A Systematic Review of Side Effects of Nucleoside and Nucleotide Drugs Used for Treatment of Chronic Hepatitis B

Evaluation of the Potency of Repurposed Antiretrovirals in HBV Therapy: A Narrative Investigation of the Traditional Medicine Alternatives

Hepatitis B is one of the killer communicable diseases, with a global estimation of 1.1 million deaths resulting from liver diseases annually. The search for HBV therapeutics has resulted in repurposing the existing antiretrovirals (ARVs) for HBV treatment, considering their shared common replication mechanisms. This review is aimed at evaluating the potencies of some of the repurposed ARVs used for HBV treatment, analyzing the common mechanisms of viral replications in HBV and HIV, and investigating the potentials of traditional medicines as an alternative treatment for HBV patients. The topical keywords drug repurposing, drug repositioning, antiretrovirals, hepatitis B treatment, HBV, natural products, traditional medicines, title, and abstract were searched in PubMed, Web of Science, and Google Scholar. The advanced search included the five years, 2019-2024. The search result was filtered from 377 to 110 relevant articles. The evaluation reveals that CD4+ T cells are targeted by HIV, while HBV targets the liver with its associated diseases (cirrhosis and hepatocellular carcinoma (HCC)). Furthermore, treatments with the available repurposed ARVs only prevent or slow down the progression to cirrhosis, reduce the HCC incidence, and can improve the quality of life and increase life expectancy; however, they are not curative for HBV. Traditional medicines/natural product extracts or their phytochemicals exert anti-HBV effects through different mechanisms. Traditional medicines exert improved therapeutic effects when combined properly. The investigation further reveals that consideration of an in silico approach in HBV therapeutics might not only streamline drug development but also contribute to a deeper understanding of viral pathogenesis. Therefore, we recommend the integration of computational drug design methods with traditional medicine and natural product screening for discovering new bioactive HBV drug candidates.

Inhibition of Hepatitis B Virus Replication by a Novel GalNAc-siRNA In Vivo and In Vitro

Current antiviral therapy for the chronic hepatitis B virus (HBV) has a low clinical cure rate, high administration frequency, and limited efficacy in reducing HBsAg levels, leading to poor patient compliance. Novel agents are required to achieve HBV functional cure, and reduction of HBV antigenemia may enhance the activation of effective and long-lasting host immune control. HT-101 is a siRNA currently in phase I clinical trials with promising prospects for future applications. By designing and synthesizing siRNA targeting the conserved HBV S region, we evaluated its inhibitory effect on HBV biomarkers across four different genotypes (A-D). Additionally, potential cytotoxic effects were investigated. The in vivo effects and duration of inhibition were assessed using a HBV/adeno-associated virus mouse model. The EC50 values for HBV DNA, HBsAg, HBeAg, and HBV RNA in the supernatant of HepG2.2.15 cells were determined to be 0.3348 0.1696, 4.329, and 2.831 nM, respectively, while the CC50 of HT-101 against the viability of Hep2, H1 HeLa, MRC-5, HEK293, and Huh7 cell lines all exceeded 1 μM significantly. Compared with the vehicle group from days 7 to 70 postdosing, especially in the high-dose group (9 mpk), plasma levels of HBsAg, HBeAg, and HBV DNA were significantly reduced with mean reduction values ranging from 1.72 to 3.38 log10 copy/mL due to long-lasting suppression of HBsAg below the lower limit of quantitation (LLOQ), ultimately leading to induction of anti-HBs. In summary, the preclinical data demonstrate that HT-101 represents a significant breakthrough in reducing antigens and provides a promising strategy for functional cure of HBV.

The nucleoside antiviral prodrug remdesivir in treating COVID-19 and beyond with interspecies significance

Infectious pandemics result in hundreds and millions of deaths, notable examples of the Spanish Flu, the Black Death and smallpox. The current pandemic, caused by SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2), is unprecedented even in the historical term of pandemics. The unprecedentedness is featured by multiple surges, rapid identification of therapeutic options and accelerated development of vaccines. Remdesivir, originally developed for Ebola viral disease, is the first treatment of COVID-19 (Coronavirus disease 2019) approved by the United States Food and Drug Administration. As demonstrated by in vitro and preclinical studies, this therapeutic agent is highly potent with a broad spectrum activity against viruses from as many as seven families even cross species. However, randomized controlled trials have failed to confirm the efficacy and safety. Remdesivir improves some clinical signs but not critical parameters such as mortality. This antiviral agent is an ester/phosphorylation prodrug and excessive hydrolysis which increases cellular toxicity. Remdesivir is given intravenously, leading to concentration spikes and likely increasing the potential of hydrolysis-based toxicity. This review has proposed a conceptual framework for improving its efficacy and minimizing toxicity not only for the COVID-19 pandemic but also for future ones caused by remdesivir-sensitive viruses.

