Pharmacotherapeutic options for hepatitis B

Pharmacogenetics of tenofovir drug transporters in the context of HBV: Is there an impact?

BACKGROUND

Current treatments for chronic hepatitis B management include orally administered nucleos(t)ide analogues, such as tenofovir (TDF), which is an acyclic adenine nucleotide analogue used both in HBV and human immune deficiency virus (HIV). The course of HBV infection is mainly dependent on viral factors, such as HBV genotypes, immunological features and host genetic variables, but a few data are available in the context of HBV, in particular for polymorphisms of genes encoding proteins involved in drug metabolism and elimination. Consequently, the aim of this study was to evaluate the potential impact of genetic variants on TDF plasma and urine concentrations in patients with HBV, considering the role of HBV genotypes.

METHODS

A retrospective cohort study at the Infectious Disease Unit of Amedeo di Savoia Hospital, Torino, Italy, was performed. Pharmacokinetic analyses were performed through liquidi chromatography, whereas pharmacogenetic analyses through real-time PCR.

FINDINGS

Sixty - eight patients were analyzed: ABCC4 4976 C>T genetic variant showed an impact on urine TDF drug concentrations (p = 0.014). In addition, SLC22A6 453 AA was retained in the final regression multivariate model considering factors predicting plasma concentrations, while ABCC4 4976 TC/CC was the only predictor of urine concentrations in the univariate model.

INTERPRETATION

In conclusion, this is the first study showing a potential impact of genetic variants on TDF plasma and urine concentrations in the HBV context, but further studies in different and larger cohorts of patients are required.

Developments in pharmacotherapeutic agents for hepatitis B - how close are we to a functional cure?

INTRODUCTION

Hepatitis B virus (HBV) remains a public health concern given its global prevalence and potential complications including hepatocellular carcinoma (HCC). Current therapies, including nucleos(t)ide analogs (NA) and interferons (IFN), are effective in chronic treatment of HBV but rarely provide a functional cure due to inadequate host response and the presence of viral DNA. Therefore, novel therapies that enhance the innate immune response while suppressing DNA transcription may provide definitive treatment of HBV.

AREAS COVERED

In this review, the authors provide a brief overview of commonly used agents and their efficacy in treatment of HBV. Newer therapies with direct antiviral agents such as bepirovirsen (antisense oligonucleotide (ASO)) and entry inhibitors such as bulevirtide have shown efficacy in reducing viral load but demonstrate further reductions in conjunction with immune modulators such as therapeutic vaccines.

EXPERT OPINION

Combination therapy is far superior to monotherapy alone, necessitating the need for both immunomodulators and direct antiviral agents in chronic treatment of HBV. Therapies that target covalently closed circular (cccDNA) with immunomodulators like therapeutic vaccines have shown promising results and may ultimately achieve functional cure. However, therapies need to be evaluated in the context of the patient, considering both financial and socioeconomic factors.

One-year efficacy of tenofovir alafenamide in patients with chronic hepatitis B: An observational study

Non-inferior antiviral efficacy and better renal safety have been reported in chronic hepatitis B patients with tenofovir alafenamide (TAF) treatment. The experience in real-world clinical practice is limited.We aimed to explore the efficacy after 1-year TAF treatment.A total of 148 patients (42 HBeAg-positive and 106 HBeAg-negative) with TAF treatment ≥1 year were included. Virological suppression (<20 IU/mL or undetectable), HBsAg level, alanine aminotransferase (ALT) normalization (≤36 U/L), and estimated glomerular filtration rate (eGFR) were analyzed at 1 year. Multivariate logistic regression analysis was performed to determine the associated factors for virological suppression and ALT normalization.Virological suppression was achieved in 83% and the 1-year median decline of hepatitis B virus DNA was 5.18 log IU/mL. ALT normalization occurred in 75.7%. HBsAg level decreased at a median of 0.27 log IU/mL with significant difference from baseline (P < .001). Baseline ALT (odds ratio [OR] 1.005, 95% confidence interval [CI] 1.000-1.010, P = .036) and hepatitis B virus DNA (OR 0.222, 95% CI 0.079-0.621, P = .004) were significant factors for 1-year virological suppression. Age (OR 1.064, 95% CI 1.003-1.130, P = .041) was associated with ALT normalization. Significant changes were observed in creatinine (mean increase 0.03 mg/dL, P = .011) and eGFR (mean decrease 2.6 mL/min/1.73 m2, P = .004) after 1-year TAF treatment.One-year TAF treatment came to good virological response, modest ALT normalization rate and significant HBsAg decline. The observation of significant changes in eGFR warranted further studies.

