Antiviral activity and resistance of HCV NS5A replication complex inhibitors

Moringa oleifera and Autophagy: Evidence from In Vitro Studies on Chaperone-Mediated Autophagy in HepG2 Cancer Cells

Hepatocellular carcinoma (HCC) is the most prevalent primary liver cancer in Sub-Saharan African countries, including South Africa (SA). Given the limitations in current HCC therapeutics, there is an increasing need for alternative adjuvant therapeutic options. As such, several cell survival mechanisms, such as autophagy, have been identified as potential adjuvant therapeutic targets in HCC treatment. Of the three most established autophagic pathways, the upregulation of chaperone-mediated autophagy (CMA) has been extensively described in various cancer cells, including HCC cells. CMA promotes tumor growth and chemotherapeutic drug resistance, thus contributing to HCC tumorigenesis. Therefore, the modulation of CMA serves as a promising adjuvant target for current HCC therapeutic strategies. Phytochemical extracts found in the medicinal plant, Moringa oleifera (MO), have been shown to induce apoptosis in numerous cancer cells, including HCC. MO leaves have the greatest abundance of phytochemicals displaying anticancer potential. However, the potential interaction between the pro-apoptotic effects of MO aqueous leaf extract and the survival-promoting role of CMA in an in vitro model of HCC remains unclear. This review aims to summarize the latest findings on the role of CMA, and MO in the progression of HCC.

HCV Core Protein-ISX Axis Promotes Chronic Liver Disease Progression via Metabolic Remodeling and Immune Suppression

Chronic hepatitis C virus (HCV) infection is an important public health issue. However, knowledge on how the virus remodels the metabolic and immune response toward hepatic pathologic environment is limited. The transcriptomic and multiple evidences reveal that the HCV core protein-intestine-specific homeobox (ISX) axis promotes a spectrum of metabolic, fibrogenic, and immune modulators (e.g., kynurenine, PD-L1, and B7-2), regulating HCV-infection relevant pathogenic phenotype in vitro and in vivo. In a transgenic mice model, the HCV core protein-ISX axis enhance metabolic disturbance (particularly lipid and glucose metabolism) and immune suppression, and finally, chronic liver fibrosis in a high-fat diet (HFD)-induced disease model. Mechanistically, cells with HCV JFH-1 replicons upregulate ISX and, consequently, the expressions of metabolic, fibrosis progenitor, and immune modulators via core protein-induced nuclear factor-κB signaling. Conversely, cells with specific ISX shRNAi inhibit HCV core protein-induced metabolic disturbance and immune suppression. Clinically, the HCV core level is significantly correlated with ISX, IDOs, PD-L1, and B7-2 levels in HCC patients with HCV infection. Therefore, it highlights the significance of HCV core protein-ISX axis as an important mechanism in the development of HCV-induced chronic liver disease and can be a specific therapeutic target clinically.

Mechanism of zinc ejection by disulfiram in nonstructural protein 5A

Hepatitis C virus (HCV) is a notorious member of the Flaviviridae family of enveloped, positive-strand RNA viruses. Non-structural protein 5A (NS5A) plays a key role in HCV replication and assembly. NS5A is a multi-domain protein which includes an N-terminal amphipathic membrane anchoring alpha helix, a highly structured domain-1, and two intrinsically disordered domains 2-3. The highly structured domain-1 contains a zinc finger (Zf)-site, and binding of zinc stabilizes the overall structure, while ejection of this zinc from the Zf-site destabilizes the overall structure. Therefore, NS5A is an attractive target for anti-HCV therapy by disulfiram, through ejection of zinc from the Zf-site. However, the zinc ejection mechanism is poorly understood. To disclose this mechanism based on three different states, A-state (NS5A protein), B-state (NS5A + Zn), and C-state (NS5A + Zn + disulfiram), we have performed molecular dynamics (MD) simulation in tandem with DFT calculations in the current study. The MD results indicate that disulfiram triggers Zn ejection from the Zf-site predominantly through altering the overall conformation ensemble. On the other hand, the DFT assessment demonstrates that the Zn adopts a tetrahedral configuration at the Zf-site with four Cys residues, which indicates a stable protein structure morphology. Disulfiram binding induces major conformational changes at the Zf-site, introduces new interactions of Cys39 with disulfiram, and further weakens the interaction of this residue with Zn, causing ejection of zinc from the Zf-site. The proposed mechanism elucidates the therapeutic potential of disulfiram and offers theoretical guidance for the advancement of drug candidates.

A mini-review on sofosbuvir and daclatasvir treatment in coronavirus disease 2019

Sofosbuvir and daclatasvir have been used successfully since 2013 for hepatitis C treatment. It has been shown by different studies that sofosbuvir can inhibit RNA polymerase of other positive-strand RNA viruses including Flaviviridae and Togaviridae. Homology between hepatitis C virus RNA polymerase and severe acute respiratory syndrome coronavirus 2 has also been established. The efficacy of sofosbuvir and daclatasvir as potential choices in treating patients with coronavirus disease 2019 and their recovery can be hypothesized.

Medicinal chemistry strategies for discovering antivirals effective against drug-resistant viruses

During the last forty years we have witnessed impressive advances in the field of antiviral drug discovery culminating with the introduction of therapies able to stop human immunodeficiency virus (HIV) replication, or cure hepatitis C virus infections in people suffering from liver disease. However, there are important viral diseases without effective treatments, and the emergence of drug resistance threatens the efficacy of successful therapies used today. In this review, we discuss strategies to discover antiviral compounds specifically designed to combat drug resistance. Currently, efforts in this field are focused on targeted proteins (e.g. multi-target drug design strategies), but also on drug conformation (either improving drug positioning in the binding pocket or introducing conformational constraints), in the introduction or exploitation of new binding sites, or in strengthening interaction forces through the introduction of multiple hydrogen bonds, covalent binding, halogen bonds, additional van der Waals forces or multivalent binding. Among the new developments, proteolysis targeting chimeras (PROTACs) have emerged as a valid approach taking advantage of intracellular mechanisms involving protein degradation by the ubiquitin-proteasome system. Finally, several molecules targeting host factors (e.g. human dihydroorotate dehydrogenase and DEAD-box polypeptide 3) have been identified as broad-spectrum antiviral compounds. Implementation of herein described medicinal chemistry strategies are expected to contribute to the discovery of new drugs effective against current and future threats due to emerging and re-emerging viral pandemics.

Cryoglobulinemic glomerulonephritis: clinical presentation and histological features, diagnostic pitfalls and controversies in the management. State of the art and the experience on a large monocentric cohort treated with B cell depletion therapy

Cryoglobulinemia is defined by the presence of immunoglobulins having the following characteristics: forming a gel when temperature is <37 °C, precipitate in a reversible manner in the serum, and redissolve after rewarming. The presence of both polyclonal IgG and monoclonal IgM (type II), or of polyclonal IgG and polyclonal IgM (type III) identifies the mixed cryoglobulinemia (MC). The identification of the Hepatitis C virus (HCV) infection in most of the cases previously defined as "essential" represented a cornerstone in the understanding the pathogenesis of this condition. The picture of MC comprehends heterogeneous clinical presentations: from arthralgias, mild palpable purpura, fatigue to severe vasculitis features with skin necrotic pattern, peripheral neuropathy and, less commonly, lungs, central nervous system, gastrointestinal tract, and heart involvement. The kidney represents the most common organ presentation, and the presence of glomerulonephritis is a key element when considering prognosis. We discuss the clinical presentation and histological features, diagnostic pitfalls, and controversies in the management of patients with cryoglobulinemic glomerulonephritis, with a special focus on reporting our experience in treating patients with B cell depletion therapy.

The incidence of resistance-associated variants to NS5A in HCV subtypes 1a and 1b in Taiwan

Background

Resistance-associated variants (RAVs) to direct-antiviral agents (DAAs) may hamper treatment. There was a lack of data on the natural prevalence of RAVs in Taiwanese HCV-infected patients. We investigated the real-life presence of RAVs in the nonstructural 5A (NS5A) region in HCV genotype 1a and 1b in chronically infected individuals in Taiwan.

Methods

In this single-center cohort study, nested polymerase chain reaction and direct sequencing analysis was used to determine the frequency of RAVs in the HCV NS5A region in patients with HCV genotype 1a (n = 55) and 1b (n = 525).

Results

In genotype 1a strains, the incidence of RAVs was 16.4% (9/55) in the NS5A region (M28V/T, n = 6, 10.9%; Q30L, n = 1, 1.8%; Y93N/H, n = 3, 5.5%). In genotype 1b, the incidence of RAVs was 17.5% (92/525) in the NS5A region (L31I/M/V, n = 7, 1.3%; Y93 H/S, n = 87, 16.5%). Patients with RAVs had significantly higher HCV RNA levels (6.1 ± 0.7 vs 5.9 ± 0.8 log IU/mL, p = 0.001) and lower rGT levels (28.9 ± 18.9 vs. 42.9 ± 57.0 U/L, p = 0.001) compared to those without RAVs. Multivariate analysis identified HCV RNA levels (odds ratio = 1.145, 95% CI: 1.060–1.237, p = 0.001) and rGT (OR = 0.989, 95% CI: 0.978–0.999, p = 0.035) as risk factors that are associated with the presence of RAVs. Importantly, there is no association between the presence of RAVs and no SVR (3.8% in patients with RAVs, 15.9% in patients without RAVs, p = 0.32).

