Scientists who study cancer cells have an eye toward developing better cancer treatments. Cell biologists and molecular biologists have uncovered how cancer cells grow, and how these cells get into the bloodstream and spread to other parts of the body. This information has led to better drugs that disrupt cancer cells, and have fewer side effects.
A new class of drugs was recently developed that works by preventing tumors from recruiting the blood vessels that feed them. These drugs are called angiogenesis inhibitors. Work on angiogenesis inhibitors began in the 1980s, when scientists in Boston purified a chemical used by cancer cells to recruit blood vessels. This molecule, called VEGF (vascular endothelial-derived growth factor), is secreted by tumors and attracts nearby blood vessels to grow toward the tumor to nourish the tumor. Early research done on cells and animals demonstrated that tumors needed this VEGF molecule to acquire a blood supply and continue to grow.
The drug discovery industry thus went to work developing a drug that chokes tumors by disrupting this VEGF blood recruitment molecule. Genentech has developed a drug Avastin (bevacisumab) that removes VEGF, preventing tumors from recruiting a new blood supply. It is a targeted therapy, a monoclonal antibody given to cancer patients through the vein that binds and removes VEGF near tumors, and starves the tumors. Avastin is approved by the US Food and Drug Administration in colon and rectal cancer, and also works in breast and lung cancer, and is being tested in nearly every form of cancer.
Since Avastin also decreases the blood supply to normal organs, it’s not surprising that it increases the risk of heart attack and stroke. It can also cause serious blood loss in lung cancer patients whose tumor shrinks rapidly, resulting in massive hemoptysis (coughing up large amounts of blood). These side effects can be life threatenting, but in appropriate patients the benefit outweighs the risk.
Avastin is a valuable new weapon in the war on cancer. Many other promising drugs are proceeding through the pipelines of the pharmaceutical and biotechnology industry. Our ability to treat cancer patients has improved dramatically over the last several years, thanks to basic research done decades earlier.