Efficacy and safety of tenofovir disoproxil fumarate and tenofovir alafenamide fumarate in preventing HBV vertical transmission of high maternal viral load

Chinese clinical practice guidelines for the prevention and treatment of mother-to-child transmission of hepatitis B virus (version 2024)

Guideline registration:

International Practice Guidelines Registry Platform (PREPARE-2023CN171).

Vertical Transmission in Mothers Taking TAF With Exceptionally High Viral Load

Published studies on tenofovir alafenamide (TAF) therapy for preventing vertical transmission of hepatitis B virus (HBV) have primarily enrolled mothers with viremic levels of approximately 7 log10 IU/mL. This study aimed to evaluate the efficacy and safety of TAF therapy in preventing mother-to-child transmission (MTCT) in mothers with exceptionally high viral loads, defined as HBV DNA levels > 2,000,000 IU/mL. Hepatitis B e antigen (HBeAg)-positive mothers with HBV DNA levels > 2,000,000 IU/mL were prospectively enrolled from four hospitals and initiated on TAF therapy between gestational weeks 26 and 28, continuing until delivery. All infants received immunoprophylaxis and were followed up to 28 weeks postpartum. The primary endpoints were the MTCT rate and the occurrence of congenital abnormalities in infants. Secondary outcomes included maternal HBV suppression at delivery and the safety of both mothers and infants. Among 137 mothers screened, 120 were enrolled in TAF therapy, and 121 infants completed the study. At delivery, 93.3% (112/120) of mothers achieved HBV DNA levels < 200,000 IU/mL. At birth, 0.8% (1/121) of infants had a congenital malformation, and 9.9% (12/121) tested positive for HBsAg. The vertical transmission rate was 2% (2/121, intention-to-treat) at 28 weeks of age. No severe adverse effects were reported in mothers or infants. On-treatment and postpartum alanine aminotransferase (ALT) flares after TAF cessation occurred in 7.5% (9/120) and 41.1% (46/112) of mothers, respectively, alongside viral rebound after cessation. Infant physical development remained within normal ranges based on national reference standards. In summary, approximately 2% of mothers on TAF therapy during late pregnancy experienced MTCT, despite proper immunoprophylaxis for their infants. Extending the treatment duration beyond 12 weeks for mothers with extremely high viral loads is recommended to improve MTCT prevention. No safety concerns were observed for either mothers or infants. Trial Registration: ClinicalTrials.gov identifier: NCT04237376.

Pregnancy and the liver

Some of the physiological changes that occur in pregnancy manifest in the liver. These alterations might exacerbate or improve some pre-existent liver diseases, while many conditions remain unaffected. Some hepatic manifestations during pregnancy are secondary to disorders unique to pregnancy. Due to improved management of chronic conditions and assisted conception methods, pregnancies in people with cirrhosis or after liver transplantation are increasingly common. With pregnancy also becoming more common in older people and with the rising prevalence of comorbidities, such as obesity, diabetes, and metabolic syndrome, hypertensive disorders of pregnancy and gestational diabetes are increasing in prevalance. Thus, a broad range of specialists might encounter liver abnormalities in pregnancy, necessitating an understanding of how the liver changes during pregnancy and the importance of multi-disciplinary input to mitigate maternal-fetal risks. From a global health perspective, pregnancy also offers a unique opportunity to influence disease management and initiate interventions that might influence the life course of pregnant people and their families. In this Review, we describe the challenges of diagnosing, risk stratifying, and managing liver disease in pregnancy, and explore factors that might affect future maternal health.

Chinese Clinical Practice Guidelines for the Prevention and Treatment of Mother-to-child Transmission of Hepatitis B Virus (Version 2024)

The Chinese Clinical Practice Guidelines for the Prevention and Treatment of Mother-to-child Transmission of Hepatitis B Virus, developed by the Chinese Society of Infectious Diseases of the Chinese Medical Association in 2019, serves as a valuable reference for standardizing the prevention of mother-to-child transmission in China. As new evidence continues to emerge, it is essential to update these guidelines regularly to optimize clinical practice and research. To this end, the Infectious Disease Physician Branch of the Chinese Medical Doctor Association and the Chinese Society of Infectious Diseases of the Chinese Medical Association, in collaboration with multidisciplinary experts, have updated the guidelines based on the latest domestic and international research advancements and clinical practices, providing up-to-date guidance for clinicians and maternal and child healthcare workers.

