Virologic responses to add-on adefovir dipivoxil treatment versus entecavir monotherapy in children with lamivudine-resistant chronic hepatitis B

Pharmacotherapy options for managing hepatitis B in children

INTRODUCTION

To eliminate viral hepatitis by 2030, the World Health Organization (WHO) launched the first global health sector strategy on viral hepatitis, with particular focus given to hepatitis B and C in 2016. To achieve the reduction of mortality in children, it is indispensable to know which children should be treated and how to treat them.

AREA COVERED

In this article, the authors review the antiviral treatment of children with chronic hepatitis B virus (HBV) infection including antivirals available for children with chronic HBV infection.

EXPERT OPINION

The approvals of nucleos(t)ide analogues (NAs) and pegylated interferon (PEG-IFN) for children have lowered a hurdle to the initiation of antiviral treatment in children. The international guidelines use nearly the same criteria of antiviral treatment for children with chronic HBV infection, but the WHO guidelines provide a cautious stance on the antiviral treatment of children. Not only PEG-IFN but also NAs with a high genetic barrier to drug resistance should be the first-line treatment for children. In settings with limited medical resources, NAs can be the first-line treatment for children. Although the concept of an 'immune-tolerant phase' is challenged, evidence is not sufficient to recommend the treatment of HBeAg-positive immune-tolerant children.

Antiviral Therapy for AECHB and Severe Hepatitis B (Liver Failure)

This chapter describes the principles of antiviral therapy, treatment strategies, medications and recommendations for AECHB, HBV-ACLF, HBV-related liver cirrhosis, HBV-related HCC, and liver transplantation.

Severe exacerbation of chronic hepatitis B is closely related to continuous HBV replication. Therefore, inhibiting HBV replication to reduce viral load may block disease progression and improve the quality of life of these patients. ETV or TDF has been recommend first-line drug for the treatment of AECHB.

A hyperactive immune response due to continuous HBV replication is the main mechanism for development of severe hepatitis B. In addition to comprehensive treatment, early administration of potent nucleoside analogs can rapidly reduce HBV DNA concentration, relieve immune injury induced by HBV, and reduce liver inflammation and patient mortality. Antiviral agents have become important in the treatment of severe exacerbation of chronic hepatitis B.

Long-term antiviral treatment with nucleoside analogs can delay or reverse the progress of liver cirrhosis. Virologic response, viral resistance and adverse drug reactions should be closely monitored during treatment. The treatment should be optimized for maximum effect based on each patient’s responses.

Effective antiviral therapy can suppress HBV replication and reduce the incidence of HBV-related HCC. Patients with HBV-related HCC should receive individualized and optimal multidisciplinary comprehensive treatment. Anti-viral drugs with high efficacy, low resistance and low adverse drug reactions should be selected to improve the patient’s quality of life and prolong survival time.

Methods to prevent HBV reinfection after liver transplantation include passive immunization (HBIG), antiviral treatment (nucleoside analogs) and active immunization (hepatitis B vaccine).

Clinical trials involving sequential combination therapy with NUC and Peg-IFN have shown statistically significant decline in HBsAg levels on treatment and high rates of sustained post-treatment serologic response. Combination therapy with novel DAA and immunotherapeutic approach may hold promise to overcome both cccDNA persistence and immune escape, representing a critical step towards HBV cure.

INASL Guidelines on Management of Hepatitis B Virus Infection in Patients receiving Chemotherapy, Biologicals, Immunosupressants, or Corticosteroids

Hepatitis B Virus (HBV) reactivation in patients receiving chemotherapy, biologicals, immunosupressants, or corticosteroids is emerging to be an important cause of morbidity and mortality in patients with current or prior exposure to HBV infection. These patients suffer a dual onslaught of illness: one from the primary disease for which they are receiving the culprit drug that led to HBV reactivation, and the other from HBV reactivation itself. The HBV reactivation not only leads to a compromised liver function, which may culminate into hepatic failure; it also adversely impacts the treatment outcome of the primary illness. Hence, identification of patients at risk of reactivation before starting these drugs, and starting treatment aimed at prevention of HBV reactivation is the best strategy of managing these patients. There are no Indian guidelines on management of HBV infection in patients receiving chemotherapy, biologicals, immunosupressants, or corticosteroids for the treatment of rheumatologic conditions, malignancies, inflammatory bowel disease, dermatologic conditions, or solid-organ or bone marrow transplantation. The Indian National Association for Study of the Liver (INASL) had set up a taskforce on HBV in 2016, with a mandate to develop consensus guidelines for management of various aspects of HBV infection, relevant to India. In 2017 the taskforce had published the first INASL guidelines on management of HBV infection in India. In the present guidelines, which are in continuation with the previous guidelines, the issues on management of HBV infection in patients receiving chemotherapy, biologicals, immunosupressants, or corticosteroids are addressed.