Conclusion

RAVs, especially M28V and Y93H in the NS5A region, were highly prevalent in patients with genotype 1a and 1b HCV, respectively, in Taiwan, and they were linked to high HCV RNA levels and low rGT levels. Before using the NS5A inhibitors, the presence of mutated HCV variants should be taken into consideration.

Quadruple Therapy Offers High SVR Rates in Patients with HCV Genotype 4 with Previous Treatment Failure

BACKGROUND AND AIMS

Direct-acting antivirals (DAAs) have made a revolution in hepatitis C virus (HCV) treatment with promising reduction of HCV infection and disease morbidities. However, unfortunately, treatment failure still occurs in about 5-15% of patients treated with DAA-based combination regimens. The primary aim of the study was to assess the efficacy and safety of a quadruple regimen of (sofosbuvir, daclatasvir, and simeprevir with a weight-based ribavirin) in chronic HCV DAAs-experienced patients.

METHODS

This observational, open-label prospective study was carried out on 103 genotype 4 hepatitis C virus-infected patients who failed to achieve SVR12 after sofosbuvir-daclatasvir with or without ribavirin. Patients were treated for three months with sofosbuvir (400 mg), daclatasvir (60 mg), and simeprevir (150 mg) with a weight-based ribavirin dosage (1000-1200 mg/d). Response to treatment was determined by quantitative PCR for HCV at 3 months after the end of treatment (SVR12), and adverse events during the treatment were recorded.

RESULTS

SVR was achieved in 100 patients (97.1%) at week 12 after treatment. No dangerous or life-threatening adverse events were recorded.

CONCLUSIONS

Retreatment of HCV genotype 4 patients with quadruple therapy is a good therapeutic option and achieves high response rates with minimal side effects.

Retreatment of chronic hepatitis C virus genotype-4 patients after non-structural protein 5A inhibitors' failure: efficacy and safety of different regimens

BACKGROUND

Nonstructural protein 5A (NS5A) is an important regimen for the treatment of chronic hepatitis C virus (HCV) genotype-4 infected patients. Retreatments for NS5A virologic failure are limited. The aim of this study is to provide real-life data regarding the effectiveness and safety of retreatment with different regimens after NS5A regimen virologic failure in GT4 patients.

PATIENTS AND METHODS

A total of 524 HCV patients (mean age 48 ± 11 years, 71% males), with virologic failure to sofosbuvir+daclatasvir, n = 450 and sofosbuvir/ledipasvir, n = 74 were included in this study. Patients were retreated with sofosbuvir + ombitasvir/paritaprevir/ritonavir + ribavirin, n = 278 and sofosbuvir + simeprevir + daclatasvir + ribavirin, n = 246. Response was evaluated 12 weeks after the end of treatment (SVR12).

RESULTS

Overall, SVR12 was 95.2% [95% confidence interval (CI) 93.3%-97.1%]. In sofosbuvir + ombitasvir/paritaprevir/ritonavir + ribavirin and sofosbuvir + simeprevir + daclatasvir + ribavirin, SVR12s were 94.9% (95% CI 92.5%-97.4%) and 95.5% (95% CI 92.8%-98%), respectively. In liver cirrhosis patients, SVR12s were 96.4% (95% CI 90.7%-100%) and 98% (95% CI 94.9%-100%), respectively. Relapse in the sofosbuvir + ombitasvir/paritaprevir/ritonavir + ribavirin was n = 14 patients, and n = 11 patients in sofosbuvir + simeprevir + daclatasvir + ribavirin. Three patients developed hepatic encephalopathy, haematemesis, lower limb oedema, and one patient died in the SOF + OBV/PTV/RTV + RIB. In the sofosbuvir + simeprevir + daclatasvir + ribavirin, three patients developed hepatocellular carcinoma and one patient died. No treatment discontinuation due to anaemia.

CONCLUSION

Salvage treatment for NS5A-treatment failure is effective and well tolerated in genotype-4 patients, in both noncirrhotic and compensated cirrhotic groups.

Direct-acting Antiviral in the Treatment of Chronic Hepatitis C: Bonuses and Challenges

Owing to the rapid development and wide clinical application of direct acting antiviral (DAA) drugs in the treatment of hepatitis C virus (HCV) infection, the era of interferon-based therapy has almost come to an end. Cumulative studies show that DAA therapy renders high cure efficiency (>90%) and good safety profile, and may even bring some unexpected benefits to the patients. However, some issues of concern arise, one of which is the resistance mutation of HCV genome leading to failure of treatment. With the aim of providing some meaningful references for the treatment of chronic hepatitis C (CHC), this article summarizes the research progress on benefits of DAA accompanied by viral clearance in the treatment of chronic hepatitis and the drug resistance.

Real-life effectiveness and safety of the daclatasvir/asunaprevir combination therapy for genotype 1b chronic hepatitis C patients: An emphasis on the pretreatment NS5A resistance-associated substitution test

This study aimed to investigate the real-life effectiveness and safety of daclatasvir (DCV) and asunaprevir (ASV) combination therapy in Korean patients. We consecutively enrolled patients with genotype 1b hepatitis C virus (HCV) infection treated with at least one dose of DCV/ASV combination therapy in seven tertiary hospitals of South Korea. The sustained virologic response (SVR) rates and safety according to intention-to-treat (ITT) and per-protocol (PP) analyses were evaluated. Among the 526 enrolled patients, 91% showed negative (87%) or "undetermined" (4%) resistance-associated substitution (RAS); 9% did not undergo RAS testing. The SVR rates for ITT and PP were 89.3% and 95.0% in treatment-naive patients and 93.2% and 95.6% in treatment-experienced patients, respectively. In PP analysis, negative RAS was associated with higher SVR (96.3%) than with "undetermined RAS" (85.7%) or "not tested for RAS" (84.4%). Adverse events were reported in 185 (35.4%) patients, and events leading to discontinuation were observed in 4.3% of the study population. Forty-two (8.0%) patients developed transaminase elevation (≥2 × upper normal limit), resulting in treatment discontinuation in six (1.1%) patients. DCV/ASV combination therapy showed acceptable efficacy in genotype 1b compensated HCV-infected patients with negative pretreatment RAS. Although most adverse events were tolerable to continue antiviral treatment, adequate monitoring for transaminase elevation is warranted.

Discovery and Characterization of Potent Pan-Genotypic HCV NS5A Inhibitors Containing Novel Tricyclic Central Core Leading to Clinical Candidate

The identification of a novel class of potent pan-genotypic NS5A inhibitors with good pharmacokinetic profile suitable for potential use in treating HCV infections is disclosed here. The present series of compounds are with less complex tricyclic central core, identified through a systematic SAR study carried out on biphenyl moiety. The SAR outcome has confirmed the requirement of near planar and linear conformation of the molecule to achieve the best pan-genotypic activity. In addition, SAR with substituted imidazoles on improvement of antiviral activity is disclosed. The newly identified compounds 12, 16, 19-21 have shown desirable pharmacokinetic profiles with a favorable uptake of compounds in liver and maintained a significant concentration for up to 8 h in the liver. In addition, compounds 20 and 21 have shown superior pan-genotypic anti-HCV activity compared to ledipasvir and daclatasvir. Additional characterization and preliminary safety assessment resulted in the identification of compound 20 as a potential clinical candidate.

Developments in the treatment of HCV genotype 3 infection

Introduction: Unlike other hepatitis C virus (HCV) genotypes (GTs), patients infected with GT3 are associated with an increased risk of accelerated liver disease progression. Although early immuno-modulator therapies yielded moderate sustained virologic response (SVR) rates, treatment of GT3 patients has proven more challenging in the era of direct-acting antivirals (DAAs). Areas covered: The review provides an overview of the evolution of therapies against GT3 since the approval of the first immunomodulatory agent nearly 30 years ago. Expert opinion: A greater choice of treatment options is now available for HCV GT3-infected patients. In treatment-naïve patients with or without compensated cirrhosis, SVR rates are comparably high approaching 100% irrespective of treatment option. For treatment-experienced patients, choosing the right therapy is important, especially for those with advanced liver disease. For the few patients who fail with multiple persistent highly resistant DAA substitutions, retreatment options are limited. Additional real-world treatment comparisons are required to confirm differences in SVR in these more difficult-to-treat patients. This also includes patients infected with GT3 subtypes such as GT3b where multiple DAA-resistant substitutions occur naturally. In the absence of new drugs with non-overlapping drug-resistant profiles, an interferon-based therapy may still be beneficial in select patient populations with high-level multiple DAA-resistant substitutions.

Pooled analysis of HCV genotype 1 resistance-associated substitutions in NS5A, NS3 and NS5B pre-and post-treatment with 12 weeks of daclatasvir, asunaprevir and beclabuvir

BACKGROUND

Daclatasvir (DCV; non-structural [NS]5A inhibitor) plus asunaprevir (ASV; NS3 inhibitor) plus beclabuvir (BCV; non-nucleoside NS5B inhibitor) is an approved regimen for hepatitis C virus (HCV) genotype (GT)-1 treatment in Japan. A comprehensive analysis of pre-treatment and treatment-emergent HCV resistance to this regimen ± ribavirin (RBV) was performed.