Tenofovir Alafenamide Versus Tenofovir Disoproxil Fumarate for Preventing Vertical Transmission in Chronic Hepatitis B Mothers: A Systematic Review and Meta-Analysis

OBJECTIVE

International guidelines recommend maternal tenofovir disoproxil fumarate (TDF) therapy accompanied by infant immunoprophylaxis to prevent hepatitis B virus (HBV) mother-to-child transmission (MTCT) in highly viremic mothers. However, pooled analyses for tenofovir alafenamide (TAF) effects and comparisons between the 2 regimens are lacking.

DESIGN

In this meta-analysis, pairs of independent reviewers performed multiple database searches from inception to 31 March 2024 and extracted data from cohort studies and randomized controlled trials (RCTs) in highly viremic mothers. The outcomes of interest were the reduction of MTCT and safety in the TDF-treated, TAF-treated, and control groups.

RESULTS

We included 31 studies with 2588 highly viremic mothers receiving TDF, 280 receiving TAF, and 1600 receiving no treatment. Compared to the control, TDF therapy reduced the MTCT rate in infants aged 6-12 months (risk ratio: 0.10, 95% confidence interval [CI] .07-.16). Pairwise meta-analysis between TAF and TDF revealed similar effects on reducing MTCT (risk ratio: 1.09, 95% confidence interval .16-7.61). Network meta-analysis showed equal efficacy of the 2 regimens in reducing MTCT (risk ratio: 1.09, 95% CI .15-7.65). The surface under the cumulative ranking curve revealed TDF as the best regimen compared with TAF (probability ranking: .77 vs .72), while receiving a placebo during pregnancy had the lowest efficacy (probability ranking 0.01). There were no safety concerns for mothers and infants in all regimens.

CONCLUSIONS

Compared to placebo or no treatment, maternal TDF and TAF prophylaxis are equally effective and without safety concerns in reducing MTCT in highly viremic mothers.

Chinese Clinical Practice Guidelines for the Prevention and Treatment of Mother-to-Child Transmission of Hepatitis B Virus (Version 2024)

The Chinese Clinical Practice Guidelines for the prevention and treatment of mother-to-child transmission of hepatitis B virus, developed by the Chinese Society of Infectious Diseases of the Chinese Medical Association in 2019, serves as a valuable reference for standardizing the process of preventing mother-to-child transmission in China. As new evidence emerges, it is crucial that timely and regular updates are made to the clinical practice guidelines so as to optimize guidance for clinical practice and research. To this end, the Infectious Disease Physician Branch of Chinese Medical Doctor Association and the Chinese Society of Infectious Diseases of Chinese Medical Association, in collaboration with multidisciplinary experts, have updated the guidelines based on the latest domestic and international research advancements and clinical practice, in order to provide guidance and reference for clinicians and maternal and child healthcare workers.

Viral Hepatitis in Pregnant Mexican Women: Its Impact in Mother-Child Binomial Health and the Strategies for Its Eradication

Viral hepatitis is the main cause of infectious liver disease. During pregnancy, a risk of vertical transmission exists both during gestation and at birth. HAV, HBV, and HCV might progress similarly in pregnant and non-pregnant women. In this study, we found a prevalence of 0.22% of viral hepatitis in pregnant women, with a light preponderance of HCV over HAV and HBV. Here, it was observed that acute HAV infection is more symptomatic and has higher risks for the mother and fetus, in a similar manner to what has been reported for HEV. Histopathological alterations were observed in all except one placenta, indicating that it is an important tissue barrier. Regarding the Mexican strategies for viral hepatitis eradication, success may be related to vaccination at birth, whereas for HCV, the national program for eradication is aimed at treating the infection via direct-acting antiviral agents. The HBV strategy has positively impacted pregnant women and their children, diminishing the risk of vertical transmission. The HCV strategy is still in its early years, and it is expected to be just as successful. For acute hepatitis, HAV and HEV, programs promoting hand washing and those aimed at providing clean food and water are applicable as preventive strategies, alongside other programs such as vaccination.

Association of gestational hepatitis B virus infection and antiviral therapy with pregnancy outcomes: A retrospective study

OBJECTIVE

To explore the relationships between gestational hepatitis B virus (HBV) infection, antiviral therapy, and pregnancy outcomes.

