title: Fluorescent Affibody Molecule Administered In Vivo at a Microdose Level Labels EGFR Expressing Glioma Tumor Regions.
abstract: Fluorescence guidance in surgical oncology provides the potential to realize enhanced molecular tumor contrast with dedicated targeted tracers, potentially with a microdose injection level. For most glioma tumors, the blood brain barrier is compromised allowing some exogenous drug/molecule delivery and accumulation for imaging. The aberrant overexpression and/or activation of epidermal growth factor receptor (EGFR) is associated with many types of cancers, including glioblastoma, and so the use of a near-infrared (NIR) fluorescent molecule targeted to the EGFR receptor provides the potential for improving tumor contrast during surgery. Fluorescently labeled affibody molecule (ABY-029) has high EGFR affinity and high potential specificity with reasonably fast plasma clearance. In this study, ABY-29 was evaluated in glioma versus normal brain uptake from intravenous injection at a range of doses, down to a microdose injection level.
  
  
  
  Nude rats were inoculated with the U251 human glioma cell line in the brain. Tumors were allowed to grow for 3-4 weeks. ABY-029 fluorescence ex vivo imaging of brain slices was acquired at different time points (1-48 h) and varying injection doses from 25 to 122 μg/kg (from human protein microdose equivalent to five times microdose levels).
  
  
  
  The tumor was most clearly visualized at 1-h post-injection with 8- to 16-fold average contrast relative to normal brain. However, the tumor still could be identified after 48 h. In all cases, the ABY-029 fluorescence appeared to localize preferentially in EGFR-positive regions. Increasing the injected dose from a microdose level to five times, a microdose level increased the signal by 10-fold, and the contrast was from 8 to 16, showing that there was value in doses slightly higher than the microdose restriction. Normal tissue uptake was found to be affected by the tumor size, indicating that edema was a likely factor affecting the expected tumor to normal tissue contrast.
  
  
  
  These results suggest that the NIR-labeled affibody molecules provide an excellent potential to increase surgical visualization of EGFR-positive tumor regions.
authors.affiliation: Thayer School of Engineering, Dartmouth College, 14 Engineering Drive, Hanover, NH, 03755, USA.|CAPES Foundation, Ministry of Education of Brazil, Brasilia, DF, 70040-020, Brazil.
authors.forename: Ana Luiza Ribeiro
authors.initials: AL
authors.lastname: de Souza
authors.affiliation: Thayer School of Engineering, Dartmouth College, 14 Engineering Drive, Hanover, NH, 03755, USA.
authors.forename: Kayla
authors.initials: K
authors.lastname: Marra
authors.affiliation: Thayer School of Engineering, Dartmouth College, 14 Engineering Drive, Hanover, NH, 03755, USA.
authors.forename: Jason
authors.initials: J
authors.lastname: Gunn
authors.affiliation: Thayer School of Engineering, Dartmouth College, 14 Engineering Drive, Hanover, NH, 03755, USA.|Department of Surgery, Geisel School of Medicine, Dartmouth College, Lebanon, NH, 03756, USA.
authors.forename: Kimberley S
authors.initials: KS
authors.lastname: Samkoe
authors.affiliation: Thayer School of Engineering, Dartmouth College, 14 Engineering Drive, Hanover, NH, 03755, USA.|Department of Surgery, Geisel School of Medicine, Dartmouth College, Lebanon, NH, 03756, USA.
authors.forename: P Jack
authors.initials: PJ
authors.lastname: Hoopes
authors.affiliation: Affibody AB, SE-171 69, Solna, Sweden.
authors.forename: Joachim
authors.initials: J
authors.lastname: Feldwisch
authors.affiliation: Thayer School of Engineering, Dartmouth College, 14 Engineering Drive, Hanover, NH, 03755, USA.|Department of Surgery, Geisel School of Medicine, Dartmouth College, Lebanon, NH, 03756, USA.
authors.forename: Keith D
authors.initials: KD
authors.lastname: Paulsen
authors.affiliation: Thayer School of Engineering, Dartmouth College, 14 Engineering Drive, Hanover, NH, 03755, USA. brian.w.pogue@dartmouth.edu.|Department of Surgery, Geisel School of Medicine, Dartmouth College, Lebanon, NH, 03756, USA. brian.w.pogue@dartmouth.edu.
authors.forename: Brian W
authors.initials: BW
authors.lastname: Pogue
mesh_terms: D000818:Animals; D001932:Brain Neoplasms / Q000378:metabolism / Q000473:pathology; D045744:Cell Line, Tumor; D066246:ErbB Receptors / Q000378:metabolism*; D005260:Female; D005453:Fluorescence; D005910:Glioma / Q000378:metabolism* / Q000473:pathology; D006801:Humans; D007091:Image Processing, Computer-Assisted; D011923:Rats, Nude; D011993:Recombinant Fusion Proteins / Q000008:administration & dosage*; D012815:Signal Processing, Computer-Assisted; D013194:Staining and Labeling
chemical_list: D011993:Recombinant Fusion Proteins; D066246:ErbB Receptors
keywords: Anti-EGFR affibody molecule; Glioma; Pre-GMP ABY-029; fluorescence-guided surgery