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1.
Vaccine ; 41(4): 903-913, 2023 Jan 23.
Article in English | MEDLINE | ID: mdl-36566163

ABSTRACT

Despite the widespread effectiveness of pneumococcal conjugate vaccines on the overall incidence of invasive pneumococcal disease, the global epidemiological landscape continues to be transformed by residual disease from non-vaccine serotypes, thus highlighting the need for vaccines with expanded disease coverage. To address these needs, we have developed V116,an investigational 21-valent non-adjuvanted pneumococcal conjugate vaccine (PCV),containingpneumococcal polysaccharides (PnPs) 3, 6A, 7F, 8, 9N, 10A, 11A,12F, 15A, 16F, 17F, 19A, 20, 22F, 23A, 23B, 24F, 31, 33F, 35B, anda de-O-acetylated 15B(deOAc15B) individually conjugated to the nontoxic diphtheria toxoid CRM197 carrier protein. Preclinical studies evaluated the immunogenicity of V116 inadult monkeys, rabbits, and mice. Following one dose, V116 was found to be immunogenic in preclinical animal species and induced functional antibodies for all serotypes included in the vaccine, in addition to cross-reactive functional antibodies to serotypes 6C and 15B. In these preclinical animal studies, the increased valency of V116 did not result in serotype-specific antibody suppression when compared to lower valent vaccines V114 or PCV13. In addition, when compared with naïve controls, splenocytes from V116 to immunized animals demonstrated significant induction of CRM197-specific T cells in both IFN-γ and IL-4 ELISPOT assays, as well as Th1 and Th2 cytokine induction through in vitro stimulation assays, thus suggesting the ability of V116 to engage T cell dependent immune response pathways to aid in development of memory B cells. V116 also demonstrated significant protection in mice from intratracheal challenge with serotype 24F, a novel serotype not contained in any currently licensed vaccine.


Subject(s)
Pneumococcal Infections , Streptococcus pneumoniae , Rabbits , Mice , Animals , Pneumococcal Vaccines , Vaccines, Conjugate , Macaca mulatta , Antibodies, Bacterial , Pneumococcal Infections/prevention & control , Serogroup , Disease Models, Animal
2.
Antimicrob Agents Chemother ; 63(12)2019 09 09.
Article in English | MEDLINE | ID: mdl-31527040

ABSTRACT

Hepatitis C virus (HCV) genotype (GT) 2 represents approximately 9% of all viral infections globally. While treatment outcomes for GT2-infected patients have improved substantially with direct-acting antiviral agents (DAAs) compared to interferon-α, the presence of polymorphisms in NS5A can impact efficacy of NS5A inhibitor-containing regimens. Thus, pathways of NS5A resistance were explored in GT2 subtypes using elbasvir, an NS5A inhibitor with broad genotype activity. Resistance selection studies, resistance analysis in NS5A-inhibitor treated virologic failures, antiviral activities in replicons bearing a panel of GT2 subtype sequences and amino acid substitutions introduced by site-directed mutagenesis were performed to define determinants of inhibitor susceptibility. Elbasvir showed differential antiviral activity in replicons bearing GT2 sequences. The EC50 values for replicons bearing reference NS5A sequences for GT2a and GT2b were 0.003 and 3.4 nanomolar (nM) respectively. Studies with recombinant replicons demonstrated crosstalk between amino acid positions 28 and 31. The combination of phenylalanine and methionine at positions 28 and 31 respectively, conferred the highest potency reduction for elbasvir in GT2a and GT2b. This combination was observed in failures from the C-SCAPE trial. Addition of grazoprevir, an NS3/4A protease inhibitor, to elbasvir more effectively suppressed the emergence of resistance in GT2 at modest inhibitor concentrations (3X EC90). Ruzasvir, a potent, pan-genotype NS5A inhibitor successfully inhibited replicons bearing GT2 resistance-associated substitutions (RASs) at positions 28 and 31. The studies demonstrate crosstalk between amino acids at positions 28 and 31 in NS5A modulate inhibitor potency and may impact treatment outcomes in some HCV GT2-infected patients.