Exploring evidence-based innovative therapy for the treatment of chronic HBV infection: experimental and clinical

With the advent of various vaccines and antimicrobial agents during the 20th century, the control and containment of infectious diseases appeared to be a matter of time. However, studies unveiled the diverse natures of microbes, their lifestyle, and pathogenetic potentials. Since the ground-breaking discovery of the hepatitis B virus (HBV) by Baruch Blumberg and the subsequent development of a vaccine in the early 1980s, the main task of the scientific community has been to develop a proper management strategy for HBV-induced chronic liver diseases. In the early 1980’s, standard interferon (IFN) induced a reduction of HBV DNA levels, followed by the normalization of serum transaminases (alanine aminotransferase, ALT), in some chronic hepatitis B (CHB) patients. However, in the course of time, the limitations of standard IFN became evident, and the search for an alternative began. In the late 1980’s, nucleoside analogs entered the arena of CHB treatment as oral drugs with potent antiviral capacities. At the beginning of the 21st century, insights were developed into the scope and limitations of standard IFN, pegylated-IFN as well as nucleoside analogs for treating CHB. Considering the non-cytopathic nature of the HBV, the presence of covalently closed circular DNA (cccDNA) in the nucleus of the infected hepatocytes and HBV-induced immune-mediated liver damages, a new field of CHB management was initiated by modulating the hosts’ immune system through immune therapy. This review will discuss the nature and design of innovative immune therapy for CHB.

Comparable Incidence of Hepatocellular Carcinoma in Chronic Hepatitis B Patients Treated with Entecavir or Tenofovir

BACKGROUND/AIMS

Adherence to medication and maintained virologic response (MVR) are related to the risk of adverse clinical outcomes. This study aimed to compare the efficacy of entecavir (ETV) and tenofovir disoproxil fumarate (TDF) in relation to the adverse clinical outcomes among chronic hepatitis B (CHB) patients stratified according to adherence to medication and MVR.

METHODS

A total of 1794 treatment-naive CHB patients treated with ETV (n = 894) or TDF (n = 900) for > 1 year were identified.

RESULTS

Adherence rates were significantly higher in the TDF than in the ETV (93.4% vs. 89.1%, respectively; P < 0.001). The MVR of ETV and TDF were 64.5% and 71.7%, respectively (P = 0.001). The MVR of ETV and TDF in the good adherence group were 72.1% and 76.4%, respectively (P = 0.083); in the poor adherence group, the MVR of ETV and TDF were 63.0% and 54.0%, respectively (P = 0.384) Multivariate analysis showed that the risk of HCC and death or transplantation was similar between groups (HR 0.826, 95% CI 0.522-1.306; P = 0.413 and HR 0.636, 95% CI 0.258-1.569; P = 0.325, respectively) after adjusting for adherence to medication and MVR. In the 589 propensity-matched pairs of patients, risk of HCC and death or transplantation was similar between treatment groups after stratification according to adherence rates and MVR.

CONCLUSIONS

After adjustment for adherence and MVR, ETV, and TDF did not differ in terms of the risk of HCC and death or transplantation in all patients and propensity score-matched cohorts.

Potential Drug Targets Against Hepatitis B Virus Based on Both Virus and Host Factors

BACKGROUND

Hepatitis B is a very harmful and epidemic disease caused by hepatitis B virus (HBV). Although an effective anti-HBV vaccine is available, chronic infection poses still a huge health burden in the whole world. The present anti-HBV drugs including nucleoside analogues and interferonalpha have their limitations without exception. There is no effective drug and therapeutic method that can really and truly cure hepatitis B so far. The variability of HBV genome results in that a significant number of patients develop drug resistance during the long-term use of anti-HBV drugs. Hence, it is urgently needed to discover novel targets and develop new drugs against hepatitis B.

OBJECTIVE

The review aims to provide the theory support for designing of the anti-HBV innovative drugs by offering a summary of the current situation of antiviral potential targets.

