Clinical emergence of entecavir-resistant hepatitis B virus requires additional substitutions in virus already resistant to Lamivudine

Are the New Nucleos(t)ide Analogs Better than the Old Nucleos(t)ide Analogs?

In treatment-naïve patients with chronic hepatitis B virus (HBV) infection, entecavir (ETV), tenofovir disoproxil fumarate (TDF), and tenofovir alafenamide have a minimal or no risk of drug-resistance. These 3 nucleos(t)ide analog agents are highly potent inducing high rate of virologic response (reducing serum HBV DNA to levels undetectable by polymerase chain reaction assays) in most treatment-naïve patients. Our randomized trials have demonstrated that monotherapy with TDF can provide a successful virological response in most of the heavily pretreated patients with multidrug resistance to ETV or adefovir.

A Novel Insertion in the Hepatitis B Virus Surface Protein Leading to Hyperglycosylation Causes Diagnostic and Immune Escape

Chronic hepatitis B virus (HBV) infection is a global health threat. Mutations in the surface antigen of HBV (HBsAg) may alter its antigenicity, infectivity, and transmissibility. A patient positive for HBV DNA and detectable but low-level HBsAg in parallel with anti-HBs suggested the presence of immune and/or diagnostic escape variants. To support this hypothesis, serum-derived HBs gene sequences were amplified and cloned for sequencing, which revealed infection with exclusively non-wildtype HBV subgenotype (sgt) D3. Three distinct mutations in the antigenic loop of HBsAg that caused additional N-glycosylation were found in the variant sequences, including a previously undescribed six-nucleotide insertion. Cellular and secreted HBsAg was analyzed for N-glycosylation in Western blot after expression in human hepatoma cells. Secreted HBsAg was also subjected to four widely used, state-of-the-art diagnostic assays, which all failed to detect the hyperglycosylated insertion variant. Additionally, the recognition of mutant HBsAg by vaccine- and natural infection-induced anti-HBs antibodies was severely impaired. Taken together, these data suggest that the novel six-nucleotide insertion as well as two other previously described mutations causing hyperglycosylation in combination with immune escape mutations have a critical impact on in vitro diagnostics and likely increase the risk of breakthrough infection by evasion of vaccine-induced immunity.

Whole genome analysis of hepatitis B virus before and during long-term therapy in chronic infected patients: Molecular characterization, impact on treatment and liver disease progression

Hepatitis B virus (HBV) infection remains a serious public health concern worldwide despite the availability of an efficient vaccine and the major improvements in antiviral treatments. The aim of the present study is to analyze the mutational profile of the HBV whole genome in ETV non-responder chronic HBV patients, in order to investigate antiviral drug resistance, immune escape, and liver disease progression to Liver Cirrhosis (LC) or Hepatocellular Carcinoma (HCC). Blood samples were collected from five chronic hepatitis B patients. For each patient, two plasma samples were collected, before and during the treatment. Whole genome sequencing was performed using Sanger technology. Phylogenetic analysis comparing the studied sequences with reference ones was used for genotyping. The mutational profile was analyzed by comparison with the reference sequence M32138. Genotyping showed that the studied strains belong to subgenotypes D1, D7, and D8. The mutational analysis showed high genetic variability. In the RT region of the polymerase gene, 28 amino acid (aa) mutations were detected. The most significant mutations were the pattern rtL180M + rtS202G + rtM204V, which confer treatment resistance. In the S gene, 35 mutations were detected namely sP120T, sT126S, sG130R, sY134F, sS193L, sI195M, and sL216stop were previously described to lead to vaccine, immunotherapy, and/or diagnosis escape. In the C gene, 34 mutations were found. In particular, cG1764A, cC1766G/T, cT1768A, and cC1773T in the BCP; cG1896A and cG1899A in the precore region and cT12S, cE64D, cA80T, and cP130Q in the core region were associated with disease progression to LC and/or HCC. Other mutations were associated with viral replication increase including cT1753V, cG1764A/T, cC1766G/T, cT1768A, and cC1788G in the BCP as well as cG1896A and cG1899A in the precore region. In the X gene, 30 aa substitutions were detected, of which substitutions xT36D, xP46S, xA47T, xI88F, xA102V, xI127T, xK130M, xV131I, and xF132Y were previously described to lead to LC and/or HCC disease progression. In conclusion, our results show high genetic variability in the long-term treatment of chronic HBV patients causing several effects. This could contribute to guiding national efforts to optimize relevant HBV treatment management in order to achieve the global hepatitis elimination goal by 2030.

Long-term follow-up of treatment-naïve HBeAg-negative patients with chronic hepatitis B

BACKGROUND/AIMS

We aimed to explore long-term results of oral antiviral agents in treatment-naïve "HBeAg negative chronic hepatitis B (CHB)" and determine the factors affecting the complete virological response.

METHOD

Patients with HBeAg-negative CHB who used oral antiviral agents for at least 3 years were evaluated retrospectively.

RESULTS

A total of 173 patients were recorded. The mean duration of treatment was 62.2 ± 28.9 months. Complete virological responses (CVR) were 82.8% (n = 53/64) in tenofovir disoproxil fumarate (TDF), 84.4% (n = 49/58) in lamivudine (LAM), 83.9% (n = 26/31) in entecavir (ETV), 95% in telbivudine (LdT) (n = 19/20) (p = 0.290). Multivariate analysis revealed age ≤ 40 (p = 0.012, 95%CI = 1.38-13.76, OR = 4.36) and baseline HBV DNA value (p = 0.003, 95%CI = 1.23-2.63, OR = 1.78) as independent factors for CVR. Virological breakthrough was detected in 29 (50%) patients on LAM therapy, two (6.4%) patients on ETV therapy, and two (10%) patients on LdT therapy. Treatment was switched to another antiviral agent due to osteoporosis in four patients in the TDF group, muscle pain in nine patients in the LDT group, and headache in one patient in the ETV group. Hepatocelluler cancer was detected in five patients. HBsAg seroclearance developed in two patients. Anti-HBs seroconversion was not detected.

CONCLUSION

CVR was achieved at similar rates with all four antiviral agents, while younger age (≤ 40) and low baseline viral load were the main factors for virological response. However, drug resistance and virological breakthrough in the LAM group and side effects in the LdT group were detected during the long-term follow-up. Moreover, HBsAg seroclearance was achieved at very low rates with oral antiviral agents.

Structure-Based Discovery of N-Sulfonylpiperidine-3-carboxamides as Novel Capsid Assembly Modulators for Potent Inhibition of HBV Replication

As a key element during HBV replication, a nucleocapsid is considered a promising target for the treatment of chronic hepatitis B. The present study aimed to identify small molecules as novel capsid assembly modulators with antiviral activity. Structure-based virtual screening of an integrated compound library led to the identification of several types of HBV inhibitors. Among these inhibitors, N-sulfonylpiperidine-3-carboxamides (SPCs) potently reduced the amount of secreted HBV DNA. Through structure–activity relationship studies, we identified an SPC derivative, namely, C-39, which exhibited the highest antiviral activity without causing cytotoxicity. Mechanism studies showed that C-39 dose-dependently inhibited the formation of HBV capsid, synthesis of cccDNA, e antigen (HBeAg), viral pregenomic RNA (pgRNA), and HBV DNA levels, thereby restraining HBV replication. In summary, SPCs represent a new class of capsid assembly modulators. Further optimization of SPCs is expected to obtain new antiviral drugs against HBV infection.

