Virus Nonstructural Protein 5A Inhibitor Research Articles

Safety, Tolerability and Pharmacokinetics of Yimitasvir Phosphate Capsule, a Novel Oral Hepatitis C Virus NS5A Inhibitor, in Healthy Chinese Volunteers.

Yimitasvir is a novel oral hepatitis C virus non-structural protein 5A (NS5A) inhibitor. The aims of this first-in-human study were to evaluate the safety, tolerability and pharmacokinetics of single and multiple doses of yimitasvir in healthy adult Chinese volunteers and to assess the effect of food on yimitasvir pharmacokinetics. Randomized, double-blind, placebo-controlled, single-ascending-dose (30, 100, 200 and 400mg) and multiple-ascending-dose (100 and 200mg once daily for 7days) studies were performed in 32 and 24 subjects, respectively, in male and female adults. Additionally, the effect of food on yimitasvir pharmacokinetics was assessed with a crossover study in 15 male subjects. Yimitasvir was absorbed slowly after oral administration with a median time to maximum plasma concentration (Tmax) of 3.5-4.0h. Increases in the maximum plasma concentration (Cmax) and area under the concentration-time curve from 0 to the last measurable time point (AUC0-t) were proportional to the dose of yimitasvir over a dose range of 30-100mg, while increases were less than dose proportional over a dose range of 200-400mg in part 1, indicating that absorption at the 200-mg dose was nearly saturated. The geometric mean terminal half-life of yimitasvir was 13.4-19.7h in each cohort, supporting once-daily dosing. Faecal excretion of parent yimitasvir was the major route of elimination. Steady state was achieved following 5days of dosing with minimal accumulation. A standardized high-fat meal decreased the rate and extent of absorption. All doses of yimitasvir were well tolerated. Yimitasvir, at single doses of 30-400mg and multiple doses of 100-200mg for 7days, was well tolerated in healthy Chinese subjects. The results of this study formed the basis for the dosing schemes evaluated in a phase Ib study and subsequent phase II and phase III clinical studies. This study was registered at the China Food and Drug Administration (Registration numbers: 2014L02064 and 2014L02065) and at http://www.chictr.org.cn (Nos. CTR20140854, CTR20150048 and CTR20150123).

Hepatitis C virus NS5A inhibitor daclatasvir allosterically impairs NS4B-involved protein-protein interactions within the viral replicase and disrupts the replicase quaternary structure in a replicase assembly surrogate system.

Daclatasvir (DCV) is a highly potent direct-acting antiviral that targets the non-structural protein 5A (NS5A) of hepatitis C virus (HCV) and has been used with great clinical success. Previous studies have demonstrated its impact on viral replication complex assembly. However, the precise mechanisms by which DCV impairs the replication complex assembly remains elusive. In this study, by using HCV subgenomic replicons and a viral replicase assembly surrogate system in which the HCV NS3-5B polyprotein is expressed to mimic the viral replicase assembly, we assessed the impact of DCV on the aggregation and tertiary structure of NS5A, the protein-protein interactions within the viral replicase and the quaternary structure of the viral replicase. We found that DCV did not affect aggregation and tertiary structure of NS5A. DCV induced a quaternary structural change of the viral replicase, as evidenced by selective increase of NS4B's sensitivity to proteinase K digestion. Mechanically, DCV impaired the NS4B-involved protein-protein interactions within the viral replicase. These phenotypes were consistent with the phenotypes of several reported NS4B mutants that abolish the viral replicase assembly. The DCV-resistant mutant Y93H was refractory to the DCV-induced reduction of the NS4B-involved protein interactions and the quaternary structural change of the viral replicase. In addition, Y93H reduced NS4B-involved protein-protein interactions within the viral replicase and attenuated viral replication. We propose that DCV may induce a positional change of NS5A, which allosterically affects protein interactions within the replicase components and disrupts replicase assembly.

Preclinical Profile and Clinical Efficacy of a Novel Hepatitis C Virus NS5A Inhibitor, EDP-239.

EDP-239, a novel hepatitis C virus (HCV) inhibitor targeting nonstructural protein 5A (NS5A), has been investigated in vitro and in vivo EDP-239 is a potent, selective inhibitor with potency at picomolar to nanomolar concentrations against HCV genotypes 1 through 6. In the presence of human serum, the potency of EDP-239 was reduced by less than 4-fold. EDP-239 is additive to synergistic with other direct-acting antivirals (DAAs) or host-targeted antivirals (HTAs) in blocking HCV replication and suppresses the selection of resistance in vitro Furthermore, EDP-239 retains potency against known DAA- or HTA-resistant variants, with half-maximal effective concentrations (EC50s) equivalent to those for the wild type. In a phase I, single-ascending-dose, placebo-controlled clinical trial, EDP-239 demonstrated excellent pharmacokinetic properties that supported once daily dosing. A single 100-mg dose of EDP-239 resulted in reductions in HCV genotype 1a viral RNA of >3 log10 IU/ml within the first 48 h after dosing and reductions in genotype 1b viral RNA of >4-log10 IU/ml within 96 h. (This study has been registered at ClinicalTrials.gov under identifier NCT01856426.).

A simple, effective approach for rapid development of high-throughput and reliable LC-MS/MS bioanalytical assays.

Rapidly developing LC-MS/MS assays with high-throughput and quality are challenging yet desired. Methodology & results: A simple method development approach was reported and demonstrated with the quantitative bioanalysis of BMS-984478, a hepatitis C virus nonstructural protein 5A inhibitor. An accurate, precise and robust LC-MS/MS method for the quantitation of BMS-984478 in rat and monkey plasma was developed and validated. Incurred sample reanalysis evaluation passed with 100% of samples meeting the acceptance criteria. The validated assay was successfully applied in toxicology studies without any failed runs. The approach was successfully applied to the bioanalysis of BMS-984478 in toxicology and clinical studies. This approach was shown to be effective and reliable in speeding the development of high-throughput and reliable LC-MS/MS assays.

Pharmacokinetics of hepatitis C virus NS5A inhibitor JNJ-56914845 (GSK2336805) in subjects with hepatic impairment.

JNJ-56914845 (GSK2336805) is a hepatitis C virus nonstructural protein 5A inhibitor under development for the treatment of chronic hepatitis C (CHC) infection. This open-label, parallel-group, 2-part study evaluated the pharmacokinetics and safety of a single oral 60 mg dose of JNJ-56914845 in 4 cohorts: healthy, mild, moderate, and severe hepatic impairment (n = 8/cohort). Severity of hepatic impairment was categorized using Child-Pugh score, and the healthy subjects were matched for age, sex, body mass index, and smoking status to the moderate hepatic impairment cohort. JNJ-56914845 plasma AUC0-∞ was 26%, 52%, and 45% lower in subjects with mild, moderate, and severe hepatic impairment, respectively, relative to healthy subjects with no difference in half-life among the groups. The apparent oral clearance and volume of distribution were higher in subjects with hepatic impairment. The lower plasma concentrations were largely explained by decreased plasma protein binding in hepatically impaired subjects. One subject with severe hepatic impairment had 2 non-drug-related serious adverse events: an esophageal bleed requiring hospitalization, encephalopathy. Although hepatically impaired subjects have lower exposures than healthy matched controls, they had similar or slightly higher exposures than those observed in past studies of noncirrhotic, CHC patients, suggesting that no dose adjustments for hepatic impairment will be needed.