Off-Therapy Response After Nucleos(t)ide Analogue Withdrawal in Patients With Chronic Hepatitis B: An International, Multicenter, Multiethnic Cohort (RETRACT-B Study)

Perspective on Emerging Therapies to Achieve Functional Cure of Chronic Hepatitis B

Purpose of Review

Advancements in our understanding of the hepatitis B viral (HBV) life cycle have paved the way for novel approaches to treat HBV infection. This review summarizes the various strategies being pursued to achieve a functional cure, defined as loss of hepatitis B surface antigen (HBsAg) and absence of viral replication 6 months off-therapy.

Recent Findings

Direct acting antiviral, host targeting antiviral, and immunological approaches are in various stages of development as treatment for chronic HBV infection.

Summary

Novel treatments are being developed in pursuit of a cure for HBV. Current evidence suggests a single therapeutic agent alone may be insufficient, necessitating the need for combination therapy targeting HBV and the host immune response. Ongoing research focused on identifying the best therapeutic combination holds promise in achieving functional cure for HBV.

A retrospective study to determine the correlation among HBV PreS1 antigen, HBV e antigen, alanine aminotransferase, and HBV DNA

BACKGROUND AND AIM

Hepatitis B virus (HBV) infection presents with indicators of varying clinical significance. We aimed to evaluate the correlation among HBV Pre-S1 antigen (HBV PreS1-Ag), HBV e antigen (HBeAg), HBV DNA, and alanine aminotransferase (ALT) levels.

METHODS

We retrospectively analyzed 6180 serum samples collected between 2020 and 2022 at the Shanghai General Hospital, China. Data regarding PreS1-Ag, HBeAg, ALT, and HBV DNA were compiled. Correlation analyses and cross-tabulations were employed to explore the diagnostic indicators.

RESULTS

The detection rates of both antigen indicators showed a proportional increase with HBV DNA loads. The correlation between PreS1-Ag and HBV DNA (r = 0.616) was stronger than that between HBeAg and HBV DNA (r = 0.391). The specificity of PreS1-Ag (84.30 %) was lower than that of HBeAg (97.44 %), whereas the sensitivity of HBeAg (91.13 %) significantly surpassed that of PreS1-Ag (29.56 %). Among the HBV DNA positive patients, 92.04 % tested positive for at least one indicator, which exceeded the rate of PreS1+HBeAg- and PreS1-HBeAg+ (52. 28 % and 68. 56 %, respectively). Only 1.75 % of the patients exhibited double negativity, which was lower than the percentage of patients with single negativity (1.95 % and 12.00 % for PreS1-Ag and HBeAg, respectively). The PreS1 levels correlated with ALT levels (r = 0.317); patients with PreS1-positive status had higher ALT levels than patients with PreS1-negative status.

CONCLUSION

PreS1-Ag is a more robust HBV replication indicator than HBeAg. PreS1-Ag displayed high sensitivity, whereas HBeAg demonstrated high specificity. Moreover, PreS1-Ag levels correlated with ALT levels. A combination of these indicators demonstrated dependable clinical value for detecting HBV infection and evaluating liver function.

CRISPR-Cas13b-mediated suppression of hepatitis B virus replication and protein expression

BACKGROUND & AIMS

New antiviral approaches are urgently required that target multiple aspects of the hepatitis B virus (HBV) replication cycle to improve rates of functional cure. HBV RNA represents a novel therapeutic target. Here, we programmed Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR)-Cas13b endonuclease, to specifically target the HBV pregenomic RNA (pgRNA) and viral mRNAs in a novel approach to reduce HBV replication and protein expression.

METHODS

Cas13b CRISPR RNAs (crRNAs) were designed to target multiple regions of HBV pgRNA. Mammalian cells with replication competent wildtype HBV DNA of different genotypes, a HBV stable cell line, a HBV infection model and a hepatitis B surface antigen (HBsAg)-expressing stable cell line were transfected with PspCas13b-blue fluorescent protein (BFP) and crRNAs plasmids and the impact on HBV replication and protein expression was measured. WT HBV DNA, PspCas13b-BFP and crRNA plasmids were simultaneously hydrodynamically injected into mice, and sera HBsAg was measured. PspCas13b mRNA and crRNA were also delivered by lipid nanoparticles (LNP) in a HBsAg-expressing stable cell line and the impact on secreted HBsAg determined.

RESULTS

Our HBV targeting crRNAs strongly suppressed HBV replication and protein expression in mammalian cells by up to 96% (p<0.0001). HBV protein expression was also reduced in an HBV stable cell line and in the HBV infection model. CRISPR-Cas13b crRNAs reduced HBsAg expression by 50% (p<0.0001) in vivo. LNP-encapsulated PspCas13b mRNA reduced secreted HBsAg by 87% (p=0.0168) in a HBsAg-expressing stable cell line.

CONCLUSIONS

Together, these results show that CRISPR-Cas13b can be programmed to specifically target and degrade HBV RNAs to reduce HBV replication and protein expression, demonstrating its potential as a novel therapeutic option for chronic HBV infection.

IMPACT AND IMPLICATIONS

There is an urgent need for new treatments that target multiple aspects of the HBV replication cycle. Here, we present CRISPR-Cas13b as a novel strategy to target HBV replication and protein expression paving the way for its development as a potential new treatment option for patients living with chronic hepatitis B.

Expanding indications for chronic hepatitis B treatment: Is it really desirable to treat everyone?

Chronic viral hepatitis causes an increased risk of progressive liver disease and hepatocellular carcinoma. On the wave of the World Health Organization's goal to reduce new cases and deaths from hepatitis B and C by 2030, there is an increasing call to expand the indications for treatment of chronic hepatitis B. Currently, the main goal of treatment is to achieve a functional cure due to the inability of current drugs to completely eradicate the virus. There are still many discrepancies between available guidelines in terms of eligibility for treatment as well as an uncertainty about the appropriate treatment duration. This editorial addresses key questions about the topic and whether indications for treatment should be expanded.

Limited Sustained Remission After Nucleos(t)ide Analog Withdrawal: Results From a Large, Global, Multiethnic Cohort of Patients With Chronic Hepatitis B (RETRACT-B Study)

INTRODUCTION

Complete viral suppression with nucleos(t)ide analogs (NAs) has led to a profound reduction in hepatocellular carcinoma and mortality among patients with chronic hepatitis B. Finite therapy yields higher rates of functional cure; however, initial hepatitis B virus (HBV) DNA and alanine aminotransferase (ALT) elevations are almost certain after treatment interruption. We aimed to analyze off-treatment outcomes beyond 12 months after NA cessation.

METHODS

Patients with well-suppressed chronic hepatitis B who were hepatitis B e antigen-negative at NA cessation and remained off treatment without hepatitis B surface antigen (HBsAg) loss at 12 months were included (n = 945). HBV DNA and ALT fluctuations were allowed within the first 12 months. We used Kaplan-Meier methods to analyze outcomes beyond 12 months. Sustained remission was defined as HBV DNA <2,000 IU/mL and ALT <2× upper limit of normal (ULN) and an ALT flare as ALT ≥5× ULN.

RESULTS

Cumulative probability of sustained remission was 29.7%, virological relapse was 65.2% with a mean peak HBV DNA of 5.0 ± 1.5 log 10 IU/mL, an ALT flare was 15.6% with a median peak ALT × ULN of 8.3 (5.7-11.3), HBsAg loss was 9.9% and retreatment was 34.9% at 48 months after NA cessation. A single occurrence of virological relapse or an ALT flare within the first 12 months off-treatment were associated with significantly lower rates of sustained remission beyond 12 months.

