Transporter Proteins as Therapeutic Drug Targets-With a Focus on SGLT2 Inhibitors.

Membrane transporters interact not only with endogenous substrates but are also engaged in the transport of xenobiotics, including drugs. While the coordinated function of uptake (solute carrier family-SLC and SLCO) and efflux (ATP-binding cassette family-ABC, multidrug and toxic compound extrusion family-MATE) transporter system allows vectorial drug transport, efflux carriers alone achieve barrier functions. The modulation of transport functions was proved to be effective in the treatment strategies of various pathological states. Sodium-glucose cotransporter-2 (SGLT2) inhibitors are the drugs most widely applied in clinical practice, especially in the treatment of diabetes mellitus and heart failure. Sodium taurocholate co-transporting polypeptide (NTCP) serves as virus particles (HBV/HDV) carrier, and inhibition of its function is applied in the treatment of hepatitis B and hepatitis D by myrcludex B. Inherited cholestatic diseases, such as Alagille syndrome (ALGS) and progressive familial intrahepatic cholestasis (PFIC) can be treated by odevixibat and maralixibat, which inhibit activity of apical sodium-dependent bile salt transporter (ASBT). Probenecid can be considered to increase uric acid excretion in the urine mainly via the inhibition of urate transporter 1 (URAT1), and due to pharmacokinetic interactions involving organic anion transporters 1 and 3 (OAT1 and OAT3), it modifies renal excretion of penicillins or ciprofloxacin as well as nephrotoxicity of cidofovir. This review discusses clinically approved drugs that affect membrane/drug transporter function.

Bulevirtide monotherapy in patients with chronic HDV: Efficacy and safety results through week 96 from a phase III randomized trial.

BACKGROUND & AIMS: Bulevirtide (BLV), a first-in-class entry inhibitor, is approved in Europe for the treatment of chronic hepatitis delta (CHD). BLV monotherapy was superior to delayed treatment at week (W) 48, the primary efficacy endpoint, in the MYR301 study (NCT03852719). Here, we assessed if continued BLV therapy until W96 would improve virologic and biochemical response rates, particularly among patients who did not achieve virologic response at W24. METHODS: In this ongoing, open-label, randomized phase III study, patients with CHD (N = 150) were randomized (1:1:1) to treatment with BLV 2 mg/day (n = 49) or 10 mg/day (n = 50), each for 144 weeks, or to delayed treatment for 48 weeks followed by BLV 10 mg/day for 96 weeks (n = 51). Combined response was defined as undetectable hepatitis delta virus (HDV) RNA or a decrease in HDV RNA by ≥2 log10 IU/ml from baseline and alanine aminotransferase (ALT) normalization. Other endpoints included virologic response, ALT normalization, and change in HDV RNA. RESULTS: Of 150 patients, 143 (95%) completed 96 weeks of the study. Efficacy responses were maintained and/or improved between W48 and W96, with similar combined, virologic, and biochemical response rates between BLV 2 and 10 mg. Of the patients with a suboptimal early virologic response at W24, 43% of non-responders and 82% of partial responders achieved virologic response at W96. Biochemical improvement often occurred independently of virologic response. Adverse events were mostly mild, with no serious adverse events related to BLV. CONCLUSIONS: Virologic and biochemical responses were maintained and/or increased with longer term BLV therapy, including in those with suboptimal early virologic response. BLV monotherapy for CHD was safe and well tolerated through W96. IMPACT AND IMPLICATIONS: In July 2023, bulevirtide was fully approved for the treatment of chronic hepatitis delta (CHD) in Europe based on clinical study results from up to 48 weeks of treatment. Understanding the efficacy and safety of bulevirtide over the longer term is important for healthcare providers. In this analysis, we demonstrate that bulevirtide monotherapy for 96 weeks in patients with CHD was associated with continued improvements in combined, virologic, and biochemical responses as well as liver stiffness from week 48 at both the 2 mg and 10 mg doses. Patients with suboptimal virologic responses to bulevirtide at week 24 also benefited from continued therapy, with the majority achieving virologic response or biochemical improvement by week 96. GOV IDENTIFIER: NCT03852719.

Blocking viral entry with bulevirtide reduces the number of HDV-infected hepatocytes in human liver biopsies.