Finite nucleos(t)ide analogue therapy in hepatitis B e antigen-negative chronic hepatitis B: From an "option" to an "active recommendation"

Nucleos(t)ide analogue (Nuc) including entecavir, tenofovir disoproxil fumarate, and tenofovir alafenamide may suppress hepatitis B virus (HBV) DNA profoundly but have no direct action on covalently closed circular DNA, which is a very stable template for HBV production. Therefore, decades of long-term Nuc therapy are required to maintain HBV suppression and to achieve hepatitis B surface antigen (HBsAg) loss in hepatitis B e antigen (HBeAg)-negative patients. However, there are concerns including financial burden, adherence, and willingness for indefinite long-term Nuc therapy. Patients lost to follow-up and hence not monitored may risk severe relapse that may deteriorate to hepatic decompensation or even hepatic failure. Cessation of Nuc therapy in HBeAg-negative patients was initially considered in early 2000s. Earlier findings in Asian patients that finite Nuc therapy over 2-3 years is feasible and safe have founded Asian-Pacific Association for the Study of Liver stopping rule since 2008. Subsequent studies have confirmed the feasibility and safety of the strategy of finite Nuc therapy, which has finally been accepted as "an option" by American and European liver associations since 2016. More recent large studies since 2018 have further confirmed the pivotal finding of greatly increased HBsAg loss rate (~5-year 39%) after stopping Nuc therapy. With the high HBsAg loss rate as the main justification, the paradigm shift from indefinite long-term therapy to finite Nuc therapy in HBeAg-negative patients has been changing from an "option" to an "active recommendation" aiming to achieve HBsAg loss. More studies are needed to fine-tuning the strategy, including research for the optimal duration of consolidation therapy, timing to stop, and to start retreatment.

APASL guidance on stopping nucleos(t)ide analogues in chronic hepatitis B patients

Chronic hepatitis B virus (HBV) infection is currently incurable. Long-term treatment with potent and safe nucleos(t)ide analogs (NAs) can reduce hepatocellular carcinoma (HCC) and cirrhosis-related complications through profound viral suppression. However, indefinite therapy raises several crucial issues with pros and cons. Because seroclearance of hepatitis B surface (HBsAg) as functional cure is not easily achievable, a finite therapy including sequential 48-week pegylated interferon therapy may provide an opportunity to facilitate HBsAg seroclearance by the rejuvenation of exhausted immune cells. However, the cost of stopping NA is the high incidence of virological relapse and surge of alanine aminotransferase (ALT) levels, which may increase the risk of adverse outcomes (e.g., decompensation, fibrosis progression, HCC, or liver-related mortality). So far, the APASL criteria to stop NA treatment is undetectable HBV DNA levels with normalization of ALT; however, this criterion for cessation of treatment is associated with various incidence rates of virological/clinical relapse and more than 40% of NA-stoppers eventually receive retreatment. A very intensive follow-up strategy and identification of low-risk patients for virological/clinical relapse by different biomarkers are the keys to stop the NA treatment safely. Recent studies suggested that decreasing HBsAg level at the end-of-treatment to < 100-200 IU/mL seems to be a useful marker for deciding when to discontinue NAs therapy. In addition, several viral and host factors have been reviewed for their potential roles in predicting clinical relapse. Finally, the APASL guidance has proposed rules to stop NA and the subsequent follow-up strategy to achieve a better prognosis after stopping NA. In general, for both HBeAg-positive and HBeAg-negative patients who have stopped treatment, these measurements should be done every 1-3 months at the minimum until 12 months.