METHODS

Data were pooled from five Phase 2/3 studies of DCV+ASV+BCV±RBV given for 12 weeks to GT-1a- or GT-1b-infected patients. The prevalence and impact of pre-treatment resistance-associated substitutions (RAS) in NS5A, NS3, and NS5B on sustained virological response (SVR) was assessed, as were emergent RAS and their post-treatment persistence.

RESULTS

Baseline NS5A RAS (GT-1a: M28T, Q30H/L/R/S, L31M, Y93C/H; GT-1b: L31I/M, Y93C/H) were present in 5% (26/561) of GT-1a and 16% (85/537) of GT-1b sequences. SVR12 for GT-1b without RBV was 100% (82/82) with RAS and >99% (427/428) without RAS. For GT-1a, SVR12 without RAS was 97% (85/88) with RBV and 92% (410/447) without RBV; SVR12 with RAS was 100% (2/2) with RBV and 54% (13/24) without RBV. Baseline NS3 (at R155 or D168) and NS5B (at P495) RAS were rare (≤1%). Treatment-emergent NS5A RAS (mostly Q30E/H/K/R±Y93H/N) in GT-1a persisted 60 weeks post-treatment, while NS3 RAS (mostly R155K) and NS5B-P495L/S were no longer detected after 48 or 24 weeks, respectively.

CONCLUSIONS

DCV+ASV+BCV±RBV was highly efficacious in HCV GT-1 infection, including HCV GT-1b with NS5A RAS. The fitness of treatment-emergent RAS post-treatment was NS5A > NS3 > NS5B; NS3 and NS5B RAS were generally replaced by wild-type sequence within 48 weeks.

Glecaprevir/pibrentasvir for the treatment of chronic hepatitis C: design, development, and place in therapy

Direct-acting antiviral (DAA) therapy has changed the landscape of hepatitis C virus (HCV) management and has changed the focus to the possibility of HCV elimination in the near future. Glecaprevir, an NS3/4A protease inhibitor, and pibrentasvir, an HCV NS5A inhibitor, have addressed many of the existing shortcomings in the DAA therapy spectrum. This combination has proven to be a highly efficacious pan-genotypic DAA with a high barrier to resistance as a once-daily, all-oral medication. This review explores the design and development of glecaprevir and pibrentasvir, its place in current HCV management in the midst of a myriad of DAA therapy options, and also remaining challenges.

Polymorphism in interferon λ3/interleukin-28B gene and risk to noncirrhotic chronic hepatitis C genotype 3 virus infection and its effect on the response to combined daclatasvir and sofosbuvir therapy

Hepatitis C virus (HCV) infection is a considerable public-health problem and an important cause of liver disease with about 71 million people infected worldwide and more than 399 000 people die every year from hepatitis C-related liver diseases. The present study was, therefore, initiated to investigate the association of polymorphism in interferon λ3 (IFNL3) also known as interleukin-28B (IL-28B) gene with chronic HCV infection and association of these polymorphic variants with the combination daclatasvir and sofosbuvir HCV therapy response. Genotypes were determined by the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) assay in a total of 250 chronic HCV genotype three patients and 500 number of healthy controls. Our data revealed that the TT (minor) genotype of IFNL3 (rs12979860) and GG (minor) genotype of IFNL3 (rs8099917) exhibited a significant association with chronic HCV genotype 3 infection when compared with controls. The results of treatment response showed that CC (major) genotype of IFNL3 (rs12979860) and TT (major) genotype of IFNL3 (rs8099917) are associated with the likelihood of achieving a higher sustained virological response (SVR), to combined daclatasvir and sofosbuvir therapy, in genotype 3-infected HCV patients, whereas the individuals with TT (minor) genotype of IFNL3 (rs12979860) and GG (minor) genotype of IFNL3 (rs8099917) are more susceptible to chronic HCV infection and treatment relapse, suggesting a role of IFNL3 (rs12979860) and (rs8099917) in the treatment outcome of combined daclatasvir and sofosbuvir therapy in chronic HCV genotype 3 infection.

Real World Experience of Chronic Hepatitis C Retreatment with Genotype Specific Regimens in Nonresponders to Previous Interferon-Free Therapy

Background and Aim

The development of interferon- (IFN-) free regimens substantially improved efficacy of treatment for HCV, but despite excellent effectiveness the failures still occur. The aim of our study was to evaluate the efficacy of retreatment with genotype specific direct acting antivirals- (DAA-) based regimens in nonresponders to previous IFN-free therapy.

Materials and Methods

Analysed population consisted of 31 nonresponders to IFN-free regimen, which received second IFN-free rescue therapy, selected from 6228 patients included in a national database EpiTer-2.

Results

Age and gender distribution were similar, whereas proportion of genotype 1b was slightly higher and genotype 4 lower in the whole population compared to studied one. Patients included in the study demonstrated much more advanced fibrosis. Primary therapy was discontinued in 12 patients, which were recognized as failures due to nonvirologic reason, whereas virologic reason of therapeutic failure was recognized in 19 patients which completed therapy. Overall sustained virologic response (SVR) rate was 81% and 86% in intent-to-treat (ITT) and modified ITT analysis, respectively (74% and 78% in virologic failures, 92% and 100% in nonvirologic failures). Resistance-associated substitutions (RAS) testing was carried out in 8 patients from the group of completed primary therapy and three of them had potential risk for failure of rescue therapy due to NS5A association, while two of them achieved SVR.

Conclusions

We demonstrated moderate effectiveness of genotype specific rescue therapy in failures due to virologic reason and high in those who discontinued primary therapy. Therefore rescue therapy with genotype specific regimens should be considered always if more potent regimens are not available.

Exposure-Response Analysis for Efficacy of Daclatasvir, Asunaprevir, and Beclabuvir Combinations in HCV-Infected Patients

The combination regimen of daclatasvir, asunaprevir, and beclabuvir (3DAA regimen) was developed as a fixed-dose combination for the treatment of hepatitis C virus (HCV) infection in Japan. The objectives of this analysis were to characterize the relationship between drug exposure and sustained virologic response at posttreatment week 12 (SVR12) in HCV-infected subjects and to evaluate the impact of demographic covariates and clinical factors on the exposure-response (E-R) relationship. The E-R efficacy analysis was performed with data from phase 2 and phase 3 studies in HCV-infected subjects treated with the 3DAA regimen. The relationship between the probability of achieving SVR12 and exposure to daclatasvir, asunaprevir, and beclabuvir was described using a logistic regression model and included assessments of the potential covariate effects. The impacts of the covariates on the rate of SVR12 and interactions of covariates with the individual drug effects were tested. The final model for SVR12 included effects of non-genotype-1a status, resistance-associated NS5A-Q30 substitution in genotype-1a subjects, and baseline RNA level on the intercept, and effect of prior peg-interferon failure on the beclabuvir slope. Sex, race, age, weight, fibrosis score, alanine transaminase, and cirrhosis status had no statistically significant impact on the rate of SVR12. The individual E-R relationships with each drug, were relatively flat, and the effects of exposure were not significant. With the exception of the NS5A-Q30 substitution in genotype-1a subjects, statistically significant covariate effects had little impact on SVR12 rates. Overall, the E-R model was developed that captured the high SVR12 rates and the effect of covariates for the 3DAA regimen in HCV-infected patients.

Interaction of immunosuppressants with HCV antivirals daclatasvir and asunaprevir: combined effects with mycophenolic acid

AIM

To investigate the specific effects of immunosuppressants on the antiviral action of daclatasvir and asunaprevir.

METHODS

The antiviral activity of daclatasvir (DCV) and asunaprevir (ASV) combined with immunosuppressants was tested using two in vitro models for hepatitis C virus (HCV) infection.

RESULTS

Tacrolimus, rapamycin and cyclosporine did not negatively affect the antiviral action of DCV or ASV. Mycophenolic acid (MPA) showed additive antiviral effects combined with these direct acting antivirals (DAAs). MPA induces interferon-stimulated genes (ISGs) and is a potent GTP synthesis inhibitor. DCV or ASV did not induce ISGs expression nor affected ISG induction by MPA. Rather, the combined antiviral effect of MPA with DCV and ASV was partly mediated via inhibition of GTP synthesis.

CONCLUSION

Immunosuppressants do not negatively affect the antiviral activity of DAAs. MPA has additive effect on the antiviral action of DCV and ASV. This combined benefit needs to be confirmed in prospective clinical trials.