BACKGROUND & AIMS: Bulevirtide (BLV) is a first-in-class entry inhibitor and the only approved treatment for patients chronically infected with HDV in Europe. We aimed to investigate the efficacy of BLV treatment in paired liver biopsies obtained at baseline and after 24 or 48 weeks of treatment. METHODS: We performed a combined analysis of 126 paired liver biopsies derived from three clinical trials. In the phase II clinical trial MYR202, patients with chronic hepatitis D were randomised to receive 24 weeks of BLV at 2 mg, 5 mg or 10 mg/day. Patients in MYR203 (phase II) and MYR301 (phase III) received 48 weeks of BLV at 2 mg or 10 mg/day. Tenofovir disoproxil fumarate monotherapy or delayed treatment served as comparators. Virological parameters and infection-related host genes were assessed by qPCR and immunohistochemistry. RESULTS: At week 24, median intrahepatic HDV RNA decline from baseline was 0.9Log10 with 2 mg (n = 7), 1.1Log10 with 5 mg (n = 5) and 1.4 Log10 with 10 mg (n = 7) of BLV. At week 48, median reductions were 2.2Log10 with 2 mg (n = 27) and 2.7Log10 with 10 mg (n = 37) of BLV, while HDV RNA levels did not change in the comparator arms. Notably, a drastic decline in the number of hepatitis delta antigen-positive hepatocytes and a concomitant decrease in transcriptional levels of inflammatory chemokines and interferon-stimulated genes was determined in all BLV-treatment arms. Despite the abundance of HBsAg-positive hepatocytes, replication and covalently closed circular DNA levels of the helper virus HBV were low and remained unaffected by BLV treatment. CONCLUSION: Blocking viral entry diminishes signs of liver inflammation and promotes a strong reduction of HDV infection within the liver, thus suggesting that some patients may achieve HDV cure with long-term treatment. IMPACT AND IMPLICATIONS: Chronic infection with HDV causes the most severe form of viral hepatitis, affecting approximately 12 million people worldwide. The entry inhibitor bulevirtide (BLV) is the only recently approved anti-HDV drug, which has proven efficacious and safe in clinical trials and real-word data. Here, we investigated paired liver biopsies at baseline and after 24 or 48 weeks of treatment from three clinical trials to understand the effect of the drug on viral and host parameters in the liver, the site of viral replication. We found that BLV treatment strongly reduces the number of HDV-infected cells and signs of liver inflammation. This data implies that blocking viral entry ameliorates liver inflammation and that prolonged treatment regimens might lead to HDV cure in some patients. This concept will guide the further development of therapeutic strategies and combination treatments for patients with CHD. CLINICAL TRIAL NUMBERS: NCT03546621, NCT02888106, NCT03852719.

Evaluation of the drug-drug interaction potential of the novel hepatitis B and D virus entry inhibitor bulevirtide at OATP1B in healthy volunteers.

Introduction: Bulevirtide is a first-in-class antiviral drug to treat chronic hepatitis B/D. We investigated the drug-drug interaction potential and pharmacokinetics of high-dose subcutaneous bulevirtide (5 mg twice daily) with organic anion transporting polypeptide 1B1 (OATP1B1) and cytochrome P450 (CYP) 3A4. Methods: This was a single-center, open-label, fixed-sequence drug-drug interaction trial in 19 healthy volunteers. Before and at bulevirtide steady state, participants ingested a single 40 mg dose of pravastatin. A midazolam microdose was applied to quantify CYP3A4 activity. Results: At bulevirtide steady state, pravastatin area under the concentration-time curve (AUC0-∞) increased 1.32-fold (90% CI 1.08-1.61). The 5 mg bulevirtide twice-daily treatment resulted in a mean AUC0-12 of 1210 h*ng/ml (95% CI 1040-1408) and remained essentially unchanged under the influence of pravastatin. CYP3A4 activity did not change to a clinically relevant extent. As expected, total bile acids increased substantially (35-fold) compared to baseline during bulevirtide treatment. All study medication was well tolerated. Discussion: The study demonstrated that high-dose bulevirtide inhibited OATP1B-mediated hepatic uptake of the marker substrate pravastatin but the extent is considered clinically not relevant. Changes in CYP3A4 activity were also not clinically relevant. In conclusion, this study suggests that OATP1B substrate drugs as well as CYP3A4 substrates may safely be used without dose adjustment in patients treated with bulevirtide. However, in patients using high statin doses and where concomitant factors potentially further increase statin exposure, caution may be required when using bulevirtide.

