title: Selecting tyrosine kinase inhibitors for gastrointestinal stromal tumor with secondary KIT activation-loop domain mutations.
abstract: Advanced gastrointestinal stromal tumors (GIST), a KIT oncogene-driven tumor, on imatinib mesylate (IM) treatment may develop secondary KIT mutations to confer IM-resistant phenotype. Second-line sunitinib malate (SU) therapy is largely ineffective for IM-resistant GISTs with secondary exon 17 (activation-loop domain) mutations. We established an in vitro cell-based platform consisting of a series of COS-1 cells expressing KIT cDNA constructs encoding common primary±secondary mutations observed in GISTs, to compare the activity of several commercially available tyrosine kinase inhibitors on inhibiting the phosphorylation of mutant KIT proteins at their clinically achievable plasma steady-state concentration (Css). The inhibitory efficacies on KIT exon 11/17 mutants were further validated by growth inhibition assay on GIST48 cells, and underlying molecular-structure mechanisms were investigated by molecular modeling. Our results showed that SU more effectively inhibited mutant KIT with secondary exon 13 or 14 mutations than those with secondary exon 17 mutations, as clinically indicated. On contrary, at individual Css, nilotinib and sorafenib more profoundly inhibited the phosphorylation of KIT with secondary exon 17 mutations and the growth of GIST48 cells than IM, SU, and dasatinib. Molecular modeling analysis showed fragment deletion of exon 11 and point mutation on exon 17 would lead to a shift of KIT conformational equilibrium toward active form, for which nilotinib and sorafenib bound more stably than IM and SU. In current preclinical study, nilotinib and sorafenib are more active in IM-resistant GISTs with secondary exon 17 mutation than SU that deserve further clinical investigation.
authors.affiliation: National Institute of Cancer Research, National Health Research Institutes, Tainan, Taiwan.
authors.forename: Yuan-Shuo
authors.initials: YS
authors.lastname: Hsueh
authors.forename: Chih-Lung
authors.initials: CL
authors.lastname: Lin
authors.forename: Nai-Jung
authors.initials: NJ
authors.lastname: Chiang
authors.forename: Chueh-Chuan
authors.initials: CC
authors.lastname: Yen
authors.forename: Chien-Feng
authors.initials: CF
authors.lastname: Li
authors.forename: Yan-Shen
authors.initials: YS
authors.lastname: Shan
authors.forename: Ching-Huai
authors.initials: CH
authors.lastname: Ko
authors.forename: Neng-Yao
authors.initials: NY
authors.lastname: Shih
authors.forename: Ling-Mei
authors.initials: LM
authors.lastname: Wang
authors.forename: Ting-Shou
authors.initials: TS
authors.lastname: Chen
authors.forename: Li-Tzong
authors.initials: LT
authors.lastname: Chen
mesh_terms: D020816:Amino Acid Motifs; D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology*; D001549:Benzamides / Q000494:pharmacology; D019556:COS Cells; D002522:Chlorocebus aethiops; D000069439:Dasatinib; D019008:Drug Resistance, Neoplasm / Q000235:genetics; D004354:Drug Screening Assays, Antitumor; D005770:Gastrointestinal Neoplasms / Q000188:drug therapy*; D046152:Gastrointestinal Stromal Tumors / Q000188:drug therapy*; D006801:Humans; D006860:Hydrogen Bonding; D000068877:Imatinib Mesylate; D007211:Indoles / Q000494:pharmacology; D062105:Molecular Docking Simulation; D020125:Mutation, Missense; D010879:Piperazines / Q000494:pharmacology; D011485:Protein Binding; D047428:Protein Kinase Inhibitors / Q000494:pharmacology*; D019009:Proto-Oncogene Proteins c-kit / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000235:genetics*; D011743:Pyrimidines / Q000494:pharmacology; D011758:Pyrroles / Q000494:pharmacology; D000077210:Sunitinib; D013844:Thiazoles / Q000494:pharmacology
chemical_list: D000970:Antineoplastic Agents; D001549:Benzamides; D007211:Indoles; D010879:Piperazines; D047428:Protein Kinase Inhibitors; D011743:Pyrimidines; D011758:Pyrroles; D013844:Thiazoles; D000068877:Imatinib Mesylate; D019009:Proto-Oncogene Proteins c-kit; C498826:nilotinib; D000069439:Dasatinib; D000077210:Sunitinib