3.
Article in English | MEDLINE | ID: mdl-30150466

ABSTRACT

Inhibition of NS5A has emerged as an attractive strategy to intervene in hepatitis C virus (HCV) replication. Ruzasvir (formerly MK-8408) was developed as a novel NS5A inhibitor to improve upon the potency and barrier to resistance of early compounds. Ruzasvir inhibited HCV RNA replication with 50% effective concentrations (EC50s) of 1 to 4 pM in Huh7 or Huh7.5 cells bearing replicons for HCV genotype 1 (GT1) to GT7. The antiviral activity was modestly (10-fold) reduced in the presence of 40% normal human serum. The picomolar potency in replicon cells extended to sequences of clinical isolates available in public databases that were synthesized and tested as replicons. In GT1a, ruzasvir inhibited common NS5A resistance-associated substitutions (RASs), with the exception of M28G. De novo resistance selection studies identified pathways with certain amino acid substitutions at residues 28, 30, 31, and 93 across genotypes. Substitutions at position 93 were more common in GT1 to -4, while changes at position 31 emerged frequently in GT5 and -6. With the exception of GT4, the reintroduction of selected RASs conferred a ≥100-fold potency reduction in the antiviral activity of ruzasvir. Common RASs from other classes of direct-acting antiviral agents (DAAs) did not confer cross-resistance to ruzasvir. The interaction of ruzasvir with an NS3/4A protease inhibitor (grazoprevir) and an NS5B polymerase prodrug (uprifosbuvir) was additive to synergistic, with no evidence of antagonism or cytotoxicity. The antiviral profile of ruzasvir supported its further evaluation in human trials in combination with grazoprevir and uprifosbuvir.


Subject(s)
Antiviral Agents/pharmacology , Hepacivirus/drug effects , Heterocyclic Compounds, 4 or More Rings/pharmacology , Pyrrolidines/pharmacology , Thiazoles/pharmacology , Viral Nonstructural Proteins/antagonists & inhibitors , Amides , Carbamates , Cell Line, Tumor , Cyclopropanes , Drug Resistance, Viral/drug effects , Drug Therapy, Combination/methods , Genotype , Hepatitis C, Chronic/drug therapy , Hepatitis C, Chronic/virology , Humans , Protease Inhibitors/pharmacology , Quinoxalines/pharmacology , Replicon/drug effects , Sulfonamides , Uridine/analogs & derivatives , Uridine/pharmacology
4.
J Med Chem ; 61(9): 3984-4003, 2018 05 10.
Article in English | MEDLINE | ID: mdl-29681153

ABSTRACT

We describe the discovery of MK-6169, a potent and pan-genotype hepatitis C virus NS5A inhibitor with optimized activity against common resistance-associated substitutions. SAR studies around the combination of changes to both the valine and aminal carbon region of elbasvir led to the discovery of a series of compounds with substantially improved potency against common resistance-associated substitutions in the major genotypes, as well as good pharmacokinetics in both rat and dog. Through further optimization of key leads from this effort, MK-6169 (21) was discovered as a preclinical candidate for further development.


Subject(s)
Antiviral Agents/pharmacology , Drug Discovery , Drug Resistance, Viral/drug effects , Hepacivirus/drug effects , Viral Nonstructural Proteins/antagonists & inhibitors , Animals , Antiviral Agents/pharmacokinetics , Dogs , Genotype , Hepacivirus/genetics , Hepacivirus/metabolism , Male , Rats , Tissue Distribution
5.
Article in English | MEDLINE | ID: mdl-28416549