HepG2-NTCP Subclones Exhibiting High Susceptibility to Hepatitis B Virus Infection.

HepG2 cells reconstituted with Hepatitis B virus (HBV) entry receptor sodium taurocholate co-transporting polypeptide (NTCP) are widely used as a convenient in vitro cell culture infection model for HBV replication studies. As such, it is pertinent that HBV infectivity is maintained at steady-state levels for an accurate interpretation of in vitro data. However, variations in the HBV infection efficiency due to imbalanced NTCP expression levels in the HepG2 cell line may affect experimental results. In this study, we performed single cell-cloning of HepG2-NTCP-A3 parental cells via limiting dilution and obtained multiple subclones with increased permissiveness to HBV. Specifically, one subclone (HepG2-NTCP-A3/C2) yielded more than four-fold higher HBV infection compared to the HepG2-NTCP-A3 parental clone. In addition, though HBV infectivity was universally reduced in the absence of polyethylene glycol (PEG), subclone C2 maintained relatively greater permissiveness under PEG-free conditions, suggesting the functional heterogeneity within parental HepG2-NTCP-A3 may be exploitable in developing a PEG-free HBV infection model. The increased viral production correlated with increased intracellular viral antigen expression as evidenced through HBcAg immunofluorescence staining. Further, these subclones were found to express different levels of NTCP, albeit with no remarkable morphology or cell growth differences. In conclusion, we isolated the subclones of HepG2-NTCP-A3 which support efficient HBV production and thus provide an improved in vitro HBV infection model.

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.

[Bulevirtide as the first specific agent against hepatitis D virus infections-mechanism and clinical effect]. / Bulevirtide als erster spezifischer Wirkstoff gegen Hepatitis-D-Virusinfektionen ­ Mechanismus und klinische Wirkung.

Blocking the cell entry of pathogens is a suitable approach to prevent new infections. However, the therapeutic use of entry inhibitors in chronically infected patients has had limited success. For the treatment of chronic hepatitis D virus (HDV) infections, a promising agent based on this mode of action, Bulevirtide (BLV), was conditionally approved in July 2020. Previously, no drugs were available for HDV, and treatment relied on off-label use of interferon alpha/peginterferon alpha (IFNα/Peg-IFNα). In this review, we provide an overview of the basic mechanism of action of BLV and summarize the clinical data available to date.HDV infection manifests as a co-infection or superinfection of hepatitis B virus (HBV) infections and affects 4.5-15% of HBV patients worldwide. HDV utilizes the envelope proteins of HBV for dissemination. BLV acts by blocking the HBV/HDV receptor sodium taurocholate co-transporting polypeptide (NTCP), preventing HBV/HDV entry into hepatocytes. BLV lowers HDV serum RNA levels and normalizes alanine aminotransferase (ALT) levels in HBV/HDV-infected individuals. It has an excellent safety profile, even when administered at high doses (10 mg daily) for 48 weeks. In combination with Peg-IFNα, BLV shows synergistic effects on lowering serum HDV RNA, but also on hepatitis B surface antigen (HBsAg) levels. This resulted in a functional cure in a subset of patients when 2 mg BLV plus Peg-IFNα was administered. The mechanism of this likely immune-mediated elimination will be investigated in follow-up studies.

A new high-content screening assay of the entire hepatitis B virus life cycle identifies novel antivirals.

