Clinical, biochemical, and pathological characteristics of clevudine-associated myopathy

Active site polymerase inhibitor nucleotides (ASPINs): Potential agents for chronic HBV cure regimens

Chronic hepatitis B virus (HBV) infection affects 240 to 300 million people worldwide. In the nucleus of infected hepatocytes, the HBV genome is converted to covalently closed circular DNA (cccDNA), which persists and serves as a transcriptional template for viral progeny. Therefore, a long-term cure for chronic HBV infection will require elimination of cccDNA. Although currently available nucleos(t)ide analogues (eg, tenofovir disoproxil fumarate, tenofovir alafenamide, entecavir) effectively control HBV replication, they are seldom curative (functional cure rate ∼10%) and require lifelong treatment for most patients. As such, antiviral agents with novel mechanisms of action are needed. Active site polymerase inhibitor nucleotides (ASPINs) noncompetitively distort the HBV polymerase active site to completely inhibit all polymerase functions, unlike traditional chain-terminating nucleos(t)ide analogues, which only target select polymerase functions and are consumed in the process. Clevudine, a first-generation ASPIN, demonstrated potent and prolonged HBV suppression in phase 2 and 3 clinical studies, but long-term treatment was associated with reversible myopathy in a small number of patients. ATI-2173, a novel next-generation ASPIN, is structurally similar to clevudine but targets the liver and demonstrates potent anti-HBV activity on and off treatment, and may ultimately demonstrate an improved pharmacokinetic and safety profile by significantly reducing systemic clevudine exposure. Thus, ATI-2173 is currently in clinical development as an agent for HBV cure. Here, we review the mechanism of action and preclinical and clinical profiles of clevudine and ATI-2173 to support the role of ASPINs as part of curative regimens for chronic HBV infection.

Comparison of clinical practice guidelines for the management of chronic hepatitis B: When to start, when to change, and when to stop

Clinical practice guidelines are important for guiding the management of specific diseases by medical practitioners, trainees, and nurses. In some cases, the guidelines are utilized as a reference for health policymakers in controlling diseases with a large public impact. With this in mind, practice guidelines for the management of chronic hepatitis B (CHB) have been developed in the United States, Europe, and Asian-Pacific regions to suggest the best-fit recommendations for each social and medical circumstance. Recently, the Korean Association for the Study of the Liver published a revised version of its clinical practice guidelines for the management of CHB. The guidelines included updated information based on newly available antiviral agents, the most recent opinion on the initiation and cessation of treatment, and updates for the management of drug resistance, partial virological response, and side effects. Additionally, CHB management in specific situations was comprehensively revised. This review compares the similarities and differences among the various practice guidelines to identify unmet needs and improve future recommendations.

Toxic and Endocrine Myopathies

PURPOSE OF REVIEW

This article discusses the clinical features, pathophysiology, and management of toxic and endocrine myopathies.

RECENT FINDINGS

Early detection and expeditious correction of metabolic disturbances in endocrinopathies such as Cushing syndrome, thyroid and parathyroid diseases, and acromegaly can minimize and prevent neurologic complications including myopathy. Recently proposed mechanisms of injury in patients with critical illness myopathy include inhibition of protein synthesis, mitochondrial dysfunction, disruption of the ubiquitin-proteasome system, oxidative stress, and disruption of intramuscular calcium homeostasis, which can cause a myosin-loss myopathy. Mechanisms underlying toxic myopathies include myosin loss; damage to cellular structures, including myofibrils and organelles such as lysosomes and mitochondria; inflammation; and necrosis. Presentations range anywhere from acute, painful, and necrotic myopathies, as can occur in statin myopathy, to more insidious presentations such as steroid myopathy.

SUMMARY

Endocrinopathies known to cause myopathy include thyroid and parathyroid diseases, disorders of the adrenal axis such as Cushing syndrome, and acromegaly. Patients in the intensive care unit are at risk for developing critical illness myopathy, also known as myosin-loss myopathy, which should be considered if intensive care unit acquired weakness develops. The most common toxic agents associated with myopathy include statins and other lipid-lowering medications, corticosteroids, colchicine, amiodarone, hydroxychloroquine, and chloroquine.

