Evidence of tenofovir resistance in chronic hepatitis B virus (HBV) infection: An observational case series of South African adults

Multiple risk factors for persistent HBV viraemia in an adult receiving nucleos/tide analogue therapy

Diagnosing and treating chronic hepatitis B virus (HBV) infection are key interventions to support progress towards elimination of viral hepatitis by 2030. Although nucleos/tide analogue (NA) therapy is typically highly effective, challenges remain for viral load (VL) suppression, including medication access, incomplete adherence and drug resistance. We present a case of a long-term HBV and HIV coinfected adult prescribed with sequential NA therapy regimens, with episodes of breakthrough viraemia. Multiple factors contribute to virological breakthrough, including exposure to old NA agents, initial high HBV VL, therapy interruptions, intercurrent illnesses and potential contribution from resistance mutations. The case underscores the importance of individualised treatment approaches and adherence support in achieving HBV suppression. Furthermore, it emphasises the need for improved clinical pathways addressing education, support and access to care, particularly for marginalised populations. Comprehensive data collection inclusive of under-represented individuals is crucial for maintaining retention in the care cascade and informing effective interventions.

Islatravir: evaluation of clinical development for HIV and HBV

INTRODUCTION

Islatravir (ISL) is a nucleoside reverse transcriptase translocation inhibitor (NRTTI) that inhibits HIV RT through multiple mechanisms. Contrary to all approved NtRTIs, islatravir retains a 3'OH group. In vitro and clinical data show that ISL is an ultrapotent investigational drug with high tolerability.

AREAS COVERED

The historical development of islatravir and its mechanisms of HIV and HBV inhibition and resistance are covered. Additionally, the outcomes of Phase I and Phase II clinical trials are discussed.

EXPERT OPINION

Current first-line antiretroviral therapy, preexposure, and postexposure prophylactic interventions are highly effective in maintaining low or undetectable viral load. Despite these measures, an unusually high rate of new infections every year warrants developing novel antivirals that can suppress drug-resistant HIV and improve compliance. ISL, an NRTTI once deemed a long-acting drug, was placed on a clinical hold. The outcome of ongoing clinical trials with a reduced ISL dose will decide its future clinical application. Additionally, MK-8527, which inhibits HIV via same mechanism as that of ISL may supersede ISL. Data on ISL inhibition of HBV are scarce, and preclinical data show dramatically lower ISL efficacy against HBV than currently preferred nucleos(t)ide drugs, indicating that ISL may not be a potent anti-HBV drug.

Hepatitis B Virus Prevalence and Mother-to-Child Transmission Risk in an HIV Early Intervention Cohort in KwaZulu-Natal, South Africa

Background

HIV and hepatitis B virus (HBV) prevalence are both high in KwaZulu-Natal, South Africa. HIV coinfection negatively affects HBV prognosis and can increase the likelihood of HBV mother-to-child transmission (MTCT). In an early HIV infant treatment intervention cohort of HIV-transmitting mother-child pairs in KwaZulu-Natal, we characterized maternal HBV prevalence and screened infants at risk.

Methods

Infants were treated for HIV MTCT at birth, and combination regimens incidentally active against HBV were initiated within 21 days. Maternal samples (N = 175) were screened at birth for HBV infection (HBV surface antigen [HBsAg]), exposure to HBV (HBV anti-core IgG), and vaccination responses (HBV anti-S positive without other HBV markers). Infants of mothers who were HBV positive were screened for HBsAg at 1 and 12 months.

Results

Evidence of HBV infection was present in 8.6% (n = 15) of maternal samples. Biomarkers for HBV exposure were present in 31.4% (n = 55). Evidence of HBV vaccination was uncommon in mothers (8.0%; n = 14). Despite prescription of antiretroviral therapy (ART) active against HBV, HBV DNA was detectable in 46.7% (7/15) of mothers who were HBsAg positive. Three mothers had HBV viral loads >5.3 log10 IU/mL, making them high risk for HBV MTCT. Screening of available infant samples at 1 month (n = 14) revealed no cases of HBV MTCT. At 12 months, we identified 1 HBV infection (1/13), and serologic evidence of vaccination was present in 53.8% (7/13) of infants.