ABSTRACT

Although genotype 4 (GT4)-infected patients represent a minor overall percentage of the global hepatitis C virus (HCV)-infected population, the high prevalence of the genotype in specific geographic regions coupled with substantial sequence diversity makes it an important genotype to study for antiviral drug discovery and development. We evaluated two direct-acting antiviral agents-grazoprevir, an HCV NS3/4A protease inhibitor, and elbasvir, an HCV NS5A inhibitor-in GT4 replicons prior to clinical studies in this genotype. Following a bioinformatics analysis of available GT4 sequences, a set of replicons bearing representative GT4 clinical isolates was generated. For grazoprevir, the 50% effective concentration (EC50) against the replicon bearing the reference GT4a (ED43) NS3 protease and NS4A was 0.7 nM. The median EC50 for grazoprevir against chimeric replicons encoding NS3/4A sequences from GT4 clinical isolates was 0.2 nM (range, 0.11 to 0.33 nM; n = 5). The difficulty in establishing replicons bearing NS3/4A resistance-associated substitutions was substantially overcome with the identification of a G162R adaptive substitution in NS3. Single NS3 substitutions D168A/V identified from de novo resistance selection studies reduced grazoprevir antiviral activity by 137- and 47-fold, respectively, in the background of the G162R replicon. For elbasvir, the EC50 against the replicon bearing the reference full-length GT4a (ED43) NS5A gene was 0.0002 nM. The median EC50 for elbasvir against chimeric replicons bearing clinical isolates from GT4 was 0.0007 nM (range, 0.0002 to 34 nM; n = 14). De novo resistance selection studies in GT4 demonstrated a high propensity to suppress the emergence of amino acid substitutions that confer high-potency reductions to elbasvir. Phenotypic characterization of the NS5A amino acid substitutions identified (L30F, L30S, M31V, and Y93H) indicated that they conferred 15-, 4-, 2.5-, and 7.5-fold potency losses, respectively, to elbasvir. The activity profiles of grazoprevir and elbasvir supported the testing of the direct-acting antivirals in clinical studies.


Subject(s)
Antiviral Agents/pharmacology , Benzofurans/pharmacology , Hepatitis C, Chronic/enzymology , Imidazoles/pharmacology , Protease Inhibitors/pharmacology , Quinoxalines/pharmacology , Viral Nonstructural Proteins/antagonists & inhibitors , Amides , Carbamates , Cyclopropanes , Genotype , Hepacivirus/drug effects , Hepacivirus/genetics , Replicon/genetics , Serine Proteases , Sulfonamides
6.
R I Med J (2013) ; 100(2): 18-20, 2017 Mar 01.
Article in English | MEDLINE | ID: mdl-28246654

ABSTRACT

Obesity is a chronic disease universally defined as an excess of adipose tissue resulting in body mass index (BMI) > 30.0 kg/m2. Over the past few years, the concept of prevention has gained increased awareness, thus leading to the development of additional pharmaceutical options for the treatment of obesity since 2012. Treating obesity revolves around an individualized, multi-disciplinary approach with additional focus on a healthy and supportive lifestyle to maintain the weight loss. [Full article available at http://rimed.org/rimedicaljournal-2017-03.asp].


Subject(s)
Anti-Obesity Agents/therapeutic use , Obesity/drug therapy , Weight Loss/drug effects , Anti-Obesity Agents/adverse effects , Benzazepines/adverse effects , Benzazepines/therapeutic use , Body Mass Index , Bupropion/adverse effects , Bupropion/therapeutic use , Drug Combinations , Fructose/adverse effects , Fructose/analogs & derivatives , Fructose/therapeutic use , Humans , Lactones/adverse effects , Lactones/therapeutic use , Liraglutide/adverse effects , Liraglutide/therapeutic use , Naltrexone/adverse effects , Naltrexone/therapeutic use , Orlistat , Phentermine/adverse effects , Phentermine/therapeutic use
7.
J Biol Chem ; 292(15): 6202-6212, 2017 04 14.
Article in English | MEDLINE | ID: mdl-28228479

ABSTRACT

Grazoprevir is a potent pan-genotype and macrocyclic inhibitor of hepatitis C virus (HCV) NS3/4A protease and was developed for treating chronic HCV infection. In HCV genotype (GT) 1a, grazoprevir maintains potent activity against a majority of NS3 resistance-associated amino acid substitutions, including the highly prevalent and naturally occurring Q80K polymorphism that impacts simeprevir, another NS3/4A protease inhibitor. The basis for an unexpected difference in the clinical impact of some NS3 substitutions was investigated. Phenotypic analysis of resistance-associated substitutions identified in NS3 from GT1a-infected patients who failed therapy with grazoprevir (in combination with elbasvir, an inhibitor of HCV NS5A protein) showed that positions 56, 156, and 168 in NS3 were most impactful because they diminished protein-inhibitor interactions. Although an amino acid substitution from aspartic acid to alanine at position 168 (D168A) reduced the potency of grazoprevir, its combination with R155K unexpectedly nullified this effect. Molecular dynamics and free-energy surface studies indicated that Asp-168 is important in anchoring Arg-155 for ligand binding but is not critical for Lys-155 because of the inherent flexibility of its side chain. Moreover, modeling studies supported a strong direct cation-heterocycle interaction between the Lys-155 side chain of the double substitution, R155K/D168A, and the lone pair on the quinoxaline in grazoprevir. This unique interaction provides a structural basis for grazoprevir's higher potency than simeprevir, an inhibitor to which the double substitution confers a significant reduction in potency. Our findings are consistent with the detection of R155K/D168A in NS3 from virologic failures treated with simeprevir but not grazoprevir.