RESULTS AND CONCLUSION

Since HBV is obligate intracellular parasite, and as such it depends on host cellular components and functions to replicate itself. The targeting both virus and host might be a novel therapeutic option for hepatitis B. Accordingly, we analyse the advances in the study of the potential drug targets for anti-HBV infection, focusing on targeting virus genome, on targeting host cellular functions and on targeting virus-host proteins interactions, respectively. Meanwhile, the immune targets against chronic hepatitis B are also emphasized. In short, the review provides a summary of antiviral therapeutic strategies to target virus factors, host factors and immune factors for future designing of the innovative drug against HBV infection.

Coronavirus disease 2019 (COVID-19): latest developments in potential treatments

Many viral respiratory infections can cause severe acute respiratory symptoms leading to mortality and morbidity. In the spring of 2003, the severe acute respiratory syndrome (SARS) outbreak caused by SARS-CoV spread globally. In the summer of 2012, the Middle East respiratory syndrome (MERS) outbreak caused by MERS-CoV occurred in Saudi Arabia. In the winter of 2019, the coronavirus disease 2019 (COVID-19) outbreak caused by a novel coronavirus SARS-CoV-2 occurred in China which rapidly spread worldwide causing a global pandemic. Up until 27 May 2020, there are 5.5 million confirmed cases of COVID-19 and 347,587 COVID-19 related deaths worldwide, and there has also been an unprecedented increase in socioeconomic and psychosocial issues related to COVID-19. This overview aims to review the current developments in preventive treatments and therapies for COVID-19. The development of vaccines for SARS-CoV-2 is ongoing and various clinical trials are currently underway around the world. It is hoped that existing antivirals including remdesivir and lopinavir-ritonavir might have roles in the treatment of COVID-19, but results from trials thus far have not been promising. COVID-19 causes a mild respiratory disease in the majority of cases, but in some cases, cytokine activation causes sepsis and acute respiratory distress syndrome, leading to morbidity and mortality. Immunomodulatory treatments and biologics are also being actively explored as therapeutics for COVID-19. On the other hand, the use of steroidal and nonsteroidal anti-inflammatory drugs (NSAIDs) has been discouraged based on concerns about their adverse effects. Over the past two decades, coronaviruses have caused major epidemics and outbreaks worldwide, whilst modern medicine has been playing catch-up all along.

Bayesian Network Meta-Analysis for Assessing Adverse Effects of Anti-hepatitis B Drugs

BACKGROUND AND OBJECTIVE

Oral nucleoside/nucleotide analogues (NAs) have been advocated for chronic hepatitis B (CHB) treatment with good efficacy. However, less attention has been put on their adverse events. Therefore, a Bayesian network meta-analysis (NMA) was performed to evaluate the relative safety of five NAs (lamivudine, adefovir dipivoxil, entecavir, telbivudine, and tenofovir disoproxil fumarate) in CHB treatment among adults.

METHODS

Eligible randomized clinical trials (RCTs) and prospective cohort studies were systematically and thoroughly searched until May 1, 2019. Poisson-prior-based Bayesian NMA was performed to synthesize both direct and indirect evidence with reporting hazard ratios (HRs) and 95% credible intervals (CrIs) for serious adverse events (SAEs) and hepatic/renal impairments.

RESULTS

Thirty-three RCTs and 11 prospective cohort studies were identified. As to SAEs, no statistically significant difference was found of any comparison among five NAs. In terms of hepatotoxicity, lamivudine was safer than telbivudine (HR 0.45; 95% CrI 0.21, 0.85), and entecavir increased the risk by 102% (entecavir vs lamivudine: HR 2.02; 95% CrI 1.19, 3.27).

CONCLUSIONS

The findings from this large NMA could influence clinical practice, and the methodological framework of this study could provide evidence-based support to analyze sparse safety data in the field.

Medication Nonadherence Increases Hepatocellular Carcinoma, Cirrhotic Complications, and Mortality in Chronic Hepatitis B Patients Treated With Entecavir

OBJECTIVES

Optimal adherence to nucleoside analogue treatment is necessary to achieve undetectable levels of hepatitis B virus (HBV) DNA in patients with chronic hepatitis B (CHB), and to prevent cirrhotic complications. However, any large long-term follow-up study has not been investigated the effect of adherence to entecavir (ETV) treatment on specific liver-related events (LREs), namely, hepatocellular carcinoma (HCC), cirrhotic complications, and mortality.

