Prevalence of hepatitis C virus variants resistant to NS3 protease inhibitors or the NS5A inhibitor (BMS-790052) in hepatitis patients with genotype 1b
Hepatitis C virus (HCV) of genotype 1b is the most prevalent worldwide, and the least responsive to interferon-based treatments. A combination therapy with two direct-acting antivirals has shown promising results in patients with HCV-1b, but the prevalence of drug-resistant variants before treatment is not known in the Japanese population.
To detect HCV variants resistant to NS3 protease inhibitors or the NS5A inhibitor (BMS-790052) in hepatitis patients infected with HCV-1b.
Drug-resistant mutations were determined in the 362 hepatitis patients infected with HCV-1b who had not received direct-acting antivirals before.
Amino-acid substitutions resistant to NS3 inhibitors (V36A, T54S, Q80H and D168E) were detected in 15 of the 307 (4.9%) patients, who had been examined, and T54S (3.3%) predominated over V36A (0.3%), Q80R (0.7%) and D168E (0.7%) in them. Amino-acid substitutions resistant to BMS-790052 (L31M and/or Y93H) were detected in 33 of the 294 (11.2%) patients, and Y93H (8.2%) predominated over L31M (2.7%). One of the 239 (0.4%) patients, who had been examined for amino-acid substitutions in both NS3 and NS5A regions, possessed HCV-1b variants resistant to NS3 inhibitors (T54S) and BMS-790052 (L31M).
Mutations conferring resistance to NS3 inhibitors or BMS-790052 were frequent in our treatment-naive study population, but double mutants with possible resistance to both drugs were rare. Since single mutations did not result in treatment failure in a previous pilot trial combining BMS-790052 and an NS3 inhibitor, larger trials of this drug regimen appear warranted in the Japanese population.
Available from: Qiushi Sun
- "Multiple viral proteins essential for replication have been characterized[14,15]. A clinical proof of concept has been demonstrated for small-molecule inhibitors that target structural and nonstructural proteins, including NS3/4A protease[16,17], NS5B polymerase (both active site and allosteric inhibitors)181920, NS4A, and recently, NS5A. NS3 protease has demonstrated a vital role in the replication of the HCV virus. It is a pivotal enzyme required for maturation of HCV and assists in the processing of the HCV polyprotein by cleaving four downstream sites23242526272829303132. In recent years, several NS3/4A protease inhibitors have moved into human clinical trials. "
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ABSTRACT: A high-throughput, sensitive and specific LC-ESI-MS/MS method was established for the quantitative determination of GP205, a potent inhibitor of hepatitis C virus NS3/4A protease, in rat. The analyte was isolated from 25 μL plasma sample by 96-well LLE. Good linearity was achieved within the concentration range of 2-5000 ng/mL (r2 > 0.996). The intra- and inter-day precision was less than 10%. The accuracy ranged from 0.8% to 5.5% for GP205 in quality control samples at three levels. GP205 was stable during the analysis and the storage period. The method was successfully applied to pharmacokinetic studies of GP205 in Sprague-Dawley rats. The pharmacokinetic profiles of GP205 at three dose levels with oral administration and one dose level with intravenous administration were successfully studied for the first time in SD rats, respectively. After single oral administration of GP205 at the doses of 2.5, 5, 10 mg/kg, respectively, Cmax and AUC0-τ were proportional to the doses given. The absolute bioavailability was estimated as 34% based on the AUCs of oral administration at the dose of 5 mg/kg and intravenous administration at the dose of 1 mg/kg. The data presented in this study provides useful information for further study for GP205.
Available from: Roberto Gulminetti
- "It should be underlined that while the Q54H + Y93H combination has already been reported  to provide moderate resistance to Daclatasvir, the other combinations have never been investigated, and their level of resistance is not known. In general, greater heterogeneity was confirmed in HCV genotype 1b strains [26,27]. "
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ABSTRACT: Direct-acting antiviral (DAA) agents target HCV proteins; some of these have already been approved for the treatment of HCV infection, while others are in development. However, selection of DAA-resistant viral variants may hamper treatment. The aim of this study was to illustrate potential natural DAA-resistance mutations in the HCV NS5A and NS5B regions of HCV genotypes 1a and 1b from DAA-naive patients.
Direct sequencing of HCV NS5A and NS5B regions was performed in 32 patients infected with HCV genotype 1a and 30 patients infected with HCV genotype 1b; all subjects were naive to DAAs.
In genotype 1a strains, resistance mutations in NS5A (M28V, L31M and H58P) were observed in 4/32 (12.5%) patients, and resistance mutations in NS5B (V321I, M426L, Y448H, Y452H) were observed in 4/32 (12.5%) patients. In genotype 1b, resistance mutations in NS5A (L28V, L31M, Q54H, Y93H and I280V) were observed in 16/30 (53.3%) patients, while resistance mutations in NS5B (L159F, V321I, C316N, M426L, Y452H, R465G and V499A) were observed in 27/30 (90%) patients.
Mutations conferring DAA resistance were detected in NS5A and NS5B of HCV genotypes 1a and 1b from DAA-naive patients. Although some mutations confer only a low level of resistance, the presence at baseline of mutated HCV variants should be taken into consideration in the context of DAA therapy.
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ABSTRACT: Viral resistance corresponds to the selection, during treatment, of pre-existing viral variants less susceptible to the drug’s inhibitory activity because they bear amino acid substitutions altering the drug target. Hepatitis C virus (HCV) drugs in development can be split into two groups according to their barrier to resistance. Direct-acting antiviral drugs with a low barrier to resistance include first-generation NS3-4A protease inhibitors, non-nucleoside inhibitors of HCV RNA-dependent RNA polymerase and first-generation NS5A inhibitors. HCV drugs with a high barrier to resistance include nucleoside/nucleotide analogues, possibly second-generation protease and NS5A inhibitors, and host-targeted agents, such as cyclophilin inhibitors or microRNA-122 antagonists. This article reviews recent findings that add to our knowledge and understanding of HCV resistance to direct-acting antiviral drugs and discusses them in the context of new therapeutic strategies, with and without pegylated interferon-α and/or ribavirin.
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