Insights Into the Coinfections of Human Immunodeficiency Virus-Hepatitis B Virus, Human Immunodeficiency Virus-Hepatitis C Virus, and Hepatitis B Virus-Hepatitis C Virus: Prevalence, Risk Factors, Pathogenesis, Diagnosis, and Treatment

Human immunodeficiency virus, hepatitis B virus, and hepatitis C virus are three blood-borne viruses that can cause major global health issues by increasing severe morbidity. There is a high risk of coinfection with these viruses in individuals because of their same transmission routes through blood using shared needles, syringes, other injection equipment, sexual transmission, or even vertical transmission. Coinfection can cause various liver-related illnesses, non-hepatic organ dysfunction, followed by death compared to any of these single infections. The treatment of coinfected patients is complicated due to the side effects of antiviral medication, resulting in drug resistance, hepatotoxicity, and a lack of required responses. On the other hand, coinfected individuals must be treated with multiple drugs simultaneously, such as for HIV either along with HBV or HCV and HBV and HCV. Therefore, diagnosing, treating, and controlling dual infections with HIV, HBV, or HCV is complicated and needs further investigation. This review focuses on the current prevalence, risk factors, and pathogenesis of dual infections with HIV, HBV, and HCV. We also briefly overviewed the diagnosis and treatment of coinfections of these three blood-borne viruses.

Determining the absolute configuration of vanitaracin A, an anti-hepatitis B virus agent

Vanitaracin A is an anti-hepatitis B virus (anti-HBV) compound isolated from the culture broth of the fungus Talaromyces sp. Vanitaracin A inhibits the entry of HBV into target cells with sub-micromolar IC₅₀ values. While a structure-activity relationship study is highly desirable, a synthetic approach still needs to be developed, which is difficult because the absolute configurations of the six stereogenic centers in the structure of vanitaracin A have not yet been determined. In the present study, we used the crystalline sponge method to clarify the configuration of the compound after determining the absolute configuration of the secondary alcohol using a modified Mosher ester method. Combining these analyses with the NOESY spectrum of vanitaracin A and NMR analyses of the crude side-chain carboxylic acid obtained by the alkaline hydrolysis of vanitaracin A revealed the absolute configurations of all stereogenic centers in this important compound.

Biochemical and Structural Properties of Entecavir-Resistant Hepatitis B Virus Polymerase with L180M/M204V Mutations

Entecavir (ETV) is a widely used anti-hepatitis B virus (HBV) drug. However, the emergence of resistant mutations in HBV reverse transcriptase (RT) results in treatment failure. To understand the mechanism underlying the development of ETV resistance by HBV RT, we analyzed the L180M, M204V, and L180M/M204V mutants using a combination of biochemical and structural techniques. ETV-triphosphate (ETV-TP) exhibited competitive inhibition with dGTP in both wild-type (wt) RT and M204V RT, as observed using Lineweaver-Burk plots. In contrast, RT L180M or L180M/M204V did not fit either competitive, uncompetitive, noncompetitive, or typical mixed inhibition, although ETV-TP was a competitive inhibitor of dGTP. Crystallography of HIV RTY115F/F116Y/Q151M/F160M/M184V, mimicking HBV RT L180M/M204V, showed that the F115 bulge (F88 in HBV RT) caused by the F160M mutation induced deviated binding of dCTP from its normal tight binding position. Modeling of ETV-TP on the deviated dCTP indicated that a steric clash could occur between ETV-TP methylene and the 3'-end nucleoside ribose. ETV-TP is likely to interact primarily with HBV RT M171 prior to final accommodation at the deoxynucleoside triphosphate (dNTP) binding site (Y. Yasutake, S. Hattori, H. Hayashi, K. Matsuda, et al., Sci Rep 8:1624, 2018, https://doi.org/10.1038/s41598-018-19602-9). Therefore, in HBV RT L180M/M204V, ETV-TP may be stuck at M171, a residue that is conserved in almost all HBV isolates, leading to the strange inhibition pattern observed in the kinetic analysis. Collectively, our results provide novel insights into the mechanism of ETV resistance of HBV RT caused by L180M and M204V mutations. IMPORTANCE HBV infects 257 million people in the world, who suffer from elevated risks of liver cirrhosis and cancer. ETV is one of the most potent anti-HBV drugs, and ETV resistance mutations in HBV RT have been extensively studied. Nevertheless, the mechanisms underlying ETV resistance have remained elusive. We propose an attractive hypothesis to explain ETV resistance and effectiveness using a combination of kinetic and structural analyses. ETV is likely to have an additional interaction site, M171, beside the dNTP pocket of HBV RT; this finding indicates that nucleos(t)ide analogues (NAs) recognizing multiple interaction sites within RT may effectively inhibit the enzyme. Modification of ETV may render it more effective and enable the rational design of efficient NA inhibitors.

Detection of Hepatitis B Virus M204V Mutation Quantitatively via Real-time PCR

BACKGROUND AND AIMS

Drug-resistant DNA mutations of the hepatitis B virus (HBV) affect treatment response in chronic hepatitis B patients. We have established a new, sensitive, specific, accurate and convenient real-time PCR method to detect HBV mutations quantitatively.

METHODS

Blood samples were collected from patients showing viral breakthrough, primary nonresponse, or poor response during treatment, and mutations were detected via direct sequencing to assess our method. A plasmid containing the M204V mutation was synthesized and standard curves plotted.

RESULTS

The determination coefficient for linear correlation between Ct and log plasmid copy numbers was 0.996, where Ct value was -3.723log (DNA concentration) +48.647. Coefficients of variation indicated good reproducibility. Correctness was within tolerable bias. Limit of detection was 10³ copies/mL. Specificity, accuracy, positive predictive value and negative predictive value were 92.86%, 100%, 96.88%, 100% and 94.74%, respectively.

CONCLUSIONS

These results show that our method can be used to detect HBV M204V mutations with the advantages of sensitivity, specificity and efficiency, providing a new choice for monitoring drug resistance.

3,7-Dihydroxytropolones Inhibit Initiation of Hepatitis B Virus Minus-Strand DNA Synthesis

Initiation of protein-primed (-) strand DNA synthesis in hepatitis B virus (HBV) requires interaction of the viral reverse transcriptase with epsilon (ε), a cis-acting regulatory signal located at the 5' terminus of pre-genomic RNA (pgRNA), and several host-encoded chaperone proteins. Binding of the viral polymerase (P protein) to ε is necessary for pgRNA encapsidation and synthesis of a short primer covalently attached to its terminal domain. Although we identified small molecules that recognize HBV ε RNA, these failed to inhibit protein-primed DNA synthesis. However, since initiation of HBV (-) strand DNA synthesis occurs within a complex of viral and host components (e.g., Hsp90, DDX3 and APOBEC3G), we considered an alternative therapeutic strategy of allosteric inhibition by disrupting the initiation complex or modifying its topology. To this end, we show here that 3,7-dihydroxytropolones (3,7-dHTs) can inhibit HBV protein-primed DNA synthesis. Since DNA polymerase activity of a ribonuclease (RNase H)-deficient HBV reverse transcriptase that otherwise retains DNA polymerase function is also abrogated, this eliminates direct involvement of RNase (ribonuclease) H activity of HBV reverse transcriptase and supports the notion that the HBV initiation complex might be therapeutically targeted. Modeling studies also provide a rationale for preferential activity of 3,7-dHTs over structurally related α-hydroxytropolones (α-HTs).

