For example, the anti-vascular endothelial growth factor (VEGF165) aptamer drug Macugen (formerly pegaptanib), which was approved by the FDA in 2004 to treat age-related macular degeneration of the retina, contains a phosphorothioate 3′−3′ deoxythymidine cap to promote nuclease stability, 2′-O-methylated purines and 2′-fluorinated pyrimidines. Here, VEGFA is linked to age-related macular degeneration.