DISCUSSION

Despite allowing for HBV DNA and ALT fluctuations within the first 12 months off-treatment, most patients without HBsAg loss did not maintain a sustained response thereafter. The best candidates for NA withdrawal are patients with low HBsAg levels at NA cessation, and those without profound or recurrent virological and biochemical relapses in the first off-treatment year.

Chronic Hepatitis B Finite Treatment: Similar and Different Concerns With New Drug Classes

Chronic hepatitis B, a major cause of liver disease and cancer, affects >250 million people worldwide. Currently there is no cure, only suppressive therapies. Efforts to develop finite curative hepatitis B virus (HBV) therapies are underway, consisting of combinations of multiple novel agents with or without nucleos(t)ide reverse-transcriptase inhibitors. The HBV Forum convened a webinar in July 2021, along with subsequent working group discussions to address how and when to stop finite therapy for demonstration of sustained off-treatment efficacy and safety responses. Participants included leading experts in academia, clinical practice, pharmaceutical companies, patient representatives, and regulatory agencies. This Viewpoints article outlines areas of consensus within our multistakeholder group for stopping finite therapies in chronic hepatitis B investigational studies, including trial design, patient selection, outcomes, biomarkers, predefined stopping criteria, predefined retreatment criteria, duration of investigational therapies, and follow-up after stopping therapy. Future research of unmet needs are discussed.

JNJ-73763989 and bersacapavir treatment in nucleos(t)ide analog suppressed patients with chronic hepatitis B: REEF-2

BACKGROUND & AIMS

Functional cure (FC) for chronic hepatitis B (CHB) requires finite treatment. Two agents under investigation aimed at achieving FC are small interfering RNA JNJ-73763989 (JNJ-3989) and capsid assembly modulator JNJ-56136379 (JNJ-6379; bersacapavir).

METHODS

REEF-2, a phase 2b, double-blind, placebo-controlled, randomized study (ClinicalTrials.gov Identifier: NCT04129554), enrolled 130 nucleos(t)ide analog (NA)-suppressed hepatitis B e-antigen (HBeAg)-negative CHB patients who received JNJ-3989 (200 mg subcutaneously every 4 weeks)+JNJ-6379 (250 mg oral daily)+NA (oral daily; active arm) or placebos for JNJ-3989 and JNJ-6379 + active NA (control arm) for 48 weeks followed by 48 weeks off-treatment follow-up.

RESULTS

At Follow-up Week 24, no patients achieved the primary endpoint of FC (off-treatment hepatitis B surface antigen [HBsAg] seroclearance). No patients achieved FC at Follow-up Week 48. There was pronounced on-treatment reduction in mean HBsAg from baseline at Week 48 in the active arm versus no decline in the control arm (1.89 vs 0.06 log10 IU/mL; P = 0.001). At Follow-up Week 48, reductions from baseline were >1 log10 IU/mL in 81.5% versus 12.5% of patients in the active and control arms, respectively, and 38/81 (46.9%) patients in the active arm achieved HBsAg <100 IU/mL versus 6/40 (15.0%) patients in the control arm. Off-treatment HBV DNA relapse and alanine aminotransferase (ALT) increases were less frequent in the active arm with 7/77 (9.1%) and 11/41 (26.8%) patients in the active and control arms, respectively, restarting NA during follow-up.

CONCLUSIONS

Finite 48-week treatment with JNJ-3989+JNJ-6379+NA resulted in fewer and less severe posttreatment HBV DNA increases and ALT flares, and a higher proportion of patients with off-treatment HBV DNA suppression, with or without HBsAg suppression, but did not result in FC.

CLINICALTRIALS

GOV IDENTIFIER

NCT04129554.

ALT to qHBsAg ratio predicts long-term HBsAg seroclearance after entecavir cessation in Chinese patients with chronic hepatitis B

BACKGROUND & AIMS

Factors predicting HBsAg seroclearance after treatment cessation, irrespective of nucleos(t)ide analogue (NA) resumption, have important clinical implications. We evaluated predictors of long-term HBsAg seroclearance after entecavir cessation.

METHODS

This study followed-up Chinese patients with chronic hepatitis B from two previous studies of entecavir cessation. All patients were non-cirrhotic, HBeAg-negative, with undetectable HBV DNA (<20 IU/ml) at end-of-treatment (EOT). They were monitored closely for 48 weeks with regular HBV DNA, quantitative HBsAg (qHBsAg) and alanine aminotransferase (ALT) measurements. Entecavir was resumed at HBV DNA >2,000 IU/ml, irrespective of ALT levels. After the initial 48 weeks, patients were assessed every 6 months, regardless of entecavir resumption, to monitor for HBsAg seroclearance.

RESULTS

A total of 194 patients (63.4% male, mean age 49.9 years, on entecavir for a median of 47.2 months) were recruited; 94 (48.5%) and 158 (81.4%) patients had EOT qHBsAg <100 IU/ml and <1,000 IU/ml, respectively; 151 (77.8%) patients were eventually resumed on entecavir. After follow-up for a median of 70.7 (51.0-118.2) months, 28 (14.4%) patients had HBsAg seroclearance. qHBsAg levels at weeks 36 and 48 after EOT independently predicted HBsAg seroclearance (both p <0.01), whereas qHBsAg from EOT to week 24 only trended towards statistical significance. The ratio of ALT/qHBsAg at all time points from EOT to week 48 independently predicted HBsAg seroclearance (hazard ratios ranging from 1.003-1.028, all p <0.01) with excellent diagnostic performance (area under the receiver-operating characteristic curve 0.799-0.933, negative predictive value >90% at different time points), regardless of whether entecavir was resumed.

CONCLUSIONS

The ALT/qHBsAg ratio after entecavir cessation predicts HBsAg seroclearance, even in patients who were resumed on treatment. Its use may mitigate the risk of severe hepatitis flares in patients managed by observation without treatment resumption.

IMPACT AND IMPLICATIONS

Current predictors of HBsAg seroclearance after finite nucleos(t)ide analogue (NA) therapy have suboptimal predictive value. We demonstrated that the ALT/qHBsAg ratio may be able to reflect the balance between host control and virological activity. The ALT/qHBsAg ratio at different time points from end-of-treatment till week 48 independently and accurately predicted HBsAg seroclearance in patients who have stopped entecavir. The ALT/qHBsAg ratio may be utilized by clinicians for patient selection and retreatment decisions in finite NA therapy.

Sustained response and HBsAg loss after nucleo(s)tide analogue discontinuation in chronic hepatitis B patients: the prospective SNAP study

BACKGROUND & AIM(S)

Current guidelines suggest that nucleos(t)ide analogues (NA) can be discontinued before HBsAg loss in a selected group of chronic hepatitis B (CHB) patients. We aimed to study the safety and off-treatment response after NA cessation.

METHODS

This is a prospective, multicentre, cohort study in which eligible patients discontinued NA therapy. Adult patients, with a CHB mono-infection, HBeAg-negative, without a (history of) liver cirrhosis, who had achieved long-term viral suppression were eligible. Follow-up visits were planned at week 2-4-8-12-24-36-48-72-96. Re-treatment criteria included severe hepatitis (ALT >10x ULN), signs of imminent liver failure (bilirubin >1.5x ULN or INR >1.5), or at the physician's own discretion.

RESULTS

In total, 33 patients were enrolled. Patients were predominantly Caucasian (45.5%) and had genotype A/B/C/D/unknown in 3/4/6/10/10 (9.1/12.1/18.2/30.3/30.3%). At week 48, 15 patients (45.5%) achieved a sustained response (HBV DNA <2,000 IU/mL). At week 96, 13 patients (39.4%) achieved a sustained response, 4 (12.1%) achieved HBsAg loss, and 12 (36.4%) were re-treated. Severe hepatitis was the main reason for re-treatment (n=7, 21.2%). One patient with severe hepatitis developed jaundice, without signs of hepatic decompensation. Re-treatment was successful in all patients.