Japan Society of Hepatology Guidelines for the Management of Hepatitis B Virus Infection: 2019 update

The Drafting Committee for Hepatitis Management Guidelines established by the Japan Society of Hepatology published the first version of the Guidelines for the Management of Hepatitis B in 2013 (first English version in 2014), and has since been publishing updates to the Guidelines as new drugs become available, with the latest original Japanese version being Version 3.1. Herein, the Drafting Committee publishes the second English version that contains all the changes made since the first English version of the guidelines was published in 2014. This 2019 version covers: (i) the nucleos(t)ide analogs, tenofovir disoproxil fumarate and tenofovir alafenamide; (ii) updates to treatment recommendations and management of drug-resistant hepatitis B virus that reflect the new availability of these drugs; and (iii) new information about hepatitis B virus reactivation with each update. This latest update also contains information about treatment goals, indications for treatment and cessation of nucleos(t)ide analog therapy, most of which were covered by the first version.

Revisiting HBV resistance to entecavir with a phenotypic approach

Treatment adaptation after hepatitis B virus (HBV) treatment failure relies on genotypic resistance testing. However, the results of such tests are not always consistent with treatment response. These discrepancies may be due to differences in resistance levels between isolates with the same genotypic resistance testing profiles. We explored this hypothesis by investigating six cases of entecavir treatment failure with an integrative strategy combining genotypic and phenotypic resistance testing, medical record review and therapeutic drug monitoring. Among isolates with genotypic reduced susceptibility to entecavir, one displayed a higher level of resistance to entecavir (mean fold change in entecavir IC₅₀ of 1 508 ± 531 vs. 318 ± 53, p = 0.008). This isolate harbored a substitution (rt250L) at a position reported to be associated with resistance (rt250V). Reversion to wild-type amino acid at this position partially restored susceptibility to entecavir, confirming that the rt250L mutation was responsible for the high level of resistance to entecavir. This is the first description of entecavir treatment failure associated with selection of the rt250L mutation without other entecavir resistance mutations. One isolate with genotypic resistance to entecavir, harboring the rt173L mutation, displayed a lower level of resistance than the other, harboring the rt202G mutation (mean fold change of 323 ± 124 vs. 6 036 ± 2 100, p = 0.20). These results suggest that isolates harboring the rt250L mutations should be considered resistant to entecavir, whereas isolates harboring the rt173L mutations should be considered to display reduced susceptibility to entecavir. An integrative approach to antiviral drug resistance in HBV would provide a more accurate assessment of entecavir treatment failures and help to improve the accuracy of genotypic testing algorithms.

Rimonabant suppresses RNA transcription of hepatitis B virus by inhibiting hepatocyte nuclear factor 4α

Chronic infection with hepatitis B virus (HBV) sometime induces lethal cirrhosis and hepatocellular carcinoma. Although nucleot(s)ide analogs are used as main treatment for HBV infection, the emergence of the drug-resistant viruses has become a problem. To discover novel antivirals with low side effects and low risk of emergence of resistant viruses, screening for anti-HBV compounds was performed with compound libraries of inhibitors targeting G-protein-coupled receptors (GPCRs). HepG2-hNTCP C4 cells infected with HBV were treated with various GPCR inhibitors and harvested at 14 day postinfection for quantification of core protein in the first screening or relaxed circular DNA in the second screening. Finally, we identified a cannabinoid receptor 1 inhibitor, rimonabant, as a candidate showing anti-HBV effect. In HepG2-hNTCP C4 cells, treatment with rimonabant suppressed HBV propagation at the viral RNA transcription step but had no effect on entry or covalently closed circular DNA level. The values of half maximal inhibitory concentration, half maximal effective concentration, and selectivity index of rimonabant in primary human hepatocyte (PHH) are 2.77 μm, 40.4 μm, and 14.6, respectively. Transcriptome analysis of rimonabant-treated primary hepatocytes by RNA sequencing revealed that the transcriptional activity of hepatocyte nuclear factor 4α (HNF4α), which is known to stimulate viral RNA synthesis, was depressed. By treatment of PHH with rimonabant, the expression level of HNF4α protein and the production of the messenger RNAs (mRNAs) of downstream factors promoted by HNF4α were reduced while the amount of HNF4α mRNA was not altered. These results suggest that treatment with rimonabant suppresses HBV propagation through the inhibition of HNF4α activity.

Present and Future Therapies for Chronic Hepatitis B

Chronic hepatitis B (CHB) remains the leading cause of liver-related morbidity and mortality across the world. If left untreated, approximately one-third of these patients will progress to severe end-stage liver diseases including liver failure, cirrhosis, and hepatocellular carcinoma (HCC). High level of serum HBV DNA is strongly associated with the development of liver failure, cirrhosis, and HCC. Therefore, antiviral therapy is crucial for the clinical management of CHB. Current antiviral drugs including nucleoside/nucleotide analogues (NAs) and interferon-α (IFN-α) can suppress HBV replication and reduce the progression of liver disease, thus improving the long-term outcomes of CHB patients. This chapter will discuss the standard and optimization antiviral therapies in treatment-naïve and treatment-experienced patients, as well as in the special populations. The up-to-date advances in the development of new anti-HBV agents will be also discussed. With the combination of the current antiviral drugs and the newly developed antiviral agents targeting the different steps of the viral life cycle or the newly developed agents modulating the host immune responses, the ultimate eradication of HBV will be achieved in the future.

Evans Blue Inhibits HBV Replication Through a Dual Antiviral Mechanism by Targeting Virus Binding and Capsid Assembly

Chronic hepatitis B (CHB) is a global health problem caused by human hepatitis B virus (HBV). Current treatment with interferons and nucleos(t)ide analogs (NAs) can cause population tolerance and drug resistance. Therefore, new antiviral drugs, especially those targeting host factors, are urgently needed. Here, we identified Evans blue as a new HBV inhibitor by screening an FDA drug library using Huh7D^hNTCP cells and confirmed the antiviral activity in primary human hepatocytes and human sodium taurocholate cotransporting polypeptide (hNTCP)-transfected porcine primary hepatocytes. Our efficacy study showed that Evans blue has an IC₅₀ of 2 μM against HBV infection in Huh7D^hNTCP cells, and no apparent toxicity at up to 1000 μM. The IC₅₀ of Evans blue against HBV in primary human hepatocytes was approximately 5 μM. Mechanism studies revealed that Evans blue has a dual anti-HBV effect. It inhibits both the binding of viral preS1 to host cells through the host factor NTCP and the virus capsid assembly by targeting the host factor BK channel. The K_D of the direct interaction between Evans blue and NTCP is 8.82E-8 M. Evans blue can suppress capsid assembly at micromolar concentrations by reducing the cytosolic calcium ion concentration. Since the antiviral effects on HBV binding and assembly are both achieved through targeting host factors, Evans blue inhibits the infection of nucleos(t)ide analog drug-resistant HBV strains in Huh7D^hNTCP cells. Taken together, our results suggest that Evans blue may be a promising anti-HBV drug candidate in the classes of both entry and assembly inhibitors.

