Afinitor Study Stopped Early Because of Good Results

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Afinitor (chemical name: everolimus) is a targeted therapy medicine approved by the U.S. Food and Drug Administration (FDA) to treat advanced-stage kidney cancer. It's being studied as a treatment for other cancers, including breast cancer.

Novartis, the company that makes Afinitor, announced in July 2011 that a study looking at the benefits of Afinitor to treat certain advanced-stage and metastatic breast cancers was stopped early because of good results. Women who got Afinitor and the hormonal therapy Aromasin (chemical name: exemestane) were less likely to have the cancer grow during the study than women who got only Aromasin. Based on these results, Novartis may ask the FDA to approve Afinitor to treat certain advanced-stage or metastatic breast cancers.

Afinitor is an mTOR (mammalian target of rapamycin) inhibitor. mTOR is a kinase, a type of protein. Kinases help all cells (both healthy and cancer cells) get the energy they need. When kinases don't act normally or are overactive they help certain breast cancers grow. mTOR inhibitors work by interfering with the mTOR kinase. Afinitor is a pill taken by mouth.

More than 700 women diagnosed with certain advanced-stage or metastatic breast cancers that were hormone-receptor-positive and HER2-negative were in the BOLERO-2 study. The women diagnosed with advanced-stage cancer had locally advanced breast cancer, which is cancer that has spread beyond the breast to the chest wall below the breast or the skin on top of the breast. Metastatic breast cancer is cancer that has spread to parts of the body away from the breast, such as the bones or liver. The women in the study had been treated with hormonal therapy before the study -- either Femara (chemical name letrozole) or Arimidex (chemical name: anastrazole) -- but the cancer had stopped responding to that treatment.

About 66% of the women were randomly chosen to get Aromasin along with Afinitor. The other 33% got Aromasin and a placebo (a sugar pill that looked like Afinitor).

An early analysis found that women who got Aromasin and Afinitor were less likely to have the cancer grow compared to women who got Aromasin and placebo. The time a woman lives without the cancer growing is called progression-free survival. The researchers haven't said how large the difference in progression-free survival was between the two groups or whether the women who got Afinitor lived longer than the women who didn't get Afinitor.

A more detailed and complete analysis is expected to be released. Still, the researchers stopped the study because of the difference in progression-free survival so women getting placebo could switch to Afinitor if they and their doctors wanted to do so.

Doctors continue to look for new treatments for women diagnosed with locally advanced or metastatic breast cancer that has stopped responding to standard treatments. While these early research results are promising, doctors want to review the complete analysis to be sure about the benefits of Afinitor for treating advanced-stage breast cancer. It's not clear from the early analysis whether overall survival (the time the women lived, with or without the cancer growing) was better in women who got Afinitor. The overall survival information is important because the FDA may be less willing to approve Afinitor to treat advanced-stage breast cancer if the study shows no improvement in overall survival.

If you're being treated for advanced-stage breast cancer, you and your doctor may be considering a number of treatment options, especially if the cancer has stopped responding to standard treatments. If you're willing to participate in a clinical trial, you may have even more options, possibly including an experimental treatment such as Afinitor. Talk to your doctor about clinical trials that might be a good fit for you and your unique situation. Visit the Clinical Trials pages for more information.

And stay tuned to for the latest news on the BOLERO-2 study.

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