Subject(s)
Hepacivirus/enzymology , Molecular Dynamics Simulation , Mutation, Missense , Quinoxalines/chemistry , Viral Nonstructural Proteins/antagonists & inhibitors , Viral Nonstructural Proteins/chemistry , Amides , Amino Acid Substitution , Carbamates , Cell Line, Tumor , Cyclopropanes , Hepacivirus/genetics , Hepatitis C/drug therapy , Hepatitis C/enzymology , Hepatitis C/genetics , Humans , Quinoxalines/therapeutic use , Simeprevir/chemistry , Simeprevir/therapeutic use , Sulfonamides , Viral Nonstructural Proteins/genetics , Viral Nonstructural Proteins/metabolism
8.
J Med Chem ; 60(1): 290-306, 2017 01 12.
Article in English | MEDLINE | ID: mdl-27808515

ABSTRACT

We describe the research that led to the discovery of compound 40 (ruzasvir, MK-8408), a pan-genotypic HCV nonstructural protein 5A (NS5A) inhibitor with a "flat" GT1 mutant profile. This NS5A inhibitor contains a unique tetracyclic indole core while maintaining the imidazole-proline-valine Moc motifs of our previous NS5A inhibitors. Compound 40 is currently in early clinical trials and is under evaluation as part of an all-oral DAA regimen for the treatment of chronic HCV infection.


Subject(s)
Antiviral Agents/chemistry , Antiviral Agents/pharmacology , Hepacivirus/drug effects , Heterocyclic Compounds, 4 or More Rings/chemistry , Heterocyclic Compounds, 4 or More Rings/pharmacology , Polymorphism, Genetic , Pyrrolidines/chemistry , Pyrrolidines/pharmacology , Thiazoles/chemistry , Thiazoles/pharmacology , Viral Nonstructural Proteins/antagonists & inhibitors , Animals , Antiviral Agents/pharmacokinetics , Cell Line , Dogs , Haplorhini , Hepacivirus/genetics , Heterocyclic Compounds, 4 or More Rings/pharmacokinetics , Humans , Pyrrolidines/pharmacokinetics , Rats , Structure-Activity Relationship , Thiazoles/pharmacokinetics
9.
J Med Chem ; 59(22): 10228-10243, 2016 11 23.
Article in English | MEDLINE | ID: mdl-27792320

ABSTRACT

The discovery of potent and pan-genotypic HCV NS5A inhibitors faces many challenges including the significant diversity among genotypes, substantial potency shift conferred on some key resistance-associated variants, inconsistent SARs between different genotypes and mutants, and the lacking of models of inhibitor/protein complexes for rational inhibitor design. As part of ongoing efforts on HCV NS5A inhibition at Merck, we now describe the discovery of a novel series of chromane containing NS5A inhibitors. SAR studies around the "Z" group of the tetracyclic indole scaffold explored fused bicyclic rings as alternates to the phenyl group of elbasvir (1, MK-8742) and identified novel chromane and 2,3-dihydrobenzofuran derivatives as "Z" group replacements offered good potency across all genotypes. This effort, incorporating the C-1 fluoro substitution at the tetracyclic indole core, led to the discovery of a new series of NS5A inhibitors, such as compounds 14 and 25-28, with significantly improved potency against resistance-associated variants, such as GT2b, GT1a Y93H, and GT1a L31V. Compound 14 also showed reasonable PK exposures in preclinical species (rat and dog).