Pediatric hepatitis B treatment

Although the introduction of hepatitis B vaccine has been contributing to the reduction in the prevalence of hepatitis B virus (HBV) carriers worldwide, the treatment of children with chronic HBV infection is a challenge to be addressed. HBeAg seroconversion, which induces low replication of HBV, is widely accepted as the first goal of antiviral treatment in children with chronic hepatitis B. However, spontaneous HBeAg seroconversion is highly expected in children with chronic HBV infection. Therefore, the identification of children who need antiviral treatment to induce HBeAg seroconversion is essential in the management of chronic HBV infection. Guidelines and experts' opinion show how to identify children who should be treated and how to treat them. If decompensated cirrhosis is absent, interferon-alpha is the first-line antiviral treatment. Nucleos(t)ide analogues (NAs), such as lamivudine, adefovir, entecavir and tenofovir, are also available for the treatment of children, although the approval age differs among them. If decompensated cirrhosis is present, NAs are the first-line antivirals. When the emergence of drug-resistant HBV variants is taken into consideration, entecavir (approved for age 2 years or older) and tenofovir (age 12 years or older), which have high genetic barriers, will play a central role in the treatment of HBV infection. However, the optimal duration of NA treatment and adverse events of long-term NA treatment remain unclear in children. In resource-constrained countries and regions, the financial burden of visiting hospitals, receiving routine blood examination and purchasing antiviral drugs is heavy. Moreover, there is no clear evidence that the induction of HBeAg seroconversion by antiviral treatment prevents the progression of liver disease to cirrhosis and hepatocellular carcinoma in children with chronic HBV infection. It is thus imperative to clarify the clinical impact of antiviral treatment in children with HBV infection.

Continuous up to 4 Years Entecavir Treatment of HBV-Infected Adolescents - A Longitudinal Study in Real Life

This study evaluated the long-term (up to 4 years) efficacy and safety of entecavir ETV treatment and analysed the significance of baseline and on-treatment factors in long-term ETV outcomes in adolescents with chronic hepatitis B (CHB). We determined the cumulative virological and serological outcomes of 44 adolescents with CHB receiving ETV for up to 4 years. To investigate the dynamics of HBV DNA, ALT activity and hepatitis B e antigen (HBeAg) seroconversion over time and their associations with the considered factors, generalized estimating equation (GEE) models were used. The cumulative rates of undetectable HBV DNA (<20 IU/ml) and HBeAg seroconversion after 4 years were 89.7% and 55.4%, respectively. In the study group, we showed that having undetectable HBV DNA at the 6th or 12th month of therapy predicted the achievement of a sustained response rate (SRR, defined as the loss of HBV DNA, loss of HBeAg and ALT normalization) at year 3 of ETV therapy (P = 0.048, OR = 5.83; P = 0.012; OR = 14.57, respectively). The GEE analysis indicated that of the different factors, the duration of ETV therapy had a strong impact on the achievement of virological suppression, HBeAg seroconversion and SRR in adolescents. Each month after the initiation of therapy, the odds of loss of HBV DNA increased by approximately 5% (OR = 1.05, P<0.0001), on average. Additionally, the GEE analysis revealed that adolescents with an age at infection of ≥10 years had 3 times higher odds of achieving undetectable HBV DNA than patients with a younger infection age (OR = 3.67, P = 0.028). None of the ETV-treated patients reported significant adverse effects. ETV is an effective and safe treatment option for adolescents with CHB. Undetectable HBV DNA in the 6th and/or 12th month of ETV treatment and older age at infection could predict maintained virological suppression.