Clevudine Induced Mitochondrial Myopathy

Clevudine was approved as an antiviral agent for hepatitis B virus, which showed marked, rapid inhibition of virus replication without significant toxicity. However, several studies have reported myopathy associated with clevudine therapy. Also, we experienced seven patients who suffered from myopathy during clevudine therapy. To characterize clevudine-induced myopathy, we collected previously reported cases of clevudine myopathy and analyzed all the cases including our cases. We searched electronic databases that were published in English or Korean using PubMed and KoreaMed. Ninety-five cases with clevudine myopathy, including our seven cases, were selected and analyzed for the demographic data, clinical features, and pathologic findings. The 95 patients with clevudine-induced myopathy comprised 52 women and 43 men aged 48.9 years (27-76 years). The patients received clevudine therapy for about 14.2 months (5-24 months) before the development of symptoms. Weakness mainly involved proximal extremities, especially in the lower extremities, and bulbar and neck weakness were observed in some cases (13.7%). Creatine kinase was elevated in the majority of patients (97.9%). Myopathic patterns on electromyography were observed in most patients examined (98.1%). Muscle biopsy presented patterns compatible with mitochondrial myopathy in the majority (90.2%). The weakness usually improved within about 3 months after the discontinuation of clevudine. Though clevudine has been known to be safe in a 6-month clinical trial, longer clevudine therapy for about 14 months may cause reversible mitochondrial myopathy. Careful clinical attention should be paid to patients with long-term clevudine therapy.

Management of Clevudine-Resistant Chronic Hepatitis B: A Multicenter Cohort Study

Background/Aims

Data are lacking regarding the management of chronic hepatitis B (CHB) with resistance to clevudine (CLV). This study evaluated the efficacy of different rescue therapies for CLV-resistant CHB.

Methods

Patients with CLV-resistant CHB were enrolled in the cohort, and all patients developed virologic breakthrough during CLV therapy and had confirmed-genotypic resistance to CLV (rtM204I mutation) before enrollment.

Results

Of the 107 patients, 12 received adefovir (ADV), 21 received a CLV plus ADV combination (CLV+ADV), 34 received a lamivudine plus ADV combination (LAM+ADV), and 40 received entecavir (ETV) therapy for 48 weeks. The CLV+ADV group had the lowest hepatitis B virus (HBV) DNA level (p<0.0001) and showed the greatest reduction of HBV DNA levels from baseline compared to all other groups (p=0.004) at week 48. HBV DNA was undetectable (<70 IU/mL) in 0%, 57.1%, 21.2%, and 27.5% (p=0.003) of the patients in each group, respectively, at week 48. At the end of the study, the mean alanine transaminase (ALT) level, rate of ALT normalization, and rate of hepatitis B envelope antigen loss or seroconversion did not differ between groups.

Conclusions

CLV+ADV combination therapy in patients with CLV-resistant CHB more effectively suppresses HBV replication than ETV, ADV, or LAM+ADV therapy.

Chronic hepatitis B: a critical discussion

Telbivudine (LdT) is an antiviral agent currently used in the treatment of chronic hepatitis B virus, which was first approved by the US FDA in 2006. The safety of LdT is of great importance for patients that receive long-term treatment for this condition. It has been confirmed that patients treated with LdT have significantly elevated creatine kinase levels. However, the mechanism responsible for this adverse reaction is unclear. This review summarizes the current literature of the adverse reactions of LdT and the possible mechanisms that are involved in chronic hepatitis B infection. Thus, we aim to provide guidance on best practices in using LdT and to provide evidence of the possible mechanisms of LdT-associated adverse reactions.