METHODS

We retrospectively selected hepatitis B surface antigen (HBsAg)-positive pregnant women hospitalized for delivery at Fujian Medical University Affiliated Hospital from October 1, 2016 to October 1, 2020. The control group included randomly selected healthy pregnant women hospitalized for delivery during the same time.

RESULTS

Overall, 1115 participants were enrolled and grouped into control (n = 380) and HBsAg-positive groups (n = 735), which were further divided into groups I (n = 407; low viral load), II (n = 207; high viral load without antiviral therapy), and III (n = 121; high viral load with antiviral therapy). Pregnant women with HBV were positively correlated with the incidence of intrahepatic cholestasis of pregnancy (ICP) (adjusted odds ratio [aOR] 5.1, 95% confidence interval [CI] 2.62-9.92, P < 0.001), neonatal jaundice (aOR 10.56, 95% CI 4.49-24.83, P < 0.001), and neonatal asphyxia (aOR 5.03, 95% CI 1.46-17.27, P = 0.01). Aspartate aminotransferase (AST) greater than the upper limit of normal (ULN) was an independent risk factor for increased ICP incidence (aOR 3.49, 95% CI 1.26-9.67, P = 0.019). Antiviral therapy considerably reduced HBV DNA and improved liver function. High viral load and antiviral therapy did not correlate significantly with adverse pregnancy outcomes (P < 0.05).

CONCLUSION

Pregnant women with HBV have significantly elevated incidence of ICP, neonatal jaundice, and neonatal asphyxia not significantly correlated with viral load. AST greater than ULN independently increases the risk of ICP. Antiviral therapy effectively reduces viral replication and improves liver function without increasing the risk of adverse outcomes.

Tenofovir alafenamide or tenofovir disoproxil fumarate in pregnancy to prevent HBV transmission: Maternal ALT trajectory and infant outcomes

BACKGROUND

The use of antiviral agents, specifically tenofovir disoproxil fumarate (TDF), in pregnant women to prevent mother-to-child HBV transmission is a key step towards hepatitis elimination. However, data on using tenofovir alafenamide (TAF) is insufficient. The frequent occurrence of postpartum ALT flares may impact the clinical implementation.

METHODS

The maternal and infant outcomes were compared in multi-centre trials of high viral load HBsAg/HBeAg+ pregnant women receiving TAF or TDF from the third trimester until 2 weeks postpartum with intensive follow-ups. To explore the dynamic pre- and postpartum changes in ALT levels, we used a group-based trajectory model for analysing data of 332 women from three prospective studies.

RESULTS

After treatment, the maternal HBV DNA levels significantly decreased from baseline to delivery: 7.87 ± 0.59 to 3.99 ± 1.07 Log10 IU/mL TAF (n = 78) and 8.30 ± 0.36 to 4.47 ± 0.86 Log10 IU/mL (TDF, n = 53), with viral load reductions of 3.87 versus 3.83 Log10 IU/mL. The HBsAg-positive rates among 12-month-old infants were 1.28% (1/78) versus 1.82% (1/55) respectively (p = 1.00). Of the TAF or TDF-treated mothers, 25.64% versus 16.98% experienced ALT > 2X ULN, and 11.54% versus 1.89% received extended antiviral treatment. Our model revealed four distinct ALT patterns: stable ALT (87.2%), moderate (8.0%) or marked (2.4%) postpartum flares, or prepartum elevations (2.4%).

CONCLUSIONS

TAF effectively reduces mother-to-child HBV transmission, but prophylaxis failure still occurred in few cases. Postpartum ALT flares are common in women receiving TAF or TDF during pregnancy. Approximately 12.8% of mothers may require extended postpartum antiviral treatment.

CLINICAL TRIAL NUMBER

NCT03695029 (ClinicalTrials.gov).

Effectiveness and Safety of Tenofovir Alafenamide Fumarate in the Prevention of Perinatal Hepatitis B Transmission: A Meta-Analysis

AIM

This study aimed to assess the effectiveness and safety of tenofovir alafenamide fumarate (TAF) in the prevention of mother-to-child transmission (MTCT) of hepatitis B virus (HBV).

