A 1-year trial of telbivudine, lamivudine, and the combination in patients with hepatitis B e antigen-positive chronic hepatitis B

Overview of the development of HBV small molecule inhibitors

Like tuberculosis and Acquired Immune Deficiency Syndrome (AIDS), hepatitis B is a globally recognized major public health threat. Although there are many small-molecule drugs for the treatment of hepatitis B, the approved drugs cannot eradicate the pathogenic culprit covalently closed circular DNA in patients, so the patients need long-term medication to control HBV amplification. Driven by a high unmet medical need, many pharmaceutical companies and research institutions have been engaged in the development of anti-HBV drugs to achieve a functional cure for chronic hepatitis B as soon as possible. This review summarizes the pathogenesis of hepatitis B virus and the research progress in the development of anti-HBV small molecule drugs, and introduces the cccDNA formation and transcription inhibitors and core inhibitors in detail, especially emphasizes the role of chinese herbal medicine in the treatment of chronic hepatitis B. Furthermore, this review proposes three potential strategies for cccDNA eradication in the future. We believe this review will provide meaningful guidance to achieve a functional cure for viral hepatitis B in the future.

Understanding the genetics of viral drug resistance by integrating clinical data and mining of the scientific literature

Drug resistance caused by mutations is a public health threat for existing and emerging viral diseases. A wealth of evidence about these mutations and their clinically associated phenotypes is scattered across the literature, but a comprehensive perspective is usually lacking. This work aimed to produce a clinically relevant view for the case of Hepatitis B virus (HBV) mutations by combining a chronic HBV clinical study with a compendium of genetic mutations systematically gathered from the scientific literature. We enriched clinical mutation data by systematically mining 2,472,725 scientific articles from PubMed Central in order to gather information about the HBV mutational landscape. By performing this analysis, we were able to identify mutational hotspots for each HBV genotype (A-E) and gene (C, X, P, S), as well as the location of disulfide bonds associated with these mutations. Through a modelling study, we also identified a mutation position common in both the clinical data and the literature that is located at the binding pocket for a known anti-HBV drug, namely entecavir. The results of this novel approach show the potential of integrated analyses to assist in the development of new drugs for viral diseases that are more robust to resistance. Such analyses should be of particular interest due to the increasing importance of viral resistance in established and emerging viruses, such as for newly developed drugs against SARS-CoV-2.

Association of Pre-S/S and Polymerase Mutations with Acute and Chronic Hepatitis B Virus Infections in Patients from Rio de Janeiro, Brazil

Several hepatitis B virus (HBV)-related factors, including the viral load, genotype, and genomic mutations, have been linked to the development of liver diseases. Therefore, in this study we aimed to investigate the influence of HBV genetic variability during acute and chronic infection phases. A real-time nested PCR was used to detect HBV DNA in all samples (acute, n = 22; chronic, n = 49). All samples were sequenced for phylogenetic and mutation analyses. Genotype A, sub-genotype A1, was the most common genotype in the study population. A total of 190 mutations were found in the pre-S/S gene area and the acute profile revealed a greater number of nucleotide mutations (p < 0.05). However, both profiles contained nucleotide mutations linked to immune escape and an increased risk of hepatocellular carcinomas (acute, A7T; chronic, A7Q). Furthermore, 17 amino acid substitutions were identified in the viral polymerase region, including the drug resistance mutations lamivudine and entecavir (rtL180M), with statistically significant differences between the mutant and wild type strains. Owing to the natural occurrence of these mutations, it is important to screen for resistance mutations before beginning therapy.

SARS-CoV-2 RdRp Inhibitors Selected from a Cell-Based SARS-CoV-2 RdRp Activity Assay System

The COVID-19 pandemic, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), urgently needs effective prophylactic and therapeutic drugs. RNA-dependent RNA polymerase (RdRp), essential for replicating and transcribing a viral RNA genome, is highly conserved in coronaviruses; thus, it is a potential target for inhibiting coronavirus infection. In this study, we generated the cell-based SARS-CoV-2 RdRp activity assay system by modifying a previously reported cell-based MERS-CoV RdRp activity assay system to screen for SARS-CoV-2 RdRp inhibitors. The assay system consisted of an expression plasmid encoding SARS-CoV-2 RdRp and an RdRp activity reporter plasmid. RdRp activity in the cells could be conveniently detected by luminescence after transfection. We confirmed that SARS-CoV-2 RdRp replicated double-stranded RNA using immunofluorescence staining and the inhibition of RdRp activity by remdesivir and lycorine using this system. Moreover, the Z-factor of this system was calculated to be 0.798, suggesting the reproducibility and reliability of the high-throughput screening system. Finally, we screened nucleoside and nucleotide analogs and identified adefovir dipivoxil, emtricitabine, telbivudine, entecavir hydrate, moroxydine and rifampin as novel SARS-CoV-2 RdRp inhibitors and therapeutic candidates for COVID-19 This system provides an effective high-throughput screening system platform for developing potential prophylactic and therapeutic drugs for COVID-19 and emerging coronavirus infections.

Trends and strategies to combat viral infections: A review on FDA approved antiviral drugs

The infectious microscopic viruses invade living cells to reproduce themselves, and causes chronic infections such as HIV/AIDS, hepatitis B and C, flu, etc. in humans which may lead to death if not treated. Different strategies have been utilized to develop new and superior antiviral drugs to counter the viral infections. The FDA approval of HIV nucleoside reverse transcriptase inhibitor, zidovudine in 1987 boosted the development of antiviral agents against different viruses. Currently, there are a number of combination drugs developed against various viral infections to arrest the activity of same or different viral macromolecules at multiple stages of its life cycle; among which majority are targeted to interfere with the replication of viral genome. Besides these, other type of antiviral molecules includes entry inhibitors, integrase inhibitors, protease inhibitors, interferons, immunomodulators, etc. The antiviral drugs can be toxic to human cells, particularly in case of administration of combination drugs, and on the other hand viruses can grow resistant to the antiviral drugs. Furthermore, emergence of new viruses like Ebola, coronaviruses (SARS-CoV, SARS-CoV-2) emphasizes the need for more innovative strategies to develop better antiviral drugs to fight the existing and the emerging viral infections. Hence, we reviewed the strategic enhancements in developing antiviral drugs for the treatment of different viral infections over the years.

Broad spectrum antiviral nucleosides-Our best hope for the future

The current focus for many researchers has turned to the development of therapeutics that have the potential for serving as broad-spectrum inhibitors that can target numerous viruses, both within a particular family, as well as to span across multiple viral families. This will allow us to build an arsenal of therapeutics that could be used for the next outbreak. In that regard, nucleosides have served as the cornerstone for antiviral therapy for many decades. As detailed herein, many nucleosides have been shown to inhibit multiple viruses due to the conserved nature of many viral enzyme binding sites. Thus, it is somewhat surprising that up until very recently, many researchers focused more on "one bug one drug," rather than trying to target multiple viruses given those similarities. This attitude is now changing due to the realization that we need to be proactive rather than reactive when it comes to combating emerging and reemerging infectious diseases. A brief summary of prominent nucleoside analogues that previously exhibited broad-spectrum activity and are now under renewed interest, as well as new analogues, that are currently under investigation against SARS-CoV-2 and other viruses is discussed herein.