BACKGROUND & AIMS: Chronic hepatitis B is an incurable disease. Addressing the unmet medical need for therapies has been hampered by a lack of suitable cell culture models to investigate the HBV life cycle in a single experimental setup. We sought to develop a platform suitable to investigate all aspects of the entire HBV life cycle. METHODS: HepG2-NTCPsec+ cells were inoculated with HBV. Supernatants of infected cells were transferred to naïve cells. Inhibition of infection was determined in primary and secondary infected cells by high-content imaging of viral and cellular factors. Novel antivirals were triaged in cells infected with cell culture- or patient-derived HBV and in stably virus replicating cells. HBV internalisation and target-based receptor binding assays were conducted. RESULTS: We developed an HBV platform, screened 2,102 drugs and bioactives, and identified 3 early and 38 late novel HBV life cycle inhibitors using infectious HBV genotype D. Two early inhibitors, pranlukast (EC50 4.3 µM; 50% cytotoxic concentration [CC50] >50 µM) and cytochalasin D (EC50 0.07 µM; CC50 >50 µM), and 2 late inhibitors, fludarabine (EC50 0.1 µM; CC50 13.4 µM) and dexmedetomidine (EC50 6.2 µM; CC50 >50 µM), were further investigated. Pranlukast inhibited HBV preS1 binding, whereas cytochalasin D prevented the internalisation of HBV. Fludarabine inhibited the secretion of HBV progeny DNA, whereas dexmedetomidine interfered with the infectivity of HBV progeny. Patient-derived HBV genotype C was efficiently inhibited by fludarabine (EC50 0.08 µM) and dexmedetomidine (EC50 8.7 µM). CONCLUSIONS: The newly developed high-content assay is suitable to screen large-scale drug libraries, enables monitoring of the entire HBV life cycle, and discriminates between inhibition of early and late viral life cycle events. LAY SUMMARY: HBV infection is an incurable, chronic disease with few available treatments. Addressing this unmet medical need has been hampered by a lack of suitable cell culture models to study the entire viral life cycle in a single experimental setup. We developed an image-based approach suitable to screen large numbers of drugs, using a cell line that can be infected by HBV and produces large amounts of virus particles. By transferring viral supernatants from these infected cells to uninfected target cells, we could monitor the entire viral life cycle. We used this system to screen drug libraries and identified novel anti-HBV inhibitors that potently inhibit HBV in various phases of its life cycle. This assay will be an important new tool to study the HBV life cycle and accelerate the development of novel therapeutic strategies.

A Sensitive and Specific PCR-based Assay to Quantify Hepatitis B Virus Covalently Closed Circular (ccc) DNA while Preserving Cellular DNA.

Hepatitis B virus (HBV) is the major cause of liver diseases and liver cancer worldwide. After infecting hepatocytes, the virus establishes a stable episome (covalently closed circular DNA, or cccDNA) that serves as the template for all viral transcripts. Specific and accurate quantification of cccDNA is difficult because infected cells contain abundant replicative intermediates of HBV DNA that share overlapping sequences but arranged in slightly different forms. HBV cccDNA can be detected by Southern blot or qPCR methods which involve enzymatic digestion. These assays are laborious, have limited sensitivity, or require degradation of cellular DNA (which precludes simple normalization). The method described in this protocol, cccDNA inversion quantitative (cinq)PCR, instead uses a series of restriction enzyme-mediated hydrolysis and ligation reactions that convert cccDNA into an inverted linear amplicon, which is not amplified or detected from other forms of HBV DNA. Importantly, cellular DNA remains quantifiable during sample preparation, allowing normalization and markedly improving precision. Further, a second linear fragment (derived from enzymatic digestion of a separate region of the HBV DNA genome and is present in all forms of HBV DNA) can be used to simultaneously quantify total HBV levels. Graphic abstract: Selective detection of HBV cccDNA and total HBV DNA using cinqPCR (Reproduced from Tu et al., 2020a ).

Assembly and infection efficacy of hepatitis B virus surface protein exchanges in 8 hepatitis D virus genotype isolates.

