Regulatory aspects of drug approval for macular degeneration

Age-related macular degeneration (AMD) is the leading cause of blindness in developed countries with approximately 15 million people with the disease in the United States. AMD is characterized as a progressive degenerative disease of the macula. There are two forms of AMD: neovascular and non-neovascular. The non-neovascular form of AMD is more common and leads to a slow deterioration of the macula with a gradual loss of vision over a period of years. The neovascular form of the disease is responsible for the majority of cases of severe vision loss and is due to proliferation of abnormal blood vessels behind the retina. These blood vessels leak blood and fluid into the retina, which results in visual abnormalities. The development of these abnormal blood vessels is due in part to the activity of VEGF (vascular endothelial growth factor) and its inhibition is expected to impact on the onset and/or severity of vision loss associated with the proliferation of abnormal blood vessels. Age-related macular degeneration is an underserved treatment population. Visudyne (verteporfin for injection), Novartis Ophthalmics, is FDA approved for the treatment of patients with predominantly classic subfoveal choroidal neovascularization due to age-related macular degeneration, pathologic myopia or presumed ocular histoplasmosis. Pegaptanib sodium (Macugen, Eyetech Pharmaceuticals, Inc. and Pfizer, Inc.) is indicated for the treatment of neovascular (wet) age-related macular degeneration. This article will review the approval pathway for these two products and that required of future products indicated for macular degeneration.