The association between serum cytokine and chemokine levels and antiviral response by entecavir treatment in chronic hepatitis B patients

BACKGROUND

Although nucleoside/nucleotide analogue therapy is thought to suppress chronic hepatitis B (CHB) via regulation of inflammatory cytokines/chemokines, the mechanism is still unclear. In this study, serum cytokine/chemokine levels were measured in CHB patients treated with entecavir, and the association with antiviral response was analysed.

METHODS

A total of 78 Japanese patients with CHB were enrolled, and serum cytokine/chemokine levels were measured at baseline and at 12, 24 and 48 weeks of entecavir treatment using the MULTIPLEX kit.

RESULTS

Antiviral response to entecavir treatment was significantly associated with hepatitis B surface antigen (HBsAg) titre and serum interferon-gamma-inducible protein 10 (IP-10) level (12w; P=0.0002; OR=0.020 [95% CI 0.002, 0.156], P=0.003; OR=0.042 [95% CI 0.005, 0.336], respectively). HBe-positive patients whose serum macrophage-derived chemokine (MDC) level was lower (<582.83 pg/ml) and IP-10 level was higher (≥1,323.13 pg/ml) achieved hepatitis B e antigen (HBeAg) loss earlier than those who remained HBeAg-positive (P=0.044). HBsAg reduction by entecavir treatment was significantly associated with higher initial tumour necrosis factor-alpha (TNF-α) level (≥15.20 pg/ml) and higher alanine aminotransferase level (≥73 IU/l; P=0.009; OR=18.460 [95% CI 2.044, 166.709], P=0.022; OR=7.709 [95% CI 1.341, 44.327], respectively).

CONCLUSIONS

Results of the present study indicate that changes in cytokine/chemokine levels following entecavir therapy are associated with response to antiviral therapy in CHB patients. Monitoring of serum cytokine/chemokine levels could be useful for predicting reduction of HBV DNA and HBsAg and HBe seroconversion.

A Global View to HBV Chronic Infection: Evolving Strategies for Diagnosis, Treatment and Prevention in Immunocompetent Individuals

Hepatitis B Virus (HBV) is a significant public health challenge. Around 250 million people live with chronic HBV infection. With a global approach to this issue, we focus on new perspective in diagnosis, management and prevention of HBV chronic infection. Precise diagnosis of HBV status is crucial to guide patient management. Although available drugs reduce the risk of liver disease progression, they are not able to definitely eradicate HBV, and new therapeutic options are urgently needed. Thus, prevention of HBV infection is still the most effective strategy to achieve the control of the disease. Key aspects of prevention programs include surveillance of viral hepatitis, screening programs and immunization strategies. In spite of the high success rate of licensed HBV vaccines, a need for improved vaccine persists, especially in order to provide coverage of current non-responders.

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.

Endoplasmic reticulum-mediated induction of interleukin-8 occurs by hepatitis B virus infection and contributes to suppression of interferon responsiveness in human hepatocytes

The events in the immune response to hepatitis B virus (HBV) remain unclear. We analyzed the direct influence of HBV on gene expression in human hepatocytes under immunodeficient conditions using a human hepatocyte chimeric mouse model. HBV-infected or non-infected chimeric mouse livers were collected, and gene expression profiles were compared. Since IL-8 was the most significantly up-regulated gene at 8 weeks after HBV infection, we focused on IL-8 and found that HBx and the large HBs (L-HBs) protein induce transcription of IL-8 via endoplasmic reticulum stress. This stress induces IL-8 transcription via NFAT activation and contributes to suppression of interferon responsiveness in HBV-infected human hepatocytes. In the present study, we identified a novel regulatory mechanism in which the L-HBs protein activates IL-8 via endoplasmic reticulum stress, suggesting a key role for IL-8 in the immune response to HBV and a potential new target for antiviral treatments of HBV infection.

Discovery of the Novel Entecavir-Resistant Hepatitis B Virus Reverse Transcriptase A181C Substitution From an Integrated Genotypic Analysis

Entecavir (ETV) is a first-line therapy for chronic hepatitis B virus (HBV), demonstrating potent suppression of HBV DNA and a high barrier to viral resistance. Previous studies revealed that ETV-resistant (ETVr) HBV DNA resulted from substitutions in the HBV reverse transcriptase (RT) at positions rtT184, rtS202, or rtM250 in combination with lamivudine resistance (LVDr) substitutions rtM204I/V±rtL180M. In vitro, viral variants exhibit varying degrees of ETV susceptibility and replication capacity depending on specific resistance substitutions. To explore the potential for additional pathways to ETVr, HBV RT sequences from 982 evaluable patients enrolled in 17 ETV clinical studies were analyzed. Thirty novel emergent substitutions at amino acid positions not previously associated with HBV nucleos(t)ide drug resistance were observed in at least 2 patients and were identified in patient-derived HBV with a wild-type, LVDr, or ETVr RT sequence. Phenotypic analysis of these substitutions indicated that they had no effect on ETV susceptibility. Phenotypic analysis was also performed on patient-derived HBV RT sequences from 10 LVD-naive and 13 LVD-experienced patients with virologic breakthrough and emergent novel substitutions while on ETV treatment. One LVD-experienced patient-derived HBV RT harboring LVDr substitutions rtL180M+rtM204V with rtA181C displayed reduced ETV susceptibility (122-fold greater than wild-type HBV) and remained susceptible to adefovir and tenofovir. HBV harboring the rtA181C substitution without LVDr substitutions rtL180M+rtM204V remained susceptible to inhibition by ETV, adefovir, and tenofovir, although cross-resistance to LVD and telbivudine was observed. Conclusion: An integrated genotypic analysis of HBV RT sequences from patients with chronic HBV treated with ETV led to the discovery of the novel ETVr substitution rtA181C. This substitution was always detected in combination with LVDr substitutions rtL180M+rtM204V in ETV-treated patients.

Trends in hepatitis B virus resistance to nucleoside/nucleotide analogues in North China from 2009-2016: A retrospective study

Nucleos(t)ide analogues (NAs) are widely used in anti-hepatitis B virus (anti-HBV) therapy for effective inhibition of HBV replication. However, HBV resistance to NAs has emerged, resulting in virus reactivation and disease recurrence. Data on the current dynamics of HBV resistance are still rare in China. This study analysed 4491 plasma samples with HBV primary genotypic resistance mutations representative of the general HBV resistance situation in northern China from 2009-2016. We found that entecavir (ETV), representing 57.6% (12 713/22 060) of NA users in North China in 2016, has become the major NA for treating Chinese patients infected with HBV. Despite >50% of M204I/V±L180M among all HBV resistance cases annually and extensive exposure of patients to lamivudine (LAM), telbivudine (LdT) and adefovir dipivoxil (ADV), ETV resistance also showed a dramatically increased incidence, which rose to 17.1% in 2016. Moreover, A181T/V, ETV resistance mutations and multidrug resistance mutations were found more frequently in HBV genotype C compared with genotype B (21.2% vs. 8.5%, 12.4% vs. 7.9% and 5.9% vs. 3.0%, respectively), whereas M204I and N236T were more predominant in genotype B than genotype C (40.3% vs. 20.8% and 11.3% vs. 1.8%, respectively). In conclusion, we report the dynamic changes of HBV NA resistance mutation patterns and the current NA usage profile for anti-HBV treatment in North China over the past 8 years. These data provide valuable information on HBV NA resistance that is an important reference for clinicians to devise more effective treatment regimens for individual patients.