Discussion

This vulnerable cohort of HIV-transmitting mothers had a high prevalence of undiagnosed HBV. Early infant ART may have reduced the risk of MTCT in high-risk cases. Current HBV guidelines recommend ART prophylaxis, but these data underline the pressing need to increase availability of birth dose vaccines.

Advancing beyond reverse transcriptase inhibitors: The new era of hepatitis B polymerase inhibitors

Hepatitis B virus (HBV) is a genetically diverse blood-borne virus responsible for chronic hepatitis B. The HBV polymerase plays a key role in viral genome replication within the human body and has been identified as a potential drug target for chronic hepatitis B therapeutics. However, available nucleotide reverse transcriptase inhibitors only target the reverse transcriptase domain of the HBV polymerase; they also pose resistance issues and require lifelong treatment that can burden patients financially. In this study, various chemical classes are reviewed that have been developed to target different domains of the HBV polymerase: Terminal protein, which plays a vital role in the formation of the viral DNA; Reverse transcriptase, which is responsible for the synthesis of the viral DNA from RNA, and; Ribonuclease H, which is responsible for degrading the RNA strand in the RNA-DNA duplex formed during the reverse transcription process. Host factors that interact with the HBV polymerase to achieve HBV replication are also reviewed; these host factors can be targeted by inhibitors to indirectly inhibit polymerase functionality. A detailed analysis of the scope and limitations of these inhibitors from a medicinal chemistry perspective is provided. The structure-activity relationship of these inhibitors and the factors that may affect their potency and selectivity are also examined. This analysis will be useful in supporting the further development of these inhibitors and in designing new inhibitors that can inhibit HBV replication more efficiently.

Barriers that prevent adults living with HBV infection from participating in clinical research: experience from South Africa

High profile international goals have been set for the elimination of hepatitis B virus (HBV) infection as a public health threat by the year 2030. Developing and expanding equitable, accessible translational HBV research programmes that represent real-world populations are therefore an urgent priority for clinical and academic communities. We present experiences and insights by an expert interdisciplinary group focusing on barriers that impede adults living with HBV infection from participating in clinical studies. Our viewpoint describes barriers we have identified through working in a variety of settings across South Africa, including lack of education and awareness, experiences of stigma and discrimination, challenges for governance and data management, and a burden of complex morbidity. Through identifying these challenges, we propose solutions and interventions, highlight new approaches, and provide a framework for future research.

High Prevalence of Hepatitis B Virus Infection Among People With HIV in Rural and Periurban Communities in Botswana

Background

We aimed to determine the prevalence of hepatitis B virus (HBV) infection among people with human immunodeficiency virus (PWH) in rural and periurban communities in Botswana.

Methods

PWH from a previous population-based study, the Botswana Prevention Combination Project, which enrolled adults in 30 communities across Botswana (2013-2018), were screened for HBV surface antigen (HBsAg) and HBV core antibody (anti-HBc). HBsAg-positive (HBsAg+) samples were further screened for HBV core immunoglobulin M antibodies (anti-HBc immunoglobulin M [IgM]) and HBV e antigen (HBeAg). We quantified HBV viral load on participants who tested positive (n = 148) and negative for HBsAg (n = 381).