CONCLUSION

NA therapy can be ceased in a highly selected group of CHB patients if close follow-up can be guaranteed. Treatment cessation may increase the chance of HBsAg loss in selected patients, which is counterbalanced by a significant risk of severe hepatitis.

Letter: Estimating the incidence of HBsAg seroclearance after cessation of tenofovir and entecavir - potential influence of censored observation

This article is linked to Chen et al papers. To view these articles, visit https://doi.org/10.1111/apt.17602 and https://doi.org/10.1111/apt.17788

HBV DNA and HBsAg Levels at 24 Weeks Off-Treatment Predict Clinical Relapse and HBsAg Loss in HBeAg-Negative Patients Who Discontinued Antiviral Therapy

BACKGROUND & AIMS

Patients who discontinue nucleo(s)tide analogue therapy are at risk of viral rebound and severe hepatitis flares, necessitating intensive off-treatment follow-up.

METHODS

We studied the association between hepatitis B surface antigen (HBsAg) and hepatitis B virus (HBV) DNA levels at off-treatment follow-up week 24 (FU W24), with subsequent clinical relapse, and HBsAg loss in a multicenter cohort of hepatitis B e antigen (HBeAg)-negative patients with chronic hepatitis B who discontinued nucleo(s)tide analogue therapy.

RESULTS

We studied 475 patients, 82% Asian, and 55% treated with entecavir. Patients with higher HBV DNA levels at FU W24 had a higher risk of clinical relapse (hazard ratio [HR], 1.576; P < .001) and a lower chance of HBsAg loss (HR, 0.454; P < .001). Similarly, patients with higher HBsAg levels at FU W24 had a higher risk of clinical relapse (HR, 1.579; P < .001) and a lower chance of HBsAg loss (HR, 0.263; P < .001). A combination of both HBsAg <100 IU/mL and HBV DNA <100 IU/mL at FU W24 identified patients with excellent outcomes (9.9% clinical relapse and 58% HBsAg loss at 216 weeks of follow-up). Conversely, relapse rates were high and HBsAg loss rates negligible among patients with both HBsAg >100 IU/mL and HBV DNA >100 IU/mL (P < .001).

CONCLUSIONS

Among HBeAg-negative patients with chronic hepatitis B who discontinued antiviral therapy and who did not experience clinical relapse before FU W24, serum levels of HBV DNA and HBsAg at FU W24 can be used to predict subsequent clinical relapse and HBsAg clearance. A combination of HBsAg <100 IU/mL with HBV DNA <100 IU/mL identifies patients with a low risk of relapse and excellent chances of HBsAg loss and could potentially be used as an early surrogate end point for studies aiming at finite therapy in HBV.

Long-term entecavir therapy of chronic hepatitis B in real-life setting-Importance of quantitative HBsAg level

BACKGROUND

The global burden of chronic hepatitis B remains high and the best possible treatment remains long-term viral suppression expecting cure.

METHODS

Total 154 patients of chronic hepatitis B (48 HBeAg positive, e + ve) treated with oral entecavir (0.5 mg/1 mg per day) were recruited from June 2007 and followed prospectively until December 2022 for persistent HBV DNA negativity, HBeAg and HBsAg loss/seroconversion and other liver and drug-related events in real-life settings.

RESULTS

The mean duration of therapy was 6.78 (2-14) years with 1364 person-years of follow-up. All patients were HBV DNA negative by 15 months and remained so until the last follow-up. As many as 16.7% lost HBeAg after eight to 13 years of therapy, but not HBsAg. The mean fall in serum HBsAg level per year was 0.158 log IU/mL, being significantly higher in e + ve patients at baseline and until two years of therapy. The decline was significant until six years in e + ve patients compared to two years in e - ve ones. None had biochemical or virological breakthrough (except eight defaulters), flares or any untoward effects. The incidence of liver-related events, hepatocellular carcinoma and death was 10.4%, 1.9% and 14.3%, respectively, and 5.2% deaths were liver-related whose predictors were presence of cirrhosis (log rank 46.5, p > 0.001) and higher HBsAg level > 4 log IU/mL (log rank 18.15, p < 0.001) at baseline.

CONCLUSION

Long-term entecavir therapy provides additional benefits of continuous reduction of serum HBsAg levels beyond suppression of HBV DNA.

Gene-Editing and RNA Interference in Treating Hepatitis B: A Review

The hepatitis B virus (HBV) continues to cause substantial health and economic burdens, and its target of elimination may not be reached in 2030 without further efforts in diagnostics, non-pharmaceutical prevention measures, vaccination, and treatment. Current therapeutic options in chronic HBV, based on interferons and/or nucleos(t)ide analogs, suppress the virus replication but do not eliminate the pathogen and suffer from several constraints. This paper reviews the progress on biotechnological approaches in functional and definitive HBV treatments, including gene-editing tools, i.e., zinc-finger proteins, transcription activator-like effector nucleases, and CRISPR/Cas9, as well as therapeutics based on RNA interference. The advantages and challenges of these approaches are also discussed. Although the safety and efficacy of gene-editing tools in HBV therapies are yet to be demonstrated, they show promise for the revitalization of a much-needed advance in the field and offer viral eradication. Particular hopes are related to CRISPR/Cas9; however, therapeutics employing this system are yet to enter the clinical testing phases. In contrast, a number of candidates based on RNA interference, intending to confer a functional cure, have already been introduced to human studies. However, larger and longer trials are required to assess their efficacy and safety. Considering that prevention is always superior to treatment, it is essential to pursue global efforts in HBV vaccination.

Guidelines for the Prevention and Treatment of Chronic Hepatitis B (version 2022)

To facilitate the achieving of the goal of "eliminating viral hepatitis as a major public health threat by 2030" set by the World Health Organization, the Chinese Society of Hepatology together with the Chinese Society of Infectious Diseases (both are branches of the Chinese Medical Association) organized a panel of experts and updated the guidelines for prevention and treatment of chronic hepatitis B in China (version 2022). With the support of available evidence, this revision of the guidelines focuses on active prevention, large scale testing, and expansion of therapeutic indication of chronic hepatitis B with the aim of reducing the hepatitis B related disease burden.

Long-Term Hepatitis B Surface Antigen Profile and Seroclearance Following Antiviral Treatment: A Single-Center, Real-World Cohort Study

Hepatitis B surface antigen (HBsAg) seroclearance, an indicator of recovery from hepatitis B virus (HBV) infection, is uncommon in long-term nucleos(t)ide analog (NUC) therapy. We compared the incidence of HBsAg seroclearance in patients with and without NUC discontinuation to identify predictors of HBsAg seroclearance. This retrospective study enrolled adult patients with a chronic HBV infection followed for ≥12 months after NUC discontinuation (finite group) and those treated with NUCs for >3 years (non-finite group). Demographic, clinical, and laboratory data were analyzed. The study cohort included 978 patients, including 509 and 469 patients in the finite and non-finite groups, respectively. Cumulative HBsAg seroclearance incidence was significantly higher in the finite group than in the non-finite group (p = 0.006). The 5- and 10-year cumulative HBsAg seroclearance incidence were 6.6% and 18.9% in the finite group and 3% and 14.6% in the non-finite group, respectively. The likelihood of HBsAg seroclearance was higher in those with end of treatment (EOT) HBsAg levels of <100 IU/mL and in those without clinical relapse (CR). The cumulative 3-year CR incidence was 16.8%. The incidence of liver decompensation and hepatocellular carcinoma were 4.1 and 0.4 per 1000 person-years, respectively. The hepatocellular carcinoma incidence did not significantly differ between the finite and non-finite groups (p = 0.941). In conclusion, higher HBsAg seroclearance incidence in patients receiving finite therapy, and the increased likelihood of HBsAg seroclearance in those with EOT HBsAg levels of <100 IU/mL and in those without CR should be considered during decision-making of treatment options.

