Joint Antiangiogenic Effect of ATN-161 and Anti-VEGF Antibody in a Rat Model of Early Wet Age-Related Macular Degeneration

The wet form of age-related macular degeneration (AMD) is a leading cause of blindness among elderly Americans and is characterized by abnormal vessel growth, termed choroidal neovascularization (CNV). Integrin alpha 5 beta 1 is a transmembrane receptor that binds matrix macromolecules and proteinases to stimulate angiogenesis. We recently demonstrated that integrin alpha 5 beta 1 plays a critical role in the development of choroidal neovascularization. In this study, we determined the role and underlying mechanisms of integrin alpha 5 beta 1 in angiogenesis in human choroidal endothelial cells and evaluated the antiangiogenic effects of delivering a combination therapy of ATN-161, an integrin alpha 5 beta 1 inhibitor, and an anti-VEGF monoclonal antibody to rats with laser induced CNV. Vascular endothelial growth factor (VEGF) is a signaling protein that stimulates vasculogenesis and angiogenesis through a pathway that is distinct from the integrin alpha 5 beta 1 signaling pathway. Our results indicate that fibronectin binds to integrin alpha 5 beta 1 and synergizes VEGF-induced angiogenesis via two independent signaling pathways, FN/integrin alpha 5 beta 1/FAK/ERK1/2 and FN/integrin alpha 5 beta 1/FAK/AKT. Integrin alpha 5 knockdown by shRNA inhibits endothelial cell migration, tube formation, and proliferation, while ATN-161 only partially decreases integrin a5 function. Treatment with ATN-161 combined with anti-VEGF antibody showed joint effects in attenuating angiogenesis. In summary, our results provide the first evidence for the mechanisms by which integrin alpha 5 beta 1 is involved in ocular pathological neovascularization in vivo, suggesting that dual inhibition of integrin alpha 5 beta 1 and VEGF may be a promising novel therapeutic strategy for CNV in wet AMD.