title: In vitro studies of cross-resistance mutations against two hepatitis C virus serine protease inhibitors, VX-950 and BILN 2061.
abstract: VX-950 is a potent, small molecule, peptidomimetic inhibitor of the hepatitis C virus (HCV) NS3.4A serine protease and has recently been shown to possess antiviral activity in a phase I trial in patients chronically infected with genotype 1 HCV. In a previous study, we described in vitro resistance mutations against either VX-950 or another HCV NS3.4A protease inhibitor, BILN 2061. Single amino acid substitutions that conferred drug resistance (distinct for either inhibitor) were identified in the HCV NS3 serine protease domain. The dominant VX-950-resistant mutant (A156S) remains sensitive to BILN 2061. The major BILN 2061-resistant mutants (D168V and D168A) are fully susceptible to VX-950. Modeling analysis suggested that there are different mechanisms of resistance for these mutations induced by VX-950 or BILN 2061. In this study, we identified mutants that are cross-resistant to both HCV protease inhibitors. The cross-resistance conferred by substitution of Ala(156) with either Val or Thr was confirmed by characterization of the purified enzymes and reconstituted replicon cells containing the single amino acid substitution A156V or A156T. Both cross-resistance mutations (A156V and A156T) displayed significantly diminished fitness (or replication capacity) in a transient replicon cell system.
authors.affiliation: Vertex Pharmaceuticals Incorporated, Cambridge, Massachusetts 02139, USA. chao_lin@vrtx.com
authors.forename: Chao
authors.initials: C
authors.lastname: Lin
authors.forename: Cynthia A
authors.initials: CA
authors.lastname: Gates
authors.forename: B Govinda
authors.initials: BG
authors.lastname: Rao
authors.forename: Debra L
authors.initials: DL
authors.lastname: Brennan
authors.forename: John R
authors.initials: JR
authors.lastname: Fulghum
authors.forename: Yu-Ping
authors.initials: YP
authors.lastname: Luong
authors.forename: J Daniel
authors.initials: JD
authors.lastname: Frantz
authors.forename: Kai
authors.initials: K
authors.lastname: Lin
authors.forename: Sue
authors.initials: S
authors.lastname: Ma
authors.forename: Yun-Yi
authors.initials: YY
authors.lastname: Wei
authors.forename: Robert B
authors.initials: RB
authors.lastname: Perni
authors.forename: Ann D
authors.initials: AD
authors.lastname: Kwong
mesh_terms: D019943:Amino Acid Substitution; D000596:Amino Acids / Q000737:chemistry; D001224:Aspartic Acid / Q000737:chemistry; D001665:Binding Sites; D002219:Carbamates / Q000494:pharmacology*; D024882:Drug Resistance, Viral; D005799:Genes, Dominant; D016174:Hepacivirus / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics; D006801:Humans; D066298:In Vitro Techniques; D020128:Inhibitory Concentration 50; D007700:Kinetics; D047028:Macrocyclic Compounds / Q000494:pharmacology*; D008956:Models, Chemical; D008958:Models, Molecular; D009154:Mutation; D009842:Oligopeptides / Q000494:pharmacology*; D011804:Quinolines / Q000494:pharmacology*; D012367:RNA, Viral / Q000502:physiology; D012093:Replicon / Q000502:physiology; D015842:Serine Proteinase Inhibitors / Q000494:pharmacology*; D013844:Thiazoles / Q000494:pharmacology*; D017361:Viral Nonstructural Proteins / Q000737:chemistry / Q000235:genetics / Q000494:pharmacology*; D012697:Serine Endopeptidases; D043583:Nucleoside-Triphosphatase; D053487:DEAD-box RNA Helicases; D000085242:Viral Proteases
chemical_list: D000596:Amino Acids; D001224:Aspartic Acid; D002219:Carbamates; D047028:Macrocyclic Compounds; D009842:Oligopeptides; D011804:Quinolines; D012367:RNA, Viral; D015842:Serine Proteinase Inhibitors; D013844:Thiazoles; D017361:Viral Nonstructural Proteins; C479555:BILN 2061; C084422:NS3 protein, hepatitis C virus; D012697:Serine Endopeptidases; D043583:Nucleoside-Triphosphatase; D053487:DEAD-box RNA Helicases; D000085242:Viral Proteases; C486464:telaprevir