title: Association of intratumoral vascular endothelial growth factor expression and clinical outcome for patients with gastrointestinal stromal tumors treated with imatinib mesylate.
abstract: OBJECTIVE
  Imatinib mesylate (imatinib) has revolutionized clinical outcomes of patients with advanced gastrointestinal stromal tumor (GIST). However, the degree of individual benefit varies, and little is known about prognostic factors for these patients. Importantly, selected patients may be treated with an approach to target both Kit and vascular endothelial growth factor receptor (VEGFR) expression.
  
  
  METHODS
  Using tissue microarray technology, we analyzed 53 imatinib-naive GISTs for vascular endothelial growth factor (VEGF) expression from patients who then received imatinib. In multivariate analyses, we evaluated overall survival (OS) and progression-free survival (PFS) of these patients based on putative prognostic factors, including VEGF expression. In a separate study, 12 matched pre-imatinib and post-imatinib GIST patient specimens and two human GIST cell lines were assessed for VEGF production in response to imatinib.
  
  
  RESULTS
  Independent of kit genotype, patients with GIST expressing high VEGF had inferior median PFS (7.1 months versus 29 months, P = 0.42) and median OS (20 months versus not reached at >50 months; P = 0.02) compared with weak or nonexpressers of VEGF. Non-exon 11 kit mutation predicted inferior PFS but not OS. High mitotic rate was marginally predictive of improved OS. Imatinib resulted in decreased production of VEGF in only a subset of GIST patients (2 of 12) and both cell lines.
  
  
  CONCLUSIONS
  We present a study to address the prognostic factors for patients with GIST in the imatinib era. We present a rationale to consider exploration of a front-line therapy of GIST with a regimen targeting both Kit and VEGFR based on the presence of tumor VEGF levels.
authors.affiliation: Department of Sarcoma Medical Oncology, University of Texas M. D. Anderson Cancer Center, 1515 Holcombe Boulevard, Houston, TX 77030, USA.
authors.forename: John C
authors.initials: JC
authors.lastname: McAuliffe
authors.forename: Alexander J F
authors.initials: AJ
authors.lastname: Lazar
authors.forename: Dan
authors.initials: D
authors.lastname: Yang
authors.forename: Dejka M
authors.initials: DM
authors.lastname: Steinert
authors.forename: Wei
authors.initials: W
authors.lastname: Qiao
authors.forename: Peter F
authors.initials: PF
authors.lastname: Thall
authors.forename: A Kevin
authors.initials: AK
authors.lastname: Raymond
authors.forename: Robert S
authors.initials: RS
authors.lastname: Benjamin
authors.forename: Jonathan C
authors.initials: JC
authors.lastname: Trent
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000970:Antineoplastic Agents / Q000627:therapeutic use*; D001549:Benzamides; D015331:Cohort Studies; D005260:Female; D046152:Gastrointestinal Stromal Tumors / Q000188:drug therapy*; D006801:Humans; D000068877:Imatinib Mesylate; D008297:Male; D008875:Middle Aged; D010879:Piperazines / Q000627:therapeutic use*; D011379:Prognosis; D047428:Protein Kinase Inhibitors / Q000627:therapeutic use*; D011743:Pyrimidines / Q000627:therapeutic use*; D046888:Tissue Array Analysis; D016896:Treatment Outcome; D042461:Vascular Endothelial Growth Factor A / Q000032:analysis / Q000235:genetics / Q000378:metabolism*
chemical_list: D000970:Antineoplastic Agents; D001549:Benzamides; D010879:Piperazines; D047428:Protein Kinase Inhibitors; D011743:Pyrimidines; D042461:Vascular Endothelial Growth Factor A; D000068877:Imatinib Mesylate