title: Molecular Fluorescence Endoscopy Targeting Vascular Endothelial Growth Factor A for Improved Colorectal Polyp Detection.
abstract: Small and flat adenomas are known to carry a high miss-rate during standard white-light endoscopy. Increased detection rate may be achieved by molecular fluorescence endoscopy with targeted near-infrared (NIR) fluorescent tracers. The aim of this study was to validate vascular endothelial growth factor A (VEGF-A) and epidermal growth factor receptor (EGFR)-targeted fluorescent tracers during ex vivo colonoscopy with an NIR endoscopy platform.
  
  
  METHODS
  VEGF-A and EGFR expression was determined by immunohistochemistry on a large subset of human colorectal tissue samples--48 sessile serrated adenomas/polyps, 70 sporadic high-grade dysplastic adenomas, and 19 hyperplastic polyps--and tissue derived from patients with Lynch syndrome--78 low-grade dysplastic adenomas, 57 high-grade dysplastic adenomas, and 31 colon cancer samples. To perform an ex vivo colonoscopy procedure, 14 mice with small intraperitoneal EGFR-positive HCT116(luc) tumors received intravenous bevacizumab-800CW (anti-VEGF-A), cetuximab-800CW (anti-EGFR), control tracer IgG-800CW, or sodium chloride. Three days later, 8 resected HCT116(luc) tumors (2-5 mm) were stitched into 1 freshly resected human colon specimen and followed by an ex vivo molecular fluorescence colonoscopy procedure.
  
  
  RESULTS
  Immunohistochemistry showed high VEGF-A expression in 79%-96% and high EGFR expression in 51%-69% of the colorectal lesions. Both targets were significantly overexpressed in the colorectal lesions, compared with the adjacent normal colon crypts. During ex vivo molecular fluorescence endoscopy, all tumors could clearly be delineated for both bevacizumab-800CW and cetuximab-800CW tracers. Specific tumor uptake was confirmed with fluorescent microscopy showing, respectively, stromal and cell membrane fluorescence.
  
  
  CONCLUSIONS
  VEGF-A is a promising target for molecular fluorescence endoscopy because it showed a high protein expression, especially in sessile serrated adenomas/polyps and Lynch syndrome. We demonstrated the feasibility to visualize small tumors in real time during colonoscopy using a NIR fluorescence endoscopy platform, providing the endoscopist a wide-field red-flag technique for adenoma detection. Clinical studies are currently being performed in order to provide in-human evaluation of our approach.
authors.affiliation: Department of Gastroenterology and Hepatology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands.
authors.forename: Jolien J
authors.initials: JJ
authors.lastname: Tjalma
authors.affiliation: Chair for Biological Imaging & Institute for Biological and Medical Imaging, Technical University of Munich and Helmholtz Center Munich, Munich, Germany.
authors.forename: P Beatriz
authors.initials: PB
authors.lastname: Garcia-Allende
authors.affiliation: Department of Gastroenterology and Hepatology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands.
authors.forename: Elmire
authors.initials: E
authors.lastname: Hartmans
authors.affiliation: Department of Clinical Pharmacy and Pharmacology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands.
authors.forename: Anton G
authors.initials: AG
authors.lastname: Terwisscha van Scheltinga
authors.affiliation: Department of Gastroenterology and Hepatology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands.
authors.forename: Wytske
authors.initials: W
authors.lastname: Boersma-van Ek
authors.affiliation: Chair for Biological Imaging & Institute for Biological and Medical Imaging, Technical University of Munich and Helmholtz Center Munich, Munich, Germany.
authors.forename: Jürgen
authors.initials: J
authors.lastname: Glatz
authors.affiliation: Chair for Biological Imaging & Institute for Biological and Medical Imaging, Technical University of Munich and Helmholtz Center Munich, Munich, Germany.
authors.forename: Maximilian
authors.initials: M
authors.lastname: Koch
authors.affiliation: Department of Gastroenterology and Hepatology, Radboud University Medical Center, Nijmegen, The Netherlands.
authors.forename: Yasmijn J
authors.initials: YJ
authors.lastname: van Herwaarden
authors.affiliation: Department of Gastroenterology and Hepatology, Radboud University Medical Center, Nijmegen, The Netherlands.
authors.forename: Tanya M
authors.initials: TM
authors.lastname: Bisseling
authors.affiliation: Department of Pathology, Radboud University Medical Center, Nijmegen, The Netherlands.
authors.forename: Iris D
authors.initials: ID
authors.lastname: Nagtegaal
authors.affiliation: Department of Medical Oncology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands.
authors.forename: Hetty
authors.initials: H
authors.lastname: Timmer-Bosscha
authors.affiliation: Department of Gastroenterology and Hepatology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands.
authors.forename: Jan Jacob
authors.initials: JJ
authors.lastname: Koornstra
authors.affiliation: Department of Pathology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands; and.
authors.forename: Arend
authors.initials: A
authors.lastname: Karrenbeld
authors.affiliation: Department of Gastroenterology and Hepatology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands.
authors.forename: Jan H
authors.initials: JH
authors.lastname: Kleibeuker
authors.affiliation: Department of Surgery, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands.
authors.forename: Gooitzen M
authors.initials: GM
authors.lastname: van Dam
authors.affiliation: Chair for Biological Imaging & Institute for Biological and Medical Imaging, Technical University of Munich and Helmholtz Center Munich, Munich, Germany.
authors.forename: Vasilis
authors.initials: V
authors.lastname: Ntziachristos
authors.affiliation: Department of Gastroenterology and Hepatology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands w.b.nagengast@umcg.nl.
authors.forename: Wouter B
authors.initials: WB
authors.lastname: Nagengast
mesh_terms: D000818:Animals; D045744:Cell Line, Tumor; D003111:Colonic Polyps / Q000175:diagnosis* / Q000473:pathology*; D003113:Colonoscopy / Q000379:methods; D016099:Endoscopy, Gastrointestinal / Q000379:methods*; D066246:ErbB Receptors / Q000378:metabolism; D005453:Fluorescence; D005456:Fluorescent Dyes; D006801:Humans; D007150:Immunohistochemistry; D051379:Mice; D057054:Molecular Imaging / Q000379:methods*; D012004:Rectal Neoplasms / Q000175:diagnosis* / Q000473:pathology*; D015203:Reproducibility of Results; D042461:Vascular Endothelial Growth Factor A / Q000378:metabolism*
chemical_list: D005456:Fluorescent Dyes; C467484:VEGFA protein, human; D042461:Vascular Endothelial Growth Factor A; D066246:ErbB Receptors
keywords: endoscopy; molecular imaging; near-infrared fluorescence; optical imaging; vascular endothelial growth factor A