A comparative network meta-analysis of standard of care treatments in treatment-naïve chronic hepatitis B patients

Objective: Published network meta-analyses of chronic hepatitis B (CHB) treatments are either out-of-date or excluded key treatments. Therefore, we aimed to comprehensively update the efficacy evidence for the following end points: Hepatitis B surface antigen (HBsAg) loss, hepatitis B early antigen (HBeAg) seroconversion and hepatitis B virus DNA (HBV DNA) suppression. Materials & methods: Approved treatments in CHB and their combinations were evaluated. A systematic literature review was conducted to identify all randomized controlled trials in treatment-naïve CHB patients. Included studies reported at least one of the end points of interest. A frequentist probability network meta-analysis was performed for each end point. The choice of fixed effect or random-effect model was based on the I-square statistic, a measure of variation in study outcomes between studies. The analyses were performed separately for HBeAg-positive and HBeAg-negative patients. For the primary analyses, end points measured 48 ± 4 weeks after treatment initiation were considered. Results: A total of 47 randomized controlled trials (13,826 patients), covering 23 unique treatment regimens, were included: a total of 29 reported HBsAg loss, 36 reported HBeAg seroconversion and 37 reported HBV DNA suppression. For both HBsAg loss and HBeAg seroconversion, pegylated interferon-based regimens were the most effective strategy in both HBeAg-positive and HBeAg-negative patients. On the other hand, for HBV DNA suppression, nucleosides-based regimens were the most effective strategy in both HBeAg-positive and HBeAg-negative patients. Conclusion: Our findings confirm available evidence around the comparative efficacy of available CHB treatments. Therefore, they can be used to update relevant cost-effectiveness analyses and clinical guidelines.

Mechanism of Diol Dehydration by a Promiscuous Radical-SAM Enzyme Homologue of the Antiviral Enzyme Viperin (RSAD2)

3'-Deoxynucleotides are an important class of drugs because they interfere with the metabolism of nucleotides, and their incorporation into DNA or RNA terminates cell division and viral replication. These compounds are generally produced by multi-step chemical synthesis, and an enzyme with the ability to catalyse the removal of the 3'-deoxy group from different nucleotides has yet to be described. Here, using a combination of HPLC, HRMS and NMR spectroscopy, we demonstrate that a thermostable fungal radical S-adenosylmethionine (SAM) enzyme, with similarity to the vertebrate antiviral enzyme viperin (RSAD2), can catalyse the transformation of CTP, UTP and 5-bromo-UTP to their 3'-deoxy-3',4'-didehydro (ddh) analogues. We show that, unlike the fungal enzyme, human viperin only catalyses the transformation of CTP to ddhCTP. Using electron paramagnetic resonance spectroscopy and molecular docking and dynamics simulations in combination with mutagenesis studies, we provide insight into the origin of the unprecedented substrate promiscuity of the enzyme and the mechanism of dehydration of a nucleotide. Our findings highlight the evolution of substrate specificity in a member of the radical-SAM enzymes. We predict that our work will help in using a new class of the radical-SAM enzymes for the biocatalytic synthesis of 3'-deoxy nucleotide/nucleoside analogues.

Nucleos(t)ide analogues for the treatment of chronic hepatitis B: a systematic review with network meta-analysis

OBJECTIVES

Chronic hepatitis B (CHB) is a major global health problem caused by hepatitis B virus (HBV) infection, and can put patients at high risk of death from cirrhosis and liver cancer. However, CHB can be treated with nucleos(t)ide analogues. We aimed to evaluate the effectiveness and safety of nucleos(t)ide analogues for the treatment of CHB patients.

METHODS

A systematic literature search was performed. Direct comparison meta-analyses and network meta-analysis (NMA) were carried out.

RESULTS

Thirty-six randomized controlled trials (RCTs) met inclusion criteria. Compared with placebo, the nucleos(t)ide analogues were all effective in HBeAg seroconversion, HBeAg loss, and achieving undetectable HBV DNA. Telbivudine was associated with higher HBeAg seroconversion compared with entecavir. For HBeAg loss rate and proportion of achieving undetectable HBV DNA, tenofovir ranked as the best. Entecavir might be the most potent in the normalization of alanine aminotransferase (ALT). The nucleos(t)ide analogues did not have higher serious adverse events rate as compared with placebo.

CONCLUSION

The nucleos(t)ide analogues are all effective for HBeAg seroconversion, HBeAg loss, undetectable HBV DNA, and most are effective for ALT normalization in adults with CHB. RCTs of multi-center, low risk of bias, and long-term follow-up are still needed.

Telbivudine for renal transplant recipients with chronic hepatitis B infection: a randomized controlled trial with early termination

BACKGROUND

The aim of this study was to analyze changes in renal function in HBsAg-positive renal transplant recipients receiving lamivudine who did or did not switch to telbivudine.

METHODS

In this prospective randomized clinical trial (RCT), HBsAg-positive renal transplant recipients who had received lamivudine prophylaxis for at least 6 months were 1:2 randomized to receive either lamivudine or telbivudine for another 24 months. Renal function was evaluated by creatinine level and estimated glomerular filtration rate (eGFR) at the time of randomization (baseline), 6, 12, 18, and 24 months respectively.

RESULTS

This RCT was prematurely terminated after recruiting only 17 patients due to a high incidence (61.5%; 8/13) of clinical myalgia in the telbivudine group. Cox's proportional hazards model revealed that there was no independent predictor of myalgia. Based on intention-to-treat and per protocol analyses using generalized estimating equations, the patients in the randomized telbivudine group had a significantly increased eGFR and the patients in the lamivudine group had a significantly decreased eGFR at the end of follow-up compared to the values at study enrollment. However, there was no significant difference between the lamivudine and telbivudine groups.

CONCLUSIONS

The renal protective effect of telbivudine for HBsAg positive renal transplant recipients was uncertain for high incidence of myalgia and only patients who were on telbivudine for 24 months had renal function maintenance.

Modifications at the C(5) position of pyrimidine nucleosides

This review summarizes the state of knowledge on the chemical methods of C(5)-modifications of uridine and cytidine derivatives and may serve as a useful tool for synthetic chemists to choose an appropriate reaction protocol. The synthesis of 5-substituted uracil derivatives is gaining an increasing interest because of their possible applications in medicine and pharmacy. Modifications at the C(5) position of pyrimidine nucleosides can enhance their biostability, bioavailability or(and) biological activity. Among the C(5)-modified nucleosides, 5-halopyrimidines exhibit anticancer, antiviral, radio- and photosensitizing properties. Besides 5-halo-substituted derivatives, there are other examples of nucleosides with confirmed biological activity containing a C–C bond at the C(5) position in the pyrimidine ring. In recent decades, scientists have achieved great progress in the field of cross-coupling reactions. Among them, nickel-catalyzed processes provide a broad spectrum of synthetic methods that are based on less toxic and cheaper starting materials. This review summarizes the synthetic approaches based on the coupling or halogenation reactions, which enable 5-substituted pyrimidine nucleosides to be obtained. Moreover, the importance of the systems considered for medicine and pharmacy is briefly discussed.

The bibliography includes 197 references.

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.