Subject(s)
Antiviral Agents/pharmacology , Chromans/pharmacology , Drug Discovery , Drug Resistance, Viral/drug effects , Hepacivirus/drug effects , Viral Nonstructural Proteins/antagonists & inhibitors , Animals , Antiviral Agents/chemical synthesis , Antiviral Agents/chemistry , Chromans/chemical synthesis , Chromans/chemistry , Dogs , Dose-Response Relationship, Drug , Male , Microbial Sensitivity Tests , Molecular Structure , Rats , Rats, Wistar , Structure-Activity Relationship
11.
Bioorg Med Chem Lett ; 26(19): 4851-4856, 2016 10 01.
Article in English | MEDLINE | ID: mdl-27568086

ABSTRACT

As part of an ongoing effort in NS5A inhibition at Merck we now describe our efforts for introducing substitution around the tetracyclic indole core of MK-8742. Fluoro substitution on the core combined with the fluoro substitutions on the proline ring improved the potency against GT1a Y93H significantly. However, no improvement on GT2b potency was achieved. Limiting the fluoro substitution to C-1 of the tetracyclic indole core had a positive impact on the potency against the resistance associated variants, such as GT1a Y93H and GT2b, and the PK profile as well. Compounds, such as 62, with reduced potency shifts between wild type GT1a to GT2b, GT1a Y93H, and GT1a L31V were identified.


Subject(s)
Antiviral Agents/pharmacology , Benzofurans/pharmacology , Imidazoles/pharmacology , Indoles/pharmacology , Viral Nonstructural Proteins/antagonists & inhibitors , Antiviral Agents/chemistry , Antiviral Agents/pharmacokinetics , Benzofurans/chemistry , Benzofurans/pharmacokinetics , Imidazoles/chemistry , Imidazoles/pharmacokinetics , Indoles/chemistry , Indoles/pharmacokinetics , Structure-Activity Relationship
12.
Bioorg Med Chem Lett ; 26(15): 3414-20, 2016 08 01.
Article in English | MEDLINE | ID: mdl-27394665

ABSTRACT

Herein we describe our research efforts around the aryl and heteroaryl substitutions at the aminal carbon of the tetracyclic indole-based HCV NS5A inhibitor MK-8742. A series of potent NS5A inhibitors are described, such as compounds 45-47, 54, 56, and 65, which showed improved potency against clinically relevant and resistance associated HCV variants. The improved potency profiles of these compounds demonstrated an SAR that can improve the potency against GT2b, GT1a Y93H, and GT1a L31V altogether, which was unprecedented in our previous efforts in NS5A inhibition.


Subject(s)
Antiviral Agents/pharmacology , Benzofurans/pharmacology , Hepacivirus/drug effects , Imidazoles/pharmacology , Viral Nonstructural Proteins/antagonists & inhibitors , Animals , Antiviral Agents/chemical synthesis , Antiviral Agents/chemistry , Benzofurans/chemical synthesis , Benzofurans/chemistry , Dose-Response Relationship, Drug , Imidazoles/chemical synthesis , Imidazoles/chemistry , Male , Microbial Sensitivity Tests , Molecular Structure , Rats , Rats, Sprague-Dawley , Structure-Activity Relationship
13.
Bioorg Med Chem Lett ; 26(15): 3800-5, 2016 08 01.
Article in English | MEDLINE | ID: mdl-27282742

ABSTRACT

HCV NS5A inhibitors have demonstrated impressive in vitro potency profiles in HCV replicon assays and robust HCV RNA titer reduction in the clinic making them attractive components for inclusion in an all oral fixed dose combination regimen for the treatment of HCV infection. Herein we describe our continued research efforts around the alkyl "Z group" modification of the tetracyclic indole-based NS5A inhibitor MK-8742, which led to the discovery of a series of potent NS5A inhibitors. Compounds 10 and 19 are of particular interests since they are as potent as our previous leads and have much improved rat pharmacokinetic profiles.