METHODS

We performed a meta-analysis of studies from the Cochrane Library, PubMed, ClinicalTrials.gov, Web of Science, EMBASE, China National Knowledge Infrastructure (CNKI), China Medical Information Network, and Wanfang databases. The databases were searched from inception to January 7, 2023, for cohort studies and randomized controlled trials (RCTs) comparing the use of TAF antivirals to other antivirals during pregnancy. We combined the data by means of a random-effect DerSimonian-Laird model and risk ratios (RRs) or a random-effect inverse variance model and standardized mean differences (SMDs) to determine the influence on mothers and infants. Our primary outcomes were infant weight, height, head size, birth defects, and Apgar scores. Additionally, we assessed whether newborns tested positive for hepatitis B surface antigen (HBsAg) at birth and at six months of age. The secondary outcomes of our investigation were alterations in levels of HBV deoxyribonucleic acid (DNA), alanine aminotransferase (ALT), total bilirubin (TBIL), blood creatinine, and urine β2-microglobulin (β2-M) in mothers.

RESULTS

An extensive literature search identified 216 relevant publications; three cohort studies and two RCTs were included in this study. A total of 341 mothers were treated with TAF, and 342 were treated with other antiviral agents. TAF was as effective as other antiviral medications at lowering HBV MTCT rates at birth and at 6 months of age and ALT, TBIL, and HBV DNA levels. Moreover, compared with other antiviral drugs, TAF did not affect infant weight, height, head size, Apgar scores, and birth defects or maternal blood creatinine or β2-M levels.

CONCLUSIONS

TAF antiviral therapy during pregnancy was found to be safe for both mothers and fetuses.

Population Pharmacokinetics of Tenofovir Alafenamide Fumarate and Its Metabolite Tenofovir in Healthy Chinese Volunteers

Tenofovir alafenamide fumarate (TAF) is a first-line drug for treating hepatitis B virus infection. This study aimed to establish the prodrug-metabolite population pharmacokinetic (PK) model for TAF and its metabolite tenofovir (TFV) in healthy Chinese volunteers and evaluate the factors affecting the PK. Using 1043 TAF and 1198 TFV plasma sample concentrations collected from 67 healthy volunteers, a population PK model was developed using the nonlinear mixed-effects model. The 1-compartment model containing 4 transit compartments and the 2-compartment model accurately described the PK of TAF and TFV, respectively. Covariates such as meal state and sex were found to be statistically significant and potentially clinically relevant. Both internal and external validations demonstrated good stability and predictive performance of the connected model. This study elucidated the PK process by which TAF was absorbed, converted, and finally metabolized and eliminated as TFV, and explored the sources of interindividual variability between TAF and TFV.

Comparison of the efficacy and safety of TAF, TDF, and LdT to prevent the transmission of hepatitis B in pregnant women: A retrospective study

OBJECTIVE

To compare the efficacy and safety of telbivudine (LdT), tenofovir alafenamide fumarate (TAF), and tenofovir disoproxil fumarate (TDF) for preventing hepatitis B transmission in immune-tolerant pregnant women with HBV infection.

METHODS

We conducted a retrospective cohort study involving women who had hepatitis B virus deoxyribonucleic acid (HBV DNA) ≥ 2 × 105  IU/mL and initiated LdT, TDF, or TAF to prevent mother-to-child transmission (MTCT). The primary endpoint was the safety of mothers and infants. The secondary endpoints were maternal HBV DNA reduction at delivery and MTCT rate.

RESULTS

A total of 96 patients were enrolled in the study (LdT group, n = 36; TDF group, n = 35; TAF group, n = 25). All infants received hepatitis B virus immunoprophylaxis. The MTCT rate was 0%([0 of 25] vs. [0 of 35] vs. [0 of 36], p > .05). No severe liver function damage occurred in any of the mothers. Babies delivered in all groups had prenatal ultrasound screening abnormalities, but abnormality rates were not statistically significant between groups.

CONCLUSION

The application of TDF, TAF, or LdT to immune-tolerant HBV-infected pregnant women in middle-late pregnancy can successfully interrupt MTCT of the HBV virus. However, for all three groups of pregnant women who delivered babies with abnormal prenatal ultrasound screening, an expanded sample size may be needed for further observation.

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.