METHODS

This was a 10-year longitudinal observational study of treatment-naïve patients with CHB who received ETV treatment. The primary outcome was the cumulative probability of LREs. The cumulative level of adherence to medication was categorized as good (≥90%) or poor (<90%).

RESULTS

Data from 894 treatment-naïve CHB patients who received ETV were analyzed. Overall mean adherence rates were 89.1%. Patients with poor adherence had a higher risk of virologic breakthrough (VBT) (HR, 22.42; 95% CI, 19.57-52.52; P < 0.001) than those with good adherence. Multivariate analyses showed a higher risk of liver-related (HR, 14.29; 95% CI, 3.49-58.47; P < 0.001) or all-cause (HR, 4.96; 95% CI, 2.19-11.27; P < 0.001) mortality, HCC (HR, 2.86; 95% CI, 1.76-4.64; P < 0.001), and cirrhotic complications (HR, 2.86; 95% CI, 1.93-4.25; P < 0.001) with poor adherence. Medication adherence was further stratified into three groups according to adherence rates of <70%, ≥70 to <90%, and ≥90%. The dose-response analyses of adherence rates showed that the risk of LREs increased progressively as medication adherence declined. In particular, the unfavorable effects of nonadherence were more pronounced in patients with cirrhosis.

CONCLUSIONS

Poor adherence to medication was associated with a higher mortality and greater risk of HCC and cirrhotic complications, particularly among patients with liver cirrhosis.

In silico screening for human norovirus antivirals reveals a novel non-nucleoside inhibitor of the viral polymerase

Human norovirus causes approximately 219,000 deaths annually, yet there are currently no antivirals available. A virtual screening of commercially available drug-like compounds (~300,000) was performed on the suramin and PPNDS binding-sites of the norovirus RNA-dependent RNA polymerase (RdRp). Selected compounds (n = 62) were examined for inhibition of norovirus RdRp activity using an in vitro transcription assay. Eight candidates demonstrated RdRp inhibition (>25% inhibition at 10 µM), which was confirmed using a gel-shift RdRp assay for two of them. The two molecules were identified as initial hits and selected for structure-activity relationship studies, which resulted in the synthesis of novel compounds that were examined for inhibitory activity. Five compounds inhibited human norovirus RdRp activity (>50% at 10 µM), with the best candidate, 54, demonstrating an IC₅₀ of 5.6 µM against the RdRp and a CC₅₀ of 62.8 µM. Combinational treatment of 54 and the known RdRp site-B inhibitor PPNDS revealed antagonism, indicating that 54 binds in the same binding pocket. Two RdRps with mutations (Q414A and R419A) previously shown to be critical for the binding of site-B compounds had no effect on inhibition, suggesting 54 interacts with distinct site-B residues. This study revealed the novel scaffold 54 for further development as a norovirus antiviral.

Biophysical Mode-of-Action and Selectivity Analysis of Allosteric Inhibitors of Hepatitis C Virus (HCV) Polymerase

Allosteric inhibitors of hepatitis C virus (HCV) non-structural protein 5B (NS5B) polymerase are effective for treatment of genotype 1, although their mode of action and potential to inhibit other isolates and genotypes are not well established. We have used biophysical techniques and a novel biosensor-based real-time polymerase assay to investigate the mode-of-action and selectivity of four inhibitors against enzyme from genotypes 1b (BK and Con1) and 3a. Two thumb inhibitors (lomibuvir and filibuvir) interacted with all three NS5B variants, although the affinities for the 3a enzyme were low. Of the two tested palm inhibitors (dasabuvir and nesbuvir), only dasabuvir interacted with the 1b variant, and nesbuvir interacted with NS5B 3a. Lomibuvir, filibuvir and dasabuvir stabilized the structure of the two 1b variants, but not the 3a enzyme. The thumb compounds interfered with the interaction between the enzyme and RNA and blocked the transition from initiation to elongation. The two allosteric inhibitor types have different inhibition mechanisms. Sequence and structure analysis revealed differences in the binding sites for 1b and 3a variants, explaining the poor effect against genotype 3a NS5B. The indirect mode-of-action needs to be considered when designing allosteric compounds. The current approach provides an efficient strategy for identifying and optimizing allosteric inhibitors targeting HCV genotype 3a.

