mouse groups receiving pegIFNα. Genome sequencing revealed highly conserved ribozyme and L-hepatitis D antigen post-translational modification sites among all three isolates.

Conclusions

Our comparative study indicates the ability of pegIFNα to lower HDV loads in stably infected human hepatocytes in vivo and the existence of complex virus-specific determinants of IFNα responsiveness.

Impact and implications

Understanding factors counteracting HDV infections is paramount to develop curative therapies. We compared the responsiveness of three different cloned HDV strains to pegylated interferon alpha in chronically infected mice. The different responsiveness of these HDV isolates to treatment highlights a previously underestimated heterogeneity among HDV strains.

Poor clinical and virological outcome of nucleos(t)ide analogue monotherapy in HBV/HDV co-infected patients

Co-infection of Hepatitis B (HBV) and Delta viruses (HDV) represent the most severe form of viral hepatitis. While treatment with pegylated Interferon alpha (PEG-IFNα) is well established, therapy with nucleoside or nucleotide analogues (NA) has been a matter of debate. We aimed to investigate the role of NA treatment in a well-defined single centre cohort.In a retrospective approach, we observed 53 HDV RNA positive and/or anti-HDV-positive patients recruited at a German referral centre between 2000 and 2019. Patients were followed for at least 3 months (mean time of follow up: 4.6 years; range: 0.2-14.1 years). Patients who had liver transplantation or hepatocellular carcinoma at the time of presentation were excluded. 43% (n = 23) were treated with NA, 43% (n = 23) received IFNα-based therapies and 13% (n = 7) were untreated.Liver cirrhosis was already present in 53% (28/53) of patients at first presentation. During follow-up, liver-related endpoints developed in 44% of all patients (n = 23). NA-treatment was associated with a significantly worse clinical outcome (P = .01; odds ratio [OR] = 4.92; CI = 1.51-16.01) compared to both, untreated (P = .38; OR = 0.46; CI = 0.80-2.61) and IFNα-based-treated patients (P = .04; OR = 0.29; CI = 0.89-0.94) in univariate logistic regression analysis. HBsAg levels declined by more than 50% during NA-based therapy in only 7 cases (7/23; mean time: 3.6 years; range: 0.8-8.5 years) and during IFNα-based therapy in 14 cases (14/23; mean time: 2.8 years, range 0.7-8.5 years). HDV RNA became undetectable during follow up in 30% of patients receiving NA alone (7/23; mean time: 5.0 years; range: 0.6-13.5 years), in 35% of patients receiving IFNα-based therapy (8/23; mean time: 2.9 years, range: 0.3-7.6 years).The effect of NA in patients with HBV/HDV co-infection is limited. Treatment with NA was associated with a higher likelihood of clinical disease progression. Interferon alpha therapy was beneficial in reducing liver complications and improves long-term outcome.

Hepatitis delta virus: From infection to new therapeutic strategies

The hepatitis delta virus (HDV) is a small RNA virus that encodes a single protein and which requires the hepatitis B virus (HBV)-encoded hepatitis B surface antigen (HBsAg) for its assembly and transmission. HBV/HDV co-infections exist worldwide and show a higher prevalence among selected groups of HBV-infected populations, specifically intravenous drug users, practitioners of high-risk sexual behaviours, and patients with cirrhosis and hepatocellular carcinoma. The chronic form of HDV-related hepatitis is usually severe and rapidly progressive. Patterns of the viral infection itself, including the status of co-infection or super-infection, virus genotypes (both for HBV and HDV), and persistence of the virus’ replication, influence the outcome of the accompanying and manifested liver disease. Unfortunately, disease severity is burdened by the lack of an effective cure for either virus type. For decades, the main treatment option has been interferon, administered as mono-therapy or in combination with nucleos(t)ide analogues. While its efficacy has been reported for different doses, durations and courses, only a minority of patients achieve a sustained response, which is the foundation of eventual improvement in related liver fibrosis. The need for an efficient therapeutic alternative remains. Research efforts towards this end have led to new treatment options that target specific steps in the HDV life cycle; the most promising among these are myrcludex B, which inhibits virus entry into hepatocytes, lonafarnib, which inhibits farnesylation of the viral-encoded L-HDAg large hepatitis D antigen, and REP-2139, which interferes with HBsAg release and assembly.

