Surface Antigen Loss Research Articles

Towards a Functional Cure for Hepatitis B Virus: A 2022 Update on New Antiviral Strategies.

Chronic infection with hepatitis B virus (HBV) represents one of the main causes of the development of cirrhosis and its complications. Treatment with potent third-generation nucleos(t)ide analogues (NUCs) results in >99% HBV DNA undetectability, and prevents fibrosis progression and liver-related complications. However, NUCs are not able to induce the so-called functional cure, which is hepatitis B surface antigen (HBsAg) loss and anti-HBs seroconversion. Consequently, NUC treatment is currently intended as being long-term or lifelong, resulting in the need for clinical monitoring and potentially suffering from compliance issues. Consequently, drug development in HBV has the goal of developing new agents in order to achieve a functional cure for HBV. Currently, the three main strategies include the following: inhibition of viral replication, inhibition of viral antigens, and immune modulation. This review summarizes the most recent updates concerning HBV compounds among these three main classes.

Hepatocyte proliferation favours viral clearance in young children with chronic hepatitis B virus infection.

The aim of this study is to explore the correlation between hepatocyte proliferation and hepatitis B virus (HBV) clearance in young children with chronic HBV infection. We collected liver biopsy samples and clinical data corresponding to paediatric patients with chronic HBV infection. Ki-67 expression in liver tissues was evaluated by immunohistochemical staining. Eighteen patients were included and were divided into two groups based on different antiviral outcomes. Group I achieved hepatitis B surface antigen (HBsAg) loss within 48 weeks. Group II did not develop seroconversion from hepatitis B e (HBe) antigen to anti-HBe after 48 weeks. There were 10 patients in Group I and 8 in Group II, respectively. Demographical data and baseline virological and biochemical characteristics in serum across Group I and Group II were not statistically different. Histologically, mean Ki-67 expression index in Group I was 15%, while the mean index in Group II was 5%. There was a significant difference between the two groups (p < 0.01). High Ki-67 expression can contribute to viral clearance in young children with chronic HBV infection. This is the first confirmation of the association between hepatocyte proliferation and HBV clearance in vivo and has implications for novel therapeutic strategies against hepatitis B.

Describing immune factors associated with Hepatitis B surface antigen loss: A nested case-control study of a Chinese sample from Wuwei City.

BackgroundHepatitis B surface antigen (HBsAg) loss is considered a functional cure for chronic hepatitis B (CHB), however, several factors influence HBsAg loss.Methods29 CHB patients who had achieved HBsAg loss, were selected and 58 CHB patients with persistent HBsAg were matched, according to gender and age (+/- 3 years). Logistic regression and restricted cubic spline (RCS) modelling were performed.ResultsMultivariate-adjusted logistic regression, based on stepwise selection, showed that baseline HBsAg levels negatively correlated with HBsAg loss (odds ratio [OR] = 0.99, 95% confidence interval [CI] = 0.98-0.99). Interferon treatment positively related with HBsAg loss (OR = 7.99, 95%CI = 1.62-44.88). After adjusting for age, HBsAg level, ALT level, HBeAg status and interferon treatment, MMP-1 (OR = 0.66, 95%CI = 0.44-0.97), CXCL9 (OR = 0.96, 95%CI = 0.93-0.99) and TNF-R1 (OR = 0.97, 95%CI = 0.94-0.99) baseline levels all negatively correlated with HBsAg loss. Our multivariate-adjusted RCS model showed that baseline CXCL10 was associated with HBsAg loss although the relationship was “U-shaped”.ConclusionsCytokines such as MMP-1, CXCL9, CXCL10 and TNF-R1 are important factors which influence HBsAg loss. It may be possible to develop a nomogram which intercalates these factors; however, further research should consider immune processes involved in HBsAg loss.

Functional cure of hepatitis B requires silencing covalently closed circular and integrated hepatitis B virus DNA.

