An angiogenesis inhibitor is a substance that inhibits the growth of new blood vessels (angiogenesis). Some angiogenesis inhibitors are a normal part of the body's control, some are administered as drugs, and some come from diet.
Angiogenesis inhibitors were once thought to have potential as a "silver bullet" treatment applicable to many types of cancer, but this has not been the case in practice. Nonetheless, inhibitors are used to treat cancer, macular degeneration in the eye, and other diseases that involve a proliferation of blood vessels.
When solid cancers are small, they are supplied with nutrients by diffusion from nearby blood vessels. In order to grow larger, they need their own blood vessels, which they create by angiogenesis promoters such as VEGF. Drugs that interrupt that process show promise in treating cancer. However, when one angiogenesis promoter is blocked, cancers eventually grow blood vessels using another angiogenesis promoter.
Angiogenesis inhibitors are also used to treat age-related macular degeneration, in which the blood vessels of the retina of the eye become overgrown and damage vision.