title: Flumatinib, a selective inhibitor of BCR-ABL/PDGFR/KIT, effectively overcomes drug resistance of certain KIT mutants.
abstract: Activating mutations in KIT have been associated with gastrointestinal stromal tumors (GISTs). The tyrosine kinase inhibitor imatinib mesylate has revolutionized the treatment of GISTs. Unfortunately, primary or acquired resistance to imatinib does occur in GISTs and forms a major problem. Although sunitinib malate, a multi-kinase inhibitor, has shown effectiveness against imatinib-resistant GISTs, recent studies have indicated that some imatinib-resistant GISTs harboring secondary mutations in the KIT activation loop were also resistant to sunitinib. Therefore, new drugs capable of overcoming the dual drug resistance of GISTs probably have potential clinical utility. In this study, we investigated the efficacy of flumatinib, an inhibitor of BCR-ABL/PDGFR/KIT, against 32D cells transformed by various KIT mutants and evaluated its potency to overcome the drug resistance of certain mutants. Interestingly, our in vitro study revealed that flumatinib effectively overcame the drug resistance of certain KIT mutants with activation loop mutations (i.e., D820G, N822K, Y823D, and A829P). Our in vivo study consistently suggested that flumatinib had superior efficacy compared with imatinib or sunitinib against 32D cells with the secondary mutation Y823D. Molecular modeling of flumatinib docked to the KIT kinase domain suggested a special mechanism underlying the capability of flumatinib to overcome the drug-resistance conferred by activation loop mutations. These findings suggest that flumatinib could be a promising therapeutic agent against GISTs resistant to both imatinib and sunitinib because of secondary mutations in the activation loop.
authors.affiliation: Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China.
authors.forename: Jie
authors.initials: J
authors.lastname: Zhao
authors.forename: Haitian
authors.initials: H
authors.lastname: Quan
authors.forename: Yongping
authors.initials: Y
authors.lastname: Xu
authors.forename: Xiangqian
authors.initials: X
authors.lastname: Kong
authors.forename: Lu
authors.initials: L
authors.lastname: Jin
authors.forename: Liguang
authors.initials: L
authors.lastname: Lou
mesh_terms: D000631:Aminopyridines / Q000494:pharmacology*; D000818:Animals; D000970:Antineoplastic Agents / Q000009:adverse effects / Q000494:pharmacology; D001549:Benzamides / Q000009:adverse effects / Q000494:pharmacology*; D045744:Cell Line, Tumor; D019008:Drug Resistance, Neoplasm; D005260:Female; D016044:Fusion Proteins, bcr-abl / Q000037:antagonists & inhibitors*; D046152:Gastrointestinal Stromal Tumors / Q000188:drug therapy* / Q000201:enzymology / Q000235:genetics; D000068877:Imatinib Mesylate; D007211:Indoles / Q000009:adverse effects / Q000494:pharmacology; D007377:Interleukin-3 / Q000235:genetics; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D009154:Mutation; D010879:Piperazines / Q000009:adverse effects / Q000494:pharmacology; D010982:Platelet-Derived Growth Factor / Q000037:antagonists & inhibitors*; D047428:Protein Kinase Inhibitors / Q000009:adverse effects / Q000494:pharmacology*; D019009:Proto-Oncogene Proteins c-kit / Q000037:antagonists & inhibitors* / Q000235:genetics; D011743:Pyrimidines / Q000009:adverse effects / Q000494:pharmacology; D011758:Pyrroles / Q000009:adverse effects / Q000494:pharmacology; D011897:Random Allocation; D000077210:Sunitinib
chemical_list: D000631:Aminopyridines; D000970:Antineoplastic Agents; D001549:Benzamides; D007211:Indoles; D007377:Interleukin-3; D010879:Piperazines; D010982:Platelet-Derived Growth Factor; D047428:Protein Kinase Inhibitors; D011743:Pyrimidines; D011758:Pyrroles; D000068877:Imatinib Mesylate; D019009:Proto-Oncogene Proteins c-kit; D016044:Fusion Proteins, bcr-abl; C553360:flumatinib; D000077210:Sunitinib
keywords: Drug resistance; flumatinib; gastrointestinal stromal tumors; imatinib mesylate; sunitinib malate