title: Dynamics of IGF-1R expression during endocrine breast cancer treatment.
abstract: OBJECTIVE
  The aim was to assess changes in insulin-like growth factor 1 receptor (IGF-1R) expression with immunoSPECT/CT and to study the dynamics of IGF-1R expression of human breast tumors during endocrine treatment.
  
  
  METHODS
  Mice with MCF-7 xenografts were treated with estradiol or tamoxifen, and IGF-1R expression was measured by immunohistochemistry and immunoSPECT/CT using (111)In-R1507 (anti-IGF-1R antibody). Moreover, IGF-1R expression was analyzed immunohistochemically on 22 human breast tumors, treated preoperatively with endocrine therapy.
  
  
  RESULTS
  Estradiol resulted in an increased expression of IGF-1R, as measured by immunohistochemistry and immunoSPECT/CT. In contrast, tamoxifen resulted in a downregulation of IGF-1R, whereas this could not be measured with immunoSPECT/CT. A downregulation was also detectable in 9 out of 22 (41 %) human breast tumors after endocrine therapy.
  
  
  CONCLUSIONS
  Anti-estrogen treatment can cause a reduction in membranous IGF-1R expression. Based on these results, a combination of anti-IGF-1R antibodies with anti-estrogen therapy might not be a rational treatment strategy.
authors: Department of Nuclear Medicine, Radboud University Medical Center, P.O. Box 9101, 6500 HB, Nijmegen, The Netherlands, sandra.heskamp@radboudumc.nl.
authors: Sandra
authors: S
authors: Heskamp
authors: Otto C
authors: OC
authors: Boerman
authors: Janneke D M
authors: JD
authors: Molkenboer-Kuenen
authors: Rutger H T
authors: RH
authors: Koornstra
authors: Sabine C
authors: SC
authors: Linn
authors: Wim J G
authors: WJ
authors: Oyen
authors: Winette T A
authors: WT
authors: van der Graaf
authors: Hanneke W M
authors: HW
authors: van Laarhoven
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000494:pharmacology / Q000627:therapeutic use; D061067:Antibodies, Monoclonal, Humanized; D001943:Breast Neoplasms / Q000188:drug therapy* / Q000473:pathology; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D004958:Estradiol / Q000494:pharmacology / Q000627:therapeutic use*; D005260:Female; D006801:Humans; D061986:MCF-7 Cells; D051379:Mice; D008819:Mice, Nude; D008875:Middle Aged; D017526:Receptor, IGF Type 1 / Q000378:metabolism* / Q000494:pharmacology; D013629:Tamoxifen / Q000494:pharmacology / Q000627:therapeutic use*; D023041:Xenograft Model Antitumor Assays
chemical_list: D000911:Antibodies, Monoclonal; D061067:Antibodies, Monoclonal, Humanized; D013629:Tamoxifen; D004958:Estradiol; D017526:Receptor, IGF Type 1; C551399:teprotumumab