Adverse events of nucleos(t)ide analogues for chronic hepatitis B: a systematic review

Nucleos(t)ide analogues (NAs) are the main drug category used in chronic hepatitis B (CHB) treatment. Despite the fact that NAs have a favourable safety profile, undesired adverse events (AEs) may occur during the treatment of CHB. Given the eminent number of patients currently receiving NAs, even a small risk of any of these toxicities can represent a major medical issue. The main objective of this review was to analyse information available on AEs associated with the use of NAs in published studies. We choose the following MesH terms for this systematic review: chronic hepatitis B, side effects and treatment. All articles published from 1 January 1990 up to 19 February 2018 in MEDLINE of PubMed, EMBASE, the Cochrane Library and LILACS databases were searched. A total of 120 articles were selected for analysis, comprising 6419 patients treated with lamivudine (LAM), 5947 with entecavir (ETV), 3566 with tenofovir disoproxil fumarate (TDF), 3096 with telbivudine (LdT), 1178 with adefovir dipivoxil (ADV) and 876 with tenofovir alafenamide (TAF). The most common AEs in all NAs assessed were abdominal pain/discomfort, nasopharyngitis/upper respiratory tract infections, fatigue, and headache. TAF displays the highest density of AEs per patient treated among NAs (1.14 AE/treated patient). In conclusion, treatment of CHB with NAs is safe, with a low incidence of AEs. Despite the general understanding TAF being safer than TDF, the number of patients treated with TAF still is too small in comparison to other NAs to consolidate an accurate safety profile. PROSPERO Registration No. CRD42018086471.

Ten-year efficacy and safety of tenofovir disoproxil fumarate treatment for chronic hepatitis B virus infection

BACKGROUND & AIMS

Tenofovir disoproxil fumarate (TDF) is a first-line treatment for chronic hepatitis B (CHB). We aimed to describe the efficacy and safety profiles of TDF treatment for up to 10 years in a well-described cohort of CHB patients.

METHODS

Hepatitis B e antigen (HBeAg)-negative and HBeAg-positive patients from two randomised, double-blind trials (ClinicalTrials.gov: NCT00117676 and NCT00116805) completed 48 weeks of randomised treatment with TDF or adefovir dipivoxil. A subset of these patients was then eligible to receive open-label TDF treatment for up to 10 years. At Year 10, patients were assessed for virological suppression, alanine aminotransferase (ALT) normalisation, serological response, safety and tolerability.

RESULTS

Of 641 randomised and treated patients, 585 (91%) entered the open-label extension phase with 203 (32%) patients completing Year 10 of the study. At Year 10, 118/118 (100%) of HBeAg-negative patients and 78/80 (98%) of HBeAg-positive patients with available data achieved hepatitis B virus (HBV) DNA < 69 IU/mL, while 88/106 (83%) and 60/77 (78%) patients achieved ALT normalisation, respectively. Of the 23 patients with HBeAg status available at Year 10, 12 (52%) and six (27%) experienced HBeAg loss and seroconversion, respectively. No resistance to TDF was documented up to Year 10. In the period between Year 8 and Year 10, the safety profile of TDF was similar to previous reports, with few patients experiencing renal- or bone-related adverse events.

CONCLUSIONS

Over 10 years, TDF had a favourable safety profile, was well tolerated, and resulted in continued maintenance of virological suppression with no documented resistance.

Antiviral treatment for treatment-naïve chronic hepatitis B: systematic review and network meta-analysis of randomized controlled trials

BACKGROUND

Chronic hepatitis B (CHB) infection poses a significant burden to public health worldwide. Most cases are clinically silent until late in the disease course. The main goal of current therapy is to improve survival and quality of life by preventing disease progression to cirrhosis and liver failure, and consequently hepatocellular carcinoma development. The objective of this review is to provide a contemporary and comprehensive evaluation of the effectiveness of treatment options.

METHODS

We performed a systematic review of peer-reviewed literature for randomized controlled trials involving treatment-naïve CHB adult population who received antiviral therapy. The endpoints were virologic response (VR), normalization of alanine aminotransferase (ALT norm), HBeAg loss, HBeAg seroconversion, and HBsAg loss for the HBeAg-positive population; and VR and ALT norm for the HBeAg-negative population. Network meta-analysis (NMA) was performed to synthesize evidence on the efficacy of treatment.

RESULTS

Forty-two publications were selected. Twenty-three evaluated HBeAg-positive population, 13 evaluated HBeAg-negative population, and six evaluated both. We applied NMA to the efficacy outcomes of the two populations separately. Treatment strategies were ranked by the probability of achieving outcomes, and pairwise comparisons calculated from NMA were reported in odds ratios (OR). For HBeAg-positive population, tenofovir disoproxil fumarate (TDF) and tenofovir alafenamide (TAF) were the best for VR; OR vs adefovir = 14.29, 95% CI 7.69-25 and 12.5, 95% CI 4.35-33.33 respectively. TAF was the best for achieving ALT norm (OR vs placebo = 12.5, 95% CI 4.55-33.33), HBeAg loss, and seroconversion (OR vs entecavir/TDF combination = 3.03, 95% CI 1.04-8.84 and 3.33, 95% CI 1.16-10 respectively). In the HBeAg-negative population, TDF and TAF were the best for VR (OR vs adefovir = 9.79, 95% CI 2.38-42.7 and 11.71, 95% CI 1.03-150.48 respectively). Telbivudine and TAF were the best for ALT norm. Certain nucleos(t)ide combinations also had high probability of achieving positive outcomes.

CONCLUSIONS

Our results are consonant with current clinical guidelines and other evidence reviews. For both HBeAg-positive and HBeAg-negative populations, TDF and TAF are the most effective agents for virologic suppression, and TAF is effective across all outcomes.

Risk factors for resistance development against lamivudine during long-term treatment of chronic hepatitis B virus infections

BACKGROUND/AIM

The use of lamivudine for the treatment of chronic hepatitis B (CHB) is limited by high rates of lamivudine resistance. However, it is still in use in many regions. Factors associated with lamivudine resistance development have been studied in only a few European cohorts. The aim of our study was to assess the rate and risk factors for lamivudine resistance in a large real-life European cohort.

PATIENTS AND METHODS

We retrospectively analyzed patients with CHB treated in three German University centers over up to 12 years. Lamivudine resistance was defined as virologic breakthrough and presence of genotypic lamivudine resistance. The probability of resistance was estimated by Kaplan-Meier analysis and resistance predictors by Cox regression.

RESULTS

A total of 227 patients were included into the analysis (hepatitis B envelope antigen positive or negative). Rates of lamivudine resistance by years 1-7 were 7, 26, 35, 41, 46, 53, and 55%, respectively. Interestingly, two hepatitis B envelope antigen-negative patients developed resistance during the year 12 of treatment. Independent risk factors for resistance development were hepatitis B virus DNA levels of at least 10 copies/ml before and detectable hepatitis B virus DNA by month 6 of treatment.

CONCLUSION

Even after long-term response to lamivudine more than 10 years, resistance may still develop. Our findings further discourage the use of lamivudine for the treatment of CHB.

The stilbene derivatives, nucleosides, and nucleosides modified by stilbene derivatives

In this short review, including 187 references, the issues of biological activity of stilbene derivatives and nucleosides and the biological and medicinal potential of fusion of these two classes are discussed. The stilbenes, especially the stilbenoids, and nucleosides are both biologically active. Hybrids formed from binding of these compounds have not yet been broadly studied. However, those that have been investigated exhibit desirable medicinal properties. The review is divided in such parts: I. Derivative of stilbene (biomedical investigations, biological activities in cells, enzymes and hazard), parts II. naturally occurred nucleoside and its derivatives: uridine, thymidine and 5-methyluridine, cytidine, adenosine, guanosine and part III. hybrid molecules- drugs and hybrid molecules- nucleoside - stilbene and its derivative.

