It's the first time that a drug from this class of medications, called mTOR inhibitors, has been approved for this disease, the FDA said. Afinitor is already used to fight advanced kidney and neuroendocrine tumors, as well as a handful of rarer cancers.
The medicine is only approved for use by postmenopausal women battling an advanced form of estrogen-sensitive tumor known as hormone-receptor positive, HER2-negative breast cancer. Even then, Afinitor should only be used after such patients have already experienced a recurrence or progression of the tumor following prior treatment with Femara (letrozole) or Arimidex (anastrozole), the FDA said.
Adding Afinitor -- which has proven effective for other cancers -- to therapy might help these patients, the agency said.
"Afinitor is another example of the value of continuing to study drugs in additional types of cancer after their initial approval," Dr. Richard Pazdur, director of the Office of Hematology and Oncology Products in the FDA's Center for Drug Evaluation and Research, said in an agency news release.
According to the FDA, approval was based on a clinical trial involving 724 postmenopausal women with advanced breast cancer that had spread despite prior treatment with Femara or Arimidex. All of the women also took the standard breast cancer drug Aromasin (exemestane) during the trial.
The trial found that adding in Afinitor boosted average progression-free survival (the time the women lived without any progression of their tumor) by 4.6 months compared to women taking an inactive placebo.
There was a downside to using Afinitor, however: According to the FDA, side effects included rash, fatigue, diarrhea, loss of appetite and mouth ulcers. These effects were more common in women aged 65 or older, so the agency says older patients should be monitored more closely if they take Afinitor.
Dr. Stephanie Bernik, chief of surgical oncology at Lenox Hill Hospital in New York City, commented on Afinitor's approval.
"It is exciting that there continues to be advances in treating breast cancer that are allowing patients to survive longer, even in the face of metastatic disease," Bernik said. "The improved treatment for advanced-stage breast cancer offers women hope that a treatment to completely stabilize, or even eradicate the disease, might be achievable within their lifetime."
The drug is marketed by Novartis Pharmaceuticals Corp., based in East Hanover, N.J.
More information
Find out more about breast cancer at the U.S. National Cancer Institute.
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