Hepatitis D Virus and Hepatocellular Carcinoma

Hepatitis D virus (HDV) is a small, defective RNA virus that depends on hepatitis B virus (HBV) for virion assembly and transmission. It replicates within the nucleus of hepatocytes and interacts with several cellular proteins. Chronic hepatitis D is a severe and progressive disease, leading to cirrhosis in up to 80% of cases. A high proportion of patients die of liver decompensation or hepatocellular carcinoma (HCC), but the lack of large prospective studies has made it difficult to precisely define the rate of these long-term complications. In particular, the question of whether HDV is an oncogenic virus has been a matter of debate. Studies conducted over the past decade provided evidence that HDV is associated with a significantly higher risk of developing HCC compared to HBV monoinfection. However, the mechanisms whereby HDV promotes liver cancer remain elusive. Recent data have demonstrated that the molecular profile of HCC-HDV is unique and distinct from that of HBV-HCC, with an enrichment of upregulated genes involved in cell-cycle/DNA replication, and DNA damage and repair, which point to genome instability as an important mechanism of HDV hepatocarcinogenesis. These data suggest that HBV and HDV promote carcinogenesis by distinct molecular mechanisms despite the obligatory dependence of HDV on HBV.

HDV Pathogenesis: Unravelling Ariadne's Thread

Hepatitis Delta virus (HDV) lies in between satellite viruses and viroids, as its unique molecular characteristics and life cycle cannot categorize it according to the standard taxonomy norms for viruses. Being a satellite virus of hepatitis B virus (HBV), HDV requires HBV envelope glycoproteins for its infection cycle and its transmission. HDV pathogenesis varies and depends on the mode of HDV and HBV infection; a simultaneous HDV and HBV infection will lead to an acute hepatitis that will resolve spontaneously in the majority of patients, whereas an HDV super-infection of a chronic HBV carrier will mainly result in the establishment of a chronic HDV infection that may progress towards cirrhosis, liver decompensation, and hepatocellular carcinoma (HCC). With this review, we aim to unravel Ariadne’s thread into the labyrinth of acute and chronic HDV infection pathogenesis and will provide insights into the complexity of this exciting topic by detailing the different players and mechanisms that shape the clinical outcome.

From hepatitis A to E: A critical review of viral hepatitis

Viral infections affecting the liver have had an important impact on humanity, as they have led to significant morbidity and mortality in patients with acute and chronic infections. Once an unknown etiology, the discovery of the viral agents triggered interest of the scientific community to establish the pathogenesis and diagnostic modalities to identify the affected population. With the rapid scientific and technological advances in the last centuries, controlling and even curing the infections became a possibility, with a large focus on preventive medicine through vaccination. Hence, a comprehensive understanding of hepatitis A, B, C, D and E is required by primary care physicians and gastroenterologists to provide care to these patients. The review article describes the epidemiology, pathogenesis, clinical presentation, diagnostic tools and current medication regimens, with a focus on upcoming treatment options and the role of liver transplantation.

Human hepatitis D virus-specific T cell epitopes

HDV is a small, defective RNA virus that requires the HBsAg of HBV for its assembly, release, and transmission. Chronic HBV/HDV infection often has a severe clinical outcome and is difficult to treat. The important role of a robust virus-specific T cell response for natural viral control has been established for many other chronic viral infections, but the exact role of the T cell response in the control and progression of chronic HDV infection is far less clear. Several recent studies have characterised HDV-specific CD4+ and CD8+ T cell responses on a peptide level. This review comprehensively summarises all HDV-specific T cell epitopes described to date and describes our current knowledge of the role of T cells in HDV infection. While we now have better tools to study the adaptive anti-HDV-specific T cell response, further efforts are needed to define the HLA restriction of additional HDV-specific T cell epitopes, establish additional HDV-specific MHC tetramers, understand the degree of cross HDV genotype reactivity of individual epitopes and understand the correlation of the HBV- and HDV-specific T cell response, as well as the breadth and specificity of the intrahepatic HDV-specific T cell response.

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

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