Adverse effects of oral antiviral therapy in chronic hepatitis B

Oral nucleoside/nucleotide analogues (NAs) are currently the backbone of chronic hepatitis B (CHB) infection treatment. They are generally well-tolerated by patients and safe to use. To date, a significant number of patients have been treated with NAs. Safety data has accumulated over the years. The aim of this article is to review and update the adverse effects of oral NAs. NAs can cause class adverse effects (i.e., myopathy, neuropathy, lactic acidosis) and dissimilar adverse effects. All NAs carry a “Black Box” warning because of the potential risk for mitochondrial dysfunction. However, these adverse effects are rarely reported. The majority of cases are associated with lamivudine and telbivudine. Adefovir can lead to dose- and time-dependent nephrotoxicity, even at low doses. Tenofovir has significant renal and bone toxicity in patients with human immunodeficiency virus (HIV) infection. However, bone and renal toxicity in patients with CHB are not as prominent as in HIV infection. Entecavir and lamivudine are not generally associated with renal adverse events. Entecavir has been claimed to increase the risk of lactic acidosis in decompensated liver disease and high Model for End-Stage Liver Disease scores. However, current studies reported that entecavir could be safely used in decompensated cirrhosis. An increase in fetal adverse events has not been reported with lamivudine, telbivudine and tenofovir use in pregnant women, while there is no adequate data regarding entecavir and adefovir. Further long-term experience is required to highlight the adverse effects of NAs, especially in special patient populations, including pregnant women, elderly and patients with renal impairment.

The causes of drug-induced muscle toxicity

PURPOSE OF REVIEW

Clinically identified myopathies are frequently a consequence of medication toxicities. However, recognizing drug-induced myopathies is sometimes difficult. Developing a greater understanding of the underlying mechanisms of drug-induced muscle toxicity will promote enhanced awareness and recognition, and improved management of these syndromes.

RECENT FINDINGS

The adverse impact of certain drugs on muscle metabolism, muscle cell atrophy, and myocyte apoptosis is increasingly clear. Glucocorticoids impair glucose handling and directly promote protein catabolism. Statins impair mitochondrial function and alter intracellular signaling proteins, which can lead to myocyte apoptosis. Alternatively, statins can induce an autoimmune necrotizing myositis. Several medications impair autophagy, thus limiting access to the needed glycogen stores.

SUMMARY

This review provides an overview of the main underlying mechanisms of drug-induced myopathies. These myopathies will most often be related to a drug's ability to alter metabolism and protein balance, induce necrosis, or impair autophagy.

Update on hepatitis B virus infection

Chronic infection with hepatitis B virus (HBV) leads to the development of hepatocellular carcinoma and/or chronic liver failure. Despite extensive research, the immunopathogenesis is not completely understood. Viral persistence and clinical outcomes following HBV infection depend on viral factors and host factors; including genetic factors that determine a host’s immune mechanisms. The primary goal of chronic hepatitis B (CHB) treatment is to eradicate HBV or to at least maintain suppression of HBV replication. Despite recent advances in anti-viral agents for chronic HBV infection, complete eradication of the virus has been difficult to achieve. Agents for the treatment of CHB are divided mainly into two groups: immunomodulating agents and antiviral nucleos(t)ide analogues (NAs). Although NAs are safe, effective and easily administered orally, their long-term use poses the risk of drug resistance. Currently, international evidence-based guidelines have been developed to support physicians in managing CHB patients. However, treatment of patients with drug resistance is still challenging, as only a few classes of anti-HBV drugs are available and cross-resistance between drugs can occur. In addition, as the currently available genotypic test for detection of drug resistance still has limitations in identifying the different substitutions present in the same viral genome, the development of a new virologic test to overcome this limitation is necessary. Among the predictive factors associated with response to pegylated interferon (PEG-IFN) therapy, hepatitis B surface antigen quantification is considered to be a surrogate marker for monitoring response to PEG-IFN. Current practice guidelines stress the importance of profound and durable HBV viral suppression in the treatment of CHB patients. To this end, it is essential to choose a potent antiviral drug with a low risk of resistance for initial treatment of CHB to achieve sustained virological response. This review highlights recent advances in the understanding of the immunopathogenesis of HBV and currently available and developing treatment strategies against HBV infection.