Chronic hepatitis B virus (HBV) infection remains a major global health problem. Hepatitis B surface antigen (HBsAg) loss has been accepted as the definition of a functional HBV cure. Recent studies found that while covalently closed circular DNA (cccDNA) is the predominant source of HBsAg in hepatitis B e antigen–positive (HBeAg-positive) patients, integrated HBV DNA (iDNA) is the main source in HBeAg-negative patients. Consequently, achieving a functional HBV cure will require not only silencing of cccDNA but also iDNA. Assays that distinguish the source of HBsAg are needed to evaluate emerging therapies. In this issue of the JCI, Grudda et al. developed a PCR-based assay that differentiated the source of HBsAg and explored the contributing sources of HBsAg in patients on nucleos(t)ide analog antivirals. These findings provide a tool for understanding the contribution of iDNA in HBV infection and may guide therapies toward a functional HBV cure.

Discovery and preclinical evaluations of GST-HG131, a novel HBV antigen inhibitor for the treatment of chronic hepatitis B infection

Chronic hepatitis B (CHB) remains a significant health challenge worldwide. The current treatments for CHB achieve less than 10% cure rates, majority of the patients are on therapy for life. Therefore, cure of CHB is a high unmet medical need. HBV surface antigen (HBsAg) loss and seroconversion are considered as the key for the cure. RG7834 is a novel, orally bioavailable small molecule reported to reduce HBV antigens. Based on RG7834 chemistry, we designed and discovered a series of dihydrobenzopyridooxazepine (DBP) series of HBV antigen inhibitors. Extensive SAR studies led us to GST-HG131 with excellent reduction of HBV antigens (both HBsAg and HBeAg) in vitro and in vivo. GST-HG131 improved safety in rat toxicology studies over RG7834. The promising inhibitory activity, together with animal safety enhancement, merited GST-HG131 progressed into clinical development in 2020 (NCT04499443).

Nationwide retrospective study of hepatitis B virological response and liver stiffness improvement in 465 patients on nucleos(t)ide analogue.

BACKGROUNDHepatitis B virus (HBV) nucleos(t)ide analog (NA) therapy reduces liver disease but requires prolonged therapy to achieve hepatitis B surface antigen (HBsAg) loss. There is limited North American real-world data using non-invasive tools for fibrosis assessment and few have compared 1st generation NA or lamivudine (LAM) to tenofovir disoproxil fumarate (TDF).AIMTo assess impact of NA on virological response and fibrosis regression using liver stiffness measurement (LSM) (i.e., FibroScan®).METHODSRetrospective, observational cohort study from the Canadian HBV Network. Data collected included demographics, NA, HBV DNA, alanine aminotransferase (ALT), and LSM. Patients were HBV monoinfected patients, treatment naïve, and received 1 NA with minimum 1 year follow-up.RESULTSIn 465 (median 49 years, 37% female, 35% hepatitis B e antigen+ at baseline, 84% Asian, 6% White, and 9% Black). Percentage of 64 (n = 299) received TDF and 166 were LAM-treated with similar median duration of 3.9 and 3.7 years, respectively. The mean baseline LSM was 11.2 kPa (TDF) vs 8.3 kPa (LAM) (P = 0.003). At 5-year follow-up, the mean LSM was 7.0 kPa in TDF vs 6.7 kPa in LAM (P = 0.83). There was a significant difference in fibrosis regression between groups (i.e., mean -4.2 kPa change in TDF and -1.6 kPa in LAM, P < 0.05). The last available data on treatment showed that all had normal ALT, but more TDF patients were virologically suppressed (< 10 IU/mL) (n = 170/190, 89%) vs LAM-treated (n = 35/58, 60%) (P < 0.05). None cleared HBsAg.CONCLUSIONIn this real-world North American study, approximately 5 years of NA achieves liver fibrosis regression rarely leads to HBsAg loss.

Role of hepatitis B surface antibody in seroreversion of hepatitis B surface antigen in patients achieving hepatitis B surface antigen loss with pegylated interferon-based therapy.