The NTCP p.Ser267Phe Variant Is Associated With a Faster Anti-HBV Effect on First-Line Nucleos(t)ide Analog Treatment

Sodium taurocholate cotransporting polypeptide (NTCP) acts as a cellular receptor for the hepatitis B virus infection of host hepatocytes. Previously, many studies confirmed that the NTCP p.Ser267Phe variant was a protective factor against HBV-related disease progression. We therefore designed this study to investigate whether the NTCP p.Ser267Phe variant exerts an additive anti-HBV effect in chronic hepatitis B (CHB) patients on mainstream NAs treatment. After propensity score matching (PSM), a total of 136 CHB patients were included, among whom 68 were heterozygous carriers and 68 were wild-type controls. Proportions of primary nonresponse, partial virological response, virological breakthrough and hepatitis B reactivation and the HBV DNA clearance rate at each time point were compared using the chi-square test. Kaplan-Meier analysis and matched t-tests were also performed to estimate the speed of viral clearance and serum HBV DNA reduction, respectively. The proportion of primary nonresponse was significantly lower in heterozygous carriers than in wild-type controls (p < 0.001), especially in patients using entecavir (p = 0.013). Specifically, heterozygous carriers achieved HBV DNA clearance faster than wild-type controls (log-rank p = 0.0198). HBV DNA levels were reduced more in heterozygous carriers after 12 weeks (p < 0.001) and 24 weeks (p = 0.006) of treatment, especially among patients using ETV. Here, our study demonstrated that heterozygous mutations in rs2296651 enhanced the antiviral response of first-line NAs and helped to explore the possibility of combining NAs and NTCP blockers for a better anti-HBV effect.

Clinical utility of HBV surface antigen quantification in HBV e antigen-negative chronic HBV infection

Chronic hepatitis B virus (HBV) infection is a serious problem owing to its worldwide distribution and potential adverse sequelae that include cirrhosis and/or hepatocellular carcinoma. Current antiviral therapies have much improved outcomes, but few patients achieve the ultimate goal of hepatitis B surface antigen (HBsAg) loss (functional cure). As hepatitis B e antigen (HBeAg)-negative chronic HBV infection is the final phase prior to HBsAg loss, the management of patients in this phase together with quantification of HBsAg has attracted increasing clinical and research interest. This Review integrates the findings from research in HBsAg kinetics and discusses how they might inform our understanding and management of HBeAg-negative chronic HBV infection. Studies have shown that HBsAg levels are highly predictive of the presence of inactive HBV infection and that serial changes in HBsAg levels might predict HBsAg loss within 1-3 years. Data also suggest that quantitative HBsAg monitoring is important during hepatitis flare and antiviral therapy, especially in the timing of the decision to stop therapy and to start off-therapy retreatment. These findings have shed new light on the natural course of HBV infection and might lead to optimization of the management of HBeAg-negative chronic HBV infection and contribute to the paradigm shift from indefinite to finite therapy for patients with HBV infection.

Finite nucleos(t)ide analog therapy in HBeAg-negative chronic hepatitis B: an emerging paradigm shift

Potent nucleos(t)ide analogs (NUC), such as entecavir and tenofovir disoproxil fumarate, are able to suppress HBV DNA to undetectable level. These agents have no direct action on cccDNA, which is a very stable template for HBV production, hence long-term or even life-long NUC therapy is required in HBeAg-negative patients to maintain HBV suppression and to achieve the ultimate goal of HBsAg loss. However, there are concerns of indefinite or life-long NUC therapy, including drug resistance, financial burden, adherence and willingness for indefinite long-term NUC therapy. Patients lost to follow-up and hence, not monitored may risk severe relapse that may deteriorate to hepatic decompensation or even hepatic failure. This Review integrated the cumulated evidence and assessed the strategy of finite NUC therapy in HBeAg-negative patients which was first tried in early 2000s. Earlier Asian findings that 2-year NUC therapy is feasible and safe have founded APASL stopping rule for patients on NUC therapy over 2-3 years since 2008. Subsequent studies have supported the strategy of finite NUC therapy, which has finally been accepted as an option by American and European liver associations since 2016. More recent studies have further shown greatly increased HBsAg loss rate (up to 5-year 39%) after stopping NUC therapy. The cumulated evidence has shown that the paradigm shift from indefinite long-term therapy to finite NUC therapy in HBeAg-negative patients is emerging. More studies are needed to fine-tuning the strategy including research for the optimal duration of consolidation therapy, timing to stop and to start re-treatment.