Entecavir-associated myopathy: a case report and literature review

INTRODUCTION

Entecavir, a nucleoside analog (NA), is effective for treatment of chronic hepatitis B virus (HBV) infection.

METHODS

We report the case of a patient we encountered with entecavir-associated myopathy. We also performed a literature review of myopathies associated with nucleoside analogs.

RESULTS

A 44-year-old man presented with a 3-month history of myalgia and progressive weakness. He had HBV infection and had received entecavir antiviral treatment for 5 years. Laboratory tests showed that serum creatine kinase levels were significantly elevated. Muscle histopathology showed abundant T-lymphocyte infiltration of muscle fibers, and HBV surface antigen and HBV core antigen were not present in muscle fibers. Entecavir-associated myopathy was subsequently diagnosed. The patient's symptoms eventually resolved, and serum CK levels decreased rapidly after he stopped receiving entecavir treatments.

CONCLUSIONS

Patients who receive NA therapy should be closely monitored for myopathic side effects. Muscle Nerve 49:610-614, 2014.

Iatrogenic neurology

Iatrogenic disease is one of the most frequent causes of hospital admissions and constitutes a growing public health problem. The most common type of iatrogenic neurologic disease is pharmacologic, and the central and peripheral nervous systems are particularly vulnerable. Despite this, iatrogenic disease is generally overlooked as a differential diagnosis among neurologic patients. The clinical picture of pharmacologically mediated iatrogenic neurologic disease can range from mild to fatal. Common and uncommon forms of drug toxicity are comprehensively addressed in this chapter. While the majority of neurologic adverse effects are listed and referenced in the tables, the most relevant issues are further discussed in the text.

[Efficacy of entecavir switching therapy in chronic hepatitis B patients with clevudine-induced myopathy]

BACKGROUND/AIMS

Clevudine is a potent antiviral agent against HBV. However, long-term clevudine therapy may cause myopathy. This study was carried out to identify the efficacy of entecavir switching therapy in chronic hepatitis B patients experiencing clevudine-induced myopathy.

METHODS

One hundred forty six patients with chronic hepatitis B treated with 30 mg of clevudine per day for 73 weeks (range, 36-132 weeks) were enrolled. Among them, clevudine-induced myopathy occurred in 21 patients (14.4%) which was diagnosed if the patients had symptoms related to myopathy with concurrent CK and AST elevation. All the patients who were diagnosed as clevudine-induced myopathy stopped the therapy, and 17 patients (81%) were switched to entecavir 0.5 mg.

RESULTS

The patients with clevudine-induced myopathy were switched to entecavir 0.5 mg for median 68 weeks, and all of them showed disappearance of clinical myopathic symptoms and normalization of CK and AST level within median 2.2 months. Eight patients (47%) were HBeAg positive before entecavir treatment, and HBeAg seroconversion was achieved in 2 patients (25%). HBV DNA level was elevated in 3 patients (17.6%) at the time when the patients were diagnosed as myopathy, all of them achieved virological response with entecavir switching therapy. ALT level was elevated in 3 patients (17.6%) before entecavir treatment, all of them showed normalization of ALT level. During entecavir therapy, genotypic resistance to entecavir or virological breakthrough was not noted.

CONCLUSIONS

In chronic hepatitis B patients experiencing clevudine-induced myopathy, switching to entecavir 0.5 mg per day showed a resolution of myopathy and adequate viral suppression.

Virological Response and Muscular Adverse Events during Long-Term Clevudine Therapy in Chronic Hepatitis B Patients

BACKGROUND

Recently, several reports issued clevudine induced myopathy in the long term use.

OBJECTIVES

The aim of this study was to investigate antiviral effects and adverse events of clevudine monotherapy in patients with chronic hepatitis B (CHB).