It is unclear whether hepatitis B surface antibody (HBsAb) confers clinical benefits after HBsAg seroclearance, especially in hepatitis B surface antigen (HBsAg) seroreversion and maintenance of HBsAb. We evaluated this in patients (n=222) with HBsAg loss following treatment with pegylated interferon (PEG-IFN)-based therapy who completed a 48-week follow-up period. Serum hepatitis B virus (HBV) markers and biochemical indicators were evaluated every 3months. The primary endpoint was HBsAg seroreversion. Factors associated with HBsAg seroreversion were also investigated. HBsAb ≥100 mIU/ml resulted in a lower HBsAg seroreversion rate than an HBsAb-negative status (5.5% vs. 29.5%, p &lt; .001); however, the seroreversion rate was not significantly different between patients with HBsAb 10-100 mIU/ml and those in the HBsAb-negative group. Patients with HBsAb ≥100 mIU/ml had a lower HBsAb loss rate than those with HBsAb 10-100 mIU/ml (7.3% vs. 21.7%, p=.005). The final HBsAg seroreversion and HBV DNA relapse rates were 13.5% and 1.8%, respectively. HBsAb ≥100 mIU/ml at the off-treatment time (odds ratio [OR] 0.110, 95% confidence interval [CI]: 0.034-0.353, p &lt; .001) and treatment time to attain HBsAg loss &gt;28 weeks (OR 2.508, 95% CI: 1.068-5.890, p=.035) were predictors of HBsAg seroreversion. Consolidation therapy for 12-24 weeks resulted in higher HBsAb titres than consolidation therapy for ≤12 weeks in HBsAb-negative patients at the off-treatment time (p &lt; .001). HBsAg seroconversion with HBsAb ≥100 mIU/ml decreases HBsAg seroreversion and provides an efficient maintenance rate of HBsAb. HBsAg seroconversion with high HBsAb titres may be clinically beneficial for chronic hepatitis B treated with PEG-IFN-based therapy.

Differential Relapse Patterns After Discontinuation of Entecavir vs Tenofovir Disoproxil Fumarate in Chronic Hepatitis B

Background and AimsWhether entecavir (ETV) and tenofovir disoproxil fumarate (TDF) differentially affect relapse and outcomes following treatment discontinuation across different patient subpopulations remains unclear. We aimed to compare rates of off-therapy hepatitis B surface antigen (HBsAg) loss, virological and clinical relapse, and retreatment between chronic hepatitis B (CHB) patients who discontinued TDF or ETV therapy. MethodsThis study included 1402 virally suppressed CHB patients who stopped either ETV (n = 981) or TDF (n = 421) therapy between 2001 and 2020 from 13 participating centers across North America, Europe, and Asia. All patients were hepatitis B e antigen–negative at treatment discontinuation. Inverse probability of treatment weighting was used to balance the treatment groups. Outcomes were analyzed using survival methods. ResultsDuring a median off-treatment follow-up of 18 months, HBsAg loss occurred in 96 (6.8%) patients overall. Compared with ETV, TDF was associated with a higher rate of HBsAg loss (P = .03); however, the association was no longer significant after statistical adjustment (P = .61). Virological relapse occurred earlier among TDF-treated patients (P < .01); nonetheless, rates became comparable after the first year off therapy (P = .49). TDF was significantly associated with a higher clinical relapse rate than ETV throughout follow-up (P < .01). The development of a virological or clinical relapse did not affect the rate of HBsAg loss. Retreatment rates were not significantly different between the treatment groups. ConclusionsTDF and ETV have differential relapse patterns but are associated with similar rates of HBsAg loss and retreatment following discontinuation. Finite therapy can be considered for CHB patients on either TDF or ETV therapy.

Pegylated interferon-α-2b combined with tenofovir disoproxil fumarate, granulocyte-macrophage colony-stimulating factor, and hepatitis B vaccine treatment for naïve HBeAg-positive chronic hepatitis B patients: A prospective, multicenter, randomized controlled study.