Maternal-to-Child Transmission of Hepatitis B Virus and Hepatitis Delta Virus

Maternal-to-child transmission of hepatitis B virus (HBV) and hepatitis delta virus (HDV) can lead to the risk of progressive liver disease in infants, but fortunately effective interventions exist to decrease transmission. Counseling on the risk of maternal-to-child transmission, care pathways to decrease transmission, and the implications of HBV and HDV on pregnancy outcomes are the key components of caring for pregnant people living with HBV and HDV.

Who Is at Risk for New Hepatitis B Infections Among People With HIV?

Hepatitis B virus (HBV) increases morbidity and mortality among people with HIV (PWH). We retrospectively analyzed HBV incidence among 5785 PWH. Fourteen had newly positive hepatitis B s antigen (mean 5.2 person-years of follow-up, 46.4/100 000 infections/year). These data show gaps in HBV vaccination and in the preventative efficacy of HBV-specific antiretroviral therapy.

Enhancing interventions for prevention of mother-to-child- transmission of hepatitis B virus

Prevention of mother-to-child transmission of hepatitis B virus (HBV) infection is a cornerstone of efforts to support progress towards elimination of viral hepatitis. Current guidelines recommend maternal screening, antiviral therapy during the third trimester of high-risk pregnancies, universal and timely HBV birth dose vaccination, and post-exposure prophylaxis with hepatitis B immunoglobulin for selected neonates. However, serological and molecular diagnostic testing, treatment and HBV vaccination are not consistently deployed, particularly in many high endemicity settings, and models predict that global targets for reduction in paediatric incidence will not be met by 2030. In this article, we briefly summarise the evidence for current practice and use this as a basis to discuss areas in which prevention of mother-to-child transmission can potentially be enhanced. By reducing health inequities, enhancing pragmatic use of resources, filling data gaps, developing advocacy and education, and seeking consistent investment from multilateral agencies, significant advances can be made to further reduce vertical transmission events, with wide health, societal and economic benefits.

Broadening access to tenofovir alafenamide for the treatment and prevention of HIV-1 infection

INTRODUCTION

Tenofovir alafenamide (TAF), a prodrug of tenofovir, achieves higher intracellular concentrations of tenofovir-diphosphate and 90% lower plasma concentrations of tenofovir compared to tenofovir disoproxil fumarate (TDF). TAF is associated with improved renal and bone safety outcomes.

AREAS COVERED

We review the efficacy and safety of TAF-containing regimens in adults and pediatrics. We highlight safety data during pregnancy, drug interactions during co-administration with tuberculosis treatment, and critical knowledge gaps to be addressed for the successful implementation of TAF in low- and middle-income countries. We performed a search on MEDLINE PubMed and conference websites for relevant articles published from January 2010 to March 2023.

EXPERT OPINION

Current evidence demonstrates that TAF has similar efficacy and tolerability, superior bone and renal safety, and higher rates of dyslipidemia and weight gain, compared with TDF. However, there are several knowledge gaps, in specific sub-populations, that require action. Emerging data suggests that TAF is safe during pregnancy, although fuller safety data to support TAF use in pregnancy is needed. Similarly, there is a lack of evidence that TAF can be used in combination with rifamycin-based tuberculosis treatment in PWH and TB. Further studies are needed to fill knowledge gaps and support the wider rollout of TAF.

Low levels of tenofovir in breast milk support breastfeeding in HBV-infected mothers treated with tenofovir disoproxil fumarate

OBJECTIVE

Tenofovir disoproxil fumarate (TDF) is recommended for the prevention of mother-to-infant transmission of the hepatitis B virus (HBV). This study investigated the safety of infants whose mothers continued to receive TDF while breastfeeding.

PATIENTS AND METHOD

Thirty women taking TDF daily from the second or third trimester of pregnancy to three months postpartum were enrolled. Tenofovir (TFV) concentrations in breast milk were determined and compared with those in umbilical cord (UC) blood and amniotic fluid. Infant growth parameters were assessed at birth, and at 3, 6, and 12 months. TFV uptake experiments were conducted in vitro to elucidate the mechanisms of TFV exposure via breast milk.

