Afinitor Before Surgery Doesn’t Help Treat HER2-Negative Breast Cancer

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Some women diagnosed with higher-stage breast cancer are treated with chemotherapy, targeted therapy, and/or hormonal therapy BEFORE surgery to weaken or destroy the cancer. Treatment given before surgery is called neoadjuvant treatment.

A series of studies called GeparQuinto has been looking at different types of neoadjuvant treatment for HER2-negative breast cancer. The targeted therapy Herceptin (chemical name: trastuzumab) doesn't work on HER2-negative cancer.

Results from one part of GeparQuinto have shown that women diagnosed with HER2-negative breast cancer that didn't respond to neoadjuvant chemotherapy with or without the targeted therapy Avastin (chemical name: bevacizumab) didn't get any benefit from neoadjuvant chemotherapy with paclitaxel (brand name: Taxol) and the addition of the targeted