Genotypes and Hot Spot Mutations of Hepatitis B Virus in Northwest Chinese Population and Its Correlation with Diseases Progression

Hepatitis B virus (HBV) infection is a critical incentive for chronic hepatitis B (CHB), liver cirrhosis (LC), and hepatocellular carcinoma (HCC). Different genotypes and genome mutations of HBV have been found to be related to the progression of these liver diseases. However, their clinical significance is still under debate. The objective of this study was to determine the association of HBV genotypes and hot spot mutations in the reverse transcriptase (RT) and basal core promoter-precore (BCP-PreC) region with HBV-infected diseases in a northwest Chinese population. HBV genotyping and DNA sequencing were performed in samples of 980 patients. Appropriate statistical methods were adopted to assess HBV genetic features and its clinical association. It was found that the prevalent HBV genotype in northwestern Chinese patients was HBV/C (61.33%), followed by HBV/B (36.63%). In RT region, in addition to the reported nucleoside analogue- (NA-) resistance missense mutations, new silent mutations at rt169 and rt180 were found to raise the risk of HCC in patients with HBV/C. And the heterozygous mutation status of rt169/rt180 was associated with the increased risk of both HCC and NA resistance (OR > 1, P < 0.01) regardless of HBV genotypes. In BCP-PreC region, multiple mutations and combinations, especially at nt 1762/1764 and nt 1896/1899, were characterized to be the causes of spurious HBeAg negativity and liver function injury, as well as the risk factors for HCC progression (P < 0.01). Additionally, a novel mutation at nt1799G>C was likely found to increase the risk of HCC in patients with HBV/B. These findings revealed an association between HBV genotypes and HBV genetic mutations in RT and BCP-PreC region and progression of hepatitis B. It would be helpful for risk evaluation and diagnostic improvement based on these genetic features.

Management of Hepatitis B Virus Infection: 2018 Guidelines from the Canadian Association for the Study of Liver Disease and Association of Medical Microbiology and Infectious Disease Canada

Hepatitis B virus (HBV) infection is an important public health problem in Canada. In keeping with evolving evidence and understanding of HBV pathogenesis, the Canadian Association for the Study of Liver Disease periodically publishes HBV management guidelines. The goals of the 2018 guidelines are to (1) highlight the public health impact of HBV infection in Canada and the need to improve diagnosis and linkage to care, (2) recommend current best-practice guidelines for treatment of HBV, (3) summarize the key HBV laboratory diagnostic tests, and (4) review evidence on HBV management in special patient populations and include more detail on management of HBV in pediatric populations. An overview of novel HBV tests and therapies for HBV in development is provided to highlight the recent advances in HBV clinical research. The aim and scope of these guidelines are to serve as an up-to-date, comprehensive resource for Canadian health care providers in the management of HBV infection.

The evolution of nucleoside analogue antivirals: A review for chemists and non-chemists. Part 1: Early structural modifications to the nucleoside scaffold

This is the first of two invited articles reviewing the development of nucleoside-analogue antiviral drugs, written for a target audience of virologists and other non-chemists, as well as chemists who may not be familiar with the field. Rather than providing a simple chronological account, we have examined and attempted to explain the thought processes, advances in synthetic chemistry and lessons learned from antiviral testing that led to a few molecules being moved forward to eventual approval for human therapies, while others were discarded. The present paper focuses on early, relatively simplistic changes made to the nucleoside scaffold, beginning with modifications of the nucleoside sugars of Ara-C and other arabinose-derived nucleoside analogues in the 1960's. A future paper will review more recent developments, focusing especially on more complex modifications, particularly those involving multiple changes to the nucleoside scaffold. We hope that these articles will help virologists and others outside the field of medicinal chemistry to understand why certain drugs were successfully developed, while the majority of candidate compounds encountered barriers due to low-yielding synthetic routes, toxicity or other problems that led to their abandonment.

Naturally occurring hepatitis B virus reverse transcriptase mutations related to potential antiviral drug resistance and liver disease progression

The annual number of deaths caused by hepatitis B virus (HBV)-related disease, including cirrhosis and hepatocellular carcinoma (HCC), is estimated as 887000. The reported prevalence of HBV reverse transcriptase (RT) mutation prior to treatment is varied and the impact of preexisting mutations on the treatment of naïve patients remains controversial, and primarily depends on geographic factors, HBV genotypes, HBeAg serostatus, HBV viral loads, disease progression, intergenotypic recombination and co-infection with HIV. Different sensitivity of detection methodology used could also affect their prevalence results. Several genotype-dependent HBV RT positions that can affect the emergence of drug resistance have also been reported. Eight mutations in RT (rtL80I, rtD134N, rtN139K/T/H, rtY141F, rtM204I/V, rtF221Y, rtI224V, and rtM309K) are significantly associated with HCC progression. HBeAg-negative status, low viral load, and genotype C infection are significantly related to a higher frequency and prevalence of preexisting RT mutations. Preexisting mutations are most frequently found in the A-B interdomain of RT which overlaps with the HBsAg “a” determinant region, mutations of which can lead to simultaneous viral immune escape. In conclusion, the presence of baseline RT mutations can affect drug treatment outcomes and disease progression in HBV-infected populations via modulation of viral fitness and host-immune responses.

Determination of telbivudine in the plasma of chronic hepatitis B patients in long-term treatment by high-performance liquid chromatographic-tandem mass spectrometry

Creatine kinase elevation is commonly reported in telbivudine-treated patients. However, little is known about the relationship between this adverse drug reaction and plasma concentration. In this study, a sensitive, rapid and safe quantitative bioanalytical method has been established by using LC-MS/MS for the determination of telbivudine in a clinical study of chronic hepatitis B patients. The assay was linear in a dynamic 10-10,000 ng/mL range (r² > 0.999) and total analysis time was 6 min in this method. The validated method was applied to quantitatively determine plasma concentration in chronic hepatitis B patients during long-term telbivudine treatment. The results revealed that telbivudine concentration in the creatine kinase-elevated group (707.92-2788.78 ng/mL) was significantly higher than those with normal creatine kinase (412.63-1108.32 ng/mL). This method was adapted for therapeutic drug monitoring.

Profile of Mutations in the Reverse Transcriptase and Overlapping Surface Genes of Hepatitis B Virus (HBV) in Treatment-Naïve Indonesian HBV Carriers

Mutations in the reverse transcriptase (RT) region of the hepatitis B virus (HBV) genome are an important factor in low therapeutic effectiveness. Nonetheless, the prevalence of these mutations in HBV strains isolated previously in Indonesia has not been systematically examined. Therefore, in this study, we investigated the profile of mutations in the RT region and the associations of these mutations with amino acid changes in the surface protein in the virus of treatment-naïve Indonesian HBV carriers. Overall, 96 sequences of the full-length Indonesian HBV genomes (genotype B, n = 54; genotype C, n = 42) were retrieved from the National Center for Biotechnology Information. Naturally occurring primary and/or compensatory drug resistance mutations were found in 6/54 (11.1%) genotype B strains and in 1/42 (2.4%) genotype C strains. The potential mutations underlying resistance to a nucleos(t)ide analog and/or pretreatment mutations were more frequent in both genotypes but more frequent in genotype C strains than in genotype B strains. The A-B interdomain region in the RT gene was more frequently mutated in genotype C than in genotype B (3.51 ± 2.53 vs. 1.08 ± 1.52, P ＜ 0.001). Knowledge about the mutational profiles of the RT gene and changes in the surface protein may help clinicians to select the most appropriate antiviral drug and vaccination or HBV immunoglobulin regimen for management of HBV infection in Indonesia.