Hepatitis B and C

Chronic viral hepatitis is a global health threat and financial burden. Hepatitis B and C viruses (HBV and HCV) are the most common causes of chronic viral hepatitis in the United States. Most cases are asymptomatic before adulthood. Research has resulted in effective therapy for HCV and the promise of effective therapies for HBV. For HCV, therapy is pegylated interferon and ribavirin. Clinical trials with effective direct-acting antiviral agents are underway in pediatrics. For HBV, approved agents are alpha-interferon, lamivudine, adefovir, tenofovir, and entecavir. However, treatment seldom results in functional cure and more effective therapies are urgently needed.

Oligonucleotide aptamers: potential novel molecules against viral hepatitis

Viral hepatitis, as an international public health concern, seriously affects communities and health system. In recent years, great strides have been taken for development of new potential tools against viral hepatitis. Among these efforts, a valuable strategy introduced new molecules called “aptamers”. Aptamers as potential alternatives for antibodies could be directed against any protein in infected cells and any components of viral particles. In this review, we will focus on recent advances in the diagnosis and treatment of viral hepatitis based on aptamer technology. In recent years, various types of aptamers including RNA and DNA were introduced against viral hepatitis. Some of these aptamers can be utilized for early and precise diagnosis of hepatitis infections and other group selected as therapeutic tools against viral targets. Designing diagnostic and therapeutic platforms based on aptamer technology is a promising approach in viral infections. The obtained aptamers in the recent years showed obvious potential for use as diagnostic and therapeutic tools against viral hepatitis. Although some modifications to increase the biostability and half-life of aptamers are underway, it seems these molecules will be a favorable substitute for monoclonal antibody in near future.

Profile of HBV polymerase gene mutations during entecavir treatment in patients with chronic hepatitis B

BACKGROUND/AIMS

We investigated the efficacy of entecavir (ETV) monotherapy in 54 naïve patients and 27 lamivudine (LMV) and/or adefovir (ADV) experienced patients.

METHODS

Eighty-one chronic hepatitis B patients with a viral load above 4 log 10 copies/ml and high levels of serum alanine aminotransferase were treated with ETV 0.5mg daily. The viruses of patients were sequenced before ETV therapy and after every three months of ETV therapy.

RESULTS

Eight LAM-experienced and ADV-experienced patients emerged mutations in the ETV treatment. In one of these experienced patients, the ETV-resistant mutations were detected during ETV treatment, with the virological and the biochemical breakthrough. Two LAM-experienced and ADV-naïve patients were detected mutation during 1-2 years ETV therapy. All three LAM-naïve and ADV-experienced patients were detected mutations in the ETV treatment. Five in fifty for LAM-naïve and ADV-naïve patients showed mutations in the ETV monotherapy.

CONCLUSIONS

ETV has a high genetic barrier to resistance and the efficacy in LAM-experienced and/or ADV-experienced patients were much lower than in naïve patients.

The Importance of Patient-Specific Factors for Hepatic Drug Response and Toxicity

Responses to drugs and pharmacological treatments differ considerably between individuals. Importantly, only 50%-75% of patients have been shown to react adequately to pharmacological interventions, whereas the others experience either a lack of efficacy or suffer from adverse events. The liver is of central importance in the metabolism of most drugs. Because of this exposed status, hepatotoxicity is amongst the most common adverse drug reactions and hepatic liabilities are the most prevalent reason for the termination of development programs of novel drug candidates. In recent years, more and more factors were unveiled that shape hepatic drug responses and thus underlie the observed inter-individual variability. In this review, we provide a comprehensive overview of different principle mechanisms of drug hepatotoxicity and illustrate how patient-specific factors, such as genetic, physiological and environmental factors, can shape drug responses. Furthermore, we highlight other parameters, such as concomitantly prescribed medications or liver diseases and how they modulate drug toxicity, pharmacokinetics and dynamics. Finally, we discuss recent progress in the field of in vitro toxicity models and evaluate their utility in reflecting patient-specific factors to study inter-individual differences in drug response and toxicity, as this understanding is necessary to pave the way for a patient-adjusted medicine.

