Targeting vascular endothelial growth factor: a promising strategy for treating age-related macular degeneration

Age-related macular degeneration (AMD) is the leading cause of irreversible visual loss in the industrialised world. While treatment options for advanced AMD have been rather limited until recently, the introduction of intravitreal injections of anti-angiogenic agents appears to be a promising and revolutionary mode of treatment for this blinding disease. Vascular endothelial growth factor (VEGF) appears to play a pivotal role in the pathogenesis of choroidal neovascularisation, one of the cornerstones of advanced AMD. Pegaptanib, the first anti-VEGF treatment approved for AMD patients, is a VEGF-neutralising aptamer that specifically inhibits one isoform of VEGF (VEGF-165). Although evidence suggested that pegaptanib was superior to previous treatment options, results with this agent were still unsatisfactory. Ranibizumab is a humanised anti-VEGF monoclonal antibody fragment that inhibits all isotypes of VEGF. This new drug has demonstrated a high efficacy profile in terms of inhibiting disease progression and even improving visual acuity. Bevacizumab is a full-length anti-VEGF antibody that was originally approved for use in metastatic colon cancer and is under investigation as a low-cost off-label alternative for patients with AMD. There is growing evidence that this drug may be an effective and safe alternative to the more expensive ranibizumab, although prospective multicentre trials are required to fully investigate this issue. Undoubtedly, the concept of directly injecting anti-VEGF drugs into the vitreal cavity brings new hope to many AMD patients.