title: Prediction of resistance to small molecule FLT3 inhibitors: implications for molecularly targeted therapy of acute leukemia.
abstract: Mutations in the receptor tyrosine kinase FLT3 occur frequently in patients with acute myeloid leukemia (AML) and acute lymphoblastic leukemia (ALL). Small molecules that selectively inhibit FLT3 kinase activity induce apoptosis in blasts from AML patients with FLT3 mutations and prolong survival in animal models of FLT3-induced myeloproliferative disease. A spectrum of structurally different small molecules with activity against FLT3 have been described, and their efficacy for treatment of AML and ALL is now being investigated in clinical trials. Here, we describe the results of an in vitro screen designed to identify mutations in the ATP-binding pocket of FLT3 that confer resistance to tyrosine kinase inhibitors. Mutations at four different positions (Ala-627, Asn-676, Phe-691, and Gly-697) were identified that confer varying degrees of resistance to PKC412, SU5614, or K-252a. FLT3 proteins mutated at Ala-627, Asn-676, or Phe-691 remained sensitive to higher concentrations of the inhibitors, but the G697R mutation conferred high-level resistance to each of these inhibitors as well as to six additional experimental inhibitors. These data provide insights into potential mechanisms of acquired resistance of FLT3 to small molecule inhibitors and indicate that the G697R mutation may be a clinically problematic resistance mutation that warrants proactive screening for additional inhibitors.
authors.affiliation: Division of Hematology, Department of Medicine, Brigham and Women's Hospital, Boston, MA, USA. jan.cools@med.kuleuven.ac.be
authors.forename: Jan
authors.initials: J
authors.lastname: Cools
authors.forename: Nicole
authors.initials: N
authors.lastname: Mentens
authors.forename: Pascal
authors.initials: P
authors.lastname: Furet
authors.forename: Doriano
authors.initials: D
authors.lastname: Fabbro
authors.forename: Jennifer J
authors.initials: JJ
authors.lastname: Clark
authors.forename: James D
authors.initials: JD
authors.lastname: Griffin
authors.forename: Peter
authors.initials: P
authors.lastname: Marynen
authors.forename: D Gary
authors.initials: DG
authors.lastname: Gilliland
mesh_terms: D000208:Acute Disease; D000595:Amino Acid Sequence; D000818:Animals; D019008:Drug Resistance, Neoplasm; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D007951:Leukemia, Myeloid / Q000188:drug therapy* / Q000201:enzymology / Q000235:genetics; D051379:Mice; D008958:Models, Molecular; D008969:Molecular Sequence Data; D017354:Point Mutation; D054198:Precursor Cell Lymphoblastic Leukemia-Lymphoma / Q000188:drug therapy* / Q000201:enzymology / Q000235:genetics; D017434:Protein Structure, Tertiary; D011518:Proto-Oncogene Proteins / Q000037:antagonists & inhibitors* / Q000235:genetics; D020794:Receptor Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors* / Q000235:genetics; D019311:Staurosporine / Q000031:analogs & derivatives* / Q000494:pharmacology*; D013329:Structure-Activity Relationship; D051941:fms-Like Tyrosine Kinase 3
chemical_list: D004791:Enzyme Inhibitors; D011518:Proto-Oncogene Proteins; C497971:Flt3 protein, mouse; D020794:Receptor Protein-Tyrosine Kinases; D051941:fms-Like Tyrosine Kinase 3; D019311:Staurosporine; C059539:midostaurin