BACKGROUND & AIMS: Chronic HDV infections cause the most severe form of viral hepatitis. HDV requires HBV envelope proteins for hepatocyte entry, particle assembly and release. Eight HDV and 8 HBV genotypes have been identified. However, there are limited data on the replication competence of different genotypes and the effect that different HBV envelopes have on virion assembly and infectivity. METHODS: We subcloned complementary DNAs (cDNAs) of all HDV and HBV genotypes and systematically studied HDV replication, assembly and infectivity using northern blot, western blot, reverse-transcription quantitative PCR, and in-cell ELISA. RESULTS: The 8 HDV cDNA clones initiated HDV replication with noticeable differences regarding replication efficacy. The 8 HBV-HBsAg-encoding constructs all supported secretion of subviral particles, however variations in envelope protein stoichiometry and secretion efficacy were observed. Co-transfection of all HDV/HBV combinations supported particle assembly, however, the respective pseudo-typed HDVs differed with respect to assembly kinetics. The most productive combinations did not correlate with the natural geographic distribution, arguing against an evolutionary adaptation of HDV ribonucleoprotein complexes to HBV envelopes. All HDVs elicited robust and comparable innate immune responses. HBV envelope-dependent differences in the activity of the EMA-approved entry inhibitor bulevirtide were observed, however efficient inhibition could be achieved at therapeutically applied doses. Lonafarnib also showed pan-genotypic activity. CONCLUSIONS: HDVs from different genotypes replicate with variable efficacies. Variations in HDV genomes and HBV envelope proteins are both major determinants of HDV egress and entry efficacy, and consequently assembly inhibition by lonafarnib or entry inhibition by bulevirtide. These differences possibly influence HDV pathogenicity, immune responses and the efficacy of novel drug regimens. LAY SUMMARY: HDV requires the envelope protein of HBV for assembly and to infect human cells. We investigated the ability of different HDV genotypes to infect cells and replicate. We also assessed the effect that envelope proteins from different HBV genotypes had on HDV infectivity and replication. Herein, we confirmed that genotypic differences in HDV and HBV envelope proteins are major determinants of HDV assembly, de novo cell entry and consequently the efficacy of novel antivirals.

Clinical effects of NTCP-inhibitor myrcludex B.

With extensive research on the pathogenesis and treatment of hepatitis B virus (HBV) and hepatitis D virus (HDV) infections, the current treatment of interferon and nucleoside or nucleotide analogues provides reasonable control of viral replication in chronic hepatitis B (CHB). However, drug resistance may occur as a result of long-term treatment, and continuous covalently closed circular DNA (cccDNA) can cause disease relapse after drug withdrawal. Therefore, there is an urgent need for safe and effective antiviral drugs or methods to treat HBV and HDV infections. Myrcludex B is the first entry inhibitor that can inactivate HBV and HDV receptors, compete with HBV for the sodium-taurocholate co-transporting polypeptide, which has been identified as the bona fide receptor for HBV and HDV, block HBV infection in hepatocytes, and participate in HBV transcriptional suppression. Myrcludex B plays an important role in the inhibition of HBV replication and is a potential drug for phase III clinical trials. In this article, we review the progress on the efficacy and clinical application of myrcludex B in recent years.

D e novo synthesis of hepatitis B virus nucleocapsids is dispensable for the maintenance and transcriptional regulation of cccDNA.

BACKGROUND & AIMS: Chronic HBV infection cannot be cured by current therapeutics owing to their limited ability to reduce covalently closed circular (ccc)DNA levels in the livers of infected individuals. Therefore, greater understanding of the molecular determinants of cccDNA formation and persistence is required. One key issue is the extent to which de novo nucleocapsid-mediated replenishment (reimport) contributes to cccDNA levels in an infected hepatocyte. METHODS: We engineered an infectious HBV mutant with a genome encoding a stop codon at position T67 in the HBV core open reading frame (ΔHBc HBV). Importantly, ΔHBc HBV virions cannot initiate nucleocapsid synthesis upon infection. Long-term in vitro HBV infection markers were followed for up for 9 weeks in HepG2-NTCP cells (A3 clone) and HBV DNA was quantified using a newly-developed, highly-precise PCR assay (cccDNA inversion quantitative PCR). RESULTS: ΔHBc and wild-type (WT) HBV resulted in comparable expression of HBV surface antigen (HBsAg), which could be blocked using the entry inhibitor Myrcludex B, confirming bona fide infection via the receptor sodium taurocholate cotransporting polypeptide (NTCP). In primary human hepatocytes, Huh7-NTCP, HepG2-NTCP, and HepaRG-NTCP cells, comparable copy numbers of cccDNA were formed. cccDNA levels, transcription of viral RNA, and HBsAg secretion remained comparably stable in WT and ΔHBc HBV-infected cells for at least 9 weeks. CONCLUSIONS: Our results imply that de novo synthesised HBc plays a minor role in transcriptional regulation of cccDNA. Importantly, we show that initially-formed cccDNA is stable in hepatocytes without requiring continuous replenishment in in vitro infection systems and contribution from de novo DNA-containing nucleocapsids is not required. Thus, short-term therapeutic targeting of capsid-reimport is likely an inefficient strategy in eliminating cccDNA in chronically infected hepatocytes. LAY SUMMARY: The hepatitis B virus can maintain itself in the liver for a patient's lifetime, causing liver injury and cancer. We have clarified exactly how it maintains itself in an infected cell. This now means we have a better idea at how to target the virus and cure a chronic infection.

