scholarly journals Genotypic and Phenotypic Analyses of Hepatitis C Virus Variants Observed in Clinical Studies of VX-222, a Nonnucleoside NS5B Polymerase Inhibitor

2014 ◽  
Vol 58 (9) ◽  
pp. 5456-5465 ◽  
Author(s):  
Min Jiang ◽  
Eileen Z. Zhang ◽  
Andrzej Ardzinski ◽  
Ann Tigges ◽  
Andrew Davis ◽  
...  
Keyword(s):  
Hepatitis C Virus ◽  
Hepatitis C ◽  
Clinical Studies ◽  
Phase 1 ◽  
Replication Capacity ◽  
Hcv Rna ◽  
Genotype 1 ◽  
Wild Type ◽  
Ns5b Polymerase Inhibitor ◽  
Hcv Ns5b

ABSTRACTVX-222, a thiophene-2-carboxylic acid derivative, is a selective nonnucleoside inhibitor of the hepatitis C virus (HCV) NS5B RNA-dependent RNA polymerase. In phase 1 and 2 clinical studies, VX-222 demonstrated effective antiviral efficacy, with substantial reductions in plasma HCV RNA in patients chronically infected with genotype 1 HCV. To characterize the potential for selection of VX-222-resistant variants in HCV-infected patients, the HCV NS5B gene was sequenced at baseline and during and after 3 days of VX-222 dosing (monotherapy) in a phase 1 study. Variants with the substitutions L419C/I/M/P/S/V, R422K, M423I/T/V, I482L/N/T, A486S/T/V, and V494A were selected during VX-222 dosing, and their levels declined over time after the end of dosing. Phenotypic analysis of these variants was conducted using HCV replicons carrying site-directed mutations. Of the 17 variants, 14 showed reduced susceptibility to VX-222 compared with the wild type, with the L419C/S and R422K variants having higher levels of resistance (>200-fold) than the rest of the variants (6.8- to 76-fold). The M423I and A486S variants remained susceptible to VX-222. The 50% effective concentration (EC50) for the L419P variant could not be obtained due to the poor replication of this replicon. The majority of the variants (15/17) were less fit than the wild type. A subset of the variants, predominately the L419S and R422K variants, were observed when the efficacy and safety of VX-222- and telaprevir-based regimens given for 12 weeks were investigated in genotype 1 HCV-infected patients in a phase 2 study. The NS3 and NS5B variants selected during the dual combination therapy showed reduced susceptibility to both telaprevir and VX-222 and had a lower replication capacity than the wild type. The phase 1b study has the ClinicalTrials.gov identifier NCT00911963, and the phase 2a study has ClinicalTrials.gov identifier NCT01080222.

scholarly journals Mechanism of Activation of β-d-2′-Deoxy-2′-Fluoro-2′-C-Methylcytidine and Inhibition of Hepatitis C Virus NS5B RNA Polymerase

2007 ◽  
Vol 51 (2) ◽  
pp. 503-509 ◽  
Author(s):  
Eisuke Murakami ◽  
Haiying Bao ◽  
Mangala Ramesh ◽  
Tamara R. McBrayer ◽  
Tony Whitaker ◽  
...  
Keyword(s):  
Hepatitis C Virus ◽  
Hepatitis C ◽  
Rna Polymerase ◽  
Rna Synthesis ◽  
Specific Inhibitor ◽  
Nucleoside Diphosphate Kinase ◽  
Hcv Rna ◽  
Wild Type ◽  
Wild Type Enzyme ◽  
Hcv Ns5b

ABSTRACT β-d-2′-Deoxy-2′-fluoro-2′-C-methylcytidine (PSI-6130) is a potent specific inhibitor of hepatitis C virus (HCV) RNA synthesis in Huh-7 replicon cells. To inhibit the HCV NS5B RNA polymerase, PSI-6130 must be phosphorylated to the 5′-triphosphate form. The phosphorylation of PSI-6130 and inhibition of HCV NS5B were investigated. The phosphorylation of PSI-6130 by recombinant human 2′-deoxycytidine kinase (dCK) and uridine-cytidine kinase 1 (UCK-1) was measured by using a coupled spectrophotometric reaction. PSI-6130 was shown to be a substrate for purified dCK, with a Km of 81 μM and a k cat of 0.007 s−1, but was not a substrate for UCK-1. PSI-6130 monophosphate (PSI-6130-MP) was efficiently phosphorylated to the diphosphate and subsequently to the triphosphate by recombinant human UMP-CMP kinase and nucleoside diphosphate kinase, respectively. The inhibition of wild-type and mutated (S282T) HCV NS5B RNA polymerases was studied. The steady-state inhibition constant (Ki ) for PSI-6130 triphosphate (PSI-6130-TP) with the wild-type enzyme was 4.3 μM. Similar results were obtained with 2′-C-methyladenosine triphosphate (Ki = 1.5 μM) and 2′-C-methylcytidine triphosphate (Ki = 1.6 μM). NS5B with the S282T mutation, which is known to confer resistance to 2′-C-methyladenosine, was inhibited by PSI-6130-TP as efficiently as the wild type. Incorporation of PSI-6130-MP into RNA catalyzed by purified NS5B RNA polymerase resulted in chain termination.

