title: In vivo antitumor activity of SU11248, a novel tyrosine kinase inhibitor targeting vascular endothelial growth factor and platelet-derived growth factor receptors: determination of a pharmacokinetic/pharmacodynamic relationship.
abstract: One challenging aspect in the clinical development of molecularly targeted therapies, which represent a new and promising approach to treating cancers, has been the identification of a biologically active dose rather than a maximum tolerated dose. The goal of the present study was to identify a pharmacokinetic/pharmacodynamic relationship in preclinical models that could be used to help guide selection of a clinical dose. SU11248, a novel small molecule receptor tyrosine kinase inhibitor with direct antitumor as well as antiangiogenic activity via targeting the vascular endothelial growth factor (VEGF), platelet-derived growth factor (PDGF), KIT, and FLT3 receptor tyrosine kinases, was used as the pharmacological agent in these studies. In mouse xenograft models, SU11248 exhibited broad and potent antitumor activity causing regression, growth arrest, or substantially reduced growth of various established xenografts derived from human or rat tumor cell lines. To predict the target SU11248 exposure required to achieve antitumor activity in mouse xenograft models, we directly measured target phosphorylation in tumor xenografts before and after SU11248 treatment and correlated this with plasma inhibitor levels. In target modulation studies in vivo, SU11248 selectively inhibited Flk-1/KDR (VEGF receptor 2) and PDGF receptor beta phosphorylation (in a time- and dose-dependent manner) when plasma concentrations of inhibitor reached or exceeded 50-100 ng/ml. Similar results were obtained in a functional assay of VEGF-induced vascular permeability in vivo. Constant inhibition of VEGFR2 and PDGF receptor beta phosphorylation was not required for efficacy; at highly efficacious doses, inhibition was sustained for 12 h of a 24-h dosing interval. The pharmacokinetic/pharmacodynamic relationship established for SU11248 in these preclinical studies has aided in the design, selection, and evaluation of dosing regimens being tested in human trials.
authors.affiliation: Preclinical Research and Exploratory Development, SUGEN, Inc, South San Francisco, California 94080, USA. dirk-mendel@sugen.com
authors.forename: Dirk B
authors.initials: DB
authors.lastname: Mendel
authors.forename: A Douglas
authors.initials: AD
authors.lastname: Laird
authors.forename: Xiaohua
authors.initials: X
authors.lastname: Xin
authors.forename: Sharianne G
authors.initials: SG
authors.lastname: Louie
authors.forename: James G
authors.initials: JG
authors.lastname: Christensen
authors.forename: Guangmin
authors.initials: G
authors.lastname: Li
authors.forename: Randall E
authors.initials: RE
authors.lastname: Schreck
authors.forename: Tinya J
authors.initials: TJ
authors.lastname: Abrams
authors.forename: Theresa J
authors.initials: TJ
authors.lastname: Ngai
authors.forename: Leslie B
authors.initials: LB
authors.lastname: Lee
authors.forename: Lesley J
authors.initials: LJ
authors.lastname: Murray
authors.forename: Jeremy
authors.initials: J
authors.lastname: Carver
authors.forename: Emily
authors.initials: E
authors.lastname: Chan
authors.forename: Katherine G
authors.initials: KG
authors.lastname: Moss
authors.forename: Joshua O
authors.initials: JO
authors.lastname: Haznedar
authors.forename: Juthamas
authors.initials: J
authors.lastname: Sukbuntherng
authors.forename: Robert A
authors.initials: RA
authors.lastname: Blake
authors.forename: Li
authors.initials: L
authors.lastname: Sun
authors.forename: Cho
authors.initials: C
authors.lastname: Tang
authors.forename: Todd
authors.initials: T
authors.lastname: Miller
authors.forename: Sheri
authors.initials: S
authors.lastname: Shirazian
authors.forename: Gerald
authors.initials: G
authors.lastname: McMahon
authors.forename: Julie M
authors.initials: JM
authors.lastname: Cherrington
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology*; D002455:Cell Division / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D005260:Female; D006801:Humans; D007211:Indoles / Q000494:pharmacology*; D020128:Inhibitory Concentration 50; D007700:Kinetics; D051379:Mice; D008819:Mice, Nude; D008956:Models, Chemical; D009368:Neoplasm Transplantation; D010766:Phosphorylation; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors*; D011758:Pyrroles / Q000494:pharmacology*; D017479:Receptors, Platelet-Derived Growth Factor / Q000378:metabolism*; D040262:Receptors, Vascular Endothelial Growth Factor / Q000378:metabolism*; D000077210:Sunitinib; D013997:Time Factors; D014407:Tumor Cells, Cultured
chemical_list: D000970:Antineoplastic Agents; D004791:Enzyme Inhibitors; D007211:Indoles; D011758:Pyrroles; D011505:Protein-Tyrosine Kinases; D017479:Receptors, Platelet-Derived Growth Factor; D040262:Receptors, Vascular Endothelial Growth Factor; D000077210:Sunitinib