title: Preclinical characteristics of the hepatitis C virus NS3/4A protease inhibitor ITMN-191 (R7227).
abstract: Future treatments for chronic hepatitis C virus (HCV) infection are likely to include agents that target viral components directly. Here, the preclinical characteristics of ITMN-191, a peptidomimetic inhibitor of the NS3/4A protease of HCV, are described. ITMN-191 inhibited a reference genotype 1 NS3/4A protein in a time-dependent fashion, a hallmark of an inhibitor with a two-step binding mechanism and a low dissociation rate. Under preequilibrium conditions, 290 pM ITMN-191 half-maximally inhibited the reference NS3/4A protease, but a 35,000-fold-higher concentration did not appreciably inhibit a panel of 79 proteases, ion channels, transporters, and cell surface receptors. Subnanomolar biochemical potency was maintained against NS3/4A derived from HCV genotypes 4, 5, and 6, while single-digit nanomolar potency was observed against NS3/4A from genotypes 2b and 3a. Dilution of a preformed enzyme inhibitor complex indicated ITMN-191 remained bound to and inhibited NS3/4A for more than 5 h after its initial association. In cell-based potency assays, half-maximal reduction of genotype 1b HCV replicon RNA was afforded by 1.8 nM; 45 nM eliminated the HCV replicon from cells. Peginterferon alfa-2a displayed a significant degree of antiviral synergy with ITMN-191 and reduced the concentration of ITMN-191 required for HCV replicon elimination. A 30-mg/kg of body weight oral dose administered to rats or monkeys yielded liver concentrations 12 h after dosing that exceeded the ITMN-191 concentration required to eliminate replicon RNA from cells. These preclinical characteristics compare favorably to those of other inhibitors of NS3/4A in clinical development and therefore support the clinical investigation of ITMN-191 for the treatment of chronic hepatitis C.
authors.affiliation: InterMune, Inc., 3280 Bayshore Blvd., Brisbane, CA 94005, USA. sseiwert@intermune.com
authors.forename: Scott D
authors.initials: SD
authors.lastname: Seiwert
authors.forename: Steven W
authors.initials: SW
authors.lastname: Andrews
authors.forename: Yutong
authors.initials: Y
authors.lastname: Jiang
authors.forename: Vladimir
authors.initials: V
authors.lastname: Serebryany
authors.forename: Hua
authors.initials: H
authors.lastname: Tan
authors.forename: Karl
authors.initials: K
authors.lastname: Kossen
authors.forename: P T Ravi
authors.initials: PT
authors.lastname: Rajagopalan
authors.forename: Shawn
authors.initials: S
authors.lastname: Misialek
authors.forename: Sarah K
authors.initials: SK
authors.lastname: Stevens
authors.forename: Antitsa
authors.initials: A
authors.lastname: Stoycheva
authors.forename: Jin
authors.initials: J
authors.lastname: Hong
authors.forename: Sharlene R
authors.initials: SR
authors.lastname: Lim
authors.forename: Xiaoli
authors.initials: X
authors.lastname: Qin
authors.forename: Robert
authors.initials: R
authors.lastname: Rieger
authors.forename: Kevin R
authors.initials: KR
authors.lastname: Condroski
authors.forename: Hailong
authors.initials: H
authors.lastname: Zhang
authors.forename: Mary Geck
authors.initials: MG
authors.lastname: Do
authors.forename: Christine
authors.initials: C
authors.lastname: Lemieux
authors.forename: Gary P
authors.initials: GP
authors.lastname: Hingorani
authors.forename: Dylan P
authors.initials: DP
authors.lastname: Hartley
authors.forename: John A
authors.initials: JA
authors.lastname: Josey
authors.forename: Lin
authors.initials: L
authors.lastname: Pan
authors.forename: Leonid
authors.initials: L
authors.lastname: Beigelman
authors.forename: Lawrence M
authors.initials: LM
authors.lastname: Blatt
mesh_terms: D000818:Animals; D000998:Antiviral Agents / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology; D002352:Carrier Proteins / Q000037:antagonists & inhibitors*; D045744:Cell Line, Tumor; D004353:Drug Evaluation, Preclinical; D004357:Drug Synergism; D016174:Hepacivirus / Q000187:drug effects* / Q000201:enzymology* / Q000235:genetics / Q000502:physiology; D006801:Humans; D000077190:Interferon alpha-2; D016898:Interferon-alpha / Q000494:pharmacology; D047908:Intracellular Signaling Peptides and Proteins; D008099:Liver / Q000378:metabolism; D008252:Macaca fascicularis; D011092:Polyethylene Glycols / Q000494:pharmacology; D011480:Protease Inhibitors / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology; D051381:Rats; D011994:Recombinant Proteins; D017361:Viral Nonstructural Proteins / Q000037:antagonists & inhibitors*; D014764:Viral Proteins / Q000037:antagonists & inhibitors*; D014779:Virus Replication / Q000187:drug effects; D012697:Serine Endopeptidases; D043583:Nucleoside-Triphosphatase; D053487:DEAD-box RNA Helicases; D000085242:Viral Proteases
chemical_list: D000998:Antiviral Agents; D002352:Carrier Proteins; D000077190:Interferon alpha-2; D016898:Interferon-alpha; D047908:Intracellular Signaling Peptides and Proteins; D011092:Polyethylene Glycols; D011480:Protease Inhibitors; D011994:Recombinant Proteins; D017361:Viral Nonstructural Proteins; D014764:Viral Proteins; C084422:NS3 protein, hepatitis C virus; D012697:Serine Endopeptidases; D043583:Nucleoside-Triphosphatase; D053487:DEAD-box RNA Helicases; D000085242:Viral Proteases; C455041:NS4A cofactor peptide, Hepatitis C virus; C100416:peginterferon alfa-2a