New insights into HDV persistence: The role of interferon response and implications for upcoming novel therapies.

Chronic hepatitis D (CHD), a global health problem, manifests as the most severe form of viral hepatitis. The causative agent, HDV, is the smallest known human virus; it replicates its circular single-stranded RNA genome in the nucleus of hepatocytes. HDV requires HBV-encoded envelope proteins for dissemination and de novo cell entry. However, HDV can also spread through cell division. Following entry into hepatocytes, replicative intermediates of HDV RNA are sensed by the pattern recognition receptor MDA5 (melanoma differentiation antigen 5) resulting in interferon (IFN)-ß/λ induction. This IFN response strongly suppresses cell division-mediated spread of HDV genomes, however, it only marginally affects HDV RNA replication in already infected, resting hepatocytes. Monotherapy with IFN-α/λ shows efficacy but rarely results in HDV clearance. Recent molecular insights into key determinants of HDV persistence and the accelerated development of specifically acting antivirals that interfere with the replication cycle have revealed promising new therapeutic perspectives. In this review, we briefly summarise our knowledge on replication/persistence of HDV, the newly discovered HDV-like agents, and the interplay of HDV with the IFN response and its consequences for persistence. Finally, we discuss the possible role of IFNs in combination with upcoming therapies aimed at HDV cure.

Interplay between Hepatitis D Virus and the Interferon Response.

Chronic hepatitis D (CHD) is the most severe form of viral hepatitis, with rapid progression of liver-related diseases and high rates of development of hepatocellular carcinoma. The causative agent, hepatitis D virus (HDV), contains a small (approximately 1.7 kb) highly self-pairing single-strand circular RNA genome that assembles with the HDV antigen to form a ribonucleoprotein (RNP) complex. HDV depends on hepatitis B virus (HBV) envelope proteins for envelopment and de novo hepatocyte entry; however, its intracellular RNA replication is autonomous. In addition, HDV can amplify HBV independently through cell division. Cellular innate immune responses, mainly interferon (IFN) response, are crucial for controlling invading viruses, while viruses counteract these responses to favor their propagation. In contrast to HBV, HDV activates profound IFN response through the melanoma differentiation antigen 5 (MDA5) pathway. This cellular response efficiently suppresses cell-division-mediated HDV spread and, to some extent, early stages of HDV de novo infection, but only marginally impairs RNA replication in resting hepatocytes. In this review, we summarize the current knowledge on HDV structure, replication, and persistence and subsequently focus on the interplay between HDV and IFN response, including IFN activation, sensing, antiviral effects, and viral countermeasures. Finally, we discuss crosstalk with HBV.

[Study of the inhibitory effect of cell entry inhibitory myrcludex-B synthetic peptide on HepaRG cells infected with hepatitis B virus in an in vitro infection model].