Subject(s)
Antiviral Agents/pharmacology , Benzofurans/pharmacology , Hepacivirus/drug effects , Imidazoles/pharmacology , Viral Nonstructural Proteins/antagonists & inhibitors , Animals , Antiviral Agents/chemical synthesis , Antiviral Agents/chemistry , Benzofurans/chemical synthesis , Benzofurans/chemistry , Dose-Response Relationship, Drug , Hepatitis C/drug therapy , Imidazoles/chemical synthesis , Imidazoles/chemistry , Male , Microbial Sensitivity Tests , Molecular Structure , Rats , Rats, Sprague-Dawley , Structure-Activity Relationship , Virus Replication/drug effects
14.
Bioorg Med Chem Lett ; 26(15): 3793-9, 2016 08 01.
Article in English | MEDLINE | ID: mdl-27282743

ABSTRACT

HCV NS5A inhibitors have demonstrated impressive in vitro virologic profiles in HCV replicon assays and robust HCV RNA titer reduction in the clinic making them attractive components for inclusion in an all oral fixed-dose combination (FDC) regimen for the treatment of HCV infection. Merck's effort in this area identified MK-4882 and MK-8325 as early development leads. Herein, we describe the discovery of potent macrocyclic NS5A inhibitors bearing the MK-8325 or MK-4882 core structure.


Subject(s)
Antiviral Agents/pharmacology , Drug Discovery , Hepacivirus/drug effects , Heterocyclic Compounds, 4 or More Rings/pharmacology , Macrocyclic Compounds/pharmacology , Viral Nonstructural Proteins/antagonists & inhibitors , Antiviral Agents/chemical synthesis , Antiviral Agents/chemistry , Dose-Response Relationship, Drug , Hepatitis C/drug therapy , Heterocyclic Compounds, 4 or More Rings/chemical synthesis , Heterocyclic Compounds, 4 or More Rings/chemistry , Macrocyclic Compounds/chemical synthesis , Macrocyclic Compounds/chemistry , Microbial Sensitivity Tests , Molecular Structure , Structure-Activity Relationship , Virus Replication/drug effects
15.
Antimicrob Agents Chemother ; 60(5): 2954-64, 2016 05.
Article in English | MEDLINE | ID: mdl-26926625

ABSTRACT

The selection of resistance-associated variants (RAVs) against single agents administered to patients chronically infected with hepatitis C virus (HCV) necessitates that direct-acting antiviral agents (DAAs) targeting multiple viral proteins be developed to overcome failure resulting from emergence of resistance. The combination of grazoprevir (formerly MK-5172), an NS3/4A protease inhibitor, and elbasvir (formerly MK-8742), an NS5A inhibitor, was therefore studied in genotype 1a (GT1a) replicon cells. Both compounds were independently highly potent in GT1a wild-type replicon cells, with 90% effective concentration (EC90) values of 0.9 nM and 0.006 nM for grazoprevir and elbasvir, respectively. No cross-resistance was observed when clinically relevant NS5A and NS3 RAVs were profiled against grazoprevir and elbasvir, respectively. Kinetic analyses of HCV RNA reduction over 14 days showed that grazoprevir and elbasvir inhibited prototypic NS5A Y93H and NS3 R155K RAVs, respectively, with kinetics comparable to those for the wild-type GT1a replicon. In combination, grazoprevir and elbasvir interacted additively in GT1a replicon cells. Colony formation assays with a 10-fold multiple of the EC90 values of the grazoprevir-elbasvir inhibitor combination suppressed emergence of resistant colonies, compared to a 100-fold multiple for the independent agents. The selected resistant colonies with the combination harbored RAVs that required two or more nucleotide changes in the codons. Mutations in the cognate gene caused greater potency losses for elbasvir than for grazoprevir. Replicons bearing RAVs identified from resistant colonies showed reduced fitness for several cell lines and may contribute to the activity of the combination. These studies demonstrate that the combination of grazoprevir and elbasvir exerts a potent effect on HCV RNA replication and presents a high genetic barrier to resistance. The combination of grazoprevir and elbasvir is currently approved for chronic HCV infection.


