The U.S. Food and Drug Administration Friday afternoon granted a conditional approval for Avastin to treat breast cancer patients -- despite a recommendation by an FDA expert advisory panel in December to reject the new use.
The FDA has traditionally approved drugs for late-stage cancer only if they extended or improved the quality of patients' lives. In this case, the agency's decision to approve Avastin was based on the drug's tumor-shrinking abilities.
Some experts say the basis of this decision has huge implications for the future of breast cancer drug treatments.
"The FDA's approval process for Avastin tells us that regulators are now making quality-of-life issues an important part of their decision-making," said Dr. Len Lichtenfeld, deputy chief medical officer of the American Cancer Society.
Avastin, a drug already approved for the treatment of colon and lung cancer, was OK'd for treatment of advanced breast cancer under the FDA's accelerated approval program, which allows the agency to green light products for cancer or other life-threatening diseases based on initial positive clinical data.
Full approval of the drug is pending on the FDA's complete review of three additional randomized trials on Avastin, which have been submitted by Genentech.
Lack of Proof?
Going by the current research available on Avastin, some cancer experts contend that there is simply not enough data in support of the drug to warrant full FDA approval.
"I would have voted against approval," said Dr. Anthony Elias, director of the Breast Cancer Research Program at the University of Colorado Health Sciences Center. "One trial that is negative [on Avastin] and one trial [that is] positive does not give a clear answer."
The study that Genentech, Avastin's manufacturer, submitted to the FDA found that using Avastin in combination with Taxol, a breast-cancer drug made by Bristol-Myers Squibb Corp., delayed the growth of patients' tumors for 11.3 months -- 5.5 months longer than Taxol alone.
But despite this, the study found that the women on Avastin didn't live significantly longer than those on Taxol, and they experienced more adverse side effects, such as high blood pressure, blood clots and bowel perforation. Moreover, six deaths were linked to Avastin's toxicity.
A Last Hope for Some
While the drug has not yet been proved to extend the lives of women battling breast cancer, some experts say the approval of Avastin is justified solely on the basis that it could improve the quality of life of those with the disease.
In that respect, Avastin would not be the first drug whose approval was pegged to the possibility that it could lead to an easier life for cancer patients, rather than a longer one. Last March, the FDA decided to approve another breast cancer drug, called Tykerb, for similar reasons.
"As we move forward with targeted therapies, we're going to run into this situation more and more frequently," Lichtenfeld said. "So if we start thinking in terms of converting cancer from a fatal disease to a chronic disease ... drugs that improve quality of life will become more important."
Breast cancer is a curable disease, but once it has metastasized it is considered treatable but not curable. The American Cancer Society estimates that 40,000 women die of metastatic breast cancer each year. Of those, Genentech estimates that 38,000 have tumors that might respond to Avastin.
"Athough metastatic breast cancer remains incurable despite drugs like Herceptin, Avastin and others, it is eminently treatable," said Dr. Joseph Sparano, associate chairman of the department of oncology at the Montefiore Medical Center in New York. "In my view, a drug that doubles the chance of controlling the disease but doesn't affect survival is just as useful as one that prolongs survival by a few months."
Genentech estimates that 75 percent of women found to have breast cancer that has already spread have tumors that are HER2-negative -- and thus may be helped by Avastin.
Avastin works by replicating the body's own weapons -- antibodies that block the growth of blood vessels that feed tumors.
Breast cancer is the second most common form of cancer and the second leading cancer killer among American women. According to the American Cancer Society, an estimated 178,000 women in the United states were diagnosed with breast cancer in 2007.