Oral Nucleos(t)ide Analogs Alone After Liver Transplantation in Chronic Hepatitis B With Preexisting rt204 Mutation

BACKGROUND

There is currently limited data regarding the use of oral antiviral therapy alone without hepatitis B immune globulin for chronic hepatitis B patients with preexisting lamivudine (LAM) resistance (LAM-R) undergoing liver transplantation.

METHODS

This is a cohort study determining the effectiveness and long-term outcome in this group of patients.

RESULTS

Fifty-seven consecutive chronic hepatitis B patients with preexisting rt204 LAM-R mutations or virological load refractory to LAM undergoing liver transplantation were included, with a median follow-up of 73 months. Fifty-five (96.5%) patients received a regimen that included the use of nucleotide analogs. The cumulative rate of hepatitis B surface antigen seroclearance at 1, 5, and 10 years was 82%, 88%, and 91%, respectively. At the time of transplantation, 39 (72%) patients had detectable hepatitis B virus (HBV) DNA, with a median of 4.5 log copies/mL. The cumulative rate of HBV undetectability was 91% at 1 year, increasing to 100% by 5 years. After 1 year of liver transplantation, over 90% of the patients had undetectable HBV DNA, and from 8 years onward, 100% had undetectable HBV DNA. The overall long-term survival was excellent, with a 12-year survival of 87%. There was no HBV-related graft loss, and no retransplantation or deaths due to HBV reactivation.

CONCLUSION

Oral antiviral therapy alone without hepatitis B immune globulin is highly effective in preventing HBV reactivation and graft loss from recurrent hepatitis B after liver transplantation in patients with preexisting LAM resistance HBV. The long-term outcome was excellent, with survival of 87% at 12 years after transplantation, without any mortality related to HBV reactivation.

Clinical characteristics of patients with chronic hepatitis B who developed genotypic resistance to entecavir: Real-life experience

BACKGROUND/AIMS

Clinical characteristics of patients with chronic hepatitis B (CHB) who developed genotypic resistance to entecavir (ETV) were compared to those without resistance.

METHODS

Two hundred fifty eight CHB patients who underwent ETV treatment in our institution from July 2007 to May 2013 were included.

RESULTS

Eight (3.1%) patients developed genotypic resistance to ETV during the follow-up period. The patterns of genotypic resistance to ETV were as follows: L180M + M204V + S202G (n=3); M204I + V173M (n=1); I169V + V173M (n=1); L180M + M204V + V173L (n=1); L180M + M204V + V173L + M250V (n=1); M204I + V214A + P237H (n=1). The cumulative occurrence rates of genotypic resistance to ETV were not significantly different between CHB patients with prior nucleos(t)tide analogues (NA) exposure (NA experienced, n=56) and NA naïve patients (n=202, P=0.823 by log rank comparison). Older age, higher baseline log10hepatitis B virus-deoxynucleic acid (log10HBV-DNA), higher log10HBV-DNA at 3, 6, 12 and 24 months after baseline, and complete virologic response (CVR, undetectable serum HBV-DNA by polymerase chain reaction 6 months after ETV treatment) were significant contributors to the development of genotypic resistance to ETV. Multivariate analyses showed higher log10HBV-DNA 6 months after baseline and absence of CVR were independent and significant contributors to the development of ETV resistance.

CONCLUSIONS

Clinical characteristics of patients who developed ETV resistance were higher log10HBV-DNA 6 months after baseline and absence of CVR during the ETV treatment.

Selection of the highly replicative and partially multidrug resistant rtS78T HBV polymerase mutation during TDF-ETV combination therapy

BACKGROUND & AIMS

Patients chronically infected with the hepatitis B virus (HBV) and receiving long-term treatment with nucleoside or nucleotide analogues are at risk of selecting HBV strains with complex mutational patterns. We herein report two cases of HBV-infected patients with insufficient viral suppression, despite dual antiviral therapy with entecavir (ETV) and tenofovir (TDF). One patient died from aggressive hepatocellular carcinoma (HCC).

METHODS

Serum samples from the two patients at different time points were analyzed using ultra-deep pyrosequencing analysis. HBV mutations were identified and transiently transfected into hepatoma cells in vitro using replication-competent HBV vectors, and functionally analyzed. We assessed replication efficacy, resistance to antivirals and potential impact on HBV secretion (viral particles, exosomes).

RESULTS

Sequencing analyses revealed the selection of the rtS78T HBV polymerase mutation in both cases that simultaneously creates a premature stop codon at sC69 and thereby deletes almost the entire small HBV surface protein. One of the patients had an additional 261bp deletion in the preS1/S2 region. Functional analyses of the mutations in vitro revealed that the rtS78T/sC69∗ mutation, but not the preS1/S2 deletion, significantly enhanced viral replication and conferred reduced susceptibility to ETV and TDF. The sC69∗ mutation caused truncation of HBs protein, leading to impaired detection by commercial HBsAg assay, without causing intracellular HBsAg retention or affecting HBV secretion.

CONCLUSIONS

The rtS78T/sC69∗ HBV mutation, associated with enhanced replication and insufficient response to antiviral treatment, may favor long-term persistence of these isolates. In addition to the increased production of HBV transcripts and the sustained secretion of viral particles in the absence of antigenic domains of S protein, this HBV mutation may predispose patients to carcinogenic effects.

LAY SUMMARY

Long-term treatment with antiviral drugs carries the risk of selecting mutations in the hepatitis B virus (HBV). We herein report two cases of patients with insufficient response to dual tenofovir and entecavir therapy. Molecular analyses identified a distinct mutation, rtS78T/sC69∗, that abolishes HBsAg detection, enhances replication, sustains exosome-mediated virion secretion and decreases susceptibility to antivirals, thereby representing a potentially high-risk mutation for HBV-infected individuals.

HBV Drug Resistance Substitutions Existed before the Clinical Approval of Nucleos(t)ide Analogues: A Bioinformatic Analysis by GenBank Data Mining

Naturally occurring nucleos(t)ide analogue resistance (NUCr) substitution frequencies in the reverse transcriptase (RT) of the hepatitis B virus (HBV) were studied extensively after the clinical approval of nucleos(t)ide analogues (NUCs; year of approval 1998). We aimed to study NUCr substitutions in HBV RT sequences obtained before 1998 and better understand the evolution of RT sequences without NUC pressures. Our strategy was to retrieve HBV sequences from GenBank deposited before 1998. The initial search used the keywords "hepatitis B virus" or "HBV" and 1139 sequences were found. Data analyses included information extraction: sequence quality control and amino acid substitution analysis on 8 primary NUCr and 3 secondary substitution codons. Three hundred and ninety-four RT-containing sequences of 8 genotypes from 25 countries in 4 continents were selected. Twenty-seven (6.9%) sequences were found to harbor substitutions at NUCr-related codons. Secondary substitutions (rtL80V and rtV173G/A/L) occurred more frequently than primary NUCr substitutions (rtI169L; rtA181G; T184A/S; rtS202T/R; rtM204L and rtM250K). Typical amino acid substitutions associated with NUCr were of rtL80V, rtV173L and rtT184A/S. We confirm the presence of naturally occurring typical HBV NUCr substitutions with very low frequencies, and secondary substitutions are more likely to occur than primary NUCr substitutions without the selective pressure of NUCs.