Resistance Analysis of a 3-Day Monotherapy Study with Glecaprevir or Pibrentasvir in Patients with Chronic Hepatitis C Virus Genotype 1 Infection

Glecaprevir (an NS3/4A protease inhibitor) and pibrentasvir (an NS5A inhibitor) are potent and pangenotypic hepatitis C virus (HCV) direct-acting antivirals. This report describes the baseline polymorphisms and treatment-emergent substitutions in NS3 or NS5A detected in samples from HCV genotype 1-infected patients receiving 3-day monotherapy of glecaprevir or pibrentasvir, respectively. None of the NS3 polymorphisms detected in the 47 baseline samples collected prior to glecaprevir monotherapy conferred reduced susceptibility to glecaprevir. The NS3 A156T substitution, which conferred resistance to glecaprevir but had low replication efficiency, emerged in one genotype 1a-infected patient among the 35 patients with available post-baseline sequence data. Baseline NS5A polymorphisms were detected in 12 of 40 patients prior to pibrentasvir monotherapy; most polymorphisms were single-position NS5A amino acid substitutions that did not confer resistance to pibrentasvir. Among the 19 patients with available post-baseline NS5A sequence data, 3 had treatment-emergent NS5A substitutions during pibrentasvir monotherapy. All treatment-emergent NS5A substitutions were linked multiple-position, almost exclusively double-position, substitutions that conferred resistance to pibrentasvir. Replicons engineered with these double-position substitutions had low replication efficiency. In conclusion, resistance-conferring substitutions emerged in a small number of genotype 1-infected patients during glecaprevir or pibrentasvir monotherapy; unlike other NS5A inhibitors, pibrentasvir did not select single-position NS5A substitutions during monotherapy.

Population Pharmacokinetic Analysis for Daclatasvir and Asunaprevir in Japanese Subjects With Chronic Hepatitis C Virus Infection

Daclatasvir is a nonstructural protein 5A replication complex inhibitor, and asunaprevir is a nonstructural protein 3 protease inhibitor for hepatitis C virus (HCV). In 2014, the combination therapy of daclatasvir and asunaprevir received the first global approval in Japan as the first nonribavirin, all‐oral therapy for HCV treatment. The population pharmacokinetics (popPK) of daclatasvir and asunaprevir were characterized by nonlinear mixed‐effects modeling using 3801 and 2626 concentration data from 336 and 265 Japanese HCV subjects, respectively. The plasma pharmacokinetic profiles of daclatasvir and asunaprevir were described by a 1‐compartment model. Parameter estimates (interindividual variability) of daclatasvir apparent clearance (CL/F) and apparent volume of the central compartment (V/F) were 5.29 L/h (39.4%) and 64.2 L (38.1%). The effects of all statistically significant covariates on daclatasvir PK parameters were within or overlapped the 80% to 125% boundaries, suggesting a lack of clinical relevance. Parameter estimates (interindividual variability) of asunaprevir CL/F and V/F were 52.1 L/h (41.5%) and 75.1 L (93.4%), respectively. Baseline and time‐varying aspartate aminotransferase (AST) and cirrhosis on CL/F and formulation (soft‐gel capsule or tablet) on F were included as significant covariates in the asunaprevir popPK model. The effects of all covariates exceeded the 80% to 125% boundaries, indicating that the asunaprevir soft‐gel capsule had higher bioavailability than the tablet and that asunaprevir exposure increased with cirrhosis and increasing baseline and time‐varying AST values. The popPK models adequately described the PK profiles of daclatasvir and asunaprevir in Japanese HCV subjects.

Exposure-Response (Efficacy) Analysis of Daclatasvir and Asunaprevir in Japanese Patients With Hepatitis C Virus Infection

The treatment of hepatitis C virus (HCV) infection has been revolutionized by the development of all-oral combination regimens of direct-acting antiviral agents. The current analysis characterized the relationship between exposures of daclatasvir (DCV; tablets) and asunaprevir (ASV; capsules) and sustained virologic response (SVR) in Japanese patients who are HCV genotype (GT) 1b nonresponders to pegylated interferon (IFN) α/ribavirin or IFNβ/ribavirin, and IFN-based therapy-ineligible naive/intolerant patients receiving DCV and ASV, and provided insight into patient covariates that were most closely associated with efficacy. The relationship between the probability of achieving SVR at 12 weeks after treatment (SVR12) and average steady-state plasma concentrations estimated from population pharmacokinetic models for DCV and ASV is described using a logistic regression model with data from a phase 2 and a phase 3 study in Japanese patients infected with HCV GT 1b (N=265). The functional form characterization, which describes a relationship between DCV and ASV average steady-state plasma concentrations and SVR12, as well as covariate identification (demographic, laboratory, and prognostic and treatment covariates) were investigated during model development. The presence of the signature nonstructural protein 5A Y93H mutation at baseline was the only significant parameter of SVR12 in the final exposure-response model. Model evaluation plots demonstrate that the final model was able to predict the observed SVR rates. Exposure-response analysis supports the clinical utility of the combination regimen of 60-mg once-daily DCV and 100-mg twice-daily ASV in Japanese patients infected with HCV GT 1b.

Population Pharmacokinetic Analysis of Daclatasvir in Subjects with Chronic Hepatitis C Virus Infection

BACKGROUND AND OBJECTIVE

Daclatasvir is a potent, pangenotypic once-daily hepatitis C virus (HCV) NS5A inhibitor that is approved for the treatment of chronic HCV infection. The objective of this analysis was to characterize the pharmacokinetics of daclatasvir in subjects with chronic HCV infection.

METHODS

A population pharmacokinetic (PPK) model was developed to evaluate effects of covariates on daclatasvir pharmacokinetics in subjects with chronic HCV infection (n = 2149 from 11 studies). All significant demographic, laboratory, prognostic and treatment covariates (p < 0.05) from univariate screening were included in the full model. The final model was reached by backward elimination (p < 0.001) and simulations were performed to further evaluate the effects of covariates on daclatasvir exposures. The plasma pharmacokinetics of daclatasvir was described by a two-compartment model with linear elimination. Absorption was modeled as a zero-order release followed by a first-order absorption into the central compartment.

RESULTS

The typical value of apparent clearance (CL/F) was 5.7 L/h (1.58% relative standard error [RSE]) and of apparent volume of the central compartment (V _c/F) was 58.6 L (2.00% RSE). Modest inter-individual variability was estimated for CL/F (35.1%) and V _c/F (29.5%). Statistically significant covariates in the final model were sex, race, virus genotype, baseline creatinine clearance, and alanine aminotransferase (ALT) on CL/F and sex, race, and body weight on V _c/F. Covariate effects demonstrated a 30% higher area under the plasma concentration-time curve at steady state (AUC_ss) in female subjects; effects of all other covariates were <16%.

CONCLUSIONS

The model adequately described the daclatasvir pharmacokinetics and estimated relatively small covariate effects. Considering the exposure range for the therapeutic dose of daclatasvir 60 mg once daily and the favorable safety profile, the small difference in exposures due to these covariates is not considered clinically relevant.

Daclatasvir Plus Asunaprevir for the Treatment of Patients with Hepatitis C Virus Genotype 1b Infection: Real-World Efficacy, Changes in Liver Stiffness and Fibrosis Markers, and Safety

BACKGROUND/AIMS

The treatment with daclatasvir plus asunaprevir (DCV+ASV) is associated with potent antiviral effects in patients with genotype 1b hepatitis C virus (HCV) infection. We investigated the real-world efficacy, changes in liver stiffness and noninvasive fibrosis markers, and the safety of DCV+ASV treatment in Korean patients.

METHODS

In total, 363 patients with chronic hepatitis C were treated with DCV+ASV between August 2015 and January 2017. Finally, we analyzed the data of 270 patients who were monitored for at least 12 weeks after the end of treatment.

RESULTS

The mean age was 60.7 years, and females predominated (60.4%). Most patients (64.8%) were treatment-naïve, and 56 patients (20.7%) had cirrhosis. Two hundred fifty-seven (95.2%) and 251 (93.0%) patients achieved end-of-treatment responses and sustained virological responses at 12 weeks posttreatment (SVR12), respectively. The SVR12 rates were higher in patients who were ＜65 years of age, males, without cirrhosis and had lower HCV RNA levels. All LS values and fibrosis-4 and aspartate aminotransferase-to-platelet ratio index values declined from baseline to the time of assessment of SVR12.

CONCLUSIONS

The DCV+ASV therapy resulted in a high SVR12 and improved liver fibrosis; the treatment was well tolerated in patients with genotype 1b HCV infections.

Long-term follow-up of clinical trial patients treated for chronic HCV infection with daclatasvir-based regimens

BACKGROUND & AIMS

Daclatasvir has achieved high sustained virologic response (SVR) rates in diverse hepatitis C virus (HCV) populations. This study evaluated the long-term efficacy and safety of daclatasvir-based regimens administered during clinical studies.

METHODS

Patients enrolled within 6 months of parent study completion or protocol availability at the study sites. The primary objective was durability of SVR at follow-up Week 12 (SVR12). Secondary objectives included analysing HCV sequences in non-responders or responders who relapsed, and characterization of liver disease progression.