Results

Of 3304 participants tested, 271 (8% [95% confidence interval {CI}, 7%-9%]) were HBsAg+ while 1788 (56% [95% CI, 54%-57%]) of 3218 PWH whom we tested had positive anti-HBc. Approximately 88% of HBsAg+ participants were on antiretroviral therapy (ART), 40% and 56% of whom were receiving lamivudine- and tenofovir-containing ART, respectively. Male sex (relative risk ratio [RRR], 1.8 [95% CI, 1.2-2.7]) and the northern geographic region (RRR, 2.5 [95% CI, 1.4-4.7]) were independent predictors of HBV infection (HBsAg+). Of 381 persons with negative HBsAg who were tested for occult HBV, 126 (33% [95% CI, 29%-38%]) had positive HBV DNA. Eleven participants were highly viremic with high HBV viral load while on a lamivudine- or tenofovir-containing regimen. Ten (91%) of these participants also had positive HBeAg serology, while 4 (36%) had positive anti-HBc IgM serology.

Conclusions

The prevalence of HBV was high among PWH in Botswana while on ART regimens with activity against HBV.

Health inequalities in the management of chronic hepatitis B virus infection in patients from sub-Saharan Africa in high-income countries

Chronic hepatitis B virus disproportionately affects migrant communities in high-income countries, reflecting increased migration from sub-Saharan Africa. Chronic hepatitis B virus is endemic in sub-Saharan Africa, yet the natural history of chronic infection experienced by patients remains incompletely understood, with evidence of variability across genotypes and regions within sub-Saharan Africa. Clinical guidelines recommending treatment thresholds are not specific to sub-Saharan African patients and are based on natural history studies from Western Pacific Asian countries. Access to standard of care treatment is available for sub-Saharan African people with chronic hepatitis B virus infection in high-income countries; however, the evidence base for these treatments was not established in this cohort and areas of uncertainty remain, particularly regarding HCC surveillance and treatment discontinuation. Participation in phase III clinical trials for chronic hepatitis B therapies is almost non-existent amongst sub-Saharan African patients, even when residing in high-income countries that participate in multicentre trials. Engagement with sub-Saharan African patients with chronic hepatitis B in high-income countries is challenging because of the stigma associated with the diagnosis, absence of routine screening systems and the complexities involved in navigating the healthcare system. Nonetheless, improved engagement is critical if we are to achieve global hepatitis B virus elimination.

Whole genome analysis of hepatitis B virus before and during long-term therapy in chronic infected patients: Molecular characterization, impact on treatment and liver disease progression

Hepatitis B virus (HBV) infection remains a serious public health concern worldwide despite the availability of an efficient vaccine and the major improvements in antiviral treatments. The aim of the present study is to analyze the mutational profile of the HBV whole genome in ETV non-responder chronic HBV patients, in order to investigate antiviral drug resistance, immune escape, and liver disease progression to Liver Cirrhosis (LC) or Hepatocellular Carcinoma (HCC). Blood samples were collected from five chronic hepatitis B patients. For each patient, two plasma samples were collected, before and during the treatment. Whole genome sequencing was performed using Sanger technology. Phylogenetic analysis comparing the studied sequences with reference ones was used for genotyping. The mutational profile was analyzed by comparison with the reference sequence M32138. Genotyping showed that the studied strains belong to subgenotypes D1, D7, and D8. The mutational analysis showed high genetic variability. In the RT region of the polymerase gene, 28 amino acid (aa) mutations were detected. The most significant mutations were the pattern rtL180M + rtS202G + rtM204V, which confer treatment resistance. In the S gene, 35 mutations were detected namely sP120T, sT126S, sG130R, sY134F, sS193L, sI195M, and sL216stop were previously described to lead to vaccine, immunotherapy, and/or diagnosis escape. In the C gene, 34 mutations were found. In particular, cG1764A, cC1766G/T, cT1768A, and cC1773T in the BCP; cG1896A and cG1899A in the precore region and cT12S, cE64D, cA80T, and cP130Q in the core region were associated with disease progression to LC and/or HCC. Other mutations were associated with viral replication increase including cT1753V, cG1764A/T, cC1766G/T, cT1768A, and cC1788G in the BCP as well as cG1896A and cG1899A in the precore region. In the X gene, 30 aa substitutions were detected, of which substitutions xT36D, xP46S, xA47T, xI88F, xA102V, xI127T, xK130M, xV131I, and xF132Y were previously described to lead to LC and/or HCC disease progression. In conclusion, our results show high genetic variability in the long-term treatment of chronic HBV patients causing several effects. This could contribute to guiding national efforts to optimize relevant HBV treatment management in order to achieve the global hepatitis elimination goal by 2030.