RESULTS

TFV concentrations in breast milk ranged from 1.4 to 11.7 ng/mL within 24 h after dosing in the third month postpartum. The median trough concentration of TFV in breast milk was 3.7 (interquartile range, 2.6-6.2) ng/mL, which is lower than that in UC blood (median = 53.5 ng/mL) and amniotic fluid (median = 531.0 ng/mL). The low permeability of TFV in MCF-10A cells may explain the minimal exposure to TFV in breast milk. Body weights, body lengths, and head circumferences of the breastfed infants were comparable to the national standards for physical development.

CONCLUSION

Infant exposure to TFV from breast milk is much lower than the exposure from placental transfer and swallowing from amniotic fluid. The physical growth parameters of all infants in this study were normal. The findings indicate that breastfeeding is safe for infants of HBV-infected mothers who continue to receive TDF through three months postpartum.

The Use of Tenofovir Disoproxil Fumarate and Tenofovir Alafenamide for Preventing Vertical Transmission of Hepatitis B

BACKGROUND

Mother-to-child transmission (MTCT) of hepatitis B virus may occur in highly viremic mothers despite the infants receiving appropriate immunoprophylaxis. We aimed to review tenofovir disoproxil fumarate (TDF) and tenofovir alafenamide (TAF) data for preventing MTCT.

METHODS AND DATA SELECTION

We performed a systematic review between January 1, 2015 and December 31, 2021 on PUBMED, EMBASE, Cochrane, CNKI, and Wanfang databases. Data was extracted from randomized controlled trials or cohort studies in English or Chinese. The outcomes of interest included the efficacy and safety of TDF versus TAF or TDF/TAF versus placebo for preventing MTCT (PROSPERO registration: CRD42021256656).

RESULTS

Data from forty-three studies (13 randomized controlled trials, 30 nonrandomized studies) were included in the review. All infants in the studies received appropriate immunoprophylaxis. Among 3656 highly viremic mothers treated with TDF, hepatitis B virus DNA suppression to the levels <200,000 IU/mL at delivery was achieved in 34% to 100% of mothers. MTCT rates were 0 to 5% and 2 to 83% in mothers treated with TDF and in those who received no treatment, respectively. Congenital malformation rates were 0 to 2.1% in the TDF groups, which did not differ from the nontreated groups. Similar findings were reported in 4 studies that enrolled 326 mothers for maternal TAF therapy, resulting in 0% of MTCT and 0% infant malformation. All studies observed that TDF or TAF maternal therapy reduced MTCT rates significantly without safety concerns when compared with untreated groups, except for 1 RCT that failed the therapeutic endpoint.

CONCLUSIONS

TDF is well established for preventing MTCT in highly viremic mothers, whereas TAF may become an option as data emerges.

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.

Tenofovir Alafenamide for Pregnant Chinese Women With Active Chronic Hepatitis B: A Multicenter Prospective Study

BACKGROUND & AIMS

Data on long-term tenofovir alafenamide (TAF) therapy for pregnant women with active chronic hepatitis B (CHB) (immune clearance and reactivation phases, currently and previously diagnosed) and their infants are lacking.

METHODS

Pregnant women with active CHB treated with TAF and tenofovir disoproxil fumarate (TDF) were enrolled in this multicenter prospective study, and infants received immunoprophylaxis. The primary outcomes were rates of adverse (safety) events in pregnant women and defects in infants and fetuses. The secondary outcomes were virologic responses in pregnant women, infants' safety, hepatitis B surface antigen (HBsAg) status, and growth conditions.

RESULTS

One hundred three and 104 pregnant women were enrolled and 102 and 104 infants were born in the TAF and TDF groups, respectively. In the TAF group, the mean age, gestational age, alanine aminotransferase level, and viral loads at treatment initiation were 29.3 years, 1.3 weeks, 122.2 U/L, and 5.1 log10 IU/mL, respectively. TAF was well-tolerated, and the most common adverse event was nausea (29.1%) during a mean of 2 years of treatment. Notably, 1 (1.0%) TAF-treated pregnant woman underwent induced abortion due to noncausal fetal cleft lip and palate. No infants in either group had birth defects. In the TAF group, the hepatitis B e antigen seroconversion rate was 20.7% at postpartum month 6, infants had normal growth parameters, and no infants were positive for HBsAg at 7 months. The TDF group had comparable safety and effectiveness profiles.

CONCLUSIONS

TAF administered throughout or beginning in early pregnancy is generally safe and effective for pregnant women with active CHB and their infants.