Hepatitis B surface antigen (HBsAg) loss or seroconversion is an ideal treatment endpoint for patients with chronic hepatitis B but is rarely achievable inhepatitis B e-antigen(HBeAg)-positive patients using existing treatment strategies. In this study, the effect of pegylated interferon (peg-IFN) alfa-2b plus tenofovir disoproxil fumarate (TDF), granulocyte-macrophage colony-stimulating factor (GM-CSF), and hepatitis B vaccine was evaluated.This randomized controlled trial was conducted at nine liver centers in Chinese university hospitals from May 2018 to July 2020. Patients (n = 303) enrolled were randomly administered peg-IFN-α-2b combined with TDF, GM-CSF, and hepatitis B vaccine (experimental group); peg-IFN-α-2b plus TDF (control group 2); or interferon-α-2b alone (control group 1). The primary efficacy endpoint was HBsAg seroconversion at 48 weeks and the secondary endpoint included safety.No differences in baseline HBsAg levels were observed among the groups. The primary endpoint was achieved in three (3.0%), one (1.03%), and one (1.19%) patient in the experimental group, control group 2, and control group 1, respectively. The incidence of HBsAg seroconversion at week 48 was not significantly different among the three groups (p = 0.629). However, the decrease in serum levels of HBsAg at week 48 was significantly higher in the experimental and control group 2 compared with that in control group 1 (p = 0.008 and 0.006, respectively). No significant difference between the experimental and control group 2 was observed (p = 0.619). Adverse events were not significantly different among the groups except for the lower incidence of neutropenia in the experimental group.Peg-IFN-α-2b combined with TDF, GM-CSF, and hepatitis B vaccine is not superior to peg-IFN-α-2b combined with TDF in HBeAg-positive naïve patients. Clinical Trials Registration:ChiCTR1800016173.

Robust antiviral responses in severe hepatitis flare persist after early retreatment cessation and lead toward hepatitis B surface antigen loss: A proof‐of‐concept study

Hepatitis B flare has been interpreted as result of immune response against upsurging hepatitis B virus (HBV) and its antigen(s) that may lead to HBV decline/clearance spontaneously. It has been speculated that antiviral therapy could halt the effective immune response with viral persistent as a consequence. A proof-of-concept study was conducted to investigate this issue. Serial biochemical, quantitative hepatitis B surface antigen (HBsAg), interferon-γ (IFN-γ) and tumor-necrosis factor-α (TNF-α) assays were performed in four patients with severe hepatitis flare who had achieved precipitous HBsAg decline within 4weeks of antiviral therapy. TNF-α and IFN-γ were found to be elevated in parallel to upsurging HBV DNA and HBsAg levels in all patients. Higher levels of TNF-α and IFN-γ and levels relative to qHBsAg were observed during and after early termination of therapy within 4weeks in two patients and were followed by further HBsAg decline to <5 IU/ml and even achieved HBsAg loss in one patient. The patient who had stopped therapy on day 44 showed minimal HBsAg decline afterward and the patient who continued therapy showed a 10-fold rebound of qHBsAg from its nadir. The subsequent IFN-γ and TNF-α activity of these two patients was minimal. The results suggest that patients with severe hepatitis flare who achieved precipitous HBsAg decline may have robust immune response to clear the virus, and early termination of antiviral therapy may allow the protective immune response to continue and accelerate HBV decline toward HBsAg loss.

THU365 - Statin use and surface antigen loss in patients with chronic hepatitis B

THU365 - Statin use and surface antigen loss in patients with chronic hepatitis B

Current Perspectives on Nucleos(t)ide Analogue Therapy for the Long-Term Treatment of Hepatitis B Virus.

The hepatitis B virus (HBV) infection remains a global public health problem. This review presents updated recommendations for the optimal current treatment of choice with nucleos(t)ide analogues (NA). Current clinical practice guidelines on the management of chronic hepatitis B (CHB) by the Asian Pacific Association for the Study of the Liver, the European Association for the Study of the Liver and the American Association for the Study of Liver Diseases have been considered. Patients with chronic HBV infection are at increased risk of liver disease progression to cirrhosis and hepatocellular carcinoma (HCC) development. The main goal of therapy is to improve survival preventing disease progression and HCC. The induction of long-term suppression of HBV replication represents the main endpoint of current treatment strategies, while hepatitis B surface antigen (HBsAg) loss is the optimal endpoint. The typical indication for treatment requires elevated HBV desoxyribonucleic acid (DNA), elevated alanine aminotransferase and/or at least moderate histological lesions, while all cirrhotic patients with detectable HBV DNA should be treated. The long-term administration of a potent NA with high barrier to resistance, ie, entecavir, tenofovir disoproxil fumarate or tenofovir alafenamide, represents the treatment of choice. However, HBsAg seroclearance is anecdotal with NA. Treated patients should be monitored for therapy response, adherence, risk of disease progression, and risk of HCC development. This review aims to assess the evolving trends on the potent NA and the new perspectives on finite therapy.

