First Cancer Drug to Starve Tumor
The first drug in a class of drugs designed to treat cancer by compromising
its blood supply has been approved by the FDA. The drug, called Avastin (bevacizumab),
prevents angiogenesis, the formation of new blood vessels that supply the tumor
with blood, oxygen and other nutrients and allow it to grow and spread to other
sites in the body.
Avastin is now approved for patients with metastatic
colorectal cancer. This new drug will not be cheap --- a year's supply costs
about $50,000. Avastin given along with traditional chemotherapy currently can extend life expectancy
by about five months. Not a lot of extra time, but it is a step in the right
direction.
Barbara K. Hecht,
Ph.D.
Frederick Hecht, M.D.
Medical Editors, MedicineNet.com
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FDA Approves First Angiogenesis
Inhibitor to Treat Colorectal Cancer
FDA today approved Avastin (bevacizumab) as a first-line treatment for
patients with metastatic colorectal cancer -- cancer that has spread to other
parts of the body. Avastin, a monoclonal antibody, is the first product to be approved that works by preventing the
formation of new blood vessels, a process known as angiogenesis. Avastin was
shown to extend patients' lives by about five months when given intravenously as
a combination treatment along with standard chemotherapy drugs for colon cancer (the "Saltz regimen" also known as
IFL). IFL treatment includes ironotecan, 5-fluorouracil (5FU) and leucovorin.
Avastin is a genetically engineered version of a mouse antibody that contains
both human and mouse components. (Antibodies are substances produced by the
body's immune system to fight foreign
substances.) Special technology also allows it to be produced in large
quantities in the laboratory.
This new monoclonal antibody is believed to work by
targeting and inhibiting the function of a natural protein called "vascular endothelial growth factor" (VEGF)
that stimulates new blood vessel formation. When VEGF is
targeted and bound to Avastin, it cannot stimulate the growth of blood vessels,
thus denying tumors blood, oxygen and other nutrients needed for growth.
Angiogenesis inhibitors such as Avastin have been studied, first in the
laboratory and then in patients, for three decades with the hope they might
prevent the growth of cancer. This is the first such product that has been
proven to delay tumor growth and more importantly, significantly extend the
lives of patients.
"The approval of Avastin is the result of many years of
research and development exploring a promising new approach to fighting cancer,
and it is one of a number of recent new treatments for colorectal cancer that
taken together, have significantly improved the armamentarium for fighting this
disease," said Mark B. McClellan, M.D., Ph.D., FDA Commissioner. "These medical
achievements reflect the innovation of drug developers and the hard work of
FDA's cancer review teams, and they are proof of the promise offered by
biomedical innovation. The dedication of everyone involved in these efforts is
making a real difference in the lives of cancer patients."
Colorectal cancer -- cancer of the colon or rectum -- is
the third most common cancer affecting men and women in the U.S. and, according
to the Centers for Disease Control and Prevention (CDC), is the second leading cause of
cancer-related death. Colorectal cancer is also one of the most commonly
diagnosed cancers in the U.S.; approximately 147,500 new cases were diagnosed in
2003.
The safety and efficacy of Avastin was primarily shown
in a randomized, double-blind clinical trial of more than 800 patients with
metastatic colorectal cancer designed to find out whether Avastin extended the
lives of patients. Roughly half the patients received IFL, the standard
chemotherapy combination, and the other half received Avastin once every two
weeks in addition to IFL. Overall, patients given Avastin in combination with
IFL survived about five months longer and the average time before tumors started
regrowing or new tumors appeared was four months longer than patients receiving
IFL alone. The overall response rate to the treatment was 45% compared to 35%
for the control arm of
the trial.
Serious, but uncommon, side-effects of Avastin include formation of holes in
the colon (gastrointestinal perforation)
generally requiring surgery and sometimes leading to intra-abdominal infections,
impaired wound healing, and bleeding from the lungs or internally. Other, more
common, side-effects are high blood pressure, tiredness, blood clots, diarrhea,
decreased white blood cells (lowering immunity to diseases) headache, appetite loss and mouth sores.
Avastin is manufactured by Genentech, Inc., South San Francisco, Calif.
Source: FDA Press Release #P04-23, February 26, 2004
Last Editorial Review: 2/28/2004
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