Long-term real-world entecavir therapy in treatment-naïve hepatitis B patients: base-line hepatitis B virus DNA and hepatitis B surface antigen levels predict virologic response

BACKGROUND/AIMS

Entecavir is a potent nucleoside analogue with high efficacy and barrier for resistance. We aimed to investigate the long-term efficacy and viral resistance rate of entecavir and explore the factors associated with virologic response, including quantitative hepatitis B surface antigen (qHBsAg) levels.

METHODS

One thousand and nine treatment-naïve chronic hepatitis B (CHB) patients were evaluated for cumulative rates of virologic response, biochemical response, and entecavir mutations. The role of baseline qHBsAg for virologic response was assessed in 271 patients with qHBsAg prior to entecavir treatment.

RESULTS

The median duration of entecavir treatment was 26.5 months. The cumulative rate of virologic response at years 1, 3, and 5 were 79.0%, 95.6%, and 99.4%, respectively. The cumulative rate of entecavir resistance was 1.0% and 2.1% in years 3 and 5. Multivariate analysis identified baseline hepatitis B e antigen (HBeAg) negative status (p < 0.001) and lower hepatitis B virus (HBV) DNA (p < 0.001) as predictors of virologic response. Lower qHBsAg was an independent predictor of virologic response in patients with baseline qHBsAg. There were no serious adverse events during treatment.

CONCLUSIONS

Long-term entecavir treatment of nucleos(t)ide-naïve CHB patients was associated with an excellent virologic response and a low rate of entecavir-resistant mutations at 5 years. Baseline HBV DNA load, qHBsAg levels, and HBeAg status were predictors of virologic response during entecavir treatment.

Human induced-pluripotent stem cell-derived hepatocyte-like cells as an in vitro model of human hepatitis B virus infection

In order to understand the life cycle of hepatitis B virus (HBV) and to develop efficient anti-HBV drugs, a useful in vitro cell culture system which allows HBV infection and recapitulates virus-host interactions is essential; however, pre-existing in vitro HBV infection models are often problematic. Here, we examined the potential of human induced-pluripotent stem (iPS) cell-derived hepatocyte-like cells (iPS-HLCs) as an in vitro HBV infection model. Expression levels of several genes involved in HBV infection, including the sodium taurocholate cotransporting polypeptide (NTCP) gene, were gradually elevated as the differentiation status of human iPS cells proceeded to iPS-HLCs. The mRNA levels of these genes were comparable between primary human hepatocytes (PHHs) and iPS-HLCs. Following inoculation with HBV, we found significant production of HBV proteins and viral RNAs in iPS-HLCs. The three major forms of the HBV genome were detected in iPS-HLCs by Southern blotting analysis. Anti-HBV agents entecavir and Myrcludex-B, which are a nucleoside analogue reverse transcriptase inhibitor and a synthetic pre-S1 peptide, respectively, significantly inhibited HBV infection in iPS-HLCs. These data demonstrate that iPS-HLCs can be used as a promising in vitro HBV infection model.

Management of Antiviral Resistance in Chronic Hepatitis B

The primary goal of therapy for chronic hepatitis B (CHB) is to prevent liver disease progression. Hepatitis B surface antigen (HBsAg) seroclearance or seroconversion is regarded as an optimal endpoint to discontinue treatment. However, HBsAg seroclearance occurs very rarely with nucleos(t)ide analog (NUC) treatment, and long-term, almost indefinite, NUC treatment is required for the majority of patients. In patients with drug-resistant hepatitis B virus (HBV), a combination of tenofovir disoproxil fumarate (TDF) and entecavir (ETV), which is currently regarded as the strongest combination therapy against HBV, would be potentially safe to prevent the emergence of additional HBV resistance mutations. However, long-term tolerance data are lacking, and cost may be an issue for combination therapies. Several recent, well-designed, randomized controlled trials have shown that TDF monotherapy provides similar antiviral efficacy compared with the combination of TDF and ETV. Furthermore, no additional HBV resistance mutations emerged during TDF monotherapy for up to 96 weeks. Considering a comparable antiviral efficacy, extremely low risk of TDF-resistance, lower cost, and better safety potential, TDF monotherapy would be a reasonable choice for the treatment of drug-resistant patients with CHB.

Resistance mutations of hepatitis B virus in entecavir-refractory patients

The emergence of resistance mutations in the reverse transcriptase gene of hepatitis B virus (HBV) is associated with treatment failure. Entecavir (ETV) is one of the most potent anti‐HBV reagents; it has a very low resistance rate and is used as the first‐line treatment for chronic hepatitis B. In this study, we isolated HBVs in 4 ETV‐refractory patients (2 with viral breakthrough, 1 with partial virological response, and 1 with flare‐up) and assessed ETV resistance using replication‐competent 1.38‐fold HBV genome‐length molecular clones. The full genome sequences of infected HBVs in ETV‐refractory patients were determined. The HBV molecular clones were generated with the patient‐derived sequences. After transfection of these molecular clones into HepG2 cells, viral replications and ETV susceptibilities were evaluated by measuring the amount of intracellular core‐particle‐associated HBV DNA using Southern blotting and real‐time polymerase chain reaction. Among these cases, ETV‐resistant variants were detected in 2 patients with viral breakthrough and responsible amino acid mutations in reverse transcriptase were successfully identified in these variants. No ETV‐resistant mutation was detected in the other cases. The identified ETV‐resistant mutations did not confer resistance to tenofovir disoproxil fumarate. Conclusion: The HBV replication model with patient‐derived sequences is useful for assessing replication efficiency, susceptibility to anti‐HBV reagents, and responsible resistance mutations and can aid in choosing the appropriate treatment strategy for treatment‐failure cases of chronic hepatitis B. (Hepatology Communications 2017;1:110‐121)

Recapitulation of treatment response patterns in a novel humanized mouse model for chronic hepatitis B virus infection

There are ~350 million chronic carriers of hepatitis B (HBV). While a prophylactic vaccine and drug regimens to suppress viremia are available, chronic HBV infection is rarely cured. HBV's limited host tropism leads to a scarcity of susceptible small animal models and is a hurdle to developing curative therapies. Mice that support engraftment with human hepatoctyes have traditionally been generated through crosses of murine liver injury models to immunodeficient backgrounds. Here, we describe the disruption of fumarylacetoacetate hydrolase directly in the NOD Rag1^-/- IL2RγNULL (NRG) background using zinc finger nucleases. The resultant human liver chimeric mice sustain persistent HBV viremia for >90 days. When treated with standard of care therapy, HBV DNA levels decrease below detection but rebound when drug suppression is released, mimicking treatment response observed in patients. Our study highlights the utility of directed gene targeting approaches in zygotes to create new humanized mouse models for human diseases.

An evaluation of entecavir for the treatment of chronic hepatitis B infection in adults

Entecavir is a nucleoside analogue of 2'-deoxyguanosine whose intracellular triphosphate form inhibits replication of the hepatitis B virus. Entecavir is recommended as a first-line monotherapy option for nucleos(t)ide-naïve patients with HBeAg-positive or -negative chronic hepatitis B infection. Entecavir has a three-step mechanism of action: It maintains viral suppression with a greater than 90% chance of undetectable hepatitis B virus DNA during continuous therapy, improves liver histology, and reduces the risk of liver failure or hepatocellular carcinoma development. The safety profile of long-term entecavir therapy is favorable; however, its optimal treatment duration is unknown. Entecavir monotherapy is not a rescue option for patients with lamivudine/adefovir resistance or baseline lamivudine-resistant mutants; rather, combination treatment is recommended for patients with lamivudine/adefovir resistance.

