title: In vitro resistance studies of hepatitis C virus serine protease inhibitors, VX-950 and BILN 2061: structural analysis indicates different resistance mechanisms.
abstract: We have used a structure-based drug design approach to identify small molecule inhibitors of the hepatitis C virus (HCV) NS3.4A protease as potential candidates for new anti-HCV therapies. VX-950 is a potent NS3.4A protease inhibitor that was recently selected as a clinical development candidate for hepatitis C treatment. In this report, we describe in vitro resistance studies using a subgenomic replicon system to compare VX-950 with another HCV NS3.4A protease inhibitor, BILN 2061, for which the Phase I clinical trial results were reported recently. Distinct drug-resistant substitutions of a single amino acid were identified in the HCV NS3 serine protease domain for both inhibitors. The resistance conferred by these mutations was confirmed by characterization of the mutant enzymes and replicon cells that contain the single amino acid substitutions. The major BILN 2061-resistant mutations at Asp(168) are fully susceptible to VX-950, and the dominant resistant mutation against VX-950 at Ala(156) remains sensitive to BILN 2061. Modeling analysis suggests that there are different mechanisms of resistance to VX-950 and BILN 2061.
authors.affiliation: Vertex Pharmaceuticals Inc., Cambridge, Massachusetts 02139, USA. chao_lin@vrtx.com
authors.forename: Chao
authors.initials: C
authors.lastname: Lin
authors.forename: Kai
authors.initials: K
authors.lastname: Lin
authors.forename: Yu-Ping
authors.initials: YP
authors.lastname: Luong
authors.forename: B Govinda
authors.initials: BG
authors.lastname: Rao
authors.forename: Yun-Yi
authors.initials: YY
authors.lastname: Wei
authors.forename: Debra L
authors.initials: DL
authors.lastname: Brennan
authors.forename: John R
authors.initials: JR
authors.lastname: Fulghum
authors.forename: Hsun-Mei
authors.initials: HM
authors.lastname: Hsiao
authors.forename: Sue
authors.initials: S
authors.lastname: Ma
authors.forename: John P
authors.initials: JP
authors.lastname: Maxwell
authors.forename: Kevin M
authors.initials: KM
authors.lastname: Cottrell
authors.forename: Robert B
authors.initials: RB
authors.lastname: Perni
authors.forename: Cynthia A
authors.initials: CA
authors.lastname: Gates
authors.forename: Ann D
authors.initials: AD
authors.lastname: Kwong
mesh_terms: D000596:Amino Acids / Q000737:chemistry; D001224:Aspartic Acid / Q000737:chemistry; D001665:Binding Sites; D002219:Carbamates / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D004351:Drug Resistance; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D005799:Genes, Dominant; D016174:Hepacivirus / Q000201:enzymology*; D020128:Inhibitory Concentration 50; D007700:Kinetics; D047028:Macrocyclic Compounds; D008956:Models, Chemical; D008958:Models, Molecular; D009154:Mutation; D009842:Oligopeptides / Q000494:pharmacology*; D010957:Plasmids / Q000378:metabolism; D017434:Protein Structure, Tertiary; D011804:Quinolines; D015842:Serine Proteinase Inhibitors / Q000494:pharmacology*; D013844:Thiazoles / Q000494:pharmacology*; D013997:Time Factors; D017361:Viral Nonstructural Proteins / Q000037:antagonists & inhibitors / Q000737:chemistry*; D012697:Serine Endopeptidases; D043583:Nucleoside-Triphosphatase; D053487:DEAD-box RNA Helicases; D000085242:Viral Proteases
chemical_list: D000596:Amino Acids; D001224:Aspartic Acid; D002219:Carbamates; D004791:Enzyme Inhibitors; D047028:Macrocyclic Compounds; D009842:Oligopeptides; D011804:Quinolines; 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