Incidence and predictors of hepatitis B surface antigen seroclearance after cessation of nucleos(t)ide analogue therapy in hepatitis B e antigen-negative chronic hepatitis B

Hepatitis B surface antigen (HBsAg) loss is a rare event during nucleos(t)ide analogue (Nuc) therapy. Limited data suggest that stopping Nuc therapy may increase HBsAg loss rate in hepatitis B e antigen-negative patients. A large study was conducted to investigate this issue in more detail. Of the 1,075 hepatitis B e antigen-negative patients treated with Nuc for a median of 156 (61-430) weeks, 5 showed HBsAg seroclearance during treatment at an estimated annual incidence of 0.15%. Of the patients who remained HBsAg-seropositive, 691 (52.3 years old, 86% male, 44.6% cirrhosis) had stopped Nuc therapy by the Asian-Pacific Association for the Study of the Liver stopping rule and then were prospectively followed up. Baseline and on-treatment clinical and viral features, treatment duration, consolidation duration, time to undetectable hepatitis B virus DNA, time to normal alanine aminotransferase, end-of-treatment HBsAg, and HBsAg log reduction were compared between patients with and without HBsAg seroclearance after end of treatment. During a median off-therapy follow-up period of 155 (2-614) weeks, HBsAg seroclearance was confirmed in 42 patients. The 6-year cumulative incidence was 13% with an estimated annual incidence of 1.78%. Cox regression analysis showed that shorter time to undetectable hepatitis B virus DNA (<12 weeks), greater HBsAg reduction during therapy (>1 log₁₀ ), lower end-of-treatment HBsAg level (<100 IU/mL), patients with sustained response, and relapsers not retreated were factors for off-therapy HBsAg seroclearance.

CONCLUSION

The incidence of HBsAg seroclearance after stopping Nuc was much higher than that during therapy and highest in patients without virologic and clinical relapse; patients with clinical relapse who remained untreated had a 7.34 times higher incidence of HBsAg clearance than those who received retreatment, suggesting that transient untreated clinical relapse may drive sufficient immune control to functional cure. (Hepatology 2017).

Phase IV randomized clinical study: Peginterferon alfa-2a with adefovir or entecavir pre-therapy for HBeAg-positive chronic hepatitis B

BACKGROUND

Efficacy of sequential therapy with nucleos(t)ide analogues and interferons versus monotherapy in patients with hepatitis B e antigen (HBeAg)-positive chronic hepatitis B (CHB) remains unexplored. We aimed to assess efficacy and safety of sequential therapy with adefovir (ADV) or entecavir (ETV) followed by peginterferon (PEG-IFN) alfa-2a in Taiwanese patients with HBeAg-positive.

METHODS

This randomized, placebo-controlled, double-blind trial was conducted at nine sites in Taiwan from April 2010 to October 2013. Patients (N = 280) were randomized 1:1:1 to receive placebo, ETV or ADV alone for four weeks, combined with PEG-IFN alfa-2a for two weeks, then PEG-IFN alfa-2a alone for 46 weeks. The primary efficacy end point was HBeAg seroconversion at 48 weeks post-treatment.

RESULTS

No significant differences were observed among groups for HBeAg seroconversion (PEG-IFN alfa-2a+placebo, 36.3%; PEG-IFN alfa-2a+ETV, 29.5%; and PEG-IFN alfa-2a+ADV, 27.4%), HBeAg loss (37.4%, 32.2%, and 28.6%, respectively) or change in hepatitis B surface antigen (HBsAg) levels from baseline (-0.56 IU/mL, -0.60 IU/mL, and -0.41 IU/mL, respectively). However, hepatitis B virus DNA levels were higher with PEG-IFN alfa-2a+placebo than PEG-IFN alfa+ETV at week 64 (p = 0.0412), 76 (p = 0.0311), and 88 (p = 0.0113), and alanine aminotransferase (ALT) normalization rate was higher with PEG-IFN alfa-2a+placebo than PEG-IFN alfa-2a+ADV (p = 0.0283) or PEG-IFN alfa-2a+ETV (p = 0.0369) at week 88. Sub-analysis of results revealed an association between on-treatment HBsAg and ALT levels and efficacy 48 weeks post-treatment. Safety was comparable among treatment groups.

CONCLUSION

Pre-therapy with ADV or ETV followed by PEG-IFN alfa-2a is not superior to PEG-IFN alfa-2a monotherapy in Taiwanese patients with HBeAg-positive CHB.

CLINICAL TRIAL ID

NCT: 00922207.

