Antivascular endothelial growth factors in age-related macular degeneration

Age-related macular degeneration (AMD) is the leading cause of irreversible vision loss in adults aged over 50 years in developed countries. Until recently, argon laser photocoagulation and photo-dynamic therapy (PDT) were the only treatments available for the neovascular form of AMD. The introduction of new intravitreally injectable inhibitors of vascular endothelial growth factor (VEGF) revolutionized the management of the wet form. Pegaptanib was the first anti-VEGF agent to be approved by the US Food and Drug Administration (FDA) for use in neovascular AMD. The VISION study showed that patients receiving pegaptanib lost vision in a smaller rate than those treated with conventional care. Bevacizumab is a full-length recombinant humanized monoclonal antibody which binds to all isoforms of VEGF-A. It is licensed for the intravenous administration for the treatment of malignant solid tumors and is available for off-label use in the treatment of AMD-related CNV. Numerous retrospective studies have shown beneficial effects of bevacizumab in patients with neovascular AMD. Ranibizumab is a recombinant, humanized antibody antigen-binding fragment (Fab) that binds to all known active forms of VEGF-A. The US FDA approved ranibizumab for treatment of all subtypes of choroidal neovascularization secondary to AMD. VEGF trap is a pharmacologically engineered protein that binds VEGF with higher affinity than pegaptanib or ranibizumab and thus prevents VEGF binding to its cellular receptor offering a theoretically longer interval between necessary treatments. A number of studies have shown that OCT imaging allows identification of functionally relevant factors like subretinal fluid or retinal thickness, which are important for the establishment of optimized individual dosing regimen during anti-angiogenesis therapies.