First-in-human randomized study of RNAi therapeutic RG6346 for chronic hepatitis B virus infection

BACKGROUND & AIMS

RG6346 is an N-acetyl-D-galactosamine (GalNAc)-conjugated, double-stranded RNA interference agent targeting the HBV genome S-region. We investigated the safety, tolerability, pharmacokinetics, and pharmacodynamics of RG6346 in healthy volunteers and patients with chronic HBV infection (CHB).

METHODS

This first-in-human, adaptive, randomized, double-blinded, phase I study recruited three groups of participants: Group A, 30 healthy volunteers received single-dose RG6346 at 0.1, 1.5, 3.0, 6.0, or 12.0 mg/kg, or placebo; Group B, nucleos(t)ide analogue-naïve participants with CHB received single-dose RG6346 at 3.0 mg/kg (n = 6) or placebo (n = 3); Group C, participants with nucleos(t)ide-suppressed CHB received four doses (every 28 days) of RG6346 at 1.5, 3.0, or 6.0 mg/kg (n = 4 in each cohort) or placebo (n = 6).

RESULTS

RG6346 treatment for up to 4 months was safe and well tolerated. The most common adverse event was a mild injection site reaction. Several nucleos(t)ide-naïve participants exhibited self-resolving transaminase elevations with preserved liver function. By the end of RG6346 treatment in Group C (Day 112), the mean reduction from baseline in hepatitis B surface antigen (HBsAg) was 1.39, 1.80, and 1.64 log10 IU/ml in the 1.5, 3.0, and 6.0 mg/kg cohorts, respectively. Of the 12 participants in Group C, 11 (91.7%) achieved a ≥1 log10 IU/ml reduction in HBsAg (3 of 11 [27.3%] had the response sustained at conditional follow-up Day 448). No dose-response relationship was apparent between RG6346 and serum HBsAg levels. The RG6346-induced HBsAg response was independent of hepatitis B e antigen status. Moderate-to-marked sustained reductions of hepatitis B core-related antigen, HBV RNA, HBV DNA (in nucleos[t]ide analogue-naïve participants), and hepatitis B e antigen levels were observed.

CONCLUSIONS

These favorable safety and pharmacodynamic data support the clinical development of RG6346 as the backbone of a finite antiviral treatment regimen, with the goal of sustained HBsAg loss (functional cure) in patients with CHB.

CLINICAL TRIAL NUMBER

ClinicalTrials.gov NCT03772249.

IMPACT AND IMPLICATIONS

Currently available therapies for chronic HBV infection are associated with low rates of functional cure and new, more efficacious treatments are needed. This first-in-human study of RG6346, an RNA interference therapy, showed a favorable safety profile as well as marked and durable reductions in hepatitis B surface antigen levels. These results support the continued development of RG6346 as the backbone of a finite treatment regimen targeting high functional cure rates and are important for HBV researchers and physicians.

Safety considerations for withdrawal of nucleos(t)ide analogues in patients with chronic hepatitis B: First, do no harm

Nucleos(t)ide analogues (NA) are widely used to treat hepatitis B virus (HBV) infection, but they cannot eradicate the virus and treatment duration can be lifelong if the endpoint is set at seroclearance of the hepatitis B surface antigen (HBsAg). As an alternative strategy, finite NA therapy without the prerequisite of HBsAg seroclearance has been proposed to allow treatment cessation in patients with sustained undetectable HBV viremia for two to three years. However, reactivation of viral replication almost always follows NA withdrawal. Whereas HBV reactivation might facilitate HBsAg seroclearance in some, it could lead to serious acute flare-ups in a certain proportion of patients. Occurrence and consequences of NA withdrawal flares are complicated with various factors involving the virus, host, and treatment. Accurate risk prediction for severe flares following NA cessation is essential to ensure patient safety. The risks of life-threatening flares in patients who discontinued NA according to the stopping rules of current guidelines or local reimbursement policies have recently been quantitatively estimated in large-scale studies, which also provided empirical evidence to help identify vulnerable patients at risk of devastating outcomes. Moreover, risk predictors were further explored and validated to hopefully aid in patient selection and management. In this narrative review with a focus on patient safety, we summarize and discuss current literature on the incidence of severe flares following NA cessation, risk stratification for candidate selection, rules of posttreatment monitoring, and indications for treatment resumption. We also share our thoughts on the limitations of existing knowledge and suggestions for future research.

Incidence of Hepatic Decompensation After Nucleos(t)ide Analog Withdrawal: Results From a Large, International, Multiethnic Cohort of Patients With Chronic Hepatitis B (RETRACT-B Study)

INTRODUCTION

Despite improvements in the management of chronic hepatitis B (CHB), risk of cirrhosis and hepatocellular carcinoma remains. While hepatitis B surface antigen loss is the optimal end point, safe discontinuation of nucleos(t)ide analog (NA) therapy is controversial because of the possibility of severe or fatal reactivation flares.

METHODS

This is a multicenter cohort study of virally suppressed, end-of-therapy (EOT) hepatitis B e antigen (HBeAg)-negative CHB patients who stopped NA therapy (n = 1,557). Survival analysis techniques were used to analyze off-therapy rates of hepatic decompensation and differences by patient characteristics. We also examined a subgroup of noncirrhotic patients with consolidation therapy of ≥12 months before cessation (n = 1,289). Hepatic decompensation was considered related to therapy cessation if diagnosed off therapy or within 6 months of starting retreatment.

RESULTS

Among the total cohort (11.8% diagnosed with cirrhosis, 84.2% start-of-therapy HBeAg-negative), 20 developed hepatic decompensation after NA cessation; 10 events were among the subgroup. The cumulative incidence of hepatic decompensation at 60 months off therapy among the total cohort and subgroup was 1.8% and 1.1%, respectively. The hepatic decompensation rate was higher among patients with cirrhosis (hazard ratio [HR] 5.08, P < 0.001) and start-of-therapy HBeAg-positive patients (HR 5.23, P < 0.001). This association between start-of-therapy HBeAg status and hepatic decompensation remained significant even among the subgroup (HR 10.5, P < 0.001).

DISCUSSION

Patients with cirrhosis and start-of-therapy HBeAg-positive patients should be carefully assessed before stopping NAs to prevent hepatic decompensation. Frequent monitoring of viral and host kinetics after cessation is crucial to determine patient outcome.

Editorial: Mitigating the risk of severe hepatitis flare following nucleoside analogue discontinuation-Insights from a real-world study. Authors' reply

This article is linked to Hsu et al papers. To view these articles, visit https://doi.org/10.1111/apt.17614 and https://doi.org/10.1111/apt.17630

Lower pretreatment HBV DNA levels are associated with better off-treatment outcomes after nucleo(s)tide analogue withdrawal in patients with HBeAg-negative chronic hepatitis B: A multicentre cohort study

Background & Aims

Pretreatment predictors of finite nucleo(s)tide analogue (NUC) therapy remain elusive. We studied the association between pretreatment HBV DNA levels and outcomes after therapy cessation.