Combinations of Oseltamivir and T-705 Extend the Treatment Window for Highly Pathogenic Influenza A(H5N1) Virus Infection in Mice

Current anti-influenza therapy depends on administering drugs soon after infection, which is often impractical. We assessed whether combinations of oseltamivir (a neuraminidase inhibitor) and T-705 (a nonspecific inhibitor of viral polymerases) could extend the window for treating lethal infection with highly pathogenic A(H5N1) influenza virus in mice. Combination therapy protected 100% of mice, even when delayed until 96 h postinoculation. Compared to animals receiving monotherapy, mice receiving combination therapy had reduced viral loads and restricted viral spread in lung tissues, limited lung damage, and decreased inflammatory cytokine production. Next-generation sequencing showed that virus populations in T-705–treated mice had greater genetic variability, with more frequent transversion events, than did populations in control and oseltamivir-treated mice, but no substitutions associated with resistance to oseltamivir or T-705 were detected. Thus, combination therapy extended the treatment window for A(H5N1) influenza infection in mice and should be considered for evaluation in a clinical setting.

Nephrotoxicity caused by oral antiviral agents in patients with chronic hepatitis B treated in a hospital for tropical diseases in Thailand

BACKGROUND

There is increasing concern about the potential for nephrotoxicity in patients with chronic hepatitis B (CHB) treated long-term with nucleotide analogs.

METHODS

We examined renal dysfunction and its associated risk factors in patients with CHB treated with antiviral regimens containing either nucleosides or nucleotide analogs. We undertook a retrospective cohort study from 2006 to 2014 at the Hospital for Tropical Diseases, Bangkok, Thailand, and analyzed the data of 102 patients with a median follow-up time of 44.5 months (range 4-101 months).

RESULTS

Seventy-three patients were treated with an antiviral regime containing a nucleoside analog, and 29 with a regime containing a nucleotide analog. Abnormally elevated serum creatinine concentration was observed in 12 patients (11.8 %) after 8 years of treatment. Thirty one percent of patients treated with nucleotide analogs had elevated serum creatinine levels and three of these patients (10.3 %) developed nephrotoxicity. In contrast, serum creatinine concentrations were elevated in three of the 73 patients treated with a nucleoside analog (4.1 %), and none developed nephrotoxicity. The incidence of renal dysfunction by the nucleotide analog regimen was cumulative, with 11.1, 21.0, 26.5 and 47.6 % of patients affected after 2, 4, 6 and 8 years, respectively. Univariate and multivariate analysis indicated that a nucleotide analog-based regimen significantly predicted renal dysfunction (odds ratio 10.5, 95 % confidence intervals 2.6-42.4, P <0.001).

CONCLUSION

The long-term use of nucleotide analogs increased the risk of nephrotoxicity in patients with CHB. Thus, the regular assessment of renal function is recommended for all patients with CHB, particularly those treated with a nucleotide analog.

Telbivudine in liver transplant recipients: Renal protection does not overcome the risk of polyneuropathy and myopathy

The recently reported benefit of telbivudine for renal function has not been systematically studied in long-term liver transplantation (LT) recipients who are at high risk for renal impairment. We aimed to examine whether switching lamivudine therapy to telbivudine could improve renal function in LT recipients who have impaired renal function. This single-center, prospective cohort study enrolled LT recipients who were on lamivudine for hepatitis B virus (HBV) prophylaxis and who had renal impairment for at least 1 year. Lamivudine was switched to telbivudine. The primary outcome was to evaluate the change in renal function at weeks 12, 24, 36, and 48. The secondary outcomes were to assess the efficacy of telbivudine for HBV prophylaxis and the safety profile of telbivudine in the posttransplant setting. After 45 patients were enrolled, the study was terminated early because of increased rates of polyneuropathy/myopathy. During telbivudine treatment (median, 64 weeks), estimated glomerular filtration rate (eGFR) increased in 34 patients (76%). The improvement in renal function was prominent after 24 weeks of telbivudine treatment. Telbivudine was effective as prophylaxis against HBV recurrence. Twenty-six patients (58%) developed polyneuropathy and/or myopathy. The 1-year estimated incidence of polyneuropathy/myopathy was 28%. Diabetes was the strongest predictor of polyneuropathy/myopathy (hazard ratio, 4.13; 95% confidence interval, 1.49-11.50; P = 0.007). In conclusion, although it seems to have a favorable effect in the improvement of renal function and seems to be effective in the prevention of HBV recurrence, the high risk of polyneuropathy and myopathy hampers the use of telbivudine in LT recipients.