Current antiviral drugs and their analysis in biological materials - Part II: Antivirals against hepatitis and HIV viruses

This review is a Part II of the series aiming to provide comprehensive overview of currently used antiviral drugs and to show modern approaches to their analysis. While in the Part I antivirals against herpes viruses and antivirals against respiratory viruses were addressed, this part concerns antivirals against hepatitis viruses (B and C) and human immunodeficiency virus (HIV). Many novel antivirals against hepatitis C virus (HCV) and HIV have been introduced into the clinical practice over the last decade. The recent broadening portfolio of these groups of antivirals is reflected in increasing number of developed analytical methods required to meet the needs of clinical terrain. Part II summarizes the mechanisms of action of antivirals against hepatitis B virus (HBV), HCV, and HIV, their use in clinical practice, and analytical methods for individual classes. It also provides expert opinion on state of art in the field of bioanalysis of these drugs. Analytical methods reflect novelty of these chemical structures and use by far the most current approaches, such as simple and high-throughput sample preparation and fast separation, often by means of UHPLC-MS/MS. Proper method validation based on requirements of bioanalytical guidelines is an inherent part of the developed methods.

Factors Associated With Persistent Increase in Level of Alanine Aminotransferase in Patients With Chronic Hepatitis B Receiving Oral Antiviral Therapy

BACKGROUND & AIMS

Despite complete suppression of viral DNA with antiviral agents, in some patients with chronic hepatitis B (CHB), serum levels of alanine aminotransferase (ALT) do not normalize. We investigated factors associated with persistent increases in ALT level in patients with CHB given long-term tenofovir disoproxil fumarate.

METHODS

We analyzed data from 471 hepatitis B e antigen (HBeAg)-positive and HBeAg-negative patients with CHB participating in 2 phase 3 trials. We identified patients with an increased level of ALT (above the upper limit of normal range) after 5 years (240 weeks) of tenofovir disoproxil fumarate therapy. We analyzed findings from liver biopsy specimens collected from 467 patients (99%) at baseline and 339 patients (72%) at year 5 of treatment; biopsy specimens were evaluated by an independent pathologist. We performed stepwise, forward, multivariate regression analyses of specified baseline characteristics and on-treatment response parameters to identify factors associated with persistent increases in ALT level.

RESULTS

Of the 471 patients, 87 (18%) still had an increased ALT level at year 5 of treatment. Factors associated significantly with a persistent increase in ALT level were a steatosis score of 5% or greater (grade 1 or more) at baseline (odds ratio [OR], 2.236; 95% confidence interval [CI], 1.031-4.852; P = .042) and at year 5 (OR, 3.392; 95% CI, 1.560 ≥ 7.375; P = .002), HBeAg seropositivity at baseline (OR, 3.297; 95% CI, 1.653-6.576; P < .001), and age 40 years or older (OR, 2.099; 95% CI, 1.014-4.342; P = .046). Of the 42 HBeAg-positive patients with steatosis at baseline, 21 (50%) had an increased ALT level at year 5 of treatment. Patients with persistent increases in ALT level were more likely to have an increase in steatosis at year 5 than those with a normal ALT level.

CONCLUSIONS

HBeAg seropositivity and hepatic steatosis contribute to persistent increases in ALT level in patients with CHB receiving suppressive antiviral treatment. ClinicalTrials.gov registration numbers: NCT00117676 and NCT00116805.

Treatment of hepatitis B virus with combination therapy now and in the future

Chronic Hepatitis B continues as a significant public health problem despite the availability of safe and effective antivirals and a highly effective protective vaccine. Current therapy, however rarely leads to cure and lifelong therapy is often required, contributing to poor uptake and ongoing morbidity. New insights into the hepatitis B viral life cycle and the host immune response have expanded the potential targets for drug therapies with interesting antiviral candidates and novel immunotherapeutic approaches in early stage development. Yet, HBV persistence is multifactorial - due to an intrahepatic reservoir and ongoing HBV-mediated immune dysregulation, making "cure" unlikely to be realized through even the most efficacious monotherapy. Building on the success seen in the treatment of hepatitis C (HCV) and human immunodeficiency virus (HIV), combination therapy may be an essential strategy to improve efficacy and decrease viral breakthrough. Combinations acting on immune and viral targets are particularly attractive. However, creating synergy while balancing efficacy and safety remains a clear challenge. Various approaches to combination therapy are reviewed, highlighting strengths and challenges of each potential strategy. Overall, combination therapies are attractive as the next step towards cure and are a key strategy for achieving treatment with finite durations and durable endpoints.

Entecavir to Telbivudine Switch Therapy in Entecavir-Treated Patients with Undetectable Hepatitis B Viral DNA

PURPOSE

This study examined 2-year outcome of consecutive therapy using entecavir (ETV) followed by telbivudine (LdT) in subjects with undetectable hepatitis B virus (HBV) DNA level and normal alanine aminotransferase level after the initial 6 months of ETV treatment.

MATERIALS AND METHODS

Sixty subjects were randomized to continue with ETV or switch to LdT. Significant difference in baseline characteristics was not found between the two groups. Persistent HBV DNA level of 20-60 IU/mL in three consecutive samples collected three months apart or singly measured HBV DNA level of >60 IU/mL was defined as virological rebound.

RESULTS

During 96 weeks of follow-up, all subjects of the ETV-only group (n=30) resulted in undetectable HBV DNA level. On the other hand, 83.3% (n=25) of the LdT-switched group showed treatment success. Virological rebound time varied from week 24 to 84 after switching to LdT. HBV DNA level was 180 to 2940 IU/mL at rebound time. All subjects with virological rebound (n=5) showed drug-resistant mutation: three had mutation rtM204I, and two had mutation rtM204V. Consecutive treatment using ETV followed by LdT showed virological rebound in 16.7% of subjects during 96 weeks of follow-up. HBV DNA negativity during initial ETV therapy could not be achieved in patients who switched to LdT.

CONCLUSION

Consecutive treatment using ETV followed by lamivudine was ineffective for treating chronic hepatitis B. LdT was found as a more potent antiviral agent than lamivudine. However, this conclusion requires larger-scale, long-term prospective reviews of the treatment effects of ETV-LdT switch therapy.

Synergistic Interactions between Hepatitis B Virus RNase H Antagonists and Other Inhibitors

Combination therapies are standard for management of human immunodeficiency virus (HIV) and hepatitis C virus (HCV) infections; however, no such therapies are established for human hepatitis B virus (HBV). Recently, we identified several promising inhibitors of HBV RNase H (here simply RNase H) activity that have significant activity against viral replication in vitro Here, we investigated the in vitro antiviral efficacy of combinations of two RNase H inhibitors with the current anti-HBV drug nucleoside analog lamivudine, with HAP12, an experimental core protein allosteric modulator, and with each other. Anti-HBV activities of the compounds were tested in a HepG2-derived cell line by monitoring intracellular core particle DNA levels, and cytotoxicity was assessed by 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium (MTS) assay. The antiviral efficiencies of the drug combinations were evaluated using the median-effect equation derived from the mass-action law principle and combination index theorem of Chou and Talalay. We found that combinations of two RNase H inhibitors from different chemical classes were synergistic with lamivudine against HBV DNA synthesis. Significant synergism was also observed for the combination of the two RNase H inhibitors. Combinations of RNase H inhibitors with HAP12 had additive antiviral effects. Enhanced cytotoxicity was not observed in the combination experiments. Because of these synergistic and additive effects, the antiviral activity of combinations of RNase H inhibitors with drugs that act by two different mechanisms and with each other can be achieved by administering the compounds in combination at doses below the respective single drug doses.

