Antineovascular agents in the treatment of eye diseases

Neovascularization is a common and potentially visually threatening complication of eye diseases such as diabetic retinopathy (DR) and age-related macular degeneration (AMD). An antiangiogenic therapy is aimed at inhibiting the growth of new blood vessels and should prevent onset or progression of neovascularization. Accumulated evidence indicates that growth factors, endothelial cell surface receptors, and extracellular matrix (ECM) proteins are major mediators of neovascularization and appealing targets for pharmacotherapeutical intervention. Vascular endothelial growth factor (VEGF) plays a critical role in the pathogenesis of retinal neovascularization (in linking tissue ischemia to angiogenesis), and is likely to contribute also significantly to choroidal neovascularization (CNV). Several antineovascular agents antagonize the function of VEGF, by blocking its proangiogenic activity. Indeed, VEGF targeting or disruption of VEGF signalling is the most effective strategy known so far in the pharmacological treatment of ocular neovascularization. Other compounds such as pigment epithelium-derived factor (PEDF) either aim at balancing the levels of pro-angiogenic and angiostatic molecules, target inflammation (cyclooxygenase inhibitors, steroids) or comprise modifiers of the ECM such as inhibitors of matrix metalloproteinases (MMPs) and agents that block the action of integrins. Vascular targeting agents (combretastatin) promote removal of newly formed vessels. This review provides an update on recent investigations directed at the pharmacotherapeutical management of ocular neovascular diseases, placing special emphasis on the underlying target molecules and relevant intracellular signalling pathways.