title: Electrophysiological toxicity testing of VEGF Trap-Eye in an isolated perfused vertebrate retina organ culture model.
abstract: OBJECTIVE
  Age-related macular degeneration (AMD) is the leading cause of visual impairment in Western nations. Since the discovery of the importance of vascular endothelial growth factor (VEGF) in the pathogenesis of neovascular AMD, anti-VEGF agents including pegaptanib, ranibizumab and bevacizumab provide a treatment option to improve vision in affected persons. VEGF Trap-Eye (Aflibercept) is a new agent available for the treatment of exudative AMD. The molecule is a receptor decoy with a longer half-life and a higher affinity to VEGF compared with ranibizumab or bevacizumab. The presented study has been designed to evaluate the short-term toxic effects of VEGF Trap-Eye on retinal function during and after direct exposure to the drug.
  
  
  METHODS
  Isolated bovine retinas were perfused with an oxygen-saturated nutrient solution, and the electroretinogram (ERG) was recorded using silver/silver chloride electrodes. A total of 0.5 mg or 2 mg VEGF Trap-Eye was added to the nutrient solution and retinas were exposed for 45 min, followed by a washout period of 100 min. The percentage of a- and b-wave reduction at the end of the washout was compared with the baseline values. Additionally, retinal whole mount cultures were exposed for 24 hr to VEGF Trap-Eye, and the amount of apoptotic cells were determined using the terminal deoxynucleotidyl transferase-mediated uridine 5'-triphosphate-biotin nick end labelling (TUNEL) assay.
  
  
  RESULTS
  During simulation of intraocular application, no significant reduction in the a-wave amplitude for 0.5 mg (2.70%, p = 0.37) and 2 mg (3.84%, p = 0.37) VEGF Trap-Eye and b-wave amplitude for 0.5 mg (19.68%, p = 0.17) and 2 mg (24.1%, p = 0.06) VEGF Trap-Eye was observed at the end of the washout. However, there were significant changes in a-wave and b-wave amplitudes directly after exposure to 0.5 mg VEGF Trap-Eye (18.4%, p = 0.004 and 43.1%, p = 0.006, respectively).
  
  
  CONCLUSIONS
  The presented data suggest that intraocular application of up to 2 mg VEGF Trap-Eye does not induce irreversible toxic retinal damage. However, short-term results showed a negative effect directly after the application for 0.5 mg and 2 mg VEGF Trap-Eye.
authors.affiliation: Center for Ophthalmology, University Eye Hospital, Eberhard-Karls University of Tübingen, Tübingen, Germany.
authors.forename: Kai
authors.initials: K
authors.lastname: Januschowski
authors.forename: Sven
authors.initials: S
authors.lastname: Schnichels
authors.forename: Ulrike
authors.initials: U
authors.lastname: Hagemann
authors.forename: Vanessa
authors.initials: V
authors.lastname: Koch
authors.forename: Johanna
authors.initials: J
authors.lastname: Hofmann
authors.forename: Martin S
authors.initials: MS
authors.lastname: Spitzer
authors.forename: Karl-Ulrich
authors.initials: KU
authors.lastname: Bartz-Schmidt
authors.forename: Peter
authors.initials: P
authors.lastname: Szurman
authors.forename: Matthias
authors.initials: M
authors.lastname: Lüke
authors.forename: Sabine
authors.initials: S
authors.lastname: Aisenbrey
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D002417:Cattle; D004596:Electroretinography / Q000187:drug effects*; D020287:In Situ Nick-End Labeling; D008954:Models, Biological; D009924:Organ Culture Techniques; D040262:Receptors, Vascular Endothelial Growth Factor / Q000633:toxicity*; D011993:Recombinant Fusion Proteins / Q000633:toxicity*; D012160:Retina / Q000187:drug effects*
chemical_list: D011993:Recombinant Fusion Proteins; C533178:aflibercept; D040262:Receptors, Vascular Endothelial Growth Factor
keywords: aflibercept; electroretinogram; intraocular toxicity; retinal toxicity; superfused retina