Subject(s)
Antiviral Agents/pharmacology , Protease Inhibitors/pharmacology , Quinoxalines/pharmacology , Amides , Benzofurans/pharmacology , Carbamates , Cyclopropanes , Drug Therapy, Combination , Genotype , Hepacivirus/drug effects , Imidazoles/pharmacology , Mutation/genetics , Replicon/drug effects , Replicon/genetics , Ribavirin/pharmacology , Sulfonamides
16.
Antimicrob Agents Chemother ; 59(11): 6922-9, 2015 Nov.
Article in English | MEDLINE | ID: mdl-26303801

ABSTRACT

Elbasvir is an investigational NS5A inhibitor with in vitro activity against multiple HCV genotypes. Antiviral activity of elbasvir was measured in replicons derived from wild-type or resistant variants of genotypes 1a, 1b, and 3. The barrier to resistance was assessed by the number of resistant colonies selected by exposure to various elbasvir concentrations. In a phase 1b dose-escalating study, virologic responses were determined in 48 noncirrhotic adult men with chronic genotype 1 or 3 infections randomized to placebo or elbasvir from 5 to 50 mg (genotype 1) or 10 to 100 mg (genotype 3) once daily for 5 days. The NS5A gene was sequenced from plasma specimens obtained before, during, and after treatment. Elbasvir suppressed the emergence of resistance-associated variants (RAVs) in vitro in a dose-dependent manner. Variants selected by exposure to high elbasvir concentrations typically encoded multiple amino acid substitutions (most commonly involving loci 30, 31, and 93), conferring high-level elbasvir resistance. In the monotherapy study, patients with genotype 1b had greater reductions in HCV RNA levels than patients with genotype 1a at all elbasvir doses; responses in patients with genotype 3 were generally less pronounced than for genotype 1, particularly at lower elbasvir doses. M28T, Q30R, L31V, and Y93H in genotype 1a, L31V and Y93H in genotype 1b, and A30K, L31F, and Y93H in genotype 3 were the predominant RAVs selected by elbasvir monotherapy. Virologic findings in patients were consistent with the preclinical observations. NS5A-RAVs emerged most often at amino acid positions 28, 30, 31, and 93 in both the laboratory and clinical trial. (The MK-8742 P002 trial has been registered at ClinicalTrials.gov under identifier NCT01532973.).


Subject(s)
Benzofurans/pharmacology , Hepacivirus/drug effects , Imidazoles/pharmacology , Adolescent , Adult , Female , Genotype , Hepacivirus/genetics , Humans , Male , Middle Aged , Replicon/genetics , Young Adult
17.
Clin Infect Dis ; 59(12): 1657-65, 2014 Dec 15.
Article in English | MEDLINE | ID: mdl-25266289

ABSTRACT

BACKGROUND: Virologic failure following treatment of hepatitis C virus (HCV) genotype 1 with direct-acting antiviral agents is often accompanied by the emergence of resistant variants. MK-5172 is an investigational once-daily protease inhibitor. We analyzed variants in treatment-naive noncirrhotic patients with virologic failure on MK-5172 (100-800 mg/day) plus pegylated interferon alfa/ribavirin (peg-IFN/RBV) during a phase 2 trial. METHODS: Population and selective clonal sequencing were performed at baseline and at virologic failure in the 4 MK-5172 dosing arms. MK-5172 activity was determined using a mutant replicon assay. RESULTS: Six of 266 (2.3%) MK-5172 recipients satisfied prespecified criteria for virologic failure, all with genotype 1a infection. Five patients with virologic failure were in the MK-5172 100-mg arm, including 4 patients with low plasma MK-5172 levels documented during triple therapy. Variants associated with >4-fold loss of potency were detected in 3 of the 4 patients with genotype 1a breakthrough while on MK-5172. The fifth patient had undetectable HCV-RNA levels at the end of triple therapy but subsequently broke through during the peg-IFN/RBV tail 16 weeks after completion of MK-5172. Three patients had D168 variants at virologic failure, including 2 with the D168A variant associated with a 95-fold loss of potency. The sole apparent relapse was actually a genotype 3a reinfection in the MK-5172 200-mg group. CONCLUSIONS: Virologic failure occurred uncommonly (6/266 [2.3%]) in MK-5172/peg-IFN/RBV recipients. The most prevalent treatment-emergent variants were detected at the D168 locus. D168A variants conferring approximately 2-log reduction in MK-5172 susceptibility emerged in 2 of the 4 evaluable patients with genotype 1a breakthrough. Clinical Trials Registration. NCT01353911.