scholarly journals Resistance Analysis of the Hepatitis C Virus NS3 Protease Inhibitor Asunaprevir

2012 ◽  
Vol 56 (7) ◽  
pp. 3670-3681 ◽  
Author(s):  
Fiona McPhee ◽  
Jacques Friborg ◽  
Steven Levine ◽  
Chaoqun Chen ◽  
Paul Falk ◽  
...  
Keyword(s):  
Hepatitis C Virus ◽  
Hepatitis C ◽  
Protease Inhibitor ◽  
Clinical Studies ◽  
Replication Capacity ◽  
Replication Complex ◽  
Hcv Genotype ◽  
Genotype 1A ◽  
Genotype 1B ◽  
Ns3 Protease

ABSTRACTAsunaprevir (BMS-650032) is a potent hepatitis C virus (HCV) NS3 protease inhibitor demonstrating efficacy in alfa interferon-sparing, direct-acting antiviral dual-combination regimens (together with the NS5A replication complex inhibitor daclatasvir) in patients chronically infected with HCV genotype 1b. Here, we describe a comprehensivein vitrogenotypic and phenotypic analysis of asunaprevir-associated resistance against genotypes 1a and 1b using HCV replicons and patient samples obtained from clinical studies of short-term asunaprevir monotherapy. During genotype 1a resistance selection using HCV replicons, the primary NS3 protease substitutions identified were R155K, D168G, and I170T, which conferred low- to moderate-level asunaprevir resistance (5- to 21-fold) in transient-transfection susceptibility assays. For genotype 1b, a higher level of asunaprevir-associated resistance was observed at the same selection pressures, ranging from 170- to 400-fold relative to the wild-type control. The primary NS3 protease substitutions identified occurred predominantly at amino acid residue D168 (D168A/G/H/V/Y) and were associated with high-level asunaprevir resistance (16- to 280-fold) and impaired replication capacity. In asunaprevir single-ascending-dose and 3-day multiple-ascending-dose studies in HCV genotype 1a- or 1b-infected patients, the predominant pre-existing NS3 baseline polymorphism was NS3-Q80K. This substitution impacted initial virologic response rates in a single-ascending-dose study, but its effects after multiple doses were more ambiguous. Interestingly, for patient NS3 protease sequences containing Q80 and those containing K80, susceptibilities to asunaprevir were comparable when tested in an enzyme assay. No resistance-associated variants emerged in these clinical studies that significantly impacted susceptibility to asunaprevir. Importantly, asunaprevir-resistant replicons remained susceptible to an NS5A replication complex inhibitor, consistent with a role for asunaprevir in combination therapies.

scholarly journals In VitroActivity and Resistance Profile of Dasabuvir, a Nonnucleoside Hepatitis C Virus Polymerase Inhibitor

2014 ◽  
Vol 59 (3) ◽  
pp. 1505-1511 ◽  
Author(s):  
Warren Kati ◽  
Gennadiy Koev ◽  
Michelle Irvin ◽  
Jill Beyer ◽  
Yaya Liu ◽  
...  
Keyword(s):  
Hepatitis C Virus ◽  
Hepatitis C ◽  
Clinical Isolates ◽  
Genotype 1 ◽  
Subgenomic Replicon ◽  
Hcv Genotype ◽  
Genotype 1A ◽  
Treatment Naïve ◽  
Hcv Genotype 1 ◽  
Hcv Ns5b

ABSTRACTDasabuvir (ABT-333) is a nonnucleoside inhibitor of the RNA-dependent RNA polymerase encoded by the hepatitis C virus (HCV) NS5B gene. Dasabuvir inhibited recombinant NS5B polymerases derived from HCV genotype 1a and 1b clinical isolates, with 50% inhibitory concentration (IC50) values between 2.2 and 10.7 nM, and was at least 7,000-fold selective for the inhibition of HCV genotype 1 polymerases over human/mammalian polymerases. In the HCV subgenomic replicon system, dasabuvir inhibited genotype 1a (strain H77) and 1b (strain Con1) replicons with 50% effective concentration (EC50) values of 7.7 and 1.8 nM, respectively, with a 13-fold decrease in inhibitory activity in the presence of 40% human plasma. This level of activity was retained against a panel of chimeric subgenomic replicons that contained HCV NS5B genes from 22 genotype 1 clinical isolates from treatment-naive patients, with EC50s ranging between 0.15 and 8.57 nM. Maintenance of replicon-containing cells in medium containing dasabuvir at concentrations 10-fold or 100-fold greater than the EC50resulted in selection of resistant replicon clones. Sequencing of the NS5B coding regions from these clones revealed the presence of variants, including C316Y, M414T, Y448C, Y448H, and S556G, that are consistent with binding to the palm I site of HCV polymerase. Consequently, dasabuvir retained full activity against replicons known to confer resistance to other polymerase inhibitors, including the S282T variant in the nucleoside binding site and the M423T, P495A, P495S, and V499A single variants in the thumb domain. The use of dasabuvir in combination with inhibitors targeting HCV NS3/NS4A protease (ABT-450 with ritonavir) and NS5A (ombitasvir) is in development for the treatment of HCV genotype 1 infections.