Hepatitis B Virus Research in South Africa

Despite being vaccine-preventable, hepatitis B virus (HBV) infection remains the seventh leading cause of mortality in the world. In South Africa (SA), over 1.9 million people are chronically infected with HBV, and 70% of all Black chronic carriers are infected with HBV subgenotype A1. The virus remains a significant burden on public health in SA despite the introduction of an infant immunization program implemented in 1995 and the availability of effective treatment for chronic HBV infection. In addition, the high prevalence of HIV infection amplifies HBV replication, predisposes patients to chronicity, and complicates management of the infection. HBV research has made significant progress leading to better understanding of HBV epidemiology and management challenges in the SA context. This has led to recent revision of the national HBV infection management guidelines. Research on developing new vaccines and therapies is underway and progress has been made with designing potentially curative gene therapies against HBV. This review summarizes research carried out in SA on HBV molecular biology, epidemiology, treatment, and vaccination strategies.

Tenofovir disoproxil fumarate therapy to prevent hepatitis B virus vertical transmission-A review of maternal and infant outcomes

Hepatitis B virus (HBV) is a global health problem. Vertical transmission of HBV from HBV surface antigen (HBsAg)-positive mothers to their infants is the most common cause of HBV infection worldwide. The use of passive-active immunoprophylaxis is >90% effective in reducing the risk of vertical transmission, but immunoprophylaxis failure can occur in infants born to mothers with high viraemia. Thus, it is recommended that pregnant women with HBV-DNA level >200 000 IU/ml receive nucleos(t)ide analogue (NA) treatment [i.e. tenofovir disoproxil fumarate (TDF), lamivudine or telbivudine] during third trimester to prevent infant immunoprophylaxis failure. TDF is recommended as the first-line therapy based on available data on efficacy, safety and resistance profile. However, maternal immunological reconstitution following parturition can increase immune-mediated flares to viral antigens that is potentially exacerbated following TDF withdrawal. In this article, we review available data on the efficacy and safety of TDF administration to prevent HBV mother-to-child transmission. We also discuss changes in maternal viral markers [i.e. HBV-DNA, HBV e antigen and HBsAg] and alanine aminotransferase during follow-up post-partum in mothers received NA to prevent HBV vertical transmission.

Long-term follow-up of treatment-naïve HBeAg-negative patients with chronic hepatitis B

BACKGROUND/AIMS

We aimed to explore long-term results of oral antiviral agents in treatment-naïve "HBeAg negative chronic hepatitis B (CHB)" and determine the factors affecting the complete virological response.

METHOD

Patients with HBeAg-negative CHB who used oral antiviral agents for at least 3 years were evaluated retrospectively.

RESULTS

A total of 173 patients were recorded. The mean duration of treatment was 62.2 ± 28.9 months. Complete virological responses (CVR) were 82.8% (n = 53/64) in tenofovir disoproxil fumarate (TDF), 84.4% (n = 49/58) in lamivudine (LAM), 83.9% (n = 26/31) in entecavir (ETV), 95% in telbivudine (LdT) (n = 19/20) (p = 0.290). Multivariate analysis revealed age ≤ 40 (p = 0.012, 95%CI = 1.38-13.76, OR = 4.36) and baseline HBV DNA value (p = 0.003, 95%CI = 1.23-2.63, OR = 1.78) as independent factors for CVR. Virological breakthrough was detected in 29 (50%) patients on LAM therapy, two (6.4%) patients on ETV therapy, and two (10%) patients on LdT therapy. Treatment was switched to another antiviral agent due to osteoporosis in four patients in the TDF group, muscle pain in nine patients in the LDT group, and headache in one patient in the ETV group. Hepatocelluler cancer was detected in five patients. HBsAg seroclearance developed in two patients. Anti-HBs seroconversion was not detected.

