A novel approach in cancer research is the study of a group of compounds called angiogenesis inhibitors. These are drugs that block angiogenesis, the development of new blood vessels. Solid tumors cannot grow without inducing the formation of new blood vessels to supply the nutritional needs of the tumor. By blocking the development of new blood vessels, researchers are hoping to cut off the tumor's supply of oxygen and nutrients, and therefore its continued growth and spread to other parts of the body.

About 20 angiogenesis inhibitors are currently being tested in human trials. Most are in early phase I or II clinical (human) studies. Phase I/II trials include a limited number of people to determine the safety, dosage, effectiveness, and side effects of a drug.