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.

The role of tenofovir disoproxil fumarate for preventing vertical transmission of hepatitis B

Background

Since immunoprophylaxis failure can occur if maternal serum hepatitis B virus (HBV) DNA levels are >200,000 IU/ml, tenofovir disoproxil fumarate (TDF) therapy has been investigated for preventing mother to child transmission (PMTCT).

Methods

A literature search for maternal TDF therapy for PMTCT between 1/1/2015 and 7/1/21 on PUBMED, EMBASE, Cochrane, CNKI, and Wanfang databases was performed. Data from RCTs in English or Chinese were extracted and reviewed. The outcomes of interest included the efficacy and safety of TDF versus placebo for PMTCT.

Results

Among 11 RCTs identified from the databases, the risk-of-bias was low. All studies demonstrated that maternal TDF therapy initiated from the second or third trimester for highly viremic chronic hepatitis B mothers is highly effective and safe in the PMTCT of HBV, except one RCT performed in Thailand which showed no therapeutic advantage on TDF treatment versus placebo for PMTCT (0% vs 3% transmission). Recent emerging data suggest that maternal TDF therapy initiated at the 2nd or early 3rd trimester in mothers with HBV DNA >200,000 IU/ml achieved viremic control before delivery. In the 4-year long follow-up study for maternal TDF therapy, there were no impacts on infants’ physical growth, psychological or mental development, and bone mineral density after fetal exposure to TDF. In the light of updated efficacy and safety data from RCTs, an algorithm was proposed. The approaches in resource-limit areas were discussed.

Conclusions

TDF is safe for both mothers and infants as the preferred therapy for PMTCT in highly viremic mothers. TDF should be initiated at the second or early third trimester in the combination of the appropriate infants’ immunoprophylaxis.

Review article: switching patients with chronic hepatitis B to tenofovir alafenamide-a review of current data

BACKGROUND

The nucleos(t)ide analogues (NAs) entecavir (ETV), tenofovir disoproxil fumarate (TDF) and tenofovir alafenamide (TAF) are preferred treatment options for patients with chronic hepatitis B infection (CHB). However, resistance to ETV has been reported, especially with prior exposure to other NAs, and long-term TDF treatment has been associated with decline in renal function and loss of bone mineral density in some patients. Consequently, TAF may be preferable to ETV, TDF or other NAs in specific circumstances such as in patients with risk of bone or renal complications, elderly patients or those with previous NA experience.

AIM

To provide a summary of the available efficacy and safety data following switch to TAF from other NAs in patients with CHB in clinical studies and real-world settings.

METHODS

Literature searches were performed on PubMed and abstracts from three major international liver congresses between 2019 and 2021. Studies that included efficacy and/or safety data for patients with CHB switching from any NA to TAF were selected.

RESULTS

Thirty-six papers and abstracts were included in this narrative review. Switching from TDF to TAF maintained or improved virological and biochemical responses with improved bone and renal safety. Switching from ETV or other NAs to TAF maintained or improved virological and biochemical responses and varying results for bone and renal safety.

CONCLUSIONS

Switching to TAF appears to maintain or improve virological, biochemical and bone- and renal-related safety outcomes. These data support the concept of switching to TAF in some patients with CHB based on their individual circumstances.

Safety of current antiviral drugs for chronic hepatitis B

INTRODUCTION

Oral nucleos(t)ide analogues (NUCs) are recommended as first-line therapy for chronic hepatitis B due to higher HBV-DNA suppression rates and safety profile. Long-term treatment with NUCs is often necessary to achieve durable viral suppression.

AREAS COVERED

This review provides an overview of the long-term safety data that have become available since entecavir (ETV) and tenofovir disoproxil fumarate (TDF) were first approved, and recent data on tenofovir alafenamide (TAF) in patients with CHB.

EXPERT OPINION

NUCs generally show remarkable safety in patients taking them for long periods. Nevertheless, renal and bone toxicity may occur in a minority of patients on TDF therapy. These effects have been overcome by the recent release of TAF. Moreover, the currently available data do not allow firm conclusions on superiority of TDF on ETV about HCC risk reduction. Observational studies involving more homogeneous cohorts are therefore needed; furthermore long-term studies assessing impact of TAF on this important topic are warranted.