CONCLUSION

CVR was achieved at similar rates with all four antiviral agents, while younger age (≤ 40) and low baseline viral load were the main factors for virological response. However, drug resistance and virological breakthrough in the LAM group and side effects in the LdT group were detected during the long-term follow-up. Moreover, HBsAg seroclearance was achieved at very low rates with oral antiviral agents.

Endemic HBV among hospital in-patients in Bangladesh, including evidence of occult infection

Bangladesh is one of the top-ten most heavily burdened countries for viral hepatitis, with hepatitis B (HBV) infections responsible for the majority of cases. Recombinant and occult HBV infections (OBI) have been reported previously in the region. We investigated an adult fever cohort (n=201) recruited in Dhaka, to determine the prevalence of HBV and OBI. A target-enrichment deep sequencing pipeline was applied to samples with HBV DNA >3.0 log₁₀ IU ml⁻¹. HBV infection was present in 16/201 (8 %), among whom 3/16 (19 %) were defined as OBI (HBsAg-negative but detectable HBV DNA). Whole genome deep sequences (WGS) were obtained for four cases, identifying genotypes A, C and D. One OBI case had sufficient DNA for sequencing, revealing multiple polymorphisms in the surface gene that may contribute to the occult phenotype. We identified mutations associated with nucleos(t)ide analogue resistance in 3/4 samples sequenced, although the clinical significance in this cohort is unknown. The high prevalence of HBV in this setting illustrates the importance of opportunistic clinical screening and DNA testing of transfusion products to minimise OBI transmission. WGS can inform understanding of diverse disease phenotypes, supporting progress towards international targets for HBV elimination.

Characterization of mutations in the reverse transcriptase region of hepatitis B virus in treated and untreated chronic hepatitis B patients

BACKGROUND

The reverse transcriptase (RT) region of the hepatitis B virus (HBV) is the target of antiviral treatment. However, the discrepancy in RT mutations between nucleos(t)ide analogue (NA)-treated and -untreated chronic hepatitis B (CHB) patients is un clear.

METHODS

Serum samples were collected from 119 NA-treated and 135 NA-untreated patients. The sampling time was decided by the clinician. Full-length HBV RT regions were amplified using nest polymerase chain reaction. The mutations within the RT region were analysed by direct sequencing.

RESULTS

The incidence of RT mutations in treated patients was higher than that in untreated patients (p<0.05). The classic drug-resistant mutations were detected in 44.5% (53/119) of treated patients, which was significantly higher than in untreated patients (6.7% [9/135]) (p<0.05). The non-classical mutations showed their complexity and diversity in both patient groups. Multiple mutations (three or more) were more frequent in treated patients than in untreated patients (p<0.05). Several novel mutations might be related to NA resistance.

CONCLUSIONS

The selection pressures of NAs accelerated the development of RT mutations, especially within the functional domain. Mutations in the RT region occurred not only at classical sites, but also at other non-classical sites, which might be related to drug resistance and/or viral replication. The biological function and fitness of HBV isolates harbouring these novel mutations need further in vitro and in vivo verification experiments.

Suboptimal Response to Tenofovir Alafenamide in Two Patients With HBeAg-Positive Hepatitis B: A Case Report

Tenofovir alafenamide (TAF) is one of the most potent first-line nucleot(s)ide analogs for treating chronic hepatitis B virus (HBV) infections. To date, no cases of TAF drug resistance and/or suboptimal response have been reported. To our knowledge, this is the first report of two adult male patients presenting a suboptimal response response to TAF monotherapy. Our study indicates long-term observations and extensive data are needed to further evaluate the efficacy and safety of TAF, and highlights the need for the development of robust novel direct-acting antivirals and immune therapies for HBV.