PATIENTS AND METHODS

The subjects were 110 treatment-naïve CHB patients. They were treated with 30 mg clevudine/day for more than six months. Virological and biochemical tests, including that for serum creatine kinase (CK), were monitored at baseline and at 3-month intervals during treatment period.

RESULTS

In HBeAg-positive patients, the cumulative rates of virological response were 74.0 %, 68.5 %, and 67.3 % after one, two, and three years of clevudine treatment, respectively. Cumulative rates of HBeAg loss or seroconversion were 17.8 %, 30 %, and 31.5 % after one, two and, three years of clevudine treatment, respectively. In HBeAg-negative patients, the cumulative rates of virological response were 97.3 %, 100 %, and 94.6 %, respectively. Virological breakthrough occurred in 27 patients. The rtM204I mutation in HBV polymerase was predominantly detected. Muscular adverse events were observed in 15 patients. All patients with myopathy recovered after the cessation of clevudine monotherapy. Fluctuations in CK level during the clevudine treatment period were frequently observed irrespective of development of myopathy. Multiple episodes of CK elevation were significantly related to the development of myopathy.

CONCLUSIONS

Long-term clevudine monotherapy is effective for suppression of serum HBV DNA level and normalization of serum alanine amino transaminase levels, but associated with occurrence of rtM204I mutation. Clevudine-induced muscular adverse events are not uncommon, although they are totally reversible after cessation of the treatment. Muscular adverse events and serum CK level should be carefully monitored during long-term treatment with clevudine.

Two cases of telbivudine-induced myopathy in siblings with chronic hepatitis B

Telbivudine is an L-nucleoside analogue with potent antiviral activity against hepatitis B virus (HBV). Clinical trials have shown that telbivudine has a more potent and sustained antiviral activity with a lower frequency of viral resistance than lamivudine. Although there are several reports concerning the safety profile of telbivudine, most adverse events are described as mild and transient in nature. Here we report two cases of telbivudine-induced myopathy in patients with chronic hepatitis B who were siblings.

Long-term treatment outcomes of clevudine in antiviral-naive patients with chronic hepatitis B

AIM: To evaluate the treatment outcomes of clevudine compared with entecavir in antiviral-naive patients with chronic hepatitis B (CHB).

METHODS: We retrospectively analyzed the clinical data of CHB patients treated with clevudine 30 mg/d and compared their clinical outcomes with patients treated with entecavir 0.5 mg/d. The biochemical response, as assessed by serum alanine aminotransferase (ALT) activity, virologic response, as assessed by serum hepatitis B virus DNA (HBV DNA) titer, serologic response, as assessed by hepatitis B e antigen (HBeAg) status, and virologic breakthrough with genotypic mutations were assessed.

RESULTS: Two-hundred and fifty-four patients [clevudine (n = 118) vs entecavir (n = 136)] were enrolled. In clevudine-treated patients, the cumulative rates of serum ALT normalization were 83.9% at week 48 and 91.5% at week 96 (80.9% and 91.2% in the entecavir group, respectively), the mean titer changes in serum HBV DNA were -6.03 and -6.55 log₁₀ copies/mL (-6.35 and -6.86 log₁₀ copies/mL, respectively, in the entecavir group), and the cumulative non-detection rates of serum HBV DNA were 72.6% and 83.1% (74.4% and 83.8%, respectively, in the entecavir group). These results were similar to those of entecavir-treated patients. The cumulative rates of HBeAg seroconversion were 21.8% at week 48 and 25.0% at week 96 in patients treated with clevudine, which was similar to patients treated with entecavir (22.8% and 27.7%, respectively). The virologic breakthrough in the clevudine group occurred in 9 (7.6%) patients at weeks 48 and 15 (12.7%) patients at week 96, which primarily corresponded to genotypic mutations of rtM204I and/or rtL180M. There was no virologic breakthrough in the entecavir group.

CONCLUSION: In antiviral-naive CHB patients, long-term treatment outcomes of clevudine were not inferior to those of entecavir, except for virologic breakthrough.

