title: Ponatinib inhibits polyclonal drug-resistant KIT oncoproteins and shows therapeutic potential in heavily pretreated gastrointestinal stromal tumor (GIST) patients.
abstract: OBJECTIVE
  KIT is the major oncogenic driver of gastrointestinal stromal tumors (GIST). Imatinib, sunitinib, and regorafenib are approved therapies; however, efficacy is often limited by the acquisition of polyclonal secondary resistance mutations in KIT, with those located in the activation (A) loop (exons 17/18) being particularly problematic. Here, we explore the KIT-inhibitory activity of ponatinib in preclinical models and describe initial characterization of its activity in patients with GIST.
  
  
  METHODS
  The cellular and in vivo activities of ponatinib, imatinib, sunitinib, and regorafenib against mutant KIT were evaluated using an accelerated mutagenesis assay and a panel of engineered and GIST-derived cell lines. The ponatinib-KIT costructure was also determined. The clinical activity of ponatinib was examined in three patients with GIST previously treated with all three FDA-approved agents.
  
  
  RESULTS
  In engineered and GIST-derived cell lines, ponatinib potently inhibited KIT exon 11 primary mutants and a range of secondary mutants, including those within the A-loop. Ponatinib also induced regression in engineered and GIST-derived tumor models containing these secondary mutations. In a mutagenesis screen, 40 nmol/L ponatinib was sufficient to suppress outgrowth of all secondary mutants except V654A, which was suppressed at 80 nmol/L. This inhibitory profile could be rationalized on the basis of structural analyses. Ponatinib (30 mg daily) displayed encouraging clinical activity in two of three patients with GIST.
  
  
  CONCLUSIONS
  Ponatinib possesses potent activity against most major clinically relevant KIT mutants and has demonstrated preliminary evidence of activity in patients with refractory GIST. These data strongly support further evaluation of ponatinib in patients with GIST.
authors.affiliation: ARIAD Pharmaceuticals, Inc, Cambridge, MA.
authors.forename: Andrew P
authors.initials: AP
authors.lastname: Garner
authors.affiliation: ARIAD Pharmaceuticals, Inc, Cambridge, MA.
authors.forename: Joseph M
authors.initials: JM
authors.lastname: Gozgit
authors.affiliation: ARIAD Pharmaceuticals, Inc, Cambridge, MA.
authors.forename: Rana
authors.initials: R
authors.lastname: Anjum
authors.affiliation: ARIAD Pharmaceuticals, Inc, Cambridge, MA.
authors.forename: Sadanand
authors.initials: S
authors.lastname: Vodala
authors.affiliation: ARIAD Pharmaceuticals, Inc, Cambridge, MA.
authors.forename: Alexa
authors.initials: A
authors.lastname: Schrock
authors.affiliation: ARIAD Pharmaceuticals, Inc, Cambridge, MA.
authors.forename: Tianjun
authors.initials: T
authors.lastname: Zhou
authors.affiliation: Department of Pathology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA.
authors.forename: Cesar
authors.initials: C
authors.lastname: Serrano
authors.affiliation: Department of Pathology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA.
authors.forename: Grant
authors.initials: G
authors.lastname: Eilers
authors.affiliation: Department of Pathology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA.
authors.forename: Meijun
authors.initials: M
authors.lastname: Zhu
authors.affiliation: Sarcoma Center, Dept. of Medical Oncology, West German Cancer Center, University of Duisburg-Essen, Essen, Germany.
authors.forename: Julia
authors.initials: J
authors.lastname: Ketzer
authors.affiliation: ARIAD Pharmaceuticals, Inc, Cambridge, MA.
authors.forename: Scott
authors.initials: S
authors.lastname: Wardwell
authors.affiliation: ARIAD Pharmaceuticals, Inc, Cambridge, MA.
authors.forename: Yaoyu
authors.initials: Y
authors.lastname: Ning
authors.affiliation: ARIAD Pharmaceuticals, Inc, Cambridge, MA.
authors.forename: Youngchul
authors.initials: Y
authors.lastname: Song
authors.affiliation: ARIAD Pharmaceuticals, Inc, Cambridge, MA.
authors.forename: Anna
authors.initials: A
authors.lastname: Kohlmann
authors.affiliation: ARIAD Pharmaceuticals, Inc, Cambridge, MA.
authors.forename: Frank
authors.initials: F
authors.lastname: Wang
authors.affiliation: ARIAD Pharmaceuticals, Inc, Cambridge, MA.
authors.forename: Tim
authors.initials: T
authors.lastname: Clackson
authors.affiliation: Portland VA Medical Center and OHSU Knight Cancer Institute, Portland, Oregon.
authors.forename: Michael C
authors.initials: MC
authors.lastname: Heinrich
authors.affiliation: Department of Pathology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA.
authors.forename: Jonathan A
authors.initials: JA
authors.lastname: Fletcher
authors.affiliation: Sarcoma Center, Dept. of Medical Oncology, West German Cancer Center, University of Duisburg-Essen, Essen, Germany.
authors.forename: Sebastian
authors.initials: S
authors.lastname: Bauer
authors.affiliation: ARIAD Pharmaceuticals, Inc, Cambridge, MA.
authors.forename: Victor M
authors.initials: VM
authors.lastname: Rivera
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000737:chemistry / Q000494:pharmacology* / Q000627:therapeutic use; D001549:Benzamides / Q000494:pharmacology; D045744:Cell Line, Tumor; D004195:Disease Models, Animal; D004305:Dose-Response Relationship, Drug; D019008:Drug Resistance, Neoplasm / Q000235:genetics*; D005091:Exons; D005260:Female; D046152:Gastrointestinal Stromal Tumors / Q000175:diagnosis / Q000188:drug therapy / Q000235:genetics* / Q000473:pathology; D006801:Humans; D000068877:Imatinib Mesylate; D007093:Imidazoles / Q000737:chemistry / Q000494:pharmacology* / Q000627:therapeutic use; D007211:Indoles / Q000494:pharmacology; D020128:Inhibitory Concentration 50; D008958:Models, Molecular; D008968:Molecular Conformation; D009154:Mutation; D009364:Neoplasm Recurrence, Local; D010879:Piperazines / Q000494:pharmacology; D011485:Protein Binding; D047428:Protein Kinase Inhibitors / Q000737:chemistry / Q000494:pharmacology* / Q000627:therapeutic use; D019009:Proto-Oncogene Proteins c-kit / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000235:genetics*; D011724:Pyridazines / Q000737:chemistry / Q000494:pharmacology* / Q000627:therapeutic use; D011743:Pyrimidines / Q000494:pharmacology; D011758:Pyrroles / Q000494:pharmacology; D000077210:Sunitinib; D014057:Tomography, X-Ray Computed; D047368:Tumor Burden / Q000187:drug effects / Q000235:genetics; D023041:Xenograft Model Antitumor Assays
chemical_list: D000970:Antineoplastic Agents; D001549:Benzamides; D007093:Imidazoles; D007211:Indoles; D010879:Piperazines; D047428:Protein Kinase Inhibitors; D011724:Pyridazines; D011743:Pyrimidines; D011758:Pyrroles; C545373:ponatinib; D000068877:Imatinib Mesylate; D019009:Proto-Oncogene Proteins c-kit; D000077210:Sunitinib