title: Inhibition of wild-type and mutant Bcr-Abl by pyrido-pyrimidine-type small molecule kinase inhibitors.
abstract: Imatinib mesylate (STI571, Glivec), a 2-phenylaminopyrimidine small-molecule ATP competitor-type kinase inhibitor, proved to be active in Philadelphia-positive leukemias. Resistance toward imatinib develops frequently in advanced-stage Philadelphia-positive leukemia, and is even observed in chronic-phase chronic myelogenous leukemia. Point mutations within the BCR-ABL kinase domain emerged as a major mechanism of resistance toward imatinib. Mutations occur at positions that determine specific contacts of imatinib to the ATP-binding site. We aimed to examine whether pyrido-pyrimidine-type kinase inhibitors were capable of inhibiting both wild-type and mutant forms of BCR-ABL. We screened 13 different pyrido-pyrimidine with cells expressing wild-type and mutant BCR-ABL. All of the substances specifically suppressed the Bcr-Abl dependent phenotype and inhibited Bcr-Abl kinase activity with higher potency than imatinib. Two of the most active compounds were PD166326 and SKI DV-M016. Interestingly, these compounds suppressed the activation loop mutant Bcr-Abl H396P as effectively as wild-type Bcr-Abl. In addition, nucleotide-binding loop mutations (Y253H, E255K, and E255V) were selectively and potently inhibited. In contrast, T315I, a mutant located at a position that makes a direct contact with imatinib, was not affected. This observation is consistent with the hypothesis that unlike imatinib, pyrido-pyrimidine inhibitors bind Bcr-Abl regardless of the conformation of the activation loop. We conclude that pyrido-pyrimidine-type kinase inhibitors are active against different frequently observed kinase domain mutations of BCR-ABL that cause resistance toward imatinib. Resistance as a consequence of selection of mutant BCR-ABL by imatinib may be overcome using second-generation kinase inhibitors because of their higher potency and their ability to bind Bcr-Abl irrespective of the conformation of the activation loop.
authors.affiliation: Department of Internal Medicine III, Technical University of Munich, Trogerstrasse 32, D-81675 Munich, Germany.
authors.forename: Nikolas
authors.initials: N
authors.lastname: von Bubnoff
authors.forename: Darren R
authors.initials: DR
authors.lastname: Veach
authors.forename: W Todd
authors.initials: WT
authors.lastname: Miller
authors.forename: Wanqing
authors.initials: W
authors.lastname: Li
authors.forename: Jana
authors.initials: J
authors.lastname: Sänger
authors.forename: Christian
authors.initials: C
authors.lastname: Peschel
authors.forename: William G
authors.initials: WG
authors.lastname: Bornmann
authors.forename: Bayard
authors.initials: B
authors.lastname: Clarkson
authors.forename: Justus
authors.initials: J
authors.lastname: Duyster
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D001549:Benzamides; D002455:Cell Division / Q000187:drug effects; D002461:Cell Line, Transformed; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D016044:Fusion Proteins, bcr-abl / Q000037:antagonists & inhibitors* / Q000235:genetics; D006801:Humans; D000068877:Imatinib Mesylate; D015464:Leukemia, Myelogenous, Chronic, BCR-ABL Positive / Q000201:enzymology / Q000235:genetics; D051379:Mice; D010879:Piperazines / Q000494:pharmacology; D017354:Point Mutation; D054198:Precursor Cell Lymphoblastic Leukemia-Lymphoma / Q000201:enzymology / Q000235:genetics; D047428:Protein Kinase Inhibitors; D011725:Pyridines / Q000494:pharmacology; D011743:Pyrimidines / Q000494:pharmacology*
chemical_list: D001549:Benzamides; D004791:Enzyme Inhibitors; C473352:PD 166326; D010879:Piperazines; D047428:Protein Kinase Inhibitors; D011725:Pyridines; D011743:Pyrimidines; D000068877:Imatinib Mesylate; D016044:Fusion Proteins, bcr-abl