Experience of anti-viral therapy in hepatitis B-associated membranous nephropathy, including Lamivudine-resistant strains

BACKGROUND/AIMS

Chronic hepatitis B infection is a common cause of secondary membranous nephropathy (MN) in endemic areas. Lamivudine treatment improves renal outcome in patients with hepatitis B virus-associated MN (HBV-MN), but prolonged use leads to the emergence of lamivudine-resistant variants. We describe our experience treating lamivudine-resistant and other strains of HBV-MN with new antiviral drugs.

METHODS

Of the 89 patients biopsied and diagnosed with MN from 1996 to 2011, 10 positive for hepatitis B surface antigen were recruited for this study. We investigated the clinical courses, therapeutic responses, and prognoses of patients with HBV-MN.

RESULTS

The incidence of HBV-MN among the original 89 patients was 11.2%. Of these patients, four were treated with supportive care and six with antiviral drugs. One of the four patients treated with supportive care had a spontaneous remission. Four of the six patients treated with antiviral drugs were given lamivudine, and the other two were given entecavir. Two of the four patients treated with lamivudine achieved complete remission with seroconversion (i.e., development of anti-hepatitis B e antigen antibodies), whereas the other two had lamivudine-resistant strains, which were detected at 22 and 23 months after lamivudine treatment, respectively. We added adefovir to the treatment regimen for one of these patients, and for the other patient we substituted clevudine for lamivudine. Both of these patients experienced complete remission, as did the two patients initially treated with entecavir, neither of whom showed resistance to the drug.

CONCLUSIONS

New nucleoside analogues, such as entecavir, adefovir, and clevudine, can be effective for treatment of HBV-MN, including lamivudine-resistant strains.

Long-term treatment efficacy and safety of clevudine therapy in naïve patients with chronic hepatitis B

Background/Aims

Clevudine (CLV) has potent antiviral activity against chronic hepatitis B (CHB) virus infection. The long-term efficacy and safety of CLV therapy in naïve patients with CHB were investigated.

Methods

In this retrospective study, 152 naïve Korean patients with CHB who received 30 mg of CLV once daily for at least 12 months were investigated.

Results

The cumulative rates at months 12, 24, and 36, respectively, were 65.8%, 74.7%, and 74.7% for undetectable serum hepatitis B virus (HBV) DNA (<12 IU/mL); 77.6%, 86.2%, and 86.2% for normalization of serum alanine aminotransferase (<40 IU/L); 17.6%, 23.5%, and 23.5% for hepatitis B e antigen (HBeAg) loss or seroconversion; and 6.6%, 22.5%, and 30.0% for viral breakthrough. HBeAg positivity (p=0.010), baseline serum HBV DNA level ≥6 log₁₀ IU/mL (p=0.032) and detectable serum HBV DNA (≥12 IU/mL) at week 24 (p=0.023) were independently associated with the development of viral breakthrough. During follow-up, CLV-induced myopathy developed in 5.9% of patients.

Conclusions

The results of long-term CLV therapy for the treatment of naïve patients with CHB showed a high frequency of antiviral resistance and substantial associated myopathy. Therefore, we advise that CLV should not be used as a first-line treatment for naïve patients given the availability of other more potent, safer antiviral agents.

High-dose clevudine impairs mitochondrial function and glucose-stimulated insulin secretion in INS-1E cells

Background

Clevudine is a nucleoside analog reverse transcriptase inhibitor that exhibits potent antiviral activity against hepatitis B virus (HBV) without serious side effects. However, mitochondrial myopathy has been observed in patients with chronic HBV infection taking clevudine. Moreover, the development of diabetes was recently reported in patients receiving long-term treatment with clevudine. In this study, we investigated the effects of clevudine on mitochondrial function and insulin release in a rat clonal β-cell line, INS-1E.

Methods

The mitochondrial DNA (mtDNA) copy number and the mRNA levels were measured by using quantitative PCR. MTT analysis, ATP/lactate measurements, and insulin assay were performed.