Methods

Patients with chronic hepatitis B who were HBeAg negative at the start of NUC treatment were enrolled from sites in Asia and Europe. We studied the association between pretreatment HBV DNA levels and (1) clinical relapse (defined as HBV DNA >2,000 IU/ml + alanine aminotransferase >2 × the upper limit of normal or retreatment) and (2) HBsAg loss after NUC withdrawal.

Results

We enrolled 757 patients, 88% Asian, 57% treated with entecavir, with a median duration of treatment of 159 (IQR 156-262) weeks. Mean pretreatment HBV DNA levels were 5.70 (SD 1.5) log IU/ml and were low (<20,000 IU/ml) in 150 (20%) and high (>20,000 IU/ml) in 607 (80%). The cumulative risk of clinical relapse at 144 weeks after therapy cessation was 22% among patients with pretreatment HBV DNA levels <20,000 IU/ml vs. 60% among patients with pretreatment HBV DNA levels >20,000 IU/ml, whereas the cumulative probabilities of HBsAg loss were 17.5% vs. 5% (p <0.001). In multivariable analysis, pretreatment HBV DNA levels <20,000 IU/ml were independently associated with a reduced likelihood of clinical relapse (adjusted hazard ratio 0.379, p <0.001) and with an increased chance of HBsAg loss (adjusted hazard ratio 2.872, p <0.001).

Conclusions

Lower pretreatment HBV DNA levels are associated with a lower risk of clinical relapse and a higher chance of HBsAg loss after cessation of NUC therapy, independent of end-of-treatment viral antigen levels. Further studies are needed to confirm these findings in non-Asian populations.

Impact and Implications

A subgroup of patients with chronic hepatitis B may not require retreatment after stopping antiviral therapy. In this study, comprising 757 patients with chronic hepatitis B from Europe and Asia, we found that higher viral load before initiation of treatment was a risk factor for relapse after stopping treatment. Patients with a low HBV DNA level before starting antiviral therapy had the lowest risk of relapse, and a high chance of HBsAg loss, after stopping treatment. These findings can help select patients for treatment withdrawal and guide intensity of off-treatment monitoring.

Baseline serum HBV RNA is associated with the risk of hepatitis flare after stopping nucleoside analog therapy in HBeAg-negative participants

BACKGROUND AND AIMS

HBV RNA in peripheral blood reflects HBV cccDNA transcriptional activity and may predict clinical outcomes. The prospective Melbourne HBV-STOP trial studied nucleot(s)ide analog discontinuation in HBeAg-negative non-cirrhotic participants with long-term virological suppression. Ninety-six weeks after stopping treatment, the proportion of participants with virological relapse (HBV DNA > 2000 IU/mL), biochemical relapse (ALT > 2 × ULN and HBV DNA > 2000 IU/mL), or hepatitis flare (ALT > 5 × ULN and HBV DNA > 2000 IU/mL) was 89%, 58%, and 38%, respectively. We evaluated the ability of serum HBV RNA levels to predict these outcomes.

APPROACH RESULTS

HBV RNA levels were measured using the Roche cobas 6800/8800 HBV RNA Investigational Assay. Sixty-five participants had baseline and longitudinal off-treatment specimens available for RNA testing. HBV RNA was detectable at baseline in 25% of participants and was associated with a higher risk of biochemical relapse (81% vs. 51%, p value 0.04) and hepatitis flare (63% vs. 31%, p value 0.04). Participants who had undetectable serum HBV RNA as well as HBsAg ≤ 100 IU/mL at baseline were less likely to experience virological relapse (4 of 9, 44%) than participants with detectable HBV RNA and HBsAg level > 100 IU/mL (15/15, 100%; p value 0.0009). Off-treatment levels of HBV RNA were correlated with HBV DNA and were associated with the risk of hepatitis flare.

CONCLUSIONS

Serum HBV RNA may be a useful biomarker for guiding clinical decision-making before stopping nucleot(s)ide analog therapy. Baseline HBV RNA and HBsAg levels are associated with the risk of clinical relapse, hepatitis flare, and disease remission off-treatment.

Past, present, and future of long-term treatment for hepatitis B virus

The estimated world prevalence of hepatitis B virus (HBV) infection is 316 million. HBV infection was identified in 1963 and nowadays is a major cause of cirrhosis and hepatocellular carcinoma (HCC) despite universal vaccination programs, and effective antiviral therapy. Long-term administration of nucleos(t)ide analogues (NA) has been the treatment of choice for chronic hepatitis B during the last decades. The NA has shown a good safety profile and high efficacy in controlling viral replication, improving histology, and decreasing the HCC incidence, decompensation, and mortality. However, the low probability of HBV surface antigen seroclearance made necessary an indefinite treatment. The knowledge, in recent years, about the different phases of the viral cycle, and the new insights into the role of the immune system have yielded an increase in new therapeutic approaches. Consequently, several clinical trials evaluating combinations of new drugs with different mechanisms of action are ongoing with promising results. This integrative literature review aims to assess the knowledge and major advances from the past of hepatitis B, the present of NA treatment and withdrawal, and the future perspectives with combined molecules to achieve a functional cure.

New Perspectives on Development of Curative Strategies for Chronic Hepatitis B

A functional cure of chronic hepatitis B defined as sustained hepatitis B surface antigen loss after finite course of therapy is rarely achieved with current therapy but is the goal of novel treatments. Understanding the virological and immunological mechanisms of hepatitis B virus persistence has enabled the identification of novel treatment targets, drug discovery, and the evaluation of novel agents in clinical trials. Lessons were learned from early phase 1 and phase 2 trials regarding the antiviral activity and safety profile of these agents. There is a strong rationale to combine agents to reduce viral replication, reduce viral antigen load, invigorate immune responses, and induce specific adaptive immune responses. Nucleos(t)ide analogs will likely remain an essential backbone of future combinations to control viral replication and prevent resistance to antiviral drugs. In this review, we discuss perspectives on approaches to achieving functional cure, with a review of virological and immunological strategies, highlighting challenges and unresolved questions with the various attempts to achieve cure, as well as exploring alternative endpoints such as partial cure and new noninvasive viral and immunological biomarkers to stratify patients and predict/monitor antiviral response.

Withdrawal of Long-Term Nucleotide Analog Therapy in Chronic Hepatitis B: Outcomes From the Withdrawal Phase of the HBRN Immune Active Treatment Trial

INTRODUCTION

Withdrawal of nucleos(t)ide analog therapy is increasingly being evaluated in chronic hepatitis B infection as a strategy to induce hepatitis B surface antigen (HBsAg) loss. The Hepatitis B Research Network Immune-Active Trial evaluated treatment with tenofovir (TDF) for 4 years ± an initial 6 months of peginterferon-α (PegIFN) (NCT01369212) after which treatment was withdrawn.

METHODS

Eligible participants (hepatitis B e antigen [HBeAg]-/anti-HBe+, hepatitis B virus [HBV] DNA <10 3 IU/mL, no cirrhosis) who discontinued TDF were followed for at least 1 year with optional follow-up thereafter. Retreatment was based on predefined criteria.

RESULTS

Among 201 participants who received 4 years of treatment, 97 participants (45 TDF and 52 TDF + PegIFN arm, 79 Asian) discontinued TDF. HBsAg loss occurred in 5 participants, 2 within 25 weeks and 3 within 89-119 weeks postwithdrawal (cumulative rate 4.3% by 2 years). Alanine aminotransferase (ALT) flares (>5× upper limit of normal) after TDF withdrawal occurred in 36 (37.1%) participants and occurred more frequently and earlier in those HBeAg- compared with HBeAg+ at treatment initiation. ALT flares were associated with older age and higher HBV DNA pretreatment and at the visit before the flare. ALT flares were not significantly associated with HBsAg decline or loss but were associated with immune active disease at 1 year (70.6% vs 11.9%, P < 0.0001) and 2 years (66.7% vs 25.9%, P = 0.03) postwithdrawal. Treatment reinitiation was required in 13 (13.4%) participants, and 13 others remained in a sustained inactive carrier state by the end of the study follow-up. No criteria reliably predicted safe treatment withdrawal.