Efficacy of switching from adefovir to tenofovir in chronic hepatitis B patients who exhibit suboptimal responses to adefovir-based combination rescue therapy due to resistance to nucleoside analogues (SATIS study)

Background/Aims

It remains to be determined whether switching from adefovir (ADV) to tenofovir (TDF) provides better virological outcomes in patients exhibiting suboptimal responses to ADV plus nucleoside analogue (ADV+NA) therapy for NA-resistant chronic hepatitis B (CHB).

Methods

In this prospective trial, patients who showed partial responses (defined as serum hepatitis B virus [HBV] DNA >60 IU/mL) to ADV+NA therapy for NA resistance were randomly allocated to receive TDF plus NA (TDF+NA group, n=16) or to continue their current therapy (ADV+NA group, n=16). The primary end point was the proportion of patients with complete virological response (CVR, defined as serum HBV DNA <60 IU/mL) at 48 weeks.

Results

The median age was 52 years (16 men), and 28 were positive for hepatitis B e antigen (HBeAg). The baseline characteristics did not differ significantly between the two groups. The proportion with CVR was significantly higher in the TDF+NA group than in the ADV+NA group at 24 weeks (81.3% vs. 25.0%, P=0.001) and 48 weeks (87.5% vs. 37.5%, P=0.002). Furthermore, a decrease in the serum HBV DNA level of >2log₁₀ IU/mL was more likely in the TDF+NA group at both 24 and 48 weeks (68.8% vs. 56.3%, P=0.014 vs. 81.3% vs. 56.3%, P=0.001, respectively). During the follow-up, the rate of HBeAg seroconversion was higher in the TDF+NA group than the ADV+NA group (12.5% vs. 6.25%, P=0.640), as was that for the hepatitis B surface antigen (6.25% vs. 0%, P=0.080). No serious adverse events due to antiviral agents occurred.

Conclusion

In patients exhibiting suboptimal responses to ADV+NA therapy for NA-resistant CHB, switching from ADV to TDF might provide better virological outcomes.

Comparison of the Efficacies and Safety of Combined Therapy between Telbivudine Plus Adefovir and Lamivudine Plus Adefovir in Patients with Hepatitis B Virus Infection in Real-World Practice

Background and Aim

Chronic hepatitis B infection remains a significant health issue worldwide. This study evaluated the efficacy and safety of combined therapy using lamivudine plus adefovir (LAM+ADV) versus telbivudine plus adefovir (LdT+ADV) and the corresponding renal function change and safety.

Methods

This study enrolled a total of 171 patients (110 patients received LAM+ADV and 60 patients received LdT+ADV). We analyzed the changes in renal function using the estimated glomerular filtration rate (eGFR). The DNA undetectable rate, hepatitis B e antigen (HBeAg) seroconversion rate, and alanine aminotransferase (ALT) normalization rate were analyzed. We checked the serum uric acid, phosphate and creatine kinase, and lactic acid levels to analyze safety. We observed these patients for 48 to 240 weeks and checked their serum profile every 6 months.

Results

There was no statistically significant difference between the two groups in anti-hepatitis B virus (HBV) efficacy in terms of DNA undetectable rate, ALT normalization rate, and HBeAg seroconversion rate. Both the LAM+ADV and LdT+ADV groups had stable or improved renal function. However, a higher eGFR was found in the LdT+ADV group with continuous serum fluctuation during 3 years of combined therapy as well as a higher serum creatine kinase level.

Conclusions

Long-term LdT+ADV combined therapy and LAM+ADV combined therapy were both associated with stable or improved renal function. The clinical efficacy was similar between the two groups, but the LdT group had a higher serum creatine kinase level. We need to monitor the data regularly in clinical practice.

Small surface antigen variants of HBV associated with responses to telbivudine treatment in chronic hepatitis B patients

BACKGROUND

Nucleoside/nucleotide analogues are widely used to treat chronic HBV infection, but drug resistance is common. The role of HBV surface gene variants in drug resistance to nucleoside/nucleotide analogues is unknown. We are trying to investigate the dynamics of S gene mutations and how they relate to a patient's virological response in this study.

METHODS

Thirty patients with chronic hepatitis B were enrolled and serum samples were collected at multiple time points during treatment with telbivudine (LdT). The coding regions of the small surface antigen (S-HBsAg) were amplified and sequenced using the 454 GS FLX⁺ System.

RESULTS

Sequencing results revealed different dynamics of non-synonymous mutations, such as sL9P, sN40S, sG44E, sW172*, sW182* and sS187F, between patients with a complete virological response and those with a partial virological response. The viral population heterogeneity decreased at week 12 of LdT treatment in patients with a complete virological response, with a concomitant decline in non-synonymous mutations (from an average of 14 to 9.9 per sample) and an increase in the frequencies of major variants (from 14.3% to 40.4%).

CONCLUSIONS

Our findings suggest that the decrease in viral population heterogeneity at an early stage of LdT treatment was associated with the subsequent optimal virological response, and the early appearance of some specific mutations, such as sG44E, sW172* and sW182*, is a potential indicator of a partial virological response in continuing therapy.

A Cost-Utility and Cost-Effectiveness Analysis of Different Oral Antiviral Medications in Patients With HBeAg-Negative Chronic Hepatitis B in Iran: An Economic Microsimulation Decision Model

BACKGROUND

Although hepatitis B infection is the major cause of chronic liver disease in Iran, no studies have employed economic evaluations of the medications used to treat Iranian patients with chronic hepatitis B (CHB). Therefore, the cost-effectiveness of the different treatment options for this disease in Iran is unknown.

OBJECTIVES

The aim of this study was to compare the cost utility and cost-effectiveness of medication strategies tailored to local conditions in patients with HB e antigen (HBeAg)-negative CHB infection in Iran.

METHODS

An economic evaluation of the cost utility of the following five oral medication strategies was conducted: adefovir (ADV), lamivudine (LAM), ADV + LAM, entecavir (ETV), and tenofovir (TDF). A Markov microsimulation model was used to estimate the clinical and economic outcomes over the course of the patient's lifetime and based on a societal perspective. Medical and nonmedical direct costs and indirect costs were included in the study and life-years gained (LYG) and quality-adjusted life-years (QALY) were determined as measures of effectiveness. The results are presented in terms of the incremental cost-effectiveness ratio (ICER) per QALY or LYG. The model consisted of nine stages of the disease. The transition probabilities for the movement between the different stages were based on clinical evidence and international expert opinion. A probabilistic sensitivity analysis (PSA) was used to measure the effects of uncertainty in the model parameters.

RESULTS

The results revealed that the TDF treatment strategy was more effective and less costly than the other options. In addition, TDF had the highest QALY and LYG in the HBeAg-negative CHB patients, with 13.58 and 21.26 (discounted) in all comparisons. The PSA proved the robustness of the model results. The cost-effectiveness acceptability curves showed that TDF was the most cost-effective treatment in 59% - 78% of the simulations of HBeAg-negative patients, with WTP thresholds less than $14010 (maximum WTP per QALY).

CONCLUSIONS

The use of TDF in patients with HBeAg-negative CHB seemed to be a highly cost-effective strategy. Compared with the other available medication options, TDF was the most cost-saving strategy. Thus, TDF may be the best option as a first-line medication. Patients can also be switched from other medications to TDF.

