title: Preclinical analysis of the analinoquinazoline AG1478, a specific small molecule inhibitor of EGF receptor tyrosine kinase.
abstract: The tyrphostin 4-(3-chloroanilino)-6,7-dimethoxyquinazoline (AG1478) is a potent and specific inhibitor of EGFR tyrosine kinase whose favourable preclinical profile supports progression towards clinical trials. Microphysiometric evaluation revealed a short (<24 min) effective inhibition of cellular receptor response to EGF challenge in BaF/ERX cells indicating a need to maintain sustained levels of inhibitor. Initial pharmacokinetic evaluation in mice of novel AG1478 formulations in a beta-cyclodextrin (Captisol) showed monoexponential elimination from plasma (half-life 30 min) following subcutaneous administration. A two-fold dose escalation gave a 2.4-fold increase in the total AUC. Bolus i.v. and 6 h continuous infusion were investigated in rats to mimic a more clinically relevant administration regimen. Drug elimination following bolus i.v. administration was biphasic (terminal elimination half-life 30-48 min). The linear relationship between dose and AUC(0-->infinity) (r2=0.979) enabled the prediction of infusion rates and doses for sustained delivery using continuous 6 h infusions, where steady state was reached in 120 min. Plasma levels of AG1478>10 microM were achieved over the duration of the infusion. At the lowest dose, plasma drug levels after the cessation of infusion declined with a half-life of approximately 43 min. EGFR activity, measured both by autophosphorylation and downstream signalling, was inhibited in a dose-dependent manner by injection of AG1478 in mice bearing xenografts of the human glioblastoma cell line U87MG.delta2-7, which expresses a constitutively active variant of the EGF receptor. Taken together, these experiments provide essential data to assess the anti-tumour efficacy of AG1478 and will assist in the rational design of dose regimens for clinical studies.
authors.affiliation: Pharmacology and Developmental Therapeutics Unit, Trescowthick Research Laboratories, Peter MacCallum Cancer Centre, Melbourne, Vic., Australia.
authors.forename: A G
authors.initials: AG
authors.lastname: Ellis
authors.forename: M M
authors.initials: MM
authors.lastname: Doherty
authors.forename: F
authors.initials: F
authors.lastname: Walker
authors.forename: J
authors.initials: J
authors.lastname: Weinstock
authors.forename: M
authors.initials: M
authors.lastname: Nerrie
authors.forename: A
authors.initials: A
authors.lastname: Vitali
authors.forename: R
authors.initials: R
authors.lastname: Murphy
authors.forename: T G
authors.initials: TG
authors.lastname: Johns
authors.forename: A M
authors.initials: AM
authors.lastname: Scott
authors.forename: A
authors.initials: A
authors.lastname: Levitzki
authors.forename: G
authors.initials: G
authors.lastname: McLachlan
authors.forename: L K
authors.initials: LK
authors.lastname: Webster
authors.forename: A W
authors.initials: AW
authors.lastname: Burgess
authors.forename: E C
authors.initials: EC
authors.lastname: Nice
mesh_terms: D000818:Animals; D019540:Area Under Curve; D045744:Cell Line, Tumor; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000737:chemistry / Q000493:pharmacokinetics* / Q000494:pharmacology; D066246:ErbB Receptors / Q000037:antagonists & inhibitors*; D005909:Glioblastoma / Q000188:drug therapy / Q000378:metabolism / Q000473:pathology; D006801:Humans; D007275:Injections, Intravenous; D007279:Injections, Subcutaneous; D051379:Mice; D015394:Molecular Structure; D017027:Protein Tyrosine Phosphatases / Q000037:antagonists & inhibitors*; D011799:Quinazolines; D051381:Rats; D013936:Thymidine / Q000378:metabolism; D020032:Tyrphostins / Q000737:chemistry / Q000493:pharmacokinetics* / Q000494:pharmacology; D023041:Xenograft Model Antitumor Assays
chemical_list: D004791:Enzyme Inhibitors; D011799:Quinazolines; D020032:Tyrphostins; C101044:RTKI cpd; D066246:ErbB Receptors; D017027:Protein Tyrosine Phosphatases; D013936:Thymidine