DISCUSSION

Results from this trial do not support TDF withdrawal as a therapeutic strategy. HBsAg loss was infrequent within 2 years of stopping long-term TDF. If withdrawal is considered, HBV DNA should be carefully monitored with reinitiation of therapy if levels rise above 4 log 10 IU/mL to reduce the risk of ALT flares, as they were not associated with subsequent HBsAg decline or loss.

Bepirovirsen (GSK3228836) in chronic hepatitis B infection: an evaluation of phase II progress

INTRODUCTION

Chronic hepatitis B infection is a major global health issue associated with significant liver-related morbidity and mortality. While existing treatments can suppress the virus effectively, they are incapable of inducing functional cure, as defined by hepatitis B surface antigen (HBsAg) seroclearance. Currently, numerous novel compounds are being developed, including bepirovirsen, an antisense oligonucleotide (ASO).

AREAS COVERED

This review summarizes the mechanism of action, pharmacokinetics, clinical efficacy and safety data collected from phase I and II studies of bepirovirsen. The data were extracted from publications relevant to the pivotal trials of bepirovirsen, in either full manuscript or conference abstracts.

EXPERTOPINION

Bepirovirsen, a 20-mer ASO, has already entered phase III clinical evaluation using the optimal dosing regimen of 300 mg subcutaneous injection weekly for 24 weeks in nucleoside analogue-treated HBeAg-negative non-cirrhotic patients with low (<3000 IU/mL) baseline HBsAg. The durability and long-term clinical outcomes among Bepirovirsen responders will need to be evaluated. The stop-to-cure approach in those reaching HBsAg < 100 IU/mL should also be explored. In the long run, Bepirovirsen has the potential to facilitate viral hepatitis elimination.

Utility of novel viral and immune markers in predicting HBV treatment endpoints: A systematic review of treatment discontinuation studies

Background & Aims

Antivirals represent the mainstay of chronic hepatitis B treatment given their efficacy and tolerability, but rates of functional cure remain low during long-term therapy. Treatment discontinuation has emerged as a strategy to maintain partial cure and achieve functional cure in select patient groups. We aimed to evaluate how data from treatment discontinuation studies exploring novel viral and/or immune markers could be applied to the functional cure program.

Methods

Treatment discontinuation studies evaluating novel viral and/or immune markers were identified by a systematic search of the PubMed database through to October 30, 2022. Data extraction focused on information regarding novel markers, including identified cut-off levels, timing of measurement, and associated effect on study outcomes of virological relapse, clinical relapse, and HBsAg seroclearance.

Results

From a search of 4,492 citations, 33 studies comprising a minimum of 2,986 unique patients met the inclusion criteria. Novel viral markers, HBcrAg and HBV RNA, were demonstrated across most studies to be helpful in predicting off-therapy partial cure, with emerging evidence to support a link with functional cure. From novel immune marker studies, we observed that treatment discontinuation has the potential to trigger immune restoration, which may be associated with a transient virological relapse. To this end, these studies support the combination of virus-directing agents with immunomodulator therapies to induce two key steps underlying functional cure: viral antigen load reduction and restoration of the host immune response.

Conclusions

Patients with a favourable profile of novel viral and immune markers stand to benefit from a trial of antiviral treatment discontinuation alongside novel virus-directing agents with the aim of achieving functional cure without excessive risk of severe clinical relapse.

Impact and implications

Select patients with chronic hepatitis B undergoing nucleoside analogue therapy may benefit from a trial of treatment discontinuation, aiming to maintain partial cure and/or achieve functional cure. We propose a profile of novel viral and immune markers to identify patients who are likely to achieve these goals without excessive risk of hepatic decompensation. Furthermore, treatment discontinuation may also be considered as a therapeutic strategy to trigger immune restoration, which may increase the chance of functional cure when used in conjunction with novel virus-directing agents.

A multicenter randomized-controlled trial of nucleos(t)ide analogue cessation in HBeAg-negative chronic hepatitis B

BACKGROUND & AIMS

Nucleos(t)ide analogues (NUCs) are the standard and mostly lifelong treatment for chronic HBeAg-negative hepatitis B, as functional cure (loss of HBsAg) is rarely achieved. Discontinuation of NUC treatment may lead to functional cure; however, to date, the evidence for this has been based on small or non-randomized clinical trials. The STOP-NUC trial was designed with the aim of increasing the HBsAg loss rate using a NUC treatment interruption approach.

METHODS

In this multicenter, randomized-controlled trial, 166 HBeAg-negative patients with chronic hepatitis B on continuous long-term NUC treatment, with HBV DNA <172 IU/ml (1,000 copies/ml) for ≥4 years, were randomized to either stop (Arm A) or continue NUC treatment (Arm B) for a 96-week observation period. In total, 158 patients were available for final analysis, 79 per arm. The primary endpoint was sustained HBsAg loss up to week 96.

RESULTS

Our study met its primary objective by demonstrating HBsAg loss in eight patients (10.1%, 95% CI 4.8%-19.5%) in Arm A and in no patient in Arm B (p = 0.006). Among patients with baseline HBsAg levels <1,000 IU/ml, seven (28%) achieved HBsAg loss. In Arm A, re-therapy was initiated in 11 (13.9%) patients, whereas 32 (40.5%) patients achieved sustained remission. A decrease of HBsAg >1 log IU/ml was observed in 16 patients (20.3%) in Arm A and in one patient (1.3%) in Arm B. No serious adverse events related to treatment cessation occurred.

CONCLUSIONS

Cessation of NUC treatment was associated with a significantly higher rate of HBsAg loss than continued NUC treatment, which was largely restricted to patients with end of treatment HBsAg levels <1,000 IU/ml.

IMPACT AND IMPLICATIONS

As HBeAg-negative patients with chronic hepatitis B on nucleos(t)ide analogues (NUCs) rarely achieve functional cure, treatment is almost always lifelong. The STOP-NUC trial was conducted to investigate whether discontinuing long-term NUC treatment can increase the cure rate. We found that some patients achieved functional cure after stopping NUCs, which was especially pronounced in patients with HBsAg levels <1,000 at the end of NUC treatment, and that many did not need to resume therapy. The results of the Stop-NUC trial provide evidence for the concept of stopping NUC treatment as a therapeutic option that can induce functional cure.

What will it take to cure hepatitis B?

The current treatment of chronic HBV infection, pegylated interferon-α (pegIFNα) and nucleos(t)ide analog (NA), can suppress HBV replication, reverse liver inflammation and fibrosis and reduce the risks of cirrhosis, HCC, and HBV-related deaths, but relapse is common when the treatment is stopped before HBsAg loss. There have been major efforts to develop a cure for HBV, defined as sustained HBsAg loss after a finite course of therapy. This requires the suppression of HBV replication and viral protein production and the restoration of immune response to HBV. Direct-acting antivirals targeting virus entry, capsid assembly, viral protein production and secretion are in clinical trials. Immune modulatory therapies to stimulate adaptive or innate immunity and/or to remove immune blockade are being tested. NAs are included in most and pegIFNα in some regimens. Despite the combination of 2 or more therapies, HBsAg loss remains rare in part because HbsAg can be derived not only from the covalently closed circular DNA but also from the integrated HBV DNA. Achievement of a functional HBV cure will require therapies to eliminate or silence covalently closed circular DNA and integrated HBV DNA. In addition, assays to differentiate the source of circulating HBsAg and to determine HBV immune recovery, as well as standardization and improvement of assays for HBV RNA and hepatitis B core-related antigen, surrogate markers for covalently closed circular DNA transcription, are needed to accurately assess response and to target treatments according to patient/disease characteristics. Platform trials will allow the comparison of multiple combinations and channel patients with different characteristics to the treatment that is most likely to succeed. Safety is paramount, given the excellent safety profile of NA therapy.