RESULTS

Between 24 February 2012 and 17 July 2015, this study enrolled and began following 1503 recipients of daclatasvir-based regimens (follow-up cut-off, 13 October 2015); 60% were male, 18% aged ≥65 years, 87% had genotype-1a (42%) or -1b (45%) infection, and 18% had cirrhosis. Median follow-up from parent study follow-up Week 12 was 111 (range, 11-246) weeks. 1329/1489 evaluable patients were SVR12 responders; 1316/1329 maintained SVR until their latest visit. Twelve responders relapsed by (n = 9) or after (n = 3) parent study follow-up Week 24; one was reinfected. Relapse occurred in 3/842 (0.4%) and 9/487 (2%) responders treated with interferon-free or interferon-containing regimens, respectively. Hepatic disease progression and new hepatocellular carcinoma were diagnosed in 15 and 23 patients, respectively. Among non-responders, emergent non-structural protein-5A (NS5A) and -3 (NS3) substitutions were replaced by wild-type sequences in 27/157 (17%) and 35/47 (74%) patients, respectively.

CONCLUSIONS

SVR12 was durable in 99% of recipients of daclatasvir-based regimens. Hepatic disease progression and new hepatocellular carcinoma were infrequent. Emergent NS5A substitutions persisted longer than NS3 substitutions among non-responders.

Glecaprevir/Pibrentasvir in patients with hepatitis C virus genotype 1 or 4 and past direct-acting antiviral treatment failure

Patients with hepatitis C virus (HCV) who have virological failure (VF) after treatment containing a nonstructural protein 5A (NS5A) inhibitor have limited retreatment options. MAGELLAN-1 Part 2 was a randomized, open-label, phase 3 study to evaluate the efficacy and safety of ribavirin (RBV)-free glecaprevir and pibrentasvir (G/P; 300 mg/120 mg) in patients with chronic HCV and past VF on at least one NS3/4A protease and/or NS5A inhibitor-containing therapy. Patients with compensated liver disease, with or without cirrhosis, and HCV genotype (GT) 1, 4, 5, or 6 were randomized 1:1 to receive 12 or 16 weeks of G/P. The primary endpoint was sustained virological response (SVR) at 12 weeks posttreatment (SVR12). Among 91 patients treated, 87 had GT1 and 4 had GT4 infection. SVR12 was achieved by 89% (39 of 44) and 91% (43 of 47) of patients who received 12 and 16 weeks of G/P, respectively. Virological relapse occurred in 9% (4 of 44) of patients treated with 12 weeks of G/P; there were no relapses with 16 weeks of treatment. Past treatment history with one class of inhibitor (protease or NS5A) had no impact on SVR12, whereas past treatment with both classes of inhibitors was associated with lower SVR12 rate. The most common adverse event (AE) was headache (≥10% of patients), and there were no serious AEs assessed as related to study drugs or AEs leading to discontinuation.

CONCLUSION

Sixteen weeks of G/P treatment achieved a high SVR12 rate in patients with HCV GT1 infection and past failure to regimens containing either NS5A inhibitors or NS3 protease inhibitors. (Hepatology 2018;67:1253-1260).

Daclatasvir plus asunaprevir in treatment-naïve patients with hepatitis C virus genotype 1b infection

AIM

To assess daclatasvir plus asunaprevir (DUAL) in treatment-naïve patients from mainland China, Russia and South Korea with hepatitis C virus (HCV) genotype 1b infection.

METHODS

Patients were randomly assigned (3:1) to receive 24 wk of treatment with DUAL (daclatasvir 60 mg once daily and asunaprevir 100 mg twice daily) beginning on day 1 of the treatment period (immediate treatment arm) or following 12 wk of matching placebo (placebo-deferred treatment arm). The primary endpoint was a comparison of sustained virologic response at posttreatment week 12 (SVR12) compared with the historical SVR rate for peg-interferon plus ribavirin (70%) among patients in the immediate treatment arm. The first 12 wk of the study were blinded. Safety was assessed in DUAL-treated patients compared with placebo patients during the first 12 wk (double-blind phase), and during 24 wk of DUAL in both arms combined.

RESULTS

In total, 207 patients were randomly assigned to immediate (n = 155) or placebo-deferred (n = 52) treatment. Most patients were Asian (86%), female (59%) and aged < 65 years (90%). Among them, 13% had cirrhosis, 32% had IL28B non-CC genotypes and 53% had baseline HCV RNA levels of ≥ 6 million IU/mL. Among patients in the immediate treatment arm, SVR12 was achieved by 92% (95% confidence interval: 87.2-96.0), which was significantly higher than the historical comparator rate (70%). SVR12 was largely unaffected by cirrhosis (89%), age ≥ 65 years (92%), male sex (90%), baseline HCV RNA ≥ 6 million (89%) or IL28B non-CC genotypes (96%), although SVR12 was higher among patients without (96%) than among those with (53%) baseline NS5A resistance-associated polymorphisms (at L31 or Y93H). During the double-blind phase, aminotransferase elevations were more common among placebo recipients than among patients receiving DUAL. During 24 wk of DUAL therapy (combined arms), the most common adverse events (≥ 10%) were elevated alanine aminotransferase and upper respiratory tract infection; emergent grade 3-4 laboratory abnormalities were infrequently observed, and all grade 3-4 aminotransferase abnormalities (alanine aminotransferase, n = 9; aspartate transaminase, n = 6) reversed within 8-11 d. Two patients discontinued DUAL treatment; one due to aminotransferase elevations, nausea, and jaundice and the other due to a fatal adverse event unrelated to treatment. There were no treatment-related deaths.

CONCLUSION

DUAL was well-tolerated during this phase 3 study, and SVR12 with DUAL treatment (92%) exceeded the historical SVR rate for peg-interferon plus ribavirin of 70%.

Transmission genetics of drug-resistant hepatitis C virus

Antiviral development is plagued by drug resistance and genetic barriers to resistance are needed. For HIV and hepatitis C virus (HCV), combination therapy has proved life-saving. The targets of direct-acting antivirals for HCV infection are NS3/4A protease, NS5A phosphoprotein and NS5B polymerase. Differential visualization of drug-resistant and -susceptible RNA genomes within cells revealed that resistant variants of NS3/4A protease and NS5A phosphoprotein are cis-dominant, ensuring their direct selection from complex environments. Confocal microscopy revealed that RNA replication complexes are genome-specific, rationalizing the non-interaction of wild-type and variant products. No HCV antivirals yet display the dominance of drug susceptibility shown for capsid proteins of other viruses. However, effective inhibitors of HCV polymerase exact such high fitness costs for drug resistance that stable genome selection is not observed. Barriers to drug resistance vary with target biochemistry and detailed analysis of these barriers should lead to the use of fewer drugs.

Viruses are simple organisms that consist of genetic information and a few types of proteins. They cannot replicate on their own, and instead hijack the molecular machinery of a host cell to produce more of themselves.

Inside an infected cell, the genetic information of the virus is replicated and ‘read’ to create viral proteins. These components are then assembled to form a new generation of viruses. During this process, genetic errors may occur that lead to modifications in the viral proteins, and help the virus become resistant to treatment. For instance, a viral protein that used to be targeted by a drug can change slightly and not be recognized anymore.

Currently, the most efficient way to fight drug resistance is to use combination therapy, where several drugs are given at the same time. This strategy is successful, for example to treat infections with the hepatitis C virus, but it is also expensive, especially for developing countries.

An alternative approach is dominant-drug targeting, which exploits the fact that both drug-resistant and drug-susceptible viruses are ‘born’ in the same cell. There, the susceptible viruses can overwhelm and ‘mask’ the benefits of the resistant ones. For example, proteins from resistant strains, which are no longer detected by a treatment, can bind to proteins from susceptible viruses; drugs will still be able to recognize these resulting viral structures. The proteins that operate in such ways are potential dominant-drug targets. However, resistant and susceptible strains can also cohabit without any contacts if their proteins do not interact with each other.

Now, van Buuren et al. screen several viral proteins, including one called NS5A, to test whether a dominant drug target exists for the hepatitis C virus. Only a few molecules of a drug that targets NS5A can stop the virus from growing. In theory, drug-bound NS5A proteins could block their non-drug-bound neighbors, but when these drugs have been used on their own, resistance quickly emerged.

Experiments showed that NS5A is not a dominant drug target because the drug-resistant and drug-susceptible proteins do not mix. Unless ‘forced’ in the laboratory, NS5A proteins only bind to the ones produced by the same strain of virus. This explains why resistant viruses quickly take over when NS5A drugs are the sole treatment. However, other hepatitis C proteins, such as the HCV core protein, are known to mix during the assembly of the virus, and thus are likely be dominant drug targets.

