WASHINGTON — The first drug that promises to attack cancer by choking off its blood supply won federal approval Thursday, a treatment for advanced colon cancer called Avastin.
It’s not a cure, cautioned the Food and Drug Administration: Avastin can extend patients’ lives by a median of five months, meaning half do better and half worse.
But it’s a significant development. Few other drugs for advanced stages of this cancer have provided even that much benefit.
First medication of its kind
Also important, Avastin becomes the first drug proved to work according to a novel theory that tumors must form a network of blood vessels to survive — a process called angiogenesis — and that shutting down that process could fight cancer in a completely new way.
Avastin’s approval marks “a milestone in a new form of cancer therapy,” said Dr. Judah Folkman of the Harvard-affiliated Children’s Hospital of Boston, who pioneered the anti-angiogenesis theory 30 years ago.
Manufacturer Genentech Inc. “is to be congratulated for elegant scientific work that has converted a theory into a therapy,” Folkman said.
It was a long, hard road. Folkman made front-page news in 1998 with reports that his anti-angiogenesis drugs had cured mice of cancer. But early attempts to make such drugs work in people kept failing.
That may be because doctors initially tested them in the most difficult of patients, those who had failed numerous chemotherapies, said Dr. Louis Fehrenbeacher, head of Kaiser Permanente’s cancer study program who helped test Avastin. Tumors that survive repeated treatment seem to be the hardiest, and anti-angiogenesis will do its best work earlier in the disease, he said.
Lives extended, tumor growth delayed
Indeed, Avastin is approved as a first-line treatment for metastatic colon cancer, where the cancer has just spread throughout the body.
In a study of 800 people, half received intravenous Avastin in addition to routine chemotherapy every two weeks. Not only was tumor growth delayed in the Avastin patients, but they lived a median of 20 months, five months longer than those getting standard treatment.
That’s a 30 percent increase in survival, which is very exciting, said FDA Commissioner Mark McClellan.
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Some patients did better. Fehrenbeacher points to some of his who have lived almost three years.
Avastin is a monoclonal antibody, a substance that seeks out and binds to one of the more than 20 chemicals known to help tumors’ blood vessels grow. The one Avastin targets is called vascular endothelial growth factor, or VEGF. When Avastin binds to it, VEGF can’t stimulate blood vessel growth, thus keeping tumors from growing by denying them nourishing blood.
Genentech said it will begin shipping Avastin in three days. The wholesale cost will be $4,400 per month; in the study, most patients underwent 10 months of Avastin therapy.
FDA’s decision marks the second new treatment approved for advanced colorectal cancer in as many weeks. Erbitux, the drug at the center of the stock-trading scandal that brought Martha Stewart to trial, works in a different way, by blocking growth of the colon tumor itself, not its blood supply. FDA is allowing it to sell based on studies proving tumor shrinkage; no one yet knows whether Erbitux will actually help patients live longer.
More studies under way
Scientists are working to see if Avastin can treat other cancers, too. It failed as a last-ditch breast cancer treatment, but studies are under way to see if it helps in earlier stages of that disease and lung cancer, Fehrenbeacher said.
In all, 30 anti-angiogenesis drugs now are being tested in people around the world, Folkman said — including one he developed, called endostatin, that is showing promising results in a handful of patients with some rare cancers.
As for Avastin, the FDA cautioned that it occasionally causes some serious side effects including holes in the colon, impaired wound healing and internal bleeding.
More common side effects are high blood pressure, fatigue, blood clots, diarrhea, appetite loss and increased risk of infection because of decreased white blood cells.
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