Chronic hepatitis B - A scoping review on the guidelines for stopping nucleos(t)ide analogue therapy

INTRODUCTION

Nucleos(t)ide analogues (NAs) are effective in suppressing the replication of the hepatitis B virus. However, NAs cannot effectively induce hepatitis B surface antigen (HBsAg) seroclearance, which represents the optimal treatment endpoint in chronic hepatitis B (CHB). Hence, most CHB patients are advised for indefinite NA therapy, but recent data has supported the concept of finite NA therapy before HBsAg seroclearance.

AREAS COVERED

This article covered the latest evidence on stopping NAs in CHB, with focused analysis on international guidelines. Articles were retrieved by a literature search on PubMed with the keywords "chronic hepatitis B", "antiviral therapy", "nucleos(t)ide analogue", "cessation", "stopping" and "finite". Studies up till 1 December 2022 were included.

EXPERT OPINION

Finite NA therapy in CHB has potential in enhancing HBsAg seroclearance, however it also carries rare but potentially severe risks. NA cessation before HBsAg seroclearance is only suitable for a highly-selected group of patients, whereas the majority of CHB patients should be treated indefinitely or until HBsAg seroclearance. Current guidelines have provided recommendations on stopping NAs, but further research is required to optimize the monitoring and retreatment protocol after stopping NAs.

Advances in determining new treatments for hepatitis B infection by utilizing existing and novel biomarkers

INTRODUCTION

Chronic hepatitis B (CHB) infection is a major global health threat and accounts for significant liver-related morbidity and mortality. An improved understanding of how hepatitis B virus (HBV) interacts with the host immune system allows the discovery of novel biomarkers and new treatment options. Viral biomarkers including hepatitis B surface antigen (HBsAg) and newer ones like HBV RNA and hepatitis B core-related antigen appear to be useful to select patients who are likely to benefit from cessation of long-term antiviral therapy. These markers can also help to confirm target engagement for novel compounds, and efficacy in HBsAg reduction and seroclearance is deemed essential as this is how the current treatment endpoint of functional cure is defined.

AREAS COVERED

In this review, the authors discuss the current standard of care and the gaps between such standard and the ideal goals for treatment in CHB. The authors highlight novel viral and immunological biomarkers that are potentially useful to evaluate treatment response. Novel treatment approaches in relation to these novel biomarkers are also evaluated.

EXPERT OPINION

Novel serum viral biomarkers and immunological markers are indispensable in the HBV functional cure program. These will likely become part of standard monitoring soon.

Emerging Therapies for Chronic Hepatitis B and the Potential for a Functional Cure

Worldwide, an estimated 296 million people are living with chronic hepatitis B virus (HBV) infection, with a significant risk of morbidity and mortality. Current therapy with pegylated interferon (Peg-IFN) and indefinite or finite therapy with nucleoside/nucleotide analogues (Nucs) are effective in HBV suppression, hepatitis resolution, and prevention of disease progression. However, few achieve hepatitis B surface antigen (HBsAg) loss (functional cure), and relapse often occurs after the end of therapy (EOT) because these agents have no direct effect on durable template: covalently closed circular DNA (cccDNA) and integrated HBV DNA. Hepatitis B surface antigen loss rate increases slightly by adding or switching to Peg-IFN in Nuc-treated patients and this loss rate greatly increases up to 39% in 5 years with finite Nuc therapy with currently available Nuc(s). For this, great effort has been made to develop novel direct-acting antivirals (DAAs) and immunomodulators. Among the DAAs, entry inhibitors and capsid assembly modulators have little effect on reducing HBsAg levels; small interfering RNA, antisense oligonucleotides, and nucleic acid polymers in combination with Peg-IFN and Nuc may reduce HBsAg levels significantly, even a rate of HBsAg loss sustained for > 24 weeks after EOT up to 40%. Novel immunomodulators, including T-cell receptor agonists, check-point inhibitors, therapeutic vaccines, and monoclonal antibodies may restore HBV-specific T-cell response but not sustained HBsAg loss. The safety issues and the durability of HBsAg loss warrant further investigation. Combining agents of different classes has the potential to enhance HBsAg loss. Compounds directly targeting cccDNA would be more effective but are still in the early stage of development. More effort is required to achieve this goal.

Evidence of Residual Ongoing Viral Replication in Chronic Hepatitis B Patients Successfully Treated With Nucleos(t)ide Analogues

BACKGROUND

Chronic hepatitis B is usually treated with nucleos(t)ide analogues (NAs). However, a cure is rarely achieved, even with years of treatment. Here, we investigated whether viral replication is completely halted and how long covalently closed circular DNA (cccDNA) persists in patients successfully treated with NAs.

METHODS

A series of longitudinal serum samples and a collection of cross-sectional liver biopsies were obtained from patients successfully treated with NAs. Viral variants in serum HBV RNA were enumerated by deep sequencing. Viral replication intermediates in hepatocytes were directly visualized by in situ hybridization. The apparent half-life of each cccDNA was estimated.

RESULTS

Three of 6 successfully treated patients demonstrated clear evidence of a small proportion of virus evolution, although the overwhelming proportion of variants were identical or possessed a similar degree of divergence through time. The apparent half-life of variants was estimated to be from approximately 7.42 weeks to infinite. Hepatocytes remained positive for cytoplasmic nucleocapsids-associated relaxed circular DNA in 4 of 7 liver needle biopsies.

CONCLUSIONS

We conclude that even after prolonged treatment, a small proportion of the cccDNA reservoir is constantly replenished by continued low-level HBV replication, whereas a large proportion of the cccDNA reservoir persists over time.

Risk of hepatic decompensation but not hepatocellular carcinoma decreases over time in patients with hepatitis B surface antigen loss

BACKGROUND & AIMS

We examined the long-term incidence of hepatocellular carcinoma (HCC) and hepatic decompensation among chronic hepatitis B (CHB) patients who have achieved hepatitis B surface antigen (HBsAg) seroclearance.

METHODS

All adult CHB-monoinfected patients who cleared HBsAg between January 2000 and December 2020 were identified using a territory-wide database in Hong Kong. Patients who underwent liver transplantation and/or developed HCC before HBsAg seroclearance or less than 6 months follow-up were excluded. The primary and secondary endpoints were HCC and hepatic decompensation respectively.

RESULTS

We identified 9,769 patients with CHB who achieved HBsAg seroclearance (mean age 57 years, 60.0% male, 13.2% cirrhosis); most had compensated liver function at HBsAg loss. At a median (25th-75th percentile) follow-up of 4.6 (2.2-8.4) years, 106 (1.1%) patients developed HCC. Patients who developed HCC were older, more likely to be male and have cirrhosis, and had higher alanine aminotransferase and lower platelets at the time of HBsAg loss than patients without HCC. The cumulative incidence of HCC remained steady 0-7 and 8-12 years after HBsAg loss (p = 0.898) (crude annual incidence drop: -0.04%, 95% CI -0.13% to 0.04%, p = 0.265). Moreover, 124/9,640 (1.3%) patients developed hepatic decompensation. The growth in cumulative incidence of hepatic decompensation decelerated 8-12 years after HBsAg loss (p = 0.009) (crude annual incidence drop: -0.23%, 95% CI -0.40% to -0.06%, p = 0.012). In multivariable analysis, HBsAg loss for over 7 years was associated with a reduced risk of hepatic decompensation (adjusted subdistribution hazard ratio [aSHR] 0.55, 95% CI 0.31-0.97, p = 0.039) but not HCC (aSHR 1.35, 95% CI 0.83-2.19, p = 0.230).

