This is a new class of drug which is able to compromise the blood supply to treat cancer.
Avastin (bevacizumab) is believed to prevent angiogenesis, the formation of new blood vessels that supply the tumor with blood, oxygen and other nutrients and allow the tumor to grow and metastasize to other sites in the body. Additionally, Avastin may interfere with tumor growth by causing blood vessels to shrink away from a tumor.
Avastin is a monoclonal antibody, a type of genetically engineered protein that binds to another protein called vascular endothelial growth factor (VEGF), which stimulates the growth of blood vessels. Blocking VEGF is thought to be the mechanism by which Avastin cuts off the supply of vessels that spring up to feed a tumor. Avastin is also believed to cause changes in the existing blood vessels that may enhance the effect of traditional chemotherapy drugs.
Avastin was approved by the FDA in 2004 for the treatment of patients with metastatic colorectal cancer (colon cancer that has spread to other parts of the body distant from the site of the original tumor). Avastin is given along with traditional chemotherapy to treat metastatic colorectal cancer.
Research is ongoing to determine if Avastin may be successfully used as well to treat other types of cancer.
Update: 06/30/2011: FDA pulls Avastin off the market