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.

ANTIVIRAL ACTIVITY OF DIANTHUS SUPERBUSN L. AGAINST HEPATITIS B VIRUS IN VITRO AND IN VIVO

Background:

Hepatitis is a viral infection of hepatitis B virus (HBV). Limitations of drug used in the management of it opens the interest related to alternative medicine. The given study deals with the antiviral activity of Dianthus superbusn L. (DSL) against HBV in vitro & in vivo.

Material and Methods:

In vitro study liver cell line HepG2.2.15 was used by transinfected it with HBV. Cytotoxicity stduy was performed by using different concentrations of DSL such as 50, 100, 200, 500 & 1000 μg/ml. Anti HBV activity of DSL was estimated by assesing the concentration of HBsAg and HbeAg in cell culture medium by using ELISA. Whereas in vivo study was performed on ducklings and antiviral activity of DSL (100, 200, 400 mg/kg) was confirmed by estimating the serum concentration of HBV DNA and histopathology study of hepatocytes in HBV infected ducklings.

Result:

Result of the study suggested that >500 μg/ml concentration of hydroalcoholic extract of DSL was found tobe cytotoxic. It was also observed that DSL significantly (p<0.05) reduces the concentration of antigenes in cell culture media as per the concentration and days of treatment dependent. Moreover in vivo study confirms the anti viral activity of DSL (200 & 400 mg/kg) as it significantly (p<0.05) decreases the serum concenetration of HBV DNA in HBV infected dukling compared to control group. Histopathology study was also reveals the hepatprotective effect of DSL in HBV infected ducklings.

Conclusion:

The given study concludes the antiviral activity DSL against HBV by in vitro and in vivo models.

Single-Molecule Sequencing Reveals Complex Genome Variation of Hepatitis B Virus during 15 Years of Chronic Infection following Liver Transplantation

Chronic hepatitis B (CHB) is prevalent worldwide. The infectious agent, hepatitis B virus (HBV), replicates via an RNA intermediate and is error prone, leading to the rapid generation of closely related but not identical viral variants, including those that can escape host immune responses and antiviral treatments. The complexity of CHB can be further enhanced by the presence of HBV variants with large deletions in the genome generated via splicing (spHBV variants). Although spHBV variants are incapable of autonomous replication, their replication is rescued by wild-type HBV. spHBV variants have been shown to enhance wild-type virus replication, and their prevalence increases with liver disease progression. Single-molecule deep sequencing was performed on whole HBV genomes extracted from samples, including the liver explant, longitudinally collected from a subject with CHB over a 15-year period after liver transplantation. By employing novel bioinformatics methods, this analysis showed that the dynamics of the viral population across a period of changing treatment regimens was complex. The spHBV variants detected in the liver explant remained present posttransplantation, and a highly diverse novel spHBV population as well as variants with multiple deletions in the pre-S genes emerged. The identification of novel mutations outside the HBV reverse transcriptase gene that co-occurred with known drug resistance-associated mutations highlights the relevance of using full-genome deep sequencing and supports the hypothesis that drug resistance involves interactions across the full length of the HBV genome.

IMPORTANCE

Single-molecule sequencing allowed the characterization, in unprecedented detail, of the evolution of HBV populations and offered unique insights into the dynamics of defective and spHBV variants following liver transplantation and complex treatment regimens. This analysis also showed the rapid adaptation of HBV populations to treatment regimens with evolving drug resistance phenotypes and evidence of purifying selection across the whole genome. Finally, the new open-source bioinformatics tools with the capacity to easily identify potential spliced variants from deep sequencing data are freely available.

Tenofovir monotherapy versus tenofovir and entecavir combination therapy in patients with entecavir-resistant chronic hepatitis B with multiple drug failure: results of a randomised trial

OBJECTIVE

Little clinical data are available regarding the optimal treatment of patients who harbour entecavir (ETV)-resistant HBV.

DESIGN

In this multicentre randomised trial, patients who had HBV with ETV resistance-associated mutations and serum HBV DNA concentrations >60 IU/mL were randomised to receive tenofovir disoproxil fumarate (TDF, 300 mg/day) monotherapy (n=45) or TDF and ETV (1 mg/day) combination therapy (n=45) for 48 weeks.

RESULTS

Baseline characteristics were comparable between groups, including HBV DNA levels (median, 4.02 log10 IU/mL) and hepatitis B e antigen-positivity (89%). All patients had at least one ETV-resistance mutation: rtT184A/C/F/G/I/L/S (n=49), rtS202G (n=43) and rtM250L/V (n=7), in addition to rtM204V/I (n=90). All except one patient in the TDF group completed 48 weeks of treatment. At week 48, the proportion of patients with HBV DNA <15 IU/mL, the primary efficacy endpoint, was not significantly different between the TDF and TDF+ETV groups (71% vs. 73%; p>0.99). The mean change in HBV DNA levels from baseline was not significantly different between groups (-3.66 vs. -3.74 log10 IU/mL; p=0.81). Virological breakthrough occurred in one patient on TDF, which was attributed to poor drug adherence. At week 48, six and three patients in the TDF and TDF+ETV groups, respectively, retained their baseline resistance mutations (p>0.99). None developed additional resistance mutations. Safety profiles were comparable in the two groups.

CONCLUSIONS

TDF monotherapy for 48 weeks provided a virological response comparable to that of TDF and ETV combination therapy in patients infected with ETV-resistant HBV.

TRIAL REGISTRATION NUMBER

ClinicalTrials.gov ID NCT01639092.

A 96-week randomized trial of switching to entecavir in patients who achieved virological suppression on lamivudine therapy

BACKGROUND AND AIM

There are limited data assessing whether patients who achieved virological suppression on lamivudine but remain hepatitis B "e" antigen-positive should be switched to a more potent antiviral with a high genetic barrier to resistance or continue with lamivudine. We compared the safety and efficacy of switching with entecavir versus continuing lamivudine.

METHODS

This was a Phase IV, randomized, open-label, prospective study in a tertiary care setting. Seventy-three chronic hepatitis B patients who achieved virological suppression on lamivudine (serum hepatitis B virus DNA < 60 International Unit (IU)/mL) were enrolled. Entecavir or lamivudine were administered orally for up to 96 weeks. Virologic and serologic responses were measured throughout the study.

RESULTS

A significantly higher proportion of patients in the entecavir group achieved hepatitis B virus DNA < 60 IU/mL at Weeks 48 (100% [38/38] vs 62.8% [22/35]; P < 0.001) and 96 (97.4% [37/38] vs 57.1% [20/35]; P<0.001). A greater number of patients had virologic breakthrough (Week 96 cumulative incidence 42.9% vs 2.6%; P<0.001) and genotypic lamivudine resistance (28.6% [10/35] vs 0% [0/38]; P<0.001) in the lamivudine group. No serious adverse events or laboratory abnormalities were reported.

CONCLUSIONS

Even after achieving virological suppression on lamivudine therapy, the risk of emergent lamivudine resistance increases over time. Switching to entecavir resulted in a maintained virologic response and superior serologic responses versus continued lamivudine therapy. This study supports a rationale for switching to entecavir in chronic hepatitis B patients with virological suppression on lamivudine.