CONCLUSION

HCC risk persists in patients after HBsAg loss, whereas the risk of hepatic decompensation decreases over time.

IMPACT AND IMPLICATIONS

Patients with chronic hepatitis B (CHB) still have a non-negligible risk of hepatocellular carcinoma (HCC) after 12 years of HBsAg seroclearance, especially among those with cirrhosis. The risk of developing hepatic decompensation decreases over time after HBsAg seroclearance. In clinical practice, although patients with CHB who cleared HBsAg have a more favourable clinical outcome than those who remain chronically infected, long-term HCC surveillance would still be necessary for patients with cirrhosis and other high-risk subgroups after HBsAg seroclearance.

The scientific basis of combination therapy for chronic hepatitis B functional cure

Functional cure of chronic hepatitis B (CHB) - or hepatitis B surface antigen (HBsAg) loss after 24 weeks off therapy - is now the goal of treatment, but is rarely achieved with current therapy. Understanding the hepatitis B virus (HBV) life cycle and immunological defects that lead to persistence can identify targets for novel therapy. Broadly, treatments fall into three categories: those that reduce viral replication, those that reduce antigen load and immunotherapies. Profound viral suppression alone does not achieve quantitative (q)HBsAg reduction or HBsAg loss. Combining nucleos(t)ide analogues and immunotherapy reduces qHBsAg levels and induces HBsAg loss in some patients, particularly those with low baseline qHBsAg levels. Even agents that are specifically designed to reduce viral antigen load might not be able to achieve sustained HBsAg loss when used alone. Thus, rationale exists for the use of combinations of all three therapy types. Monitoring during therapy is important not just to predict HBsAg loss but also to understand mechanisms of HBsAg loss using viral and immunological biomarkers, and in selected cases intrahepatic sampling. We consider various paths to functional cure of CHB and the need to individualize treatment of this heterogeneous infection until a therapeutic avenue for all patients with CHB is available.

Current Best Practice in Hepatitis B Management and Understanding Long-term Prospects for Cure

The hepatitis B virus (HBV) is a major cause of cirrhosis and hepatocellular carcinoma worldwide. Despite an effective vaccine, the prevalence of chronic infection remains high. Current therapy is effective at achieving on-treatment, but not off-treatment, viral suppression. Loss of hepatitis B surface antigen, the best surrogate marker of off-treatment viral suppression, is associated with improved clinical outcomes. Unfortunately, this end point is rarely achieved with current therapy because of their lack of effect on covalently closed circular DNA, the template of viral transcription and genome replication. Major advancements in our understanding of HBV virology along with better understanding of immunopathogenesis have led to the development of a multitude of novel therapeutic approaches with the prospect of achieving functional cure (hepatitis B surface antigen loss) and perhaps complete cure (clearance of covalently closed circular DNA and integrated HBV DNA). This review will cover current best practice for managing chronic HBV infection and emerging novel therapies for HBV infection and their prospect for cure.

Randomized Trial of Tenofovir With or Without Peginterferon Alfa Followed by Protocolized Treatment Withdrawal in Adults With Chronic Hepatitis B

INTRODUCTION

Hepatitis B surface antigen (HBsAg) loss is associated with improved long-term outcomes of patients with chronic hepatitis B but is infrequently achieved with current monotherapies. We assessed whether combination strategies that included treatment withdrawal enhanced HBsAg loss.

METHODS

A randomized (1:1) trial of tenofovir disoproxil fumarate (TDF) for 192 weeks with or without peginterferon (PegIFN) alfa-2a for the first 24 weeks, followed by withdrawal of TDF at week 192 with 48 weeks of off-treatment follow-up to week 240. The primary endpoint was HBsAg loss at week 240.

RESULTS

Of 201 participants (52% HBeAg-positive, 12%/6% genotype A/A2, 7% cirrhosis) randomized to TDF + PegIFN (n = 102) or TDF alone (n = 99) 6 participants had lost HBsAg at the end of the treatment phase (week 192), 5 (5.3%) in the combination group and 1 (1.0%) in the TDF alone group ( P = 0.09). By week 240, 9 participants had cleared HBsAg, 5.3% in combination and 4.1% in monotherapy arms ( P = 0.73). HBsAg decline and loss occurred earlier with TDF + PegIFN than TDF, with a ≥1-logIU/mL qHBsAg decline by week 24 in 28% compared to 6% in TDF ( P = 0.04). HBsAg loss occurred in 7 of 12 (58%) with hepatitis B virus subgenotype A2 (all HBeAg-positive) compared to only 2 of 189 (1%) with other hepatitis B virus genotypes, and in 8 of 93 (8.6%) HBeAg-positive vs 1 of 87 (1.1%) HBeAg-negative.

DISCUSSION

PegIFN combined TDF followed by protocolized TDF withdrawal led to earlier but not higher percentages of HBsAg clearance. Pre-treatment HBeAg positivity and subgenotype A2 were strongly associated with HBsAg clearance.

Hepatitis B Therapeutic Vaccine: A Patent Review

Viral hepatitis has long been underrated as a danger to global health. The UN only recently called for worldwide action to tackle viral hepatitis and lessen the disease burden in its "2030 Agenda for Sustainable Development". Hepatitis B virus (HBV), which causes liver cirrhosis and malignancy, is a main cause of death globally. This review analyses innovative HBV therapeutic vaccine candidates for which a patent was filed between January 2010 and March 2022 and presents future improvement techniques for vaccine efficacy. Although there is a preventative vaccine for HBV infection, over 3% of people worldwide have the disease on a long-term basis and can no longer benefit from it. Most people will have chronic HBV infection for the rest of their lives once it has been diagnosed. Moreover, only a small percentage of treated patients experience a functional cure with persistent hepatitis B surface antigen reduction. A significant proportion of deaths are caused by liver cirrhosis and hepatocellular cancer, which are both caused by chronic hepatitis B infection. Hence, there is an urgent need for novel medications due to the inadequacies of the current therapies.

Hepatitis B functional cure and immune response

Hepatitis B virus (HBV) is a hepatotropic virus, which damage to hepatocytes is not direct, but through the immune system. HBV specific CD4⁺ T cells can induce HBV specific B cells and CD8⁺ T cells. HBV specific B cells produce antibodies to control HBV infection, while HBV specific CD8⁺ T cells destroy infected hepatocytes. One of the reasons for the chronicity of HBV infection is that it cannot effectively activate adoptive immunity and the function of virus specific immune cells is exhausted. Among them, virus antigens (including HBV surface antigen, e antigen, core antigen, etc.) can inhibit the function of immune cells and induce immune tolerance. Long term nucleos(t)ide analogues (NAs) treatment and inactive HBsAg carriers with low HBsAg level may "wake up" immune cells with abnormal function due to the decrease of viral antigen level in blood and liver, and the specific immune function of HBV will recover to a certain extent, thus becoming the "dominant population" for functional cure. In turn, the functional cure will further promote the recovery of HBV specific immune function, which is also the theoretical basis for complete cure of hepatitis B. In the future, the complete cure of chronic HBV infection must be the combination of three drugs: inhibiting virus replication, reducing surface antigen levels and specific immune regulation, among which specific immunotherapy is indispensable. Here we review the relationship, mechanism and clinical significance between the cure of hepatitis B and immune system.