Approved Antiviral Drugs over the Past 50 Years

Since the first antiviral drug, idoxuridine, was approved in 1963, 90 antiviral drugs categorized into 13 functional groups have been formally approved for the treatment of the following 9 human infectious diseases: (i) HIV infections (protease inhibitors, integrase inhibitors, entry inhibitors, nucleoside reverse transcriptase inhibitors, nonnucleoside reverse transcriptase inhibitors, and acyclic nucleoside phosphonate analogues), (ii) hepatitis B virus (HBV) infections (lamivudine, interferons, nucleoside analogues, and acyclic nucleoside phosphonate analogues), (iii) hepatitis C virus (HCV) infections (ribavirin, interferons, NS3/4A protease inhibitors, NS5A inhibitors, and NS5B polymerase inhibitors), (iv) herpesvirus infections (5-substituted 2'-deoxyuridine analogues, entry inhibitors, nucleoside analogues, pyrophosphate analogues, and acyclic guanosine analogues), (v) influenza virus infections (ribavirin, matrix 2 protein inhibitors, RNA polymerase inhibitors, and neuraminidase inhibitors), (vi) human cytomegalovirus infections (acyclic guanosine analogues, acyclic nucleoside phosphonate analogues, pyrophosphate analogues, and oligonucleotides), (vii) varicella-zoster virus infections (acyclic guanosine analogues, nucleoside analogues, 5-substituted 2'-deoxyuridine analogues, and antibodies), (viii) respiratory syncytial virus infections (ribavirin and antibodies), and (ix) external anogenital warts caused by human papillomavirus infections (imiquimod, sinecatechins, and podofilox). Here, we present for the first time a comprehensive overview of antiviral drugs approved over the past 50 years, shedding light on the development of effective antiviral treatments against current and emerging infectious diseases worldwide.

Asian-Pacific clinical practice guidelines on the management of hepatitis B: a 2015 update

Worldwide, some 240 million people have chronic hepatitis B virus (HBV), with the highest rates of infection in Africa and Asia. Our understanding of the natural history of HBV infection and the potential for therapy of the resultant disease is continuously improving. New data have become available since the previous APASL guidelines for management of HBV infection were published in 2012. The objective of this manuscript is to update the recommendations for the optimal management of chronic HBV infection. The 2015 guidelines were developed by a panel of Asian experts chosen by the APASL. The clinical practice guidelines are based on evidence from existing publications or, if evidence was unavailable, on the experts' personal experience and opinion after deliberations. Manuscripts and abstracts of important meetings published through January 2015 have been evaluated. This guideline covers the full spectrum of care of patients infected with hepatitis B, including new terminology, natural history, screening, vaccination, counseling, diagnosis, assessment of the stage of liver disease, the indications, timing, choice and duration of single or combination of antiviral drugs, screening for HCC, management in special situations like childhood, pregnancy, coinfections, renal impairment and pre- and post-liver transplant, and policy guidelines. However, areas of uncertainty still exist, and clinicians, patients, and public health authorities must therefore continue to make choices on the basis of the evolving evidence. The final clinical practice guidelines and recommendations are presented here, along with the relevant background information.

Comparative effectiveness of antiviral treatment for hepatitis B: a systematic review and Bayesian network meta-analysis

OBJECTIVE

A wide variety of competing drugs are available to patients for the treatment of chronic hepatitis B. We update a recent meta-analysis to include additional trial evidence with the aim of determining which treatment is the most effective.

METHODS

Twelve monotherapy or combination therapy were evaluated in treatment-naive individuals with hepatitis B e antigen (HBeAg) positive or negative patients. Databases were searched for randomized controlled trials in the first year of therapy. Bayesian random effects network meta-analysis was used to calculate the pairwise odds ratios, 95% credible intervals and ranking of six surrogate outcomes.

RESULTS

In total, 22 studies were identified (7508 patients): 12 studies analysed HBeAg-positive patients, six analysed HBeAg-negative patients, and four evaluated both. Tenofovir was most effective at increasing efficacy in HBeAg-positive patients, ranking first for three outcomes and increased odds of undetectable levels of hepatitis B virus (HBV) DNA compared with seven other therapies (such as lamivudine: odds ratio 33.0; 95% credible interval 7.0-292.7). For HBeAg-negative patients, the large network (seven therapies) ranked entecavir alone or in combination with tenofovir highly for reduction in HBV DNA and histologic improvement. In the smaller network (three therapies), tenofovir ranked first for undetectable HBV DNA and histologic improvement. No data existed to directly or indirectly compare these treatments.

CONCLUSION

For HBeAg-positive patients tenofovir is the most effective at increasing efficacy, whereas for HBeAg-negative patients, either tenofovir or entecavir is most effective. Further research should focus on strengthening the network connections, in particular comparing tenofovir and entecavir in HBeAg-negative patients.

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.

Prevalence and types of drug-resistant variants in Chinese patients with acute hepatitis B

The presence of therapy-associated hepatitis B virus (HBV) variants is the main drawback of antiviral therapy for HBV infection. Moreover, drug-resistant variants are more insensitive to a second agent and more therapy-associated mutations will be present. To apply better nucleos(t)ide analogues (NA) and reduce the occurrence of resistance, the prevalence and types of drug-resistant mutations in acute hepatitis B patients were investigated in this study. One hundred three HBV DNA-positive patients with symptomatic acute hepatitis B that were observed from 2011 to 2013 were enrolled. Direct polymerase chain reaction sequencing was used firstly to screen HBV reverse-transcriptase domain to detect HBV mutants. Five lamivudine-resistant variants were identified. Clonal sequencing was performed for 5 resistance-positive samples and 10 other random samples. Interestingly, all detected samples harbored drug-resistant mutations, although with different percentage. Thirteen harbored lamivudine-related alone (five) or together with other NA related mutations (five with adefovir, one with entecavir, and one with telbivudine), and two of them harbored adefovir-related mutations. Also, mutations associated with four currently used NA were all detected, and the frequency is in accordance with the popularity of NA used in clinical practice. These data suggest that drug-resistant variants are present in patients with acute hepatitis B and NA should be applied more carefully for chronic hepatitis B patients developed from acute hepatitis B.

Early kidney injury during long-term adefovir dipivoxil therapy for chronic hepatitis B

AIM: To evaluate urine β2-microglobulin (β2-M), retinol-binding protein (RBP) excretion, and renal impairment with adefovir dipivoxil (ADV) for chronic hepatitis B.

METHODS: We enrolled 165 patients with chronic hepatitis B infection who were treated with ADV monotherapy (n = 90) or ADV plus lamivudine combination therapy (n = 75). An additional 165 chronic hepatitis B patients treated with entecavir were recruited as controls. We detected serum creatinine, urine β2-M, and RBP levels, and estimated the glomerular filtration rate (eGFR) at the initiation of antiviral therapy and every 6 mo for a period of five years.

RESULTS: Urine β2-M abnormalities were observed in patients during the first (n = 3), second (n = 7), third (n = 11), fourth (n = 16), and fifth (n = 21) year of ADV treatment. Urinary RBP abnormalities were observed in patients during the first (n = 2), second (n = 8), third (n = 12), fourth (n = 15), and fifth (n = 22) year of ADV treatment. eGFR decreased 20%-30% from baseline in 20 patients, 30%-50% in 12 patients, and > 50% in 3 patients during the five years of treatment. Further analysis indicated that decreases in eGFR of ≥ 30% relative to the baseline level correlated significantly with urine RBP and β2-M abnormalities. In contrast, both serum creatinine and eGFR remained stable in patients treated with entecavir, and only one of these patients developed a urine β2-M abnormality, and two developed urine RBP abnormalities during the five years of treatment.