Daclatasvir and sofosbuvir treatment of decompensated liver disease or post-liver transplant hepatitis C virus recurrence in patients with advanced liver disease/cirrhosis in a real-world cohort

We report the findings of an early access program providing treatment for chronic hepatitis C virus infection (any genotype) with daclatasvir and sofosbuvir with/without ribavirin to patients with Child‐Pugh class C cirrhosis or prior liver transplant recipients with recurrent hepatitis C virus infection and advanced fibrosis/cirrhosis. Patients had <12‐month life expectancies per the local investigator. Patients received daclatasvir 60 mg and sofosbuvir 400 mg once daily, with/without ribavirin, for 24 weeks. Sustained virologic response (SVR) at posttreatment week 12 (SVR12) was measured. Assessments adhered to local standards. One patient (prior Child‐Pugh class C who improved to class B) enrolled by exemption was included in the overall data but not the class C cohort efficacy/safety data. Of the 77 treated patients, including 62 liver transplant recipients (genotype 1, n = 43, 69%; genotype 3, n = 16, 26%) and 14 patients with Child‐Pugh class C cirrhosis (genotype 1, n = 4, 29%; genotype 3, n = 10, 71%), 63 (82%) completed treatment. SVR12 rates by modified intention‐to‐treat analysis (excluding nonvirologic failures lost to follow‐up and withdrawal [consent/no reason]) in the overall, liver transplant, and Child‐Pugh class C cohorts were 84% (n = 64/76), 90% (n = 56/62), and 62% (n = 8/13), respectively. Rates increased to 96% (n = 64/67), 97% (n = 56/58), and 89% (n = 8/9), respectively, in patients with available virologic data (including early discontinuations); 22/23 patients with genotype 3 (96%) achieved SVR12. Single cases of virologic nonresponse and relapse (both in liver transplant recipients with genotype 1) and viral breakthrough (Child‐Pugh class C; genotype 3) occurred. Six patients died, 10 had adverse events leading to discontinuation, and 30 experienced serious adverse events. Conclusion: Daclatasvir plus sofosbuvir, with/without ribavirin, provided high SVR12 rates and was generally well tolerated in patients with life‐threatening disease and high unmet needs. (Hepatology Communications 2018;2:354‐363)

Self-association and conformational variation of NS5A domain 1 of hepatitis C virus

Direct-acting antivirals (DAAs) targeting the non-structural 5A (NS5A) protein of the hepatitis C virus (HCV) are crucial drugs that have shown exceptional clinical success in patients. However, their mode of action (MoA) remains unclear, and drug-resistant HCV strains are rapidly emerging. It is critical to characterize the behaviour of the NS5A protein in solution, which can facilitate the development of new classes of inhibitors or improve the efficacy of the currently available DAAs. Using biophysical methods, including dynamic light scattering, size exclusion chromatography and chemical cross-linking experiments, we showed that the NS5A domain 1 from genotypes 1b and 1a of the HCV intrinsically self-associated and existed as a heterogeneous mixture in solution. Interestingly, the NS5A domain 1 from genotypes 1b and 1a exhibited different dynamic equilibria of monomers to higher-order structures. Using small-angle X-ray scattering, we studied the structural dynamics of the various states of the NS5A domain 1 in solution. We also tested the effect of daclatasvir (DCV), the most prominent DAA, on self-association of the wild and DCV-resistant mutant (Y93H) NS5A domain 1 proteins, and demonstrated that DCV induced the formation of large and irreversible protein aggregates that eventually precipitated out. This study highlights the conformational variability of the NS5A domain 1 of HCV, which may be an intrinsic structural behaviour of the HCV NS5A domain 1 in solution.

In Vitro Antiviral Activity and Resistance Profile of the Next-Generation Hepatitis C Virus NS3/4A Protease Inhibitor Glecaprevir

Glecaprevir (formerly ABT-493) is a novel hepatitis C virus (HCV) NS3/4A protease inhibitor (PI) with pangenotypic activity. It inhibited the enzymatic activity of purified NS3/4A proteases from HCV genotypes 1 to 6 in vitro (half-maximal [50%] inhibitory concentration = 3.5 to 11.3 nM) and the replication of stable HCV subgenomic replicons containing proteases from genotypes 1 to 6 (50% effective concentration [EC50] = 0.21 to 4.6 nM). Glecaprevir had a median EC50 of 0.30 nM (range, 0.05 to 3.8 nM) for HCV replicons containing proteases from 40 samples from patients infected with HCV genotypes 1 to 5. Importantly, glecaprevir was active against the protease from genotype 3, the most-difficult-to-treat HCV genotype, in both enzymatic and replicon assays demonstrating comparable activity against the other HCV genotypes. In drug-resistant colony selection studies, glecaprevir generally selected substitutions at NS3 amino acid position A156 in replicons containing proteases from genotypes 1a, 1b, 2a, 2b, 3a, and 4a and substitutions at position D/Q168 in replicons containing proteases from genotypes 3a, 5a, and 6a. Although the substitutions A156T and A156V in NS3 of genotype 1 reduced susceptibility to glecaprevir, replicons with these substitutions demonstrated a low replication efficiency in vitro Glecaprevir is active against HCV with most of the common NS3 amino acid substitutions that are associated with reduced susceptibility to other currently approved HCV PIs, including those at positions 155 and 168. Combination of glecaprevir with HCV inhibitors with other mechanisms of action resulted in additive or synergistic antiviral activity. In summary, glecaprevir is a next-generation HCV PI with potent pangenotypic activity and a high barrier to the development of resistance.

The global origins of resistance-associated variants in the non-structural proteins 5A and 5B of the hepatitis C virus

New, costly, fast acting, therapies targeting the non-structural proteins 5A and 5B (NS5A and NS5B) regions of the hepatitis C virus (HCV) genome are curative in the majority of cases. Variants with certain mutations in the NS5A and NS5B regions of HCV have been shown to reduce susceptibility to direct-acting NS5A and NS5B therapy and are found in treatment naïve patients. Despite this, the ease with which these variants evolve is poorly known, as are their evolutionary and geographic origins. To address this crucial gap we inferred the evolutionary and geographic origins of resistance-associated variants (RAVs) in the HCV NS5A and NS5B regions of subtypes 1a, 1b, and 3a sequences available from global databases. We found that RAVs in the NS5A region of HCV, when prevalent, were widely dispersed throughout the phylogenetic tree of HCV with multiple independent origins and that these variants are globally distributed. In contrast, most of the NS5B C316N variants came from one of two clades in the phylogenetic tree of HCV subtype 1b. The presence of serine (S) at codon 218 of HCV NS5B appears to facilitate the evolution of the C316N RAV. Other NS5B RAVs did not arise very frequently in our data set, except for S556G in subtype 1b and with respect to geography NS5B RAVs were also globally distributed. The inferred distribution of RAVs in the NS5A region and frequency of their origin suggest a low fitness barrier without the need for co-evolution of compensatory mutations. A low fitness barrier may allow rapid selection of de novo resistance to NS5A inhibitors during therapy.

Asunaprevir and daclatasvir in hemodialysis patients with chronic hepatitis C virus genotype 1b infection

Background and Aim

Patients requiring hemodialysis show high morbidity with hepatitis C virus (HCV) infection, but there are difficulties associated with interferon‐based therapies. Asunaprevir and daclatasvir could help patients with HCV genotype 1b because the drugs have a nonrenal metabolism and show good viral eradication. We evaluated the efficacy and safety of combined asunaprevir and daclatasvir therapy.

Methods

This was a multicenter prospective trial of patients with chronic hepatitis or compensated cirrhosis from HCV genotype 1b who had end‐stage renal disease requiring chronic hemodialysis. Asunaprevir and daclatasvir were administered orally (100 mg twice daily and 60 mg once daily, respectively) for 24 weeks. The primary end‐point was the proportion of patients achieving sustained virological response 12, defined as HCV RNA <15 IU/mL undetectable at 12 weeks after completion of asunaprevir and daclatasvir treatment.

Results

Between December 2014 and December 2015, 23 dialysis patients were enrolled, and 22 patients completed the protocol therapy. Sustained virological response 12 rates were 91.3% (95% confidence interval: 72.0–98.9) in the intention‐to‐treat and 95.5% (95% confidence interval: 77.2–99.9) in the per‐protocol populations. Serum aminotransferase significantly decreased after initiation of asunaprevir and daclatasvir (P < 0.01), although the level was low at baseline. Asunaprevir and daclatasvir were well tolerated; however, one patient could not continue because of infective endocarditis and cerebral infarction.

Conclusions

Asunaprevir and daclatasvir could help patients with chronic hepatitis C receiving hemodialysis. Close collaboration with dialysis physicians is important when treating these patients because hemodialysis carries life‐threatening risks.

Prevalence of hepatitis C virus-resistant association substitutions to direct-acting antiviral agents in treatment-naïve hepatitis C genotype 1b-infected patients in western China

Background

Direct-acting antivirals (DAAs) against hepatitis C virus (HCV) are potent and highly efficacious. However, resistance-associated substitutions (RASs) relevant to DAAs can impair treatment effectiveness even at baseline. Moreover, the prevalence of baseline RASs in HCV genotype 1b-infected patients in western China is still unclear.

Materials and methods

Direct sequencing of the HCV NS3, NS5A, and NS5B regions was performed in baseline serum samples of 70 DAAs treatment-naïve HCV 1b-infected patients in western China. The sequences were analyzed with MEGA version 5.05 software. Evolutionary patterns of RASs and amino-acid covariance patterns in the NS3, NS5A, and NS5B genes were analyzed by MEGA and Cytoscape (version 3.2.1), respectively.

Results

The presence of at least one RAS in the NS3 region (C16S, T54S, Q80R/L, A87T, R117H, S122G, V132I, V170I) was observed in 85.48% (53 of 62) of patients, RASs in the NS5A region (L28M, R30Q, Q54H, P58S/T, Q62H/R, Y93H) were observed in 42.42% (28 of 66) of patients, and RASs in the NS5B region (N142S, A300T, C316N, A338V, S365A, L392I, M414L, I424V, A442T, V499A, S556G) were observed in 100% (44 of 44) of patients. Evolutionary patterns of RASs and amino-acid covariance patterns for the NS3, NS5A, and NS5B genes are reported.