Treatment strategies according to genotype for chronic hepatitis B in children

This review article was requested by editor-in-chief of this journal as 'pediatric CHB treatment' for the upcoming special issue. The main objective of chronic hepatitis B (CHB) treatment is diminishing the risk of complications related to chronic liver disease. In Asia, there are already some reports about hepatocellular carcinoma (HCC) in hepatitis B virus (HBV) infected children. The key points of treatment in children with CHB infections are selection of which patients to treat and conformation of the optimal therapy time that would reduce viral resistance. The choice of therapy is determined by the district (Western/Eastern), HBV genotype, medical accessibility, and economic state of the country. Newly developed nucleos(t)ide analogues (NAs) are potent in children with CHB. However, to improve therapeutic efficacy, physicians are recommended to follow treatment guidelines and determine the specific genotype in the CHB patient. In this article, the treatment of pediatric CHB is reviewed according to differences in genotype.

Lamivudine resistance in children with chronic hepatitis B

Currently, although lamivudine (LAM) has a low genetic barrier, only interferon-alpha and LAM are available as a first-line treatment in children with chronic hepatitis B (CHB). LAM is a potent inhibitor of hepatitis B virus-deoxyribonucleic acid (HBV-DNA) polymerase replication by termination of the proviral HBV-DNA chain. LAM has a good safety and tolerability profile in CHB patients with hepatic decompensation. However, the main disadvantages of this HBV reverse transcriptase inhibitor are: (1) pre-existing covalently closed circular DNA cannot be eradicated by LAM, thus relapse after therapy withdrawal is frequent; and (2) although the longer LAM treatment induced the higher seroconversion rate, the risk of viral resistance increased through the selection of YMDD (tyrosine, methionine, aspartate, aspartate) motif. Insufficient suppression of viral replication leads to the emergence of resistant strains that could result in virological breakthrough which is usually followed by biochemical breakthrough. Mutant strains affects additional resistance and cross resistance, leading to drug resistance in a significant number of CHB patients. In this case, efficacy of more powerful anti-viral agents with higher genetic barrier against development of resistance is diminished. Furthermore, strains that are resistant to LAM could bring about vaccine escape mutants, decreasing the efficacy of HBV vaccine. A more potent drug with a high genetic barrier to resistance needs to be approved as the first-line treatment option for CHB in children.

Hepatitis B virus infection in children

For two decades, hepatitis B vaccine has been integrated into national routine childhood vaccination programs in almost all countries. The prevalence of HBsAg has decreased in children worldwide. However, there are children who miss the benefit of hepatitis B vaccine in some regions and countries. Long-term follow-up studies have revealed the clinical outcomes of chronic hepatitis B virus infection in children. A small percentage of chronically infected children develop liver cirrhosis and hepatocellular carcinoma. However, it is controversial who should be treated and when antiviral treatment should be initiated in children. Compared with adult studies, the data are insufficient to evaluate the pathogenesis of hepatitis B infection and the efficacy of antiviral treatment in childhood. New antiviral drugs have been approved for children and adults. Also, oral antiviral drugs are administered to pregnant women to reduce the hepatitis B virus mother-to-child transmission rate.

Management of chronic hepatitis B infection

The spectrum of chronic hepatitis B infection in children ranges from asymptomatic carriage with minimal disease, to progression to cirrhosis and risk of hepatocellular carcinoma in adulthood. Identifying those who will benefit from treatment is a challenge. Interferon-based therapies have limited efficacy, while prolonged use of nucleos(t)ide analogues may promote resistance. New antiviral agents have improved barriers to resistance, but long-term outcome is not yet known. Untreated infection, however, may in some, lead to natural seroconversion and reduce risk of further disease. Hepatitis B e antigen-positive infection is the most common scenario in chronically infected children, with e antigen-negative hepatitis rarely encountered. This paper reviews the clinical guidelines published in 2013 by the National Institute for Health and Care Excellence (NICE) and the European Society of Pediatric Gastroenterology, Hepatology and Nutrition (ESPGHAN), and focuses on the guidance for treatment in e antigen-positive children. The most significant difference is the lower threshold for starting treatment recommended by NICE guidelines. The need for regular evaluation of each child, in the light of new evidence and new drugs as they emerge, must remain the focus of each clinician involved in the care of children with hepatitis B virus infection.

