Eyetech's lead product Macugen™ (pegaptanib sodium) is an anti-VEGF aptamer. The aptamer was discovered using SELEX technology. Macugen™ (pegaptanib sodium) is an oligonucleotide that acts like a high affinity antibody to VEGF. This anti-VEGF aptamer blocks blood vessel growth and inhibits neovascularization in pre-clinical models.

Age-related macular degeneration (AMD) is the most common cause of irreversible and severe vision loss among the elderly in the United States and other western countries, while diabetic macular edema (DME) is the leading cause of vision loss in diabetics.

Both AMD and DME are debilitating diseases that may cause vision loss in patients and decrease their ability to live independently. Substantial peer-reviewed research has found high concentrations of Vascular Endothelial Growth Factor ("VEGF") in the eyes of patients afflicted with AMD and DME. VEGF is one of the major factors causing abnormal blood vessel growth in the eye - known as "angiogenesis."

VEGF was initially called "Vascular Permeability Factor" because it is also responsible for causing blood vessels to leak. In addition to its anti-angiogenic properties, Eyetech's anti-VEGF aptamer has also been shown in pre-clinical models to have anti-permeability properties, preventing blood vessels from leaking. Thus, the aptamer may have an effect in preventing leakage into the retina, including the central portion of the retina, known as the macula. This leakage is the cause of DME.

If Macugen™ (pegaptanib sodium) can be shown to prevent leakage from blood vessels and/or stop the growth of new blood vessels, it may be a useful combination for the treatment of AMD and/or DME.