Conclusion

The prevalence of RASs relevant to DAAs detected in the NS3, NS5A, and NS5B regions of HCV 1b from DAA treatment-naïve patients is high. Therefore, more attention should be paid to RASs associated with DAAs in the upcoming DAA-treatment era in China.

Naturally Occurring Resistance-Associated Variants to Hepatitis C Virus Direct-Acting Antiviral Agents in Treatment-Naive HCV Genotype 6a-Infected Patients

BACKGROUND AND OBJECTIVE

The direct-acting antiviral agents (DAAs) antiviral therapy has drastically improved the prognosis of hepatitis C virus (HCV) patients. However, the viral drug resistance-associated variants (RAVs) can limit the efficacy of DAAs. For the HCV-6a is not the predominant prevalent genotype; the data on the prevalence of naturally occurring RAVs in it is scarce. Our study aims to assess the prevalence of RAVs in treatment-naive HCV-6a patients.

METHODS

Nested PCR assays were performed on 95 HCV-6a patients to amplify HCV viral regions of NS3, NS5A, and NS5B.

RESULTS

In NS3/4A region, we detected Q80K in 95.5% isolates (84/88) and D168E in 2.3% isolates (2/88). In NS5A region, we detected Q30R in 93.2% isolates (82/88), L31M in 4.6% isolates (4/88), and H58P in 6.8% isolates (6/88). In NS5B region, we detected A15G in 2.3% isolates (2/88), S96T in 1.1% isolates (1/88), and S282T in 20.7% isolates (17/88) and we detected I482L in 100% isolates (4/4), V494A in 50% isolates (2/4), and V499A in 100% isolates (4/4).

CONCLUSIONS

RAVs to DAAs preexist in treatment-naive HCV-6a patients. Further studies should address the issue of the impact of RAVs in response to DAA therapies for HCV-6a patients.

Glecaprevir and pibrentasvir for 12 weeks for hepatitis C virus genotype 1 infection and prior direct-acting antiviral treatment

Although direct-acting antiviral (DAA) therapies for chronic hepatitis C virus (HCV) infection have demonstrated high rates of sustained virologic response, virologic failure may still occur, potentially leading to the emergence of viral resistance, which can decrease the effectiveness of subsequent treatment. Treatment options for patients who failed previous DAA-containing regimens, particularly those with nonstructural protein 5A inhibitors, are limited and remain an area of unmet medical need. This phase 2, open-label study (MAGELLAN-1) evaluated the efficacy and safety of glecaprevir (GLE) + pibrentasvir (PIB) ± ribavirin (RBV) in HCV genotype 1-infected patients with prior virologic failure to HCV DAA-containing therapy. A total of 50 patients without cirrhosis were randomized to three arms: 200 mg GLE + 80 mg PIB (arm A), 300 mg GLE + 120 mg PIB with 800 mg once-daily RBV (arm B), or 300 mg GLE + 120 mg PIB without RBV (arm C). By intent-to-treat analysis, sustained virologic response at posttreatment week 12 was achieved in 100% (6/6, 95% confidence interval 61-100), 95% (21/22, 95% confidence interval 78-99), and 86% (19/22, 95% confidence interval 67-95) of patients in arms A, B, and C, respectively. Virologic failure occurred in no patients in arm A and in 1 patient each in arms B and C (two patients were lost to follow-up in arm C). The majority of adverse events were mild in severity; no serious adverse events related to study drug and no relevant laboratory abnormalities in alanine aminotransferase, total bilirubin, or hemoglobin were observed.

CONCLUSION

The combination of GLE and PIB was highly efficacious and well tolerated in patients with HCV genotype 1 infection and prior failure of DAA-containing therapy; RBV coadministration did not improve efficacy. (Hepatology 2017;66:389-397).

Sofosbuvir based treatment of chronic hepatitis C genotype 3 infections-A Scandinavian real-life study

Background and aims

Chronic hepatitis C virus (HCV) genotype 3 infection with advanced liver disease has emerged as the most challenging to treat. We retrospectively assessed the treatment outcome of sofosbuvir (SOF) based regimes for treatment of HCV genotype 3 infections in a real life setting in Scandinavia.

Methods

Consecutive patients with chronic HCV genotype 3 infection were enrolled at 16 treatment centers in Denmark, Sweden, Norway and Finland. Patients who had received a SOF containing regimen were included. The fibrosis stage was evaluated by liver biopsy or transient liver elastography. The following treatments were given according availability and local guidelines: 1) SOF + ribavirin (RBV) for 24 weeks, 2) SOF + daclatasvir (DCV) +/-RBV for 12–24 weeks, 3) SOF + pegylated interferon alpha (peg-IFN-α) + RBV for 12 weeks or 4) SOF/ledipasvir (LDV) + RBV for 12–16 weeks. The primary endpoint was sustained virological response (SVR) assessed at week 12 (SVR12) after end of treatment.

Results

We included 316 patients with a mean age of 55 years (range 24–79), 70% men, 49% treatment experienced, 58% with compensated cirrhosis and 12% with decompensated cirrhosis.In the modified intention to treat (mITT) population SVR12 was achieved in 284/311 (91%) patients. Among 26 treatment failures, five had non-response, 3 breakthrough and 18 relapse. Five patients were not included in the mITT population. Three patients died from reasons unrelated to treatment and two were lost to follow-up. The SVR12 rate was similar for all treatment regimens, but lower in men (p = 0.042), and in patients with decompensated liver disease (p = 0.004).

Conclusion

We found that sofosbuvir based treatment in a real-life setting could offer SVR rates exceeding 90% in patients with HCV genotype 3 infection and advanced liver disease.

In Vitro Antiviral Activity and Resistance Profile of the Next-Generation Hepatitis C Virus NS5A Inhibitor Pibrentasvir

Pibrentasvir (ABT-530) is a novel and pan-genotypic hepatitis C virus (HCV) NS5A inhibitor with 50% effective concentration (EC₅₀) values ranging from 1.4 to 5.0 pM against HCV replicons containing NS5A from genotypes 1 to 6. Pibrentasvir demonstrated similar activity against a panel of chimeric replicons containing HCV NS5A of genotypes 1 to 6 from clinical samples. Resistance selection studies were conducted using HCV replicon cells with NS5A from genotype 1a, 1b, 2a, 2b, 3a, 4a, 5a, or 6a at a concentration of pibrentasvir that was 10- or 100-fold over its EC₅₀ for the respective replicon. With pibrentasvir at 10-fold over the respective EC₅₀, only a small number of colonies (0.00015 to 0.0065% of input cells) with resistance-associated amino acid substitutions were selected in replicons containing genotype 1a, 2a, or 3a NS5A, and no viable colonies were selected in replicons containing NS5A from other genotypes. With pibrentasvir at 100-fold over the respective EC₅₀, very few colonies (0.0002% of input cells) were selected by pibrentasvir in genotype 1a replicon cells while no colonies were selected in other replicons. Pibrentasvir is active against common resistance-conferring substitutions in HCV genotypes 1 to 6 that were identified for other NS5A inhibitors, including those at key amino acid positions 28, 30, 31, or 93. The combination of pibrentasvir with HCV inhibitors of other classes produced synergistic inhibition of HCV replication. In summary, pibrentasvir is a next-generation HCV NS5A inhibitor with potent and pan-genotypic activity, and it maintains activity against common amino acid substitutions of HCV genotypes 1 to 6 that are known to confer resistance to currently approved NS5A inhibitors.

Efficacy and safety of daclatasvir plus asunaprevir for Korean patients with HCV genotype Ib infection: a retrospective multi-institutional study

BACKGROUND/AIMS

The combination of daclatasvir (DCV) and asunaprevir (ASV) has demonstrated a high sustained virologic response at 12 weeks (SVR12) and a low rate of adverse events in previous clinical studies. The purpose of this study was to clarify the results of treatment and side effects in Korean patients with chronic hepatitis C virus (HCV) genotype Ib infection.

METHODS

We retrospectively analyzed clinical data from chronic HCV genotype Ib patients treated with DCV+ASV from August 2015 to September 2016 at five hospitals in the Daejeon-Chungcheong area.

RESULTS

A total of 152 patients were examined for resistance associated variants (RAVs). Among them, 15 (9.9%) were positive for Y93 and one (0.7%) was positive for L31. Of 126 patients treated with DCV+ASV, 83 patients completed treatment and 76 patients were included in safety and efficacy analysis. Five (6.6%) were positive for Y93 and 12 (15.8%) exhibited cirrhotic change. DCV+ASV was the first-line treatment for 58 (76.3%) patients. Eleven (14.5%) patients relapsed after previous treatment that included interferon and seven (9.2%) of these patients were found to be intolerant of interferon. Adverse events occurred in 10 (13.2%) patients and two patients stopped the medication because of severe itching and skin rash. SVR12 was 89.5% (68/76) in all patients and 91.5% (65/71) in RAV-negative patients.