The search for nucleoside/nucleotide analog inhibitors of dengue virus

Nucleoside analogs represent the largest class of antiviral agents and have been actively pursued for potential therapy of dengue virus (DENV) infection. Early success in the treatment of human immunodeficiency virus (HIV) infection and the recent approval of sofosbuvir for chronic hepatitis C have provided proof of concept for this class of compounds in clinics. Here we review (i) nucleoside analogs with known anti-DENV activity; (ii) challenges of the nucleoside antiviral approach for dengue; and (iii) potential strategies to overcome these challenges. This article forms part of a symposium in Antiviral Research on flavivirus drug discovery.

Factors associated with adherence to nucleos(t)ide analogs in chronic hepatitis B patients: results from a 1-year follow-up study

Little is known about the factors associated with patient compliance with nucleos(t)ide analog (NUC) treatment for chronic hepatitis B (CHB). The purpose of this study was to examine the association between sociodemographic and clinical characteristics and adherence to NUCs among patients with CHB. A total of 211 CHB patients receiving NUC monotherapy were asked to report the number of prescribed doses of medication they had taken during the last 90 days. A total of four 3-month adherence scores were averaged to obtain a combined rate of NUC adherence during a 1-year follow up period. The mean age of the patients was 29.6 years, 79% were men, and 68% had no prior NUC treatment for CHB. Females, patients without a previous NUC treatment, and those who had NUC drug resistance showed better adherence to NUC treatment, and compliance was better with telbivudine than with lamivudine and entecavir.

Is increasing the dose of Entecavir effective in partial virological responders?

OBJECTIVE

To analyze the effect of increasing Entecavir (ETV) dosage in patients with chronic hepatitis B (CHB) who partially responded to ETV after 1 year.

METHODS

Twenty-three hepatitis B e antigen (HBeAg)-positive and 36 HBeAg-negative patients with CHB were treated with ETV 0.5 mg daily. After 1 year of the treatment, those with detectable hepatitis B virus (HBV-DNA) were randomized to either ETV 0.5 mg or 1 mg daily. The resistance to ETV was excluded. Both groups received ETV for 3 years. The groups were compared in aspects of undetectable DNA.

RESULTS

Group 1 was given 0.5 mg ETV and included 32 patients (20 HBeAg-negative and 12 HBeAg-positive). Group 2 was given 1 mg ETV and consisted of 27 patients (16 HBeAg-negative and eleven HBeAg-positive). Group 2 had more effective suppression of HBV-DNA while both groups had comparable rates of HBeAg loss (58% and 63% for group 1 and group 2, respectively) and alanine transaminase (ALT) normalization at the end of 4 years.

CONCLUSION

Increasing ETV dose from 0.5 mg to 1 mg after 1 year of ETV treatment may provide an effective suppression of viral replication.

Is increasing the dose of Entecavir effective in partial virological responders?

OBJECTIVE

To analyze the effect of increasing Entecavir (ETV) dosage in patients with chronic hepatitis B (CHB) who partially responded to ETV after 1 year.

METHODS

Twenty-three hepatitis B e antigen (HBeAg)-positive and 36 HBeAg-negative patients with CHB were treated with ETV 0.5 mg daily. After 1 year of the treatment, those with detectable hepatitis B virus (HBV-DNA) were randomized to either ETV 0.5 mg or 1 mg daily. The resistance to ETV was excluded. Both groups received ETV for 3 years. The groups were compared in aspects of undetectable DNA.

RESULTS

Group 1 was given 0.5 mg ETV and included 32 patients (20 HBeAg-negative and 12 HBeAg-positive). Group 2 was given 1 mg ETV and consisted of 27 patients (16 HBeAg-negative and eleven HBeAg-positive). Group 2 had more effective suppression of HBV-DNA while both groups had comparable rates of HBeAg loss (58% and 63% for group 1 and group 2, respectively) and alanine transaminase (ALT) normalization at the end of 4 years.

CONCLUSION

Increasing ETV dose from 0.5 mg to 1 mg after 1 year of ETV treatment may provide an effective suppression of viral replication.

Preventive effect of nucleoprotein on hindlimb unloading-induced capillary regression in rat soleus muscle

We investigated the preventive effects of nucleoprotein on capillary regression and mitochondrial dysfunction induced by unloading in the soleus muscle of rats. Nucleoprotein is a supplement made from soft roe of salmon, and its major components are nucleotides and protamine. Adult male Sprague-Dawley rats were divided randomly into control, hindlimb unloading (HU), and hindlimb unloading plus nucleoprotein administration (HU+ NP) groups. Hindlimb unloading was carried out for 2 weeks in the rats belonging to the HU and the HU+ NP groups. The rats of the HU+ NP group were administered nucleoprotein (500 mg/kg) using a feeding needle twice a day for 2 weeks. Hindlimb unloading resulted in capillary regression, decreased succinate dehydrogenase activity of the muscle fiber, and decreased PGC-1α expression in the soleus muscle. These effects were prevented by administration of nucleoprotein. Nucleoprotein appears to prevent capillary regression and mitochondrial dysfunction caused by unloading of the skeletal muscle. Therefore, nucleoprotein supplementation may be an effective therapy for maintaining capillary network and mitochondrial metabolism of the muscle fiber during an unloading period.