Frequent alanine aminotransferase flares and promising antiviral therapy efficacy during the preschool age: An opportunity to achieve HBsAg loss in children with mother-to-child transmitted hepatitis B.

Alanine aminotransferase (ALT) flare remains one of the determinants of initiating antiviral therapy in children with chronic hepatitis B (CHB). Insufficient data exist regarding children with CHB attributed to mother-to-child transmission. This study aimed to assess the occurrence of spontaneous ALT flares and identify factors affecting therapy-induced hepatitis B surface antigen (HBsAg) loss in the flare cohort. We retrospectively included untreated children with mother-to-child transmitted CHB. The primary outcomes were spontaneous ALT flares and therapy-induced HBsAg loss. Among 83 untreated children, 73.5% (61/83) experienced spontaneous ALT flares during the median follow-up of 14.6months (range, 0.1-177.1months), with 54.1% of the first ALT flares and 44.3% of ALT peaks occurring within 6 years of age. Thirty-six of 61 children with ALT flares received antiviral therapy, nine (25.0%) of whom achieved therapy-induced HBsAg loss with a median duration of 19.3months (range, 6.5-56.2months). The age of initiation of antiviral therapy was the sole predictor of therapy-induced HBsAg loss (HR=0.544, 95% CI 0.353-0.838, p=0.006). The restricted cubic spline showed a negative relationship between the age of initiation of antiviral therapy and HBsAg loss and identified that 6.2 years of age discriminated children with therapy-induced HBsAg loss. Kaplan-Meier estimations suggested a higher probability of HBsAg loss in children who started antiviral therapy before 6.2 years old (p=0.03). In conclusion, asymptomatic ALT flares were frequent in preschool-aged children with mother-to-child transmitted CHB, and early initiation of antiviral therapy showed promising effects in those children with ALT flares.

Pimobendan Inhibits HBV Transcription and Replication by Suppressing HBV Promoters Activity.

Current anti-HBV therapeutic strategy relies on interferon and nucleos(t)ide-type drugs with the limitation of functional cure, inducing hepatitis B surface antigen (HBsAg) loss in very few patients. Notably, the level of HBsAg has been established as an accurate indicator to evaluate the drug efficacy and predict the disease prognosis, thus exploring a novel drug targeting HBsAg will be of great significance. Herein, by screening 978 compounds from an FDA-approved drug library and determining the inhibitory function of each drug on HBsAg level in HepG2.2.15 cells supernatant, we identified that pimobendan (Pim) has a powerful antiviral activity with relatively low cytotoxicity. The inhibitory effect of Pim on HBsAg as well as other HBV markers was validated in HBV-infected cell models and HBV-transgenic mice. Mechanistically, real-time PCR and dual-luciferase reporter assay were applied to identify the partial correlation of transcription factor CAAT enhancer-binding protein α (C/EBPα) with the cccDNA transcription regulated by Pim. This indicates Pim is an inhibitor of HBV transcription through suppressing HBV promoters to reduce HBV RNAs levels and HBsAg production. In conclusion, Pim was identified to be a transcription inhibitor of cccDNA, thereby inhibiting HBsAg and other HBV replicative intermediates both in vitro and in vivo. This report may provide a promising lead for the development of new anti-HBV agent.

Dynamic Changes of Cytokine Profiles and Virological Markers Associated With HBsAg Loss During Peginterferon Alpha-2a Treatment in HBeAg-Positive Chronic Hepatitis B Patients.

