In-vitro binding analysis of anti-human vascular endothelial growth factor antibodies bevacizumab and aflibercept with canine, feline, and equine vascular endothelial growth factor.

PURPOSE: Promising results have been described for antibodies binding vascular endothelial growth factor (VEGF) in patients with corneal neovascularization. Whether veterinary patients would also benefit from this therapeutic approach has not been investigated yet. We examined binding properties of anti-human VEGF antibodies bevacizumab (Avastin®) and aflibercept (Zaltrap®) for canine, feline, and equine VEGF.

METHODS: Human, equine, feline, and canine VEGF were analyzed for sequence similarity using the "Basic Local Alignment Search Tool" (BLAST). Western-blot analysis and ELISA were used to assess binding properties.

RESULTS: BLAST analysis revealed a sequence homology of canine, feline, and equine VEGF to human VEGF-A of 93%, 92%, and 89%, respectively. Western-blot analysis showed immunoreactivity of bevacizumab with human, canine, and feline VEGF, but not with equine VEGF. Aflibercept recognized VEGF of all tested species. ELISA data indicated that bevacizumab and aflibercept bind canine VEGF in a dose-dependent manner. Feline VEGF was bound by bevacizumab and aflibercept in a dose-independent manner. ELISA study further confirmed the lack of bevacizumab binding to equine VEGF, and yielded also a dose-independent binding by aflibercept.

CONCLUSIONS: Bevacizumab and aflibercept turned out to bind VEGF with species-specific differences. Further studies are required to investigate their efficacy and safety under clinical conditions.