Results

Both INS-1E cells and HepG2 cells, which originated from human hepatoma, showed dose-dependent decreases in mtDNA copy number and cytochrome c oxidase-1 (Cox-1) mRNA level following culture with clevudine (10 μM-1 mM) for 4 weeks. INS-1E cells treated with clevudine had reduced total mitochondrial activities, lower cytosolic ATP contents, enhanced lactate production, and more lipid accumulation. Insulin release in response to glucose application was markedly decreased in clevudine-treated INS-1E cells, which might be a consequence of mitochondrial dysfunction.

Conclusions

Our data suggest that high-dose treatment with clevudine induces mitochondrial defects associated with mtDNA depletion and impairs glucose-stimulated insulin secretion in insulin-releasing cells. These findings partly explain the development of diabetes in patients receiving clevudine who might have a high susceptibility to mitochondrial toxicity.

Comparison of clevudine and entecavir for treatment-naive patients with chronic hepatitis B virus infection: two-year follow-up data

BACKGROUND/AIM

Clevudine and entecavir are highly potent antiviral agents being used in treatment of chronic hepatitis B. However, no data comparing clinical efficacy and safety of these 2 drugs over a long-term period is available. The aims of this study are to compare virologic, biochemical, and serologic response rates of clevudine and entecavir, as well as treatment failure rates up to 2 years.

METHODS

Data of patients who started clevudine (n = 86) or entecavir (n = 159) as a primary treatment for chronic hepatitis B at Korea University Ansan or Guro Hospital between January 2007 and June 2008 were analyzed.

RESULTS

Treatment responses were compared at 3-month intervals up to 24 months. Per protocol analysis showed no difference in virologic responses between the 2 groups at all time points, except at 18 months. When analyzed on intention-to-treat basis for virologic response at 24 months, the response rates were 45.3% in the clevudine group and 72.3% in the entecavir group, which are significantly different (P < 0.001). Rates of biochemical response and HBeAg seroconversion were not significantly different between the groups at all time points. Up to 24 months, antiviral resistance developed in 18 patients (24.4%) in the clevudine group. Clevudine was discontinued owing to muscle-related problems in 10 patients (11.6%).

CONCLUSIONS

Although both drugs showed potent antiviral activity, entecavir showed better virologic response at 24 months, primarily owing to treatment failures in the clevudine group that were associated with development of drug resistance and muscle-related problems.

Current Nucleos(t)ide Analogue Therapy for Chronic Hepatitis B

Although the prevalence of chronic hepatitis B has decreased considerably in recent years due to widespread use of the hepatitis B virus (HBV) vaccine, its prevalence still remains high in adults, and this can place a significant burden on health care in areas with endemic HBV. Since the introduction of nucleos(t)ide analogues (NUCs), there has been marked improvement in the care of patients with chronic hepatitis B, resulting in increased survival. However, the emergence of drug resistance in patients treated with NUCs is a major concern. The number of multi-drug resistant patients is increasing, and many patients may not respond to the currently available drugs. In this review, we describe the current status of NUC therapy for antiviral-naïve and -resistant patients.

A randomized, multi-central, controlled study of patients with hepatitis B e antigen-positive chronic hepatitis B treated by adefovir dipivoxil or adefovir dipivoxil plus bicyclol

Objective

To evaluate the efficacy and safety profiles of patients with hepatitis B e antigen (HBeAg)-positive chronic hepatitis B (CHB) treated with adefovir dipivoxil (ADV) or ADV plus bicyclol, and to optimize the treatment strategy for CHB patients.

Patients and methods

A total of 250 patients with HBeAg-positive CHB were randomized to ADV plus bicyclol combination group and ADV monotherapy group. The patients in the ADV plus bicyclol combination therapy group (n = 125) received ADV 10 mg orally q.d. and bicyclol 25 mg orally t.i.d. for 48 weeks, and those in the ADV monotherapy group (n = 125) were administered ADV 10 mg orally q.d. alone for 48 weeks. The serum aminotransferases (ALT/AST), HBV DNA, HBeAg/HBeAb, and liver biopsy were conducted before and after therapy.