ObjectiveTo explore dynamic changes of cytokines and virological markers associated with hepatitis B surface antigen (HBsAg) loss during peginterferon alpha-2a (PEG-IFN α-2a) treatment in hepatitis B e antigen (HBeAg) positive chronic hepatitis B (CHB) patients.MethodsIt was a single-center prospective cohort study. HBeAg-positive CHB patients were prospectively and consecutively enrolled. Cytokines were detected at baseline, week 12 and 24 of PEG-IFN treatment. HBsAg disappearance rate was the primary evaluation index at 48 weeks of PEG-IFN treatment.ResultsAmong 100 patients who completed the 48-week PEG-IFN α-2a treatment, 38 patients achieved serum HBeAg disappearance, 25 patients achieved HBeAg seroconversion, 9 patients achieved functional cure, 37 patients had HBsAg decline of ≥1 log IU/ml, and 8 patients produced hepatitis B surface antibody (HBsAb). Albumin (ALB), fms-like tyrosine kinase 3 ligand (FLT3-L) and interferon-alpha2 (IFN-α2) in the clinical cure group were significantly lower than those in the non-clinical-cure group at baseline. After 12 weeks of treatment, HBsAg in the clinical cure group was significantly lower than that in the non-clinical-cure group (median 1.14 vs. 3.45 log10IU/ml, Z=-4.355, P < 0.001). The decrease of HBsAg and hepatitis B virus desoxyribose nucleic acid (HBV DNA) in the clinical cure group was significantly higher than that in non-clinical-cure group (median: HBsAg 1.96 vs. 0.33 log10IU/ml, Z=-4.703, P< 0.001; HBV DNA 4.49 vs.3.13 log10IU/ml, Z=-3.053, P=0.002). The increase of IFN-α2 in the cure group was significantly higher than that in the non-clinical-cure group (497.89 vs. 344.74, Z=-2.126, P=0.034). After 24 weeks of treatment, HBsAg, HBeAg, Flt3-L, and IL-10 in the clinical cure group were significantly lower than those in the non-clinical-cure group (median: HBsAg 0.70 vs. 3.15 log10IU/ml, Z=-4.535, P< 0.001; HBeAg 1.48 vs. 13.72 S/CO, Z = 2.512, P = 0.012; Flt3-l 0.00 vs 2.24 pg/ml, Z = 3.137, P=0.002; IL-10 0.70 vs. 2.71 pg/ml, Z=-4.067, P < 0.001). HBsAg decreased significantly in the clinical cure group compared with non-clinical-cure group (median 3.27 vs. 0.45, Z=-4.463, P < 0.001).ConclusionDynamic changes of cytokines and virology markers during early PEG IFN α-2a treatment were associated with HBsAg loss in HBeAg-positive CHB patients.

Clinical Utility of SCALE-B to Predict Hepatitis B Virus Relapse, Hepatitis B Surface Antigen Loss After Antiviral Cessation in Asian Patients After 2-Year Follow-up.

BackgroundDiscontinuation of antiviral therapy in chronic hepatitis B (CHB) patients leads to a higher hepatitis B surface antigen (HBsAg) loss; yet, clinical relapse (CR) may occur. SCALE-B score was developed to predict off-treatment CR; however, validation of SCALE-B beyond a 48-week follow-up is rare. We studied whether SCALE-B and hepatitis B virus ribonucleic acid (HBV RNA) could predict outcomes in CHB patients after a 2-year follow-up.MethodsA total of 92 Thai CHB patients who stopped antiviral treatment were followed up; baseline characteristics, quantitative hepatitis B surface antigen (qHBsAg), hepatitis B core-related antigen (HBcrAg), and HBV RNA were collected at the time of discontinuation, and SCALE-B scores were calculated. Patients were followed up every 12 weeks for 48 weeks, and then, the intervals were upon primary doctors. Follow-up data regarding virological relapse (VR), CR, and HBsAg loss were obtained.ResultsThe median follow-up duration was 142 weeks; the cumulative incidences of VR, CR, and HBsAg loss were 65.2, 33.7, and 7.6%, respectively. After 48 weeks, VR and CR plateaued, but HBsAg loss increased from 2.2 to 7.6%. According to the SCALE-B strata, VR, CR, and HBsAg loss were significantly different. The highest stratum (≥ 320) was associated with higher VR, CR, and lesser HBsAg loss when compared to the lowest stratum, with adjusted hazard ratios of 5.0 (95% CIs: 1.8–14.4), 10.44 (95% CIs: 1.4–79.1), and 0.04 (95% CIs: 0.004–0.43), respectively.ConclusionAt a median follow-up of 2.5 years after discontinuing therapy, HBsAg loss in Thai patients was found to increase over time. SCALE-B is a valuable tool for predicting CR, VR, and HBsAg loss; HBV RNA is not significantly associated with long-term outcomes.Clinical Trial Registration[www.ClinicalTrials.gov], identifier [TCTR20180316007].