scholarly journals In VitroandIn VivoAntiviral Activity and Resistance Profile of the Hepatitis C Virus NS3/4A Protease Inhibitor ABT-450

2014 ◽  
Vol 59 (2) ◽  
pp. 988-997 ◽  
Author(s):  
Tami Pilot-Matias ◽  
Rakesh Tripathi ◽  
Daniel Cohen ◽  
Isabelle Gaultier ◽  
Tatyana Dekhtyar ◽  
...  
Keyword(s):  
Hepatitis C Virus ◽  
Hepatitis C ◽  
Antiviral Agents ◽  
Cross Resistance ◽  
Hcv Rna ◽  
Genotype 1 ◽  
Common Amino Acid ◽  
Direct Acting Antiviral ◽  
Genotype 1A

ABSTRACTThe development of direct-acting antiviral agents is a promising therapeutic advance in the treatment of hepatitis C virus (HCV) infection. However, rapid emergence of drug resistance can limit efficacy and lead to cross-resistance among members of the same drug class. ABT-450 is an efficacious inhibitor of HCV NS3/4A protease, with 50% effective concentration values of 1.0, 0.21, 5.3, 19, 0.09, and 0.69 nM against stable HCV replicons with NS3 protease from genotypes 1a, 1b, 2a, 3a, 4a, and 6a, respectively.In vitro, the most common amino acid variants selected by ABT-450 in genotype 1 were located in NS3 at positions 155, 156, and 168, with the D168Y variant conferring the highest level of resistance to ABT-450 in both genotype 1a and 1b replicons (219- and 337-fold, respectively). In a 3-day monotherapy study with HCV genotype 1-infected patients, ABT-450 was coadministered with ritonavir, a cytochrome P450 3A4 inhibitor shown previously to markedly increase peak, trough, and overall drug exposures of ABT-450. A mean maximum HCV RNA decline of 4.02 log10was observed at the end of the 3-day dosing period across all doses. The most common variants selected in these patients were R155K and D168V in genotype 1a and D168V in genotype 1b. However, selection of resistant variants was significantly reduced at the highest ABT-450 dose compared to lower doses. These findings were informative for the subsequent evaluation of ABT-450 in combination with additional drug classes in clinical trials in HCV-infected patients. (Study M11-602 is registered at ClinicalTrials.gov under registration no. NCT01074008.)

scholarly journals Lucidone Suppresses Hepatitis C Virus Replication by Nrf2-Mediated Heme Oxygenase-1 Induction

2012 ◽  
Vol 57 (3) ◽  
pp. 1180-1191 ◽  
Author(s):  
Wei-Chun Chen ◽  
Sheng-Yang Wang ◽  
Chien-Chih Chiu ◽  
Chin-Kai Tseng ◽  
Chun-Kuang Lin ◽  
...  
Keyword(s):  
Hepatitis C Virus ◽  
Hepatitis C ◽  
Heme Oxygenase ◽  
Interferon Response ◽  
Hcv Rna ◽  
Heme Oxygenase 1 ◽  
Related Factor ◽  
Content Type ◽  
Ns5b Polymerase Inhibitor ◽  
High Concentrations

ABSTRACTUpon screening of plant-derived natural products against hepatitis C virus (HCV) in the replicon system, we demonstrate that lucidone, a phytocompound, isolated from the fruits ofLindera erythrocarpaMakino, significantly suppressed HCV RNA levels with 50% effective concentrations of 15 ± 0.5 μM and 20 ± 1.1 μM in HCV replicon and JFH-1 infectious assays, respectively. There was no significant cytotoxicity observed at high concentrations, with a 50% cytotoxic concentration of 620 ± 5 μM. In addition, lucidone significantly induced heme oxygenase-1 (HO-1) production and led to the increase of its product biliverdin for inducing antiviral interferon response and inhibiting HCV NS3/4A protease activity. Conversely, the anti-HCV activity of lucidone was abrogated by blocking HO-1 activity or silencing gene expression of HO-1 or NF-E2-related factor 2 (Nrf2) in the presence of lucidone, indicating that the anti-HCV action of lucidone was due to the stimulation of Nrf-2-mediated HO-1 expression. Moreover, the combination of lucidone and alpha interferon, the protease inhibitor telaprevir, the NS5A inhibitor BMS-790052, or the NS5B polymerase inhibitor PSI-7977, synergistically suppressed HCV RNA replication. These findings suggest that lucidone could be a potential lead or supplement for the development of new anti-HCV agent in the future.