CONCLUSION: Urine RBP and β2-M are biomarkers of renal injury during long-term ADV treatment for chronic hepatitis B, and indicate when treatment should be switched to entecavir.

Unveiling the roles of HBV polymerase for new antiviral strategies

Infection with HBV is common worldwide, with over 350 million chronic carriers. Chronic HBV infection is associated with cirrhosis and hepatocellular carcinoma. All currently available oral antivirals are directed against the HBV polymerase enzyme, a reverse transcriptase. HBV polymerase contains several important domains and motifs which define its functions and reveal ways to further target it. This enzyme executes many functions required for the HBV replication cycle, including viral RNA binding, RNA packaging, protein priming, template switching, DNA synthesis and RNA degradation. In addition, HBV polymerase must interact with host proteins for its functions. Future therapeutics may inhibit not only the DNA synthesis steps which are carried out by the reverse transcriptase domain (as all current antivirals do) but other domains, functions and interactions which are essential to the HBV replication cycle.

Changes in serum alanine aminotransferase levels in telbivudine versus lamivudine treatment for chronic hepatitis B: a meta-analysis

OBJECTIVE

A meta-analysis to compare the efficacy and safety of telbivudine (TBV) and lamivudine (LAM) in patients with chronic hepatitis B (CHB), assessed via changes in serum alanine aminotransferase (ALT) levels.

METHOD

The electronic literature databases PubMed®, Embase®, Web of Science, Cochrane Library, CISCOM, CINAHL, Google Scholar, China BioMedicine and China National Knowledge Infrastructure were searched for relevant studies. The effect of TBV and LAM treatment on serum ALT was assessed using standard mean differences (SMDs) and 95% confidence intervals (CI).

RESULTS

The meta-analysis included six studies (TBV n = 202; LAM, n = 208). Post-treatment ALT levels were significantly lower than pretreatment values for both TBV and LAM (TBV: SMD = 3.00, 95%CI 1.91, 4.09; LAM: SMD = 2.33, 95%CI 1.58, 3.07). Post-treatment ALT was significantly lower after treatment with TBV than LAM (SMD = 0.58, 95%CI 0.21, 0.94).

CONCLUSION

Both LAM and TBV are effective in normalizing ALT levels in patients with CHB, but TBV may be a better choice due to its lower rates of drug resistance.

Partial virological response to three different nucleotide analogues in naive patients with chronic hepatitis B

BACKGROUND

The definition of partial virological response (PVR) was proposed because of its clinical relevance. PVR relates to subsequent therapeutic failure which results in the modification of the regimen. Whether this rationale can be applied to all nucleotide analogues (NA) is not clear. This study was undertaken to analyze PVR influence on therapeutic outcomes during lamivudine, entecavir or tenofovir monotherapy in NA-naive patients with chronic hepatitis B in routine clinical practice.

METHODS

We retrospectively analyzed 150 NA-naive patients with chronic hepatitis B. These subjects received lamivudine, entecavir or tenofovir monotherapy between February 2001 and July 2013.

RESULTS

Sixty-nine patients were treated with lamivudine, 35 with entecavir, and 46 with tenofovir. The median therapeutic duration was 19.5 (6-147) months. PVR rates at 24 weeks were similar among three NAs (lamivudine 33.3%, entecavir 35.0%, tenofovir 32.4%, P=0.981). For all three NAs, patients with a higher baseline viral load or HBeAg-positive status had a higher serum viral positive rate tested by polymerase chain reaction at week 24 and 48. Cumulative probability of virological breakthrough (VBR) for patients treated with lamivudine was 67% at 5 years, and PVR at 24 weeks was the independent risk factor for VBR (HR: 3.09; 95% CI: 1.09-8.74; P=0.034); also lamivudine treated patients older than 50 years seemed to have a tendency for VBR (HR: 2.80; 95% CI: 0.99-8.18; P=0.052). A majority of entecavir and tenofovir partial responders achieved and maintained virological response with prolonged monotherapy, except one entecavir treated patient who experienced VBR due to resistance mutations.

CONCLUSIONS

Management strategy for lamivudine treatment should include adaptation of regimen according to PVR as an on-treatment response parameter due to its relation with unacceptably high VBR probability. Similar conclusion should not be directly related to entecavir or tenofovir treatment.

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.

Early Viral Kinetics with Telbivudine, Tenofovir or Combination of Both in Immunotolerant Patients with Hepatitis B e Antigen-Positive Chronic Hepatitis B

Introduction

Viral kinetics has proved useful in understanding antiviral potency, determining antiviral profiles and optimizing treatment strategy.

Methods

This was a randomized, open-label study comparing the viral kinetics in 46 hepatitis B e antigen-positive patients during 12-week treatment with telbivudine monotherapy, tenofovir monotherapy or the combination of telbivudine plus tenofovir. A standard biphasic mathematical model was used to compare hepatitis B virus (HBV) DNA decay parameters.

Results

Forty-six patients received telbivudine (n = 16), tenofovir (n = 14) or telbivudine plus tenofovir (n = 16). From baseline to Week 12, the mean (SD) reduction in HBV DNA levels was not significantly different between treatment groups: −3.9 (0.9) log₁₀ copies/mL in telbivudine group, −4.2 (0.7) log₁₀ copies/mL in tenofovir group, and −4.4 (1.0) log₁₀ copies/mL in combination group. No significant difference was observed among the three groups for viral clearance rate per day (0.97, 1.02, and 0.88, respectively) or for infected cell loss rate per day (0.04, 0.05, and 0.05, respectively). Antiviral efficiency in blocking viral production was similar in the monotherapy groups (median; 99.7% in telbivudine group and 99.4% in tenofovir group), but was slightly better and more homogeneous in the combination treatment group than in the monotherapy groups: mean (SD), 99.1% (0.8%) and 98.8% (1.6%), respectively (Wald–Wolfowitz test; P = 0.038). All treatments were well tolerated and no serious adverse event was reported during the study. Of the 46 patients in the safety population, 23 experienced adverse events. Most of the adverse events were not suspected to be related to the study drug by the investigators.

Conclusion

Monotherapy with telbivudine or tenofovir showed similar antiviral effectiveness in HBV DNA reduction and viral kinetics of HBV DNA decay. Efficiency in blocking viral production was slightly improved in the combination treatment group compared to the monotherapy groups.

Electronic supplementary material

The online version of this article (doi:10.1007/s40121-014-0039-5) contains supplementary material, which is available to authorized users.

The Molecular and Structural Basis of HBV-resistance to Nucleos(t)ide Analogs

Infection with hepatitis B virus (HBV) is a worldwide health problem. Chronic hepatitis B can lead to fibrosis, liver cirrhosis, and hepatocellular carcinoma (HCC). Management of the latter two conditions often requires liver transplantation. Treatment with conventional interferon or pegylated interferon alpha can clear the virus, but the rates are very low. The likelihood, however, of viral resistance to interferon is minimal. The main problems with this therapy are the frequency and severity of side effects. In contrast, nucleos(t)ide analogs (NAs) have significantly lower side effects, but require long term treatment as sustained virological response rates are extremely low. However, long term treatment with NAs increases the risk for the development of anti-viral drug resistance. Only by understanding the molecular basis of resistance and using agents with multiple sites of action can drugs be designed to optimally prevent the occurrence of HBV antiviral resistance.