What physicians should know about the management of chronic hepatitis B in children: East side story

Understanding the natural course of chronic hepatitis B virus (HBV) infection is very important for the management and treatment of chronic hepatitis B in children. Based on treatment guidelines, the management of HBV carriers and treatment of active hepatitis have been advancing and resulted in increased survival, as well as decreased risks of complications such as liver cirrhosis and hepatocellular carcinoma. Development of a continuing medical education (CME) program for primary physicians becomes an important responsibility of pediatric hepatologists. CME could prevent misdiagnosis and unnecessary treatment that could lead to liver complications or antiviral resistance. In addition, education of patients and their parents is necessary to achieve better therapeutic outcomes.

Treatment of children with chronic viral hepatitis: what is available and what is in store

BACKGROUND

At present, therapy of children with chronic hepatitis B and C is still based on few drugs, all burdened by a series of side-effects, unsatisfactory serum conversion rates, and/or drug-resistance. Moreover, selection of subjects to treat with conventional therapies is not univocal, especially during the pediatric age when the disease course is often mild with significant spontaneous seroconversion rate. Our review deals with pros and cons points when a physician decides to design a drug therapy for a child with chronic viral hepatitis, and different possible therapeutic opportunities.

METHODS

A literature search was performed through PubMed. The newest articles, reviews, systematic reviews, and guidelines were included in this review.

RESULTS

The management of children with viral hepatitis is still controversial over whom and when to treat and the use of drug(s). Novel therapeutic strategies have been evaluated only in clinical and preclinical trials involving, for instance, "therapeutic" vaccines. The data on safety and effectiveness of new drugs are also reviewed.

CONCLUSION

The results of reported studies confirmed that at least some of the new drugs, with greater efficacy and/or minor side-effects, will be used clinically.

Chronic hepatitis B in children and adolescents: epidemiology and management

Hepatitis B virus (HBV) infection is a worldwide health problem, which can cause acute liver failure, acute hepatitis, chronic hepatitis, liver cirrhosis, and liver cancer. It is most prevalent in Asia, Africa, Southern Europe, and Latin America. Approximately 2 billion people in the world have been infected by HBV, with more than 350 million as chronic carriers. Implementation of the HBV vaccine led to a significant reduction in viral transmission in many areas of the world; however, it remains highly endemic in many developing countries. The main source of infection in childhood is via perinatal transmission or horizontal transmission during preschool years. The majority of children with chronic hepatitis B (CHB) infection are asymptomatic; however, they may develop progressive disease and are at increased risk of advanced liver disease or liver cancer before their third decade. All children with chronic HBV infection should be regularly monitored for disease progression. The goal of therapy for children with CHB is to arrest disease progression and reduce the risk of developing cirrhosis and cancer. The available medications have a low success rate because of immunotolerance in the child and the development of viral resistance to standard therapy. Therefore, case selection and determination of the best time to commence treatment are essential to increase treatment efficacy and reduce the risk of viral resistance.

Current role of Lamivudine regarding therapeutic response and resistance in children with chronic hepatitis B

PURPOSE

To identify the predictive factors of long-term therapeutic response or resistance to lamivudine treatment in children and adolescents with chronic hepatitis B.

METHODS

Eighty one children and adolescents with chronic hepatitis B were included, who received lamivudine treatment for at least 6 months. Their condition was monitored for at least 12 months (12-88 months) thereafter. Twenty one (25.9%) were preschool children (age≤6). For patients who had developed HBeAg seroconversion or breakthrough, univariate and multivariate analyses were used to identify the effects of age, gender, pretreatment alanine aminotransferase (ALT) and hepatitis B virus DNA levels.

RESULTS

HBeAg seroconversion occurred in 49 (60.5%) of the 81 patients after the initiation of the lamivudine therapy. In 65 patients whom were monitored for over 24 months, the seroconversion rate was significantly higher in younger patients (p=0.040), especially in those patients of preschool age (age≤6, p=0.031). The seroconversion rate was significantly higher in higher pretreatment ALT (p=0.003). The breakthrough occurred in 21 (25.9%) of the 81. The breakthrough rate was lower in younger aged patients (age≤6), and with higher pretreatment ALT levels, but no significant difference.

CONCLUSION

Younger age is a good predictor of HBeAg seroconversion in children with long-term lamivudine treatment as well as high pretreatment ALT levels.