Subject(s)
Hepatitis C/drug therapy , Interferons/therapeutic use , Quinoxalines/therapeutic use , Ribavirin/therapeutic use , Amides , Carbamates , Cyclopropanes , Drug Resistance, Viral , Genotype , Humans , Sulfonamides
18.
Anemia ; 2014: 634582, 2014.
Article in English | MEDLINE | ID: mdl-25587440

ABSTRACT

Hospitalized patients frequently have considerable volumes of blood removed for diagnostic testing which could lead to the development of hospital-acquired anemia. Low hemoglobin levels during hospitalization may result in significant morbidity for patients with underlying cardiorespiratory and other illnesses. We performed a retrospective study and data was collected using a chart review facilitated through an electronic medical record. A total of 479 patients who were not anemic during admission were included in analysis. In our study, we investigated the incidence of HAA and found that, between admission and discharge, 65% of patients dropped their hemoglobin by 1.0 g/dL or more, and 49% of patients developed anemia. We also found that the decrease in hemoglobin between admission and discharge did not differ significantly with smaller phlebotomy tubes. In multivariate analysis, we found that patients with longer hospitalization and those with lower BMI are at higher risk of developing HAA. In conclusion, our study confirms that hospital-acquired anemia is common. More aggressive strategies such as reducing the frequency of blood draws and expanding the use of smaller volume tubes for other laboratory panels may be helpful in reducing the incidence of HAA during hospitalization.

19.
Open Forum Infect Dis ; 1(2): ofu078, 2014 Sep.
Article in English | MEDLINE | ID: mdl-25734146

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.

20.
J Hepatol ; 59(1): 31-7, 2013 Jul.
Article in English | MEDLINE | ID: mdl-23454058

ABSTRACT

BACKGROUND & AIMS: To examine the antiviral activity of boceprevir, a hepatitis C virus (HCV) protease inhibitor, in HCV genotype (G) 2/3-infected patients. METHODS: We assessed boceprevir and telaprevir activity against an HCV G2 and G3 isolates enzyme panel, in replicon, and in phenotypic cell-based assays. Additionally, a phase I study evaluated the antiviral activity of boceprevir monotherapy (200mg BID, 400mg BID, or 400mg TID) vs. placebo for 14 days in HCV G2/3 treatment-naive patients. RESULTS: Boceprevir and telaprevir similarly inhibited G1 and G2 NS3/4A enzymes and replication in G1 and G2 replicon and cell-based assays. However, telaprevir demonstrated lower potency than boceprevir against HCV G3a enzyme (Ki=75 nM vs. 17 nM), in the G3a replicon assay (EC50=953 nM vs. 159 nM), and against HCV G3a NS3 isolates (IC50=3312 nM vs. 803 nM) in the cell-based assay. In HCV G2/3-infected patients, boceprevir (400 mg TID) resulted in a maximum mean decrease in HCV RNA of -1.60 log vs. -0.21 log with placebo. CONCLUSIONS: In vitro, boceprevir is more active than telaprevir against the HCV G3 NS3/4A enzyme in cell-based and biochemical assays and against G3 isolates in replicon assays. In HCV G2/3-infected treatment-naive patients, decreases in HCV RNA levels with boceprevir (400 mg TID) were comparable to those observed with the same dose in HCV treatment-experienced G1-infected patients.


Subject(s)
Antiviral Agents/therapeutic use , Hepacivirus/genetics , Hepatitis C, Chronic/drug therapy , Hepatitis C, Chronic/virology , Proline/analogs & derivatives , Adult , Antiviral Agents/administration & dosage , Antiviral Agents/pharmacokinetics , Female , Genotype , Hepacivirus/drug effects , Hepacivirus/enzymology , Humans , Kinetics , Male , Middle Aged , Oligopeptides/therapeutic use , Proline/administration & dosage , Proline/pharmacokinetics , Proline/therapeutic use , Protease Inhibitors/administration & dosage , Protease Inhibitors/pharmacokinetics , Protease Inhibitors/therapeutic use , RNA, Viral/blood , Replicon/drug effects , Viral Load/drug effects , Viral Nonstructural Proteins/antagonists & inhibitors
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