1.In vitro and in vivo activity of ATP-based kinase inhibitors AP23464 and AP23848 against activation-loop mutants of Kit.
Corbin AS1, Demehri S, Griswold IJ, Wang Y, Metcalf CA 3rd, Sundaramoorthi R, Shakespeare WC, Snodgrass J, Wardwell S, Dalgarno D, Iuliucci J, Sawyer TK, Heinrich MC, Druker BJ, Deininger MW. Blood. 2005 Jul 1;106(1):227-34. Epub 2005 Mar 3.
Oncogenic mutations of the Kit receptor tyrosine kinase occur in several types of malignancy. Juxtamembrane domain mutations are common in gastrointestinal stromal tumors, whereas mutations in the kinase activation loop, most commonly D816V, are seen in systemic mastocytosis and acute myelogenous leukemia. Kit activation-loop mutants are insensitive to imatinib mesylate and have been largely resistant to targeted inhibition. We determined the sensitivities of both Kit mutant classes to the adenosine triphosphate (ATP)-based inhibitors AP23464 and AP23848. In cell lines expressing activation-loop mutants, low-nM concentrations of AP23464 inhibited phosphorylation of Kit and its downstream targets Akt and signal transducer and activator of transcription 3 (STAT3). This was associated with cell-cycle arrest and apoptosis. Wild-type Kit-and juxtamembrane-mutant-expressing cell lines required considerably higher concentrations for equivalent inhibition, suggesting a therapeutic window in which cells harboring D816V Kit could be eliminated without interfering with normal cellular function.