A cell-penetrating whole molecule antibody targeting intracellular HBx suppresses hepatitis B virus via TRIM21-dependent pathway

Rationale: Monoclonal antibodies (mAbs) mostly targeting extracellular or cell surface molecules have been widely used in the treatment of various diseases. However, mAbs cannot pass through the cell membrane as efficiently as small compounds, thus limiting their use against intracellular targets. Methods to shuttle antibodies into living cells may largely expand research and application in areas based on mAbs. Hepatitis B virus X protein (HBx) is an important intracellular multi-functional viral protein in the life cycle of hepatitis B virus (HBV). HBx plays essential roles in virus infection and replication and is strongly associated with HBV-related carcinogenesis.

Methods: In this study, we developed a cell-penetrating whole molecule antibody targeting HBx (9D11-Tat) by the fusion of a cell penetrating peptide (CPP) on the C-terminus of the heavy chain of a potent mAb specific to HBx (9D11). The anti-HBV effect and mechanism of 9D11-Tat were investigated in cell and mouse models mimicking chronic HBV infection.

Results: Our results demonstrated that the recombinant 9D11-Tat antibody could efficiently internalize into living cells and significantly suppress viral transcription, replication, and protein production both in vitro and in vivo. Further analyses suggested the internalized 9D11-Tat antibody could greatly reduce intracellular HBx via Fc binding receptor TRIM21-mediated protein degradation. This process simultaneously stimulated the activations of NF-κB, AP-1, and IFN-β, which promoted an antiviral state of the host cell.

Conclusion: In summary, our study offers a new approach to target intracellular pathogenesis-related protein by engineered cell-penetrating mAb expanding their potential for therapeutic applications. Moreover, the 9D11-Tat antibody may provide a novel therapeutic agent against human chronic HBV infection.

Novel HBV mutations and their value in predicting efficacy of conventional interferon

BACKGROUND

Accumulating studies assessing the impacts of hot spot mutations on conventional interferon (IFN) efficacy come to discrepant conclusions; studies regarding the mutations in S and RT regions are also unclear. The present study aimed to evaluate the impacts of HBV mutations on the efficacy of conventional IFN.

METHODS

A total of 126 patients who received conventional IFN treatment for 48 weeks were enrolled. Biochemical and serological parameters were routinely tested. The sequences of HBV from 78 serum samples were amplified by nested-PCR; mutations were identified with sequence scanner V1.0 after ABI 3730xl direct sequencing, HBV genotypes were determined according to RT gene sequences utilizing NCBI Genotyping Tool which was based on phylogenetic analysis.

RESULTS

The baseline DNA levels of virological response (VR) group were significantly lower than those of no VR group [7.13+/-0.76 vs 7.69+/-0.56 lg (copies/mL), P=0.001]. The baseline ALT levels were significantly higher in the HBeAg clearance group (204.72+/-88.65 vs 162.80+/-85.81 IU/L, P<0.05) and HBeAg seroconversion group (204.89+/-95.68 vs 166.75+/-84.43 IU/L, P<0.05). Females and lower BMI levels (20.01+/-2.33 vs 21.65+/-3.66 kg/m2, P<0.05) were prone to acquired biochemical response (BR). PC-W28STOP (ntG1896A) was significantly higher in the combined response (CR) group than that in the no CR group (91.7% vs 39.7%, P=0.001). Multivariate logistic regression analysis showed that baseline DNA, PC-P159T (ntC2288A), BCP-N118T (ntA1726C) and BCP-L134L (ntA1775C/G/T) influenced VR independently. PC-G182C (ntG2357T), PC-S64A/T (ntT2003G/A) and BMI were independent influence factors for HBeAg clearance, HBeAg seroconversion and BR, respectively. The new predicting model concluded that baseline DNA and new mutations for VR were established successfully, and ROC analysis showed that AUC was 0.842 (P<0.001) with a sensitivity of 0.652 and a specificity of 0.933.

CONCLUSIONS

PC-P159T (ntC2288A), BCP-N118T (ntA1726C), BCP-L134L (ntA1775C/G/T), PC-G182C (ntG2357T) and PC-S64A/T (ntT2003G/A) were novel identified mutations that impacted IFN therapeutic efficacy. These novel mutations could serve as important predictors before conventional IFN treatment.