Physicians' stated trade-off preferences for chronic hepatitis B treatment outcomes in Germany, France, Spain, Turkey, and Italy

OBJECTIVE

To quantify physicians' preferences among possible outcomes associated with chronic hepatitis B treatments and to determine which outcomes are most important to physicians in making treatment decisions.

METHODS

Physicians in five countries who treat chronic hepatitis B patients completed a web-enabled, choice-format, conjoint-analysis survey. The survey presented physicians with four treatment-choice questions for three different patient types. Each treatment-choice question included a pair of hypothetical medication profiles. Medication outcomes included how long the medication has been studied (weight of evidence); the probability that a patient's viral load remains undetectable for 5 years, with a possible histological improvement or reversal of disease progression (long-term efficacy); the 5-year treatment-related risk of fracture; the 5-year treatment-related risk of renal dysfunction; and patient cost. Treatment-choice questions were derived from a predetermined experimental design with known statistical properties. For each country, the random-parameters logit was used to estimate preference weights for all outcome levels and the mean relative importance of each outcome.

RESULTS

Long-term efficacy and risk of renal dysfunction were the most important outcomes for the 788 physicians completing the survey, whereas weight of evidence was the least important. However, physicians perceived significant differences in weight of evidence timeframes. Physicians in Germany and France ranked efficacy above side-effect risk, whereas physicians in Spain, Italy, and Turkey ranked side-effect risk above efficacy in importance.

CONCLUSION

Physician preferences among treatment profiles indicate systematic differences in the relative importance of treatment outcomes. Physicians require higher efficacy for treatments with higher side-effect risk but somewhat less efficacy for treatments with longer evidence.

Frequency and risk factors of renal impairment during long-term adefovir dipivoxil treatment in chronic hepatitis B patients

BACKGROUND AND AIM

There are insufficient data on renal safety during long-term adefovir dipivoxil (ADV) treatment. We aimed to elucidate the incidence and risk factors of renal impairment in chronic hepatitis B (CHB) patients treated with ADV.

METHODS

We retrospectively enrolled 687 CHB patients (51.4% with compensated cirrhosis) treated with ADV alone (18.2%) or in combination with lamivudine (81.8%) for more than 12 months. Renal function was measured using the estimated glomerular filtration rate (eGFR), and renal dysfunction was defined as mild (20-30% decrease), moderate (30-50%), or severe (more than 50%).

RESULTS

During the median treatment duration of 27 months, 72 patients (10.5%) developed renal impairment, which was mild in 77.8% of cases, moderate in 20.8% of cases, and severe in one patient. The cumulative incidence of renal impairment at 1, 3, and 5 years was 2.6%, 14.8%, and 34.7%, respectively. Modification of the dosing interval or discontinuation of ADV was required in seven and three patients, respectively, and none of them showed a further decline in the eGFR. Although a univariate analysis revealed age, the number of exposure to radio-contrast dye, liver cirrhosis, and hepatocellular carcinoma as risk factors of renal impairment, age was the only significant risk factor identified in the multivariate analysis (odds ratio = 1.048, 95% confidence interval = 1.019-1.076, P = 0.001).

CONCLUSIONS

Renal impairment in long-term ADV users was relatively frequent, but serious renal toxicity was rare, and all cases were safely managed. Careful monitoring of renal function is required, especially in older patients.

Combination Therapy for Chronic Hepatitis B: Current Indications

Hepatitis B infection remains a major public health problem globally and in the United States, with significant use of healthcare resources. Several therapeutic agents active against viral and host targets are currently available for its treatment. The success of combination therapy in HIV infection, which has similarities to hepatitis B in both therapeutic targets and treatment options, stimulated studies on the efficacy and safety of various combinations of available drugs in the treatment of hepatitis B infection. In this review, we analyze the current role of combination therapy in chronic hepatitis B infection.