Q. I have "triple negative" breast cancer - it's not estrogen-, progesterone-, or HER2-positive, so my treatment has so far been limited to surgery, chemo, and "hope for the best," since hormone therapy drugs, or Herceptin or Tykerb, won't work for me. My oncologist would like me to try a "targeted therapy," Avastin, which he says isn't yet FDA-approved for breast cancer treatment, but that some doctors have been using as an "off-label" drug. What does all of that mean?
Editor's Note: The U.S. Food and Drug Administration on 2/22/08 approved the cancer drug Avastin for women with advanced breast cancer, going against the recommendation of its own advisory panel.
A. First, let's look at what a targeted therapy (or immune targeted therapy) is. It is a term used to describe a drug that "targets" specific properties of cancer cells: their production of protein, their use of enzymes, or their ability to form new blood vessels to support growth. They can potentially have less side effects on healthy cells, which is a plus.
Avastin (bevacizumab) is actually the first FDA-approved drug that inhibits angiogenesis: that is, it prevents cancer cells from banding together and forming new blood vessels, thus depriving the tumor they've formed of the oxygen and nutrients they needs to survive. In effect, Avastin forces tumor cells to smother and starve themselves to death.
Since your cancer won't respond to either hormone therapy (tamoxifen, aromatase inhibitors), or anti-HER2 therapy (Herceptin, Tykerb), your doctor wants to try another route. Avastin has been FDA-approved for colon and rectal cancer, and some lung cancers, but in December 2007 an FDA expert panel voted 5-4 to reject Avastin as an approved breast cancer treatment perhaps because of some panel members' perception of serious side effects-striking a blow to women willing to risk its side effects for the chance of trying this new drug, where no others are available.
And that's where the term "off-label" comes in: it means that even though the FDA hasn't approved Avastin for the treatment of breast cancer, doctors and patients see enough upside to the drug that they're willing to try it. About 200 clinical trials involving Avastin are currently going on worldwide. Avastin is approved by the FDA for metastatic lung and colon cancer. No doubt Avastin manufacturer Genentech will present it for FDA approval again in the future. It's already approved for treatment of metastatic breast cancer in Europe.
Q. So, how do I take Avastin?
A. Like many chemotherapy drugs, Avastin is given as an injection, usually every 2 weeks. The infusion should take anywhere from 30 to 90 minutes, depending on how well you tolerate the drug at the injection site; sometimes it's better to give it more slowly.
Q. And what can I expect for side effects from Avastin?
A. Unfortunately, Avastin has a downside: serious side effects, affecting up to 20% of those who take it. These worrisome side effects include kidney damage, bowel perforation, nosebleeds, high blood pressure, blood clots, stroke, heart attacks-and possibly death. Six of the 363 women in Avastin's chief clinical study-1.7%-died of side effects potentially attributable to Avastin. As always, you and your doctor need to assess your condition carefully, and make the tough decision as to whether you want to take this risk for the probable benefit.