Objective: To establish and explore the inhibitory effect of cell entry inhibitor myrcludex-B on human liver cancer cell (HepaRG) infected with hepatitis B virus (HBV) positive serum in an in vitro infection model. Methods: HepaRG induced mature cells were divided into polyethylene glycol (PEG) infection group and non-PEG infection group, and then the two infection groups were divided into treatment group with myrcludex-B peptide fragment and control group without myrcludex-B peptide fragment, and the cells were infected with the serum of HBV DNA-positive patients. The expression of HBV DNA in supernatant was detected by fluorescence quantitative PCR, and the HBsAg and HBeAg content in supernatant were detected by chemical fluorescence. Measurement data of the non-normal distribution between the two groups was determined by rank-sum test, and normal distribution was determined by t-test. P < 0.05 was considered as statistically significant. Results: In the treatment and control group the virus titers of the PEG infection group and the non-PEG infection group were (103 877.00 ± 49 013.24) copies / ml and (5 050.09 ± 631.26) copies/ml, and (116 188.57 ± 50 957.19) copies/ml, (5 119.34 ± 1 102.43) copies/ml, respectively. Virus titers of both groups with PEG infection were significantly higher than non-PEG infection group, and the difference was statistically significant (P < 0.05). In the PEG infection group, the virus titers of the peptide-treated group and the non-peptide control group were (103 877.34 ± 49 013.24) copies /ml and (116 188.57 ± 50 957.19) copies/ml, respectively, and the virus titers of the peptide-treated group was decreased significantly (P < 0.05), and the difference was statistically significant. HBsAg content in the supernatant of this group was positive at 0, 1, 2 and 3 days, while the 0 day HBsAg supernatant treated with peptide fragment was significantly lower than that of the control group without peptide fragment. Conclusion: It is feasible to infect HepaRG cells with HBV positive serum supplemented with PEG in vitro, and the cell entry inhibitor myrcludex-B has a certain inhibitory effect on hepatitis B virus infection in this experimental model.

A novel method to precisely quantify hepatitis B virus covalently closed circular (ccc)DNA formation and maintenance.

Hepatitis B virus (HBV) is the major cause of virus-associated liver disease. Persistent HBV infection is maintained by its episomal genome (covalently closed circular DNA, cccDNA), which acts as a template for viral transcripts. The formation of cccDNA is poorly characterised due to limited ability to quantify it accurately in the presence of replicative intermediates. Here, we describe a novel cccDNA quantification assay (cccDNA inversion quantitative PCR, cinqPCR), which uses restriction enzymes to invert a DNA sequence close to the gap region of Genotype D HBV strains, including the isolate widely used in experimental studies. Importantly, cinqPCR allows simultaneous normalisation to cellular DNA in a single reaction, provides absolute copy numbers without requiring a standard curve, and has high precision, sensitivity, and specificity for cccDNA compared to previous assays. We first established that cinqPCR gives values consistent with classical approaches in both in vitro and in vivo (humanised mice) HBV infections. We then used cinqPCR to find that cccDNA is formed within 12 h post-inoculation (hpi). cccDNA formation slowed by 28 hpi despite de novo synthesis of HBV DNA, indicating inefficient conversion of new viral genomes to cccDNA within infected cells. Finally, we show that cinqPCR can be used as a 96-well screening assay. Thus, we have developed an ideal method for testing current and future anti-cccDNA therapeutics with high precision and sensitivity.

Inhibition of Hepatic Bile Acid Uptake by Myrcludex B Promotes Glucagon-Like Peptide-1 Release and Reduces Obesity.

BACKGROUND & AIMS: Bile acids are important metabolic signaling molecules. Bile acid receptor activation promotes body weight loss and improves glycemic control. The incretin hormone GLP-1 and thyroid hormone activation of T4 to T3 have been suggested as important contributors. Here, we identify the hepatic bile acid uptake transporter Na+ taurocholate co-transporting polypeptide (NTCP) as target to prolong postprandial bile acid signaling. METHODS: Organic anion transporting polypeptide (OATP)1a/1b KO mice with or without reconstitution with human OATP1B1 in the liver were treated with the NTCP inhibitor Myrcludex B for 3.5 weeks after the onset of obesity induced by high fat diet-feeding. Furthermore, radiolabeled T4 was injected to determine the role of NTCP and OATPs in thyroid hormone clearance from plasma. RESULTS: Inhibition of NTCP by Myrcludex B in obese Oatp1a/1b KO mice inhibited hepatic clearance of bile acids from portal and systemic blood, stimulated GLP-1 secretion, reduced body weight, and decreased (hepatic) adiposity. NTCP inhibition did not affect hepatic T4 uptake nor lead to increased thyroid hormone activation. Myrcludex B treatment increased fecal energy output, explaining body weight reductions amongst unaltered food intake and energy expenditure. CONCLUSIONS: Pharmacologically targeting hepatic bile acid uptake to increase bile acid signaling is a novel approach to treat obesity and induce GLP1- secretion.