scholarly journals Clinical Implications of Detectable Baseline Hepatitis C Virus-Genotype 1 NS3/4A-Protease Variants on the Efficacy of Boceprevir Combined With Peginterferon/Ribavirin

2014 ◽  
Vol 1 (2) ◽  
Author(s):  
John A. Howe ◽  
Jianmin Long ◽  
Stuart Black ◽  
Robert Chase ◽  
Patricia McMonagle ◽  
...  
Keyword(s):  
Hepatitis C Virus ◽  
Hepatitis C ◽  
Sustained Virologic Response ◽  
Virologic Failure ◽  
Virologic Response ◽  
Phase Iii ◽  
Hcv Rna ◽  
Genotype 1 ◽  
Virus Genotype ◽  
The Impact

Abstract Background.  We analyzed the impact of pretreatment variants conferring boceprevir-resistance on sustained virologic response (SVR) rates achieved with boceprevir plus peginterferon-α/ribavirin (P/R) for hepatitis C virus (HCV)-genotype-1 infection. Methods.  NS3-protease-polymorphisms emerging coincident with virologic failure on boceprevir/P/R regimens were identified as resistance-associated variants (RAVs). Baseline samples pooled from 6 phase II or phase III clinical trials were analyzed for RAVs by population sequencing. Interferon (IFN)-responsiveness was predefined as >1 log reduction in HCV-RNA level during the initial 4-week lead-in treatment with P/R before boceprevir was added. The effective boceprevir-concentration inhibiting RAV growth by 50% (EC50) was determined using a replicon assay relative to the wild-type referent. Results.  Sequencing was performed in 2241 of 2353 patients (95.2%) treated with boceprevir. At baseline, RAVs were detected in 178 patients (7.9%), including 153 of 1498 genotype-1a infections (10.2%) and 25 of 742 genotype-1b infections (3.4%) (relative risk, 3.03; 95% confidence interval [CI], [2.01, 4.58]). For IFN-responders, SVR24 (SVR assessed 24 weeks after discontinuation of all study medications) rates were 78% and 76% with or without RAVs detected at baseline, respectively. For the 510 poor IFN-responders, SVR24 rates were 8 of 36 subjects (22.2% [11.7%, 38.1%]) when baseline RAVs were detected vs 174 of 474 subjects (36.7% [32.5%, 41.1%]) when baseline RAVs were not detected (relative likelihood of SVR24 [95% CI], 0.61 [0.32, 1.05]). Sustained virologic response was achieved in 7 of 8 (87.5%) IFN-nonresponders with baseline variants exhibiting ≤2-fold increased EC50 for boceprevir in a replicon assay, whereas only 1 of 15 (7%) IFN-nonresponders with baseline RAVs associated with ≥3-fold increased EC50 achieved SVR. Conclusions.  Baseline protease-variants appear to negatively impact SVR rates for boceprevir/P/R regimens only when associated with decreased boceprevir susceptibility in vitro after a poor IFN-response during the lead-in period.

scholarly journals Characterization of V36C, a Novel Amino Acid Substitution Conferring Hepatitis C Virus (HCV) Resistance to Telaprevir, a Potent Peptidomimetic Inhibitor of HCV Protease

2010 ◽  
Vol 54 (6) ◽  
pp. 2681-2683 ◽  
Author(s):  
Laetitia Barbotte ◽  
Abdelhakim Ahmed-Belkacem ◽  
Stéphane Chevaliez ◽  
Alexandre Soulier ◽  
Christophe Hézode ◽  
...  
Keyword(s):  
Hepatitis C Virus ◽  
Hepatitis C ◽  
Enzyme Assay ◽  
Inhibitory Concentration ◽  
Fold Increase ◽  
Replication Capacity ◽  
Wild Type ◽  
Hcv Protease ◽  
Moderate Resistance

ABSTRACT We characterized a novel substitution conferring moderate resistance to telaprevir, a peptidomimetic inhibitor of hepatitis C virus protease. V36C conferred a 4.0-fold increase in the telaprevir 50% inhibitory concentration in an enzyme assay and a 9.5-fold increase in the replicon model. The replication capacity of a replicon harboring V36C was close to that of the wild-type protease. This case emphasizes the complexity of hepatitis C virus resistance to protease inhibitors.

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