CONCLUSIONS

DCV+ASV showed good efficacy in patients with HCV Ib infection in Korea. Close monitoring is needed for severe adverse events and treatment failure, which were uncommon.

Real-world experience with daclatasvir plus sofosbuvir ± ribavirin for post-liver transplant HCV recurrence and severe liver disease

Optimizing therapy of post-transplant HCV recurrence remains important, especially in advanced liver disease. We evaluated daclatasvir (DCV) plus sofosbuvir (SOF), with or without ribavirin (RBV), in patients with post-liver transplant recurrence in a real-world European cohort at high risk of decompensation or death within 12 months. Recommended treatment was DCV 60 mg plus SOF 400 mg once daily for 24 weeks; RBV use/shorter treatment duration was at physicians' discretion. Patients (N = 87) were 70% male, 93% white, and mostly infected with HCV genotypes 1b (48%), 1a (32%), or 3 (9%); 37 (43%) had cirrhosis (16 decompensated), five had fibrosing cholestatic hepatitis. Sustained virologic response at post-treatment week 12 (SVR12) was 94% (80/85) in a modified intention-to-treat analysis: 95% (58/61) without RBV and 92% (22/24) with RBV, with no virologic failures. SVR12 was 100% (80/80) in an as-observed analysis excluding five nonvirologic failures. Four patients (5%) discontinued therapy for adverse events (AEs); 16 (18%) experienced serious AEs. One patient died on treatment and five during follow-up. Most AEs were associated with advanced liver disease and unrelated to therapy. No clinically significant drug-drug interactions were observed. DCV + SOF ± RBV was well tolerated and achieved high SVR12 (94%) in patients with post-transplant HCV recurrence, including patients with severe liver disease.

Efficacy and safety of simeprevir and sofosbuvir with and without ribavirin in subjects with recurrent genotype 1 hepatitis C postorthotopic liver transplant: the randomized GALAXY study

This prospective, randomized, phase 2 study in subjects with recurrent hepatitis C virus (HCV) genotype 1 postorthotopic liver transplant evaluated once-daily simeprevir 150 mg + sofosbuvir 400 mg, with and without ribavirin 1000 mg. Primary endpoint was proportion of subjects with week 12 sustained virologic response (SVR12). Thirty-three subjects without cirrhosis were randomized 1:1:1 into three arms (stratified by genotype/subtype and Q80K): Arm 1, simeprevir + sofosbuvir + ribavirin, 12 weeks; Arm 2, simeprevir + sofosbuvir, 12 weeks; Arm 3, simeprevir + sofosbuvir, 24 weeks; 13 additional subjects (two with cirrhosis, 11 without cirrhosis) entered Arm 3. All 46 subjects received at least one dose of study drug; median age, 60 years; 73.9% male; 80.4% White; 71.7% genotype/subtype 1a [12 (36.4%) of these had Q80K]; median 4.5 years post-transplant. Among randomized subjects, SVR12 was achieved by 81.8% in Arm 1, 100% in Arm 2, and 93.9% in Arm 3; two subjects did not achieve SVR12: one viral relapse (follow-up week 4; Arm 1) and one missing follow-up week 12 data. In total, five subjects had a serious adverse event, considered unrelated to treatment per investigator. Simeprevir exposure was increased relative to the nontransplant setting, but not considered clinically relevant. Simeprevir + sofosbuvir treatment, with or without ribavirin, was efficacious and well tolerated (ClinicalTrials.gov Identifier: NCT02165189).

Novel Treatment of Hepatitis C Virus Infection for Patients with Renal Impairment

Prevalence of hepatitis C virus (HCV) infection is high in patients with end-stage renal dysfunction, including patients undergoing hemodialysis (HD). The HCV infection itself can cause glomerulonephritis and puts individuals at increased risk of developing end-stage renal disease; fortunately, successful HCV eradication sometimes restore HCV-related renal dysfunction. Moreover, the prognosis of dialysis patients infected with HCV is significantly worse and the renal allograft survival in HCV-infected patients is also worse than in dialysis patients without HCV infection. If life prognosis is favorable, therefore, anti-HCV therapy is strongly recommended for HCV-infected patients with severe renal dysfunction. The standard therapy for HCV-infected patients with severe renal dysfunction has historically been interferon-based therapy. However, this therapy remains ineffective in achieving high, sustained viral response rates and the rate of adverse events and treatment discontinuation due to treatment-induced adverse events continues to be high in patients with severe renal dysfunction. Safe and effective anti-HCV therapies are urgently needed, and crucial, for patients with severe renal dysfunction. Recently, direct-acting antivirals (DAAs) that specifically target viral proteins have been developed, and these targets include the NS3, NS5A, and NS5B of HCV. Clinical trials have revealed high efficacy and safety of the DAA-based therapies, but patients with severe renal dysfunction were not included in the majority of these trials. However, several recent reports have shown high efficacy and safety for some regimens of DAA combination therapy for HCV-infected patients with severe renal dysfunction. In this review, we discuss novel treatments for HCV-infected patients with severe renal dysfunction and the pharmacokinetics of these drugs.

A Comprehensive Computational Analysis for the Binding Modes of Hepatitis C Virus NS5A Inhibitors: The Question of Symmetry

Direct-acting antivirals (DAAs) form the current standard of care (SOC) against hepatitis C virus (HCV). These drugs selectively target the viral proteins, offering a unique mechanism to avoid toxicity, to increase their efficacy, and to evolve from decades of interferon- and ribavirin-based therapy. Among the promising HCV targets for DAAs is the NS5A protein, and daclatasvir (DCV) forms a first-in-class compound that selectively targets this protein. Despite the exceptional potency of DCV (∼picomolar IC₅₀) and although several DCV derivatives have been approved for human use or are close to approval, the exact mode of action of these drugs is still incomplete. This is simply due to the vast complexity of cocrystallizing DCV with NS5A in the absence of two amphipathic helices that are required for DCV binding. In this context, computational modeling provides a unique alternative to solve this problem. Here, we build upon our recent discovery of a completely symmetrical interaction between DCV and NS5A and investigate the mode of binding of six other structures similar to DCV. The selected compounds include both symmetric and asymmetric molecules. In addition, we show that our model correlates very well with mutations that can confer resistance to DCV. The current study enhances our understanding of the mode of action of this class of HCV inhibitors and helps in defining the origin of resistance to these drugs.

Novel symmetrical phenylenediamines as potential anti-hepatitis C virus agents

BACKGROUND

Despite the great progress made in the last 10 years, alternative strategies might help improving definitive treatment options against hepatitis C virus infection.

METHODS

With the aim of identifying novel inhibitors of the hepatitis C virus-1b replication targeting the viral NS3 helicase, the structures of previously reported symmetrical inhibitors of this enzyme were rationally modified, and according to docking-based studies, four novel scaffolds were selected for synthesis and evaluation in the hepatitis C virus-1b subgenomic replicon assay.

RESULTS

Among the newly designed compounds, one new structural family was found to inhibit the hepatitis C virus-1b replication in the micromolar range. This scaffold was chosen for further exploration and different novel analogues were synthesised and evaluated.

CONCLUSIONS

Different new inhibitors of the hepatitis C virus genotype 1b replication were identified. Some of the new compounds show mild inhibition of the NS3 helicase enzyme.

Daclatasvir plus sofosbuvir, with or without ribavirin, achieved high sustained virological response rates in patients with HCV infection and advanced liver disease in a real-world cohort

OBJECTIVE

We assessed the effectiveness and safety of daclatasvir (DCV) plus sofosbuvir (SOF), with or without ribavirin (RBV), in a large real-world cohort, including patients with advanced liver disease.

DESIGN

Adults with chronic HCV infection at high risk of decompensation or death within 12 months and with no available treatment options were treated in a European compassionate use programme. The recommended regimen was DCV 60 mg plus SOF 400 mg for 24 weeks; RBV addition or shorter duration was allowed at physicians' discretion. The primary endpoint was sustained virological response at post-treatment week 12 (SVR12).

RESULTS

Of the 485 evaluable patients, 359 received DCV+SOF and 126 DCV+SOF+RBV. Most patients were men (66%), white (93%) and treatment-experienced (70%). The most frequent HCV genotypes were 1b (36%), 1a (33%) and 3 (21%), and 80% of patients had cirrhosis (42% Child-Pugh B/C; 46% Model for End-Stage Liver Disease score >10). SVR12 (modified intention-to-treat) was achieved by 91% of patients (419/460); 1 patient had virological breakthrough and 13 patients relapsed. Virological failure was not associated with treatment group (adjusted risk difference DCV+SOF minus DCV+SOF+RBV: 1.06%; 95% CI -2.22% to 4.35%). High SVR12 was observed regardless of HCV genotype or cirrhosis, liver transplant or HIV/HCV coinfection status. Twenty eight patients discontinued treatment due to adverse events (n=18) or death (n=10) and 18 died during follow-up. Deaths and most safety events were associated with advanced liver disease and not considered treatment related.

CONCLUSIONS

DCV+SOF with or without RBV achieved high SVR12 and was well tolerated in a diverse cohort of patients with severe liver disease.

TRIAL REGISTRATION NUMBER

NCT02097966.