HBsAg Loss as a Treatment Endpoint for Chronic HBV Infection: HBV Cure.

Despite the availability of effective vaccines and antiviral therapy over the past two to three decades, chronic hepatitis B virus (HBV) infection remains a major global health threat as a leading cause of cirrhosis and liver cancer. Functional HBV cure defined as hepatitis B surface antigen (HBsAg) loss and undetectable serum HBV DNA is associated with improved clinical outcomes in patients with chronic HBV infection. However, spontaneous loss of HBsAg is rare and occurs in only 1% of all HBsAg-positive individuals annually. Furthermore, the rate of functional cure with currently available antiviral therapy is even lower, <1% patients on treatment per year. Nonetheless, HBsAg loss has become the new target or therapeutic endpoint for antiviral treatment. Recently, there has been much excitement surrounding the development of novel antiviral agents such as small interfering RNA (siRNA), core assembly modulators (CAMs), nucleic acid polymers (NAPs) among others, which may be used in combination with nucleos(t)ide analogs and possibly immunomodulatory therapies to achieve functional cure in a significant proportion of patients with chronic hepatitis B. Novel assays with improved sensitivity for detection of very low levels of HBsAg and to determine the source of HBsAg production will also be required to measure efficacy of newer antiviral treatments for HBV cure. In this narrative review, we will define HBV cure, discuss various sources of HBsAg production, evaluate rates of HBsAg loss with current and future antiviral agents, review clinical factors associated with spontaneous HBsAg loss, and explore clinical implications of functional cure.

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.

Review article: hepatitis B—current and emerging therapies

The hepatitis B virus (HBV) affects an estimated 290 million individuals worldwide and is responsible for approximately 900000 deaths annually, mostly from complications of cirrhosis and hepatocellular carcinoma. Although current treatment is effective at preventing complications of chronic hepatitis B, it is not curative, and often must be administered long term. There is a need for safe, effective, finite duration curative therapy. Our aim was to provide a concise, up to date review of all currently available and emerging treatment options for chronic hepatitis B. We conducted a search of PubMed, clinicaltrials.gov, major meeting abstracts and pharmaceutical websites for publications and communications on current and emerging therapies for HBV. Currently approved treatment options for chronic hepatitis B include peginterferon alpha-2a and nucleos(t)ide analogues. Both options do not offer a 'complete cure' (clearance of covalently closed circular DNA (cccDNA) and integrated HBV DNA) and rarely achieve a 'functional cure' (hepatitis B surface antigen (HBsAg) loss). An improved understanding of the viral lifecycle, immunopathogenesis and recent advances in drug delivery technologies have led to many novel therapeutic approaches that are currently being evaluated in clinical trials including targeting of viral entry, cccDNA, viral transcription, core protein, and release of HBsAg and HBV polymerase. Additionally, novel immunological approaches that include targeting the innate and adaptive immune system and therapeutic vaccination are being pursued. The breadth and scope of novel therapies in development hold promise for regimen/s that will achieve functional cure.

A broad-spectrum nanobody targeting the C-terminus of the hepatitis B surface antigen for chronic hepatitis B infection therapy

Sustainable viral suppression with hepatitis B surface antigen (HBsAg) loss is the new treatment goal for chronic hepatitis B (CHB). The role of antibodies in therapies for persistent hepatitis B virus (HBV) infection has received constant attention. While immunotherapy holds great promise, challenges for the antibody-based prevention and control of HBV in CHB include broad HBV antigenic diversity and the need for long-term viral suppression. In this study, we identified a new anti-HBsAg nanobody (Nb), 125s, isolated from HBsAg-immunized alpaca and confirmed its excellent potency in HBsAg clearance and broad-spectrum therapeutic activity against three HBV subtypes in vivo. In addition, we characterized a novel epitope at the C-terminus of the HBsAg surface motif from amino acids 157 to 174. A 125s-based long-term passive immunization program was efficacious at HBsAg clearance and inducing cellular immune responses, offering a promising outlook for CHB immunotherapy.