Alternative Therapies for Chronic Hepatitis B Patients With Partial Virological Response to Standard Entecavir Monotherapy

BACKGROUND

Entecavir (ETV) is a first-line, oral antinucleoside agent for the treatment of chronic hepatitis B patients. Despite its high potency, some patients may still be viremic after prolonged therapy with ETV monotherapy. Long-term outcome data comparing maintained ETV monotherapy to alternative therapies in persistently viremic patients are limited. Our goal was to compare complete viral suppression (CVS) rates [hepatitis B DNA (HBV DNA)<40 to 60 IU/mL] with alternative therapies to continued ETV monotherapy in ETV partial responders.

METHODS

This is a retrospective cohort study consisting of 86 consecutive treatment-naive, ETV=0.5 mg partial responders (detectable HBV DNA after ≥12 mo on ETV) who maintained ETV=0.5 mg daily (n=29) or switched to either ETV=1.0 mg daily (n=32) or ETV/tenofovir (TDF)=0.5 mg/300 mg (n=25) in 3 US GI/liver clinics from January 2005 to January 2012. Patients were identified by International Classification of Diseases, Ninth Revision query and data were collected by individual chart review. For those who remained on ETV=0.5 mg, comparison at regimen "switch time" was done using values at 12 months from initial ETV therapy. Rates of CVS were evaluated using Kaplan-Meier methods. Multivariate Cox proportional hazard models were used to estimate hazard ratio (HR) relating to potential predictors to the desirable outcomes of CVS.

RESULTS

In all therapy groups, the majority of patients were Asian (93.1% to 100.0%), male (64.0% to 68.8%), and hepatitis B e antigen-positive (95.8% to 100.0%) and had similar baseline alanine aminotransferase (ALT) levels. However, baseline HBV DNA (7.0 vs. 7.9 vs. 7.8 log10 IU/mL, P=0.05) and HBV DNA at regimen switch point (2.9 vs. 3.7 vs. 3.6 log10 IU/mL, P=0.0014) were lower in the ETV=0.5 mg cohort compared with those switched to ETV=1.0 mg or ETV/TDF, respectively. The ETV=0.5 mg cohort also had the shortest duration of ETV=0.5 mg therapy before switch (11.8 vs. 13.5 vs. 19.2 mo, P<0.0001). After the switch point, more patients on ETV/TDF achieved CVS compared with those on ETV=0.5 mg or ETV=1.0 mg at month 6 (77.3% vs. 13.8% vs. 9.4%), month 12 (86.4% vs. 40.5% vs. 25.0%), and month 18 (100% vs. 70.2% vs. 33.3%). Compared with the ETV=0.5 mg and ETV=1.0 mg groups, the ETV/TDF group also had higher rates of ALT normalization at month 6 (73.0% vs, 46.4% vs. 63.0%), month 12 (79.7% vs. 69.5% vs. 77.9%), and month 18 (100.0% vs. 69.5% vs. 86.8%), respectively. The multivariate analyses, inclusive of baseline age and treatment duration on initial therapy with ETV=0.5 mg, indicated that the ETV/TDF combination (HR=12.19, P<0.0001) was independently and positively associated with CVS, whereas high HBV DNA levels at baseline (HR=0.77, P=0.02) and at switch point (HR=0.46, P=0.002) were negatively associated with CVS. ETV=1.0 mg dose was not a predictor for CVS compared with ETV=0.5 mg.

CONCLUSIONS

Following adjustments for HBV DNA levels and prior treatment duration, ETV/TDF combination therapy independently predicted superior viral suppression and ALT normalization in partial responders to ETV=0.5 mg daily compared with ETV=0.5 mg or ETV=1.0 mg monotherapy. In patients who continued to be viremic after 12 months of ETV=0.5 mg, one third were still viremic after another 18 months on the same therapy. Alternative therapies should be considered for these patients.

Evolution of entecavir-resistant hepatitis B virus during entecavir and adefovir dipivoxil combination therapy

The emergence of entecavir (ETV) resistance is rare, particularly in a longitudinal study. The aim of the present study was to characterize the evolution of ETV-resistant variants during antiviral therapy using entecavir monotherapy followed by ETV-adefovir dipivoxil (ADV) combination therapy. The study included a prospective cohort of 53 consecutive chronic hepatitis B (CHB) patients. During the 60-month period of ETV therapy, 2 patients exhibited ETV resistance and their medical records were comprehensively reviewed. A total of 25 consecutive serum samples were regularly collected from the 2 patients. All the samples were used to characterize the evolution of the polymerase gene mutations using pyrosequencing. The linkage of the variants was analyzed from 87 reverse transcriptase sequences of 3 selective samples using clone sequencing. The 2 patients presented with viral breakthrough during ETV monotherapy. In patient A, the rtL180M, rtS202G and rtM204V mutant variants were detected using pyrosequencing prior to virological breakthrough. Although the viral load declined following the administration of ADV, the ETV-resistant variants were persistently dominant in the viral populations. In patient B, the rtL180M, rtM204I and rtM204V mutants were present in ~70, 30 and 10% of the viral populations, respectively, at the time of study entry. In addition, rtT184F was present in ~20% of the viral population during virological breakthrough, at month 24. The rtL180M, rtT184F and rtM204V were predominant during the combination treatment. Clonal analysis further revealed that the rtS202G or rtT184F was in all cases co-localized with rtL180M and rtM204V in any single virus isolate clone. The results of the present study indicate that the addition of ADV therapy with ETV for treating ETV-resistant mutation may not inhibit the replication of ETV-resistant variants that developed previously in lamivudine-treated CHB patients.

Simultaneous determination of entecavir and lamivudine in rat plasma by UPLC-MS/MS and its application to a pharmacokinetic study

The study's aim is to develop and validate a rapid, selective and sensitive ultra-performance liquid chromatography-tandem mass spectrometry with multiple reaction monitoring (MRM) mode method for the simultaneous determination of entecavir and lamivudine in rat plasma.

A novel method for nucleos(t)ide analogues susceptibility assay of hepatitis B virus by viral polymerase transcomplementation

Nucleos(t)ide analogues (NUCs) susceptibility assay is important for the study of hepatitis B virus (HBV) drug resistance. The purpose of susceptibility assay is to test the sensitivity of a specific HBV variant to NUCs in vitro, by which assesses if and to what extent the mutant virus is resistant to a specific NUC. Among the existing susceptibility assay methods, stable cell line expressing the specific variant is one of the commonly used assessment systems based on its high repeatability. However, establishment of stable cell lines expressing individual variant is laborious and time-consuming. In the present study, we developed a novel strategy for rapidly establishing HBV replicating stable cell lines. We first established an acceptor cell line stably transfected with a polymerase-null HBV 1.1mer genome DNA, then lentiviruses expressing different mutant HBV polymerases were transduced into the acceptor cell line respectively. Stable cell lines replicating HBV DNA with the trans-complemented HBV polymerases were established by antibiotics selection. Lamivudine and entecavir susceptibility data from these polymerase-complementing cell lines were validated by comparing with other assays. Taken together, this transcomplementation strategy for establishment of stable cell lines replicating HBV DNA with clinically isolated HBV polymerase provides a new tool for NUC susceptibility assay of HBV.