Beyond Pegylated Interferon-Alpha: New Treatments for Hepatitis Delta.

Persistent coinfection with the hepatitis B/D viruses (HDV) represents the most severe form of viral hepatitis. Hepatitis D often leads to liver cirrhosis, hepatic decompensation, and hepatocellular carcinoma. The current treatment options are limited as only pegylated interferon-alpha (PEG-IFNa) has efficacy against HDV. However, treatment response is still unsatisfactory with 25-40% HDV RNA suppression after 1-2 years. In addition, late HDV RNA relapses have been described during long-term follow-up. Fortunately, new treatment options for patients with chronic hepatitis delta are now on the horizon. The hepatocyte entry inhibitor bulevirtide (formerly myrcludex B) and the farnesyl transferase inhibitor lonafarnib are currently explored in patients with chronic hepatitis delta in Phase 3 clinical studies. The nucleic acid inhibitor REP-2139-Ca and PEG-IFN-lambda are studied in Phase 2 trials. We here summarize data on the efficacy of these new antiviral drugs and the existing safety data on the treatment of HDV infection.

Optimization-by-design of hepatotropic lipid nanoparticles targeting the sodium-taurocholate cotransporting polypeptide.

Active targeting and specific drug delivery to parenchymal liver cells is a promising strategy to treat various liver disorders. Here, we modified synthetic lipid-based nanoparticles with targeting peptides derived from the hepatitis B virus large envelope protein (HBVpreS) to specifically target the sodium-taurocholate cotransporting polypeptide (NTCP; SLC10A1) on the sinusoidal membrane of hepatocytes. Physicochemical properties of targeted nanoparticles were optimized and NTCP-specific, ligand-dependent binding and internalization was confirmed in vitro. The pharmacokinetics and targeting capacity of selected lead formulations was investigated in vivo using the emerging zebrafish screening model. Liposomal nanoparticles modified with 0.25 mol% of a short myristoylated HBV derived peptide, that is Myr-HBVpreS2-31, showed an optimal balance between systemic circulation, avoidance of blood clearance, and targeting capacity. Pronounced liver enrichment, active NTCP-mediated targeting of hepatocytes and efficient cellular internalization were confirmed in mice by 111In gamma scintigraphy and fluorescence microscopy demonstrating the potential use of our hepatotropic, ligand-modified nanoparticles.

Excellent safety and effectiveness of high-dose myrcludex-B monotherapy administered for 48 weeks in HDV-related compensated cirrhosis: A case report of 3 patients.

Short-term administration of the entry inhibitor myrcludex-B (MyrB) has been shown to be safe and effective in phase II studies in patients coinfected with hepatitis B virus (HBV) and hepatitis delta virus (HDV). However, its effectiveness and safety are unknown during long-term and high-dose treatment of patients with compensated cirrhosis in real-life settings. Herein, we describe the first 3 European patients with HDV-related compensated cirrhosis who were treated with MyrB 10 mg/day for 48 weeks as a compassionate therapy. Liver function tests, bile acids, and virological markers were monitored every 4 weeks. HBV/HDV-specific T cell quantity (up to 48 and 36 weeks) and HBV RNA levels were also assessed in 2 cases. During MyrB treatment, HDV RNA levels progressively declined from 4.4 and 5.6 logs IU/ml to undetectability in 2 cases, and from 6.8 log copies/ml to 500 copies/ml for the other patient. Alanine aminotransferase normalised after 20, 12 and 28 weeks, respectively. A significant improvement in features of portal hypertension, liver function tests and alpha-fetoprotein levels were documented in 2 cases. In the male patient with histological and clinical stigmata of autoimmune hepatitis, IgG and immunoglobulins rapidly normalised. No significant changes in HBV surface antigen levels and circulating HBV/HDV-specific T cells were demonstrated; HBV DNA and HBV RNA levels remained undetectable throughout the study period. MyrB was well tolerated; patients remained fully asymptomatic despite a significant increase of bile acids. In conclusion, this report shows excellent safety and effectiveness of a 48-week course of MyrB 10 mg/day, combined with tenofovir disoproxil fumarate, for the treatment of HDV-related compensated cirrhosis.