title: Discovery and characterization of OC144-093, a novel inhibitor of P-glycoprotein-mediated multidrug resistance.
abstract: OC144-093 is a novel substituted diarylimidazole (Mr 495) generated using the OntoBLOCK system, a solid-phase combinatorial chemistry technology, in combination with high-throughput cell-based screening. OC144-093 reversed multidrug resistance (MDR) to doxorubicin, paclitaxel, and vinblastine in human lymphoma, breast, ovarian, uterine, and colorectal carcinoma cell lines expressing P-glycoprotein (P-gp) with an average EC50 of 0.032 microM. Inhibition of MDR by OC144-093 was reversible, but the effect persisted for at least 12 h after removal of compound from the culture medium. OC144-093 had no effect on the response to cytotoxic agents by cells in vitro lacking P-gp expression or expressing a multidrug resistance-associated protein (MRP-1). OC144-093 was not cytotoxic by itself against 15 normal, nontransformed, or tumor cell lines, regardless of P-gp status, with an average cytostatic IC50 of >60 microM. OC144-093 blocked the binding of [3H]azidopine to P-gp and inhibited P-gp ATPase activity. The compound was >50% p.o. bioavailable in rodents and dogs and did not alter the plasma pharmacokinetics of i.v.-administered paclitaxel. OC144-093 increased the life span of doxorubicin-treated mice engrafted with MDR P388 leukemia cells by >100% and significantly enhanced the in vivo antitumor activity of paclitaxel in MDR human breast and colon carcinoma xenograft models, without a significant increase in doxorubicin or paclitaxel toxicity. The results demonstrate that OC144-093 is an orally active, potent, and nontoxic inhibitor of P-gp-mediated multidrug resistance that exhibits all of the desired properties for treatment of P-gp-mediated MDR, as well as for prevention of MDR prior to selection and/or induction of refractory disease.
authors.affiliation: Ontogen Corporation, Carlsbad, California 92009, USA. michael.newman@ontogen.com
authors.forename: M J
authors.initials: MJ
authors.lastname: Newman
authors.forename: J C
authors.initials: JC
authors.lastname: Rodarte
authors.forename: K D
authors.initials: KD
authors.lastname: Benbatoul
authors.forename: S J
authors.initials: SJ
authors.lastname: Romano
authors.forename: C
authors.initials: C
authors.lastname: Zhang
authors.forename: S
authors.initials: S
authors.lastname: Krane
authors.forename: E J
authors.initials: EJ
authors.lastname: Moran
authors.forename: R T
authors.initials: RT
authors.lastname: Uyeda
authors.forename: R
authors.initials: R
authors.lastname: Dixon
authors.forename: E S
authors.initials: ES
authors.lastname: Guns
authors.forename: L D
authors.initials: LD
authors.lastname: Mayer
mesh_terms: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000037:antagonists & inhibitors*; D000251:Adenosine Triphosphatases / Q000378:metabolism; D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology; D000972:Antineoplastic Agents, Phytogenic / Q000494:pharmacology; D002455:Cell Division / Q000187:drug effects; D004285:Dogs; D004305:Dose-Response Relationship, Drug; D004317:Doxorubicin / Q000494:pharmacology; D018432:Drug Resistance, Multiple; D019008:Drug Resistance, Neoplasm; D005260:Female; D006801:Humans; D007093:Imidazoles / Q000737:chemistry / Q000494:pharmacology*; D020128:Inhibitory Concentration 50; D007700:Kinetics; D051379:Mice; D016513:Mice, SCID; D017239:Paclitaxel / Q000494:pharmacology; D051381:Rats; D013997:Time Factors; D014407:Tumor Cells, Cultured; D014747:Vinblastine / Q000494:pharmacology
chemical_list: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D000970:Antineoplastic Agents; D000972:Antineoplastic Agents, Phytogenic; D007093:Imidazoles; C410029:OC 144-093; D014747:Vinblastine; D004317:Doxorubicin; D000251:Adenosine Triphosphatases; D017239:Paclitaxel