Results

The serum aminotransferase levels were decreased significantly in both groups. The serum aminotransferase level in ADV plus bicyclol combination therapy group decreased greater than that in ADV monotherapy group (P < 0.01). The virological response rate in ADV plus bicyclol combination therapy group was not significantly different from that in ADV monotherapy group (P > 0.05). After treatment for 48 weeks, the Knodell necroinflammatory score of the two groups were all alleviated significantly, and the Knodell score in the combination group was significantly lower than that in the ADV monotherapy group (P < 0.05). There were no remarkable adverse events probably related to the drug in this study.

Conclusion

Adefovir dipivoxil plus bicyclol combination therapy is a safe and superior treatment regimen for patients with HBeAg-positive CHB when compared with ADV monotherapy.

Clevudine-induced viral response, associated with continued reduction of HBsAg titer, was durable after the withdrawal of therapy

BACKGROUND

This study was conducted to evaluate the durability of clevudine-induced viral response after the withdrawal of treatment.

METHODS

Patients who showed a complete response [alanine aminotransferase (ALT) normalization and hepatitis B virus (HBV) DNA <4,700 copies/mL for hepatitis B envelope antigen (HBeAg)-negative patients; ALT normalization, HBV DNA <4,700 copies/mL, and HBeAg seroconversion for HBeAg-positive patients] in the previous clevudine phase III trials were followed for an additional 96 weeks without any treatment for hepatitis B.

RESULTS

Of the 63 patients in the study cohort, 73% and 35% of the patients had HBV DNA <141,500 and <4,700 copies/mL, respectively, and 75% of the patients had normal ALT at the end of follow-up. HBeAg seroconversion was maintained in 81% of the patients and hepatitis B surface antigen (HBsAg) loss occurred in 3 patients. Continued HBsAg titer decrease (-0.5 log IU/mL) was observed in the sustained viral responders, suggesting the reduction of covalently closed circular DNA in hepatocytes.

CONCLUSIONS

The clevudine-induced viral response was durable in the majority of patients for 2 years after the withdrawal of treatment.

A comparison of 48-week treatment efficacy between clevudine and entecavir in treatment-naïve patients with chronic hepatitis B

PURPOSE

Clevudine and entecavir are currently available in Korea as antiviral drugs against chronic hepatitis B (CHB). We aimed to compare the efficacy of clevudine and entecavir therapy.

METHODS

Treatment-naïve CHB patients who received 30 mg of clevudine or 0.5 mg of entecavir a day were analyzed. Mean reduction of hepatitis B virus (HBV) DNA levels, complete virological response (cVR, undetectable HBV DNA by real-time PCR), biochemical response (recovery to normal ALT level), and hepatitis B e antigen (HBeAg) seroconversion rate at the 48th week of treatment were assessed.

RESULTS

A number of 59 patients in clevudine group and 61 patients in entecavir group were included. Mean HBV DNA reductions from baseline were similar in the clevudine and entecavir groups, -6.4 versus -6.8 log(10) copies/mL in HBeAg-positive (p = 0.417) and -6.9 versus -7.0 log(10) copies/mL in HBeAg-negative patients (p = 0.640). The proportion of patients who achieved cVR was not different between the two groups, 53 versus 55% in HBeAg-positive (p = 1.000) and 100 versus 95% in HBeAg-negative patients (p = 0.452). Biochemical response rates and HBeAg seroconversion rates were also similar in both the groups. Two (3.4%) patients in clevudine group showed virologic breakthrough with rtM204I mutation using direct sequencing analysis. Clinical myopathy occurred in two (3.4%) patients in clevudine group.

CONCLUSION

Mean reduction of viral loads was similar between clevudine and entecavir groups during 48 weeks. However, virologic breakthrough and significant myopathy were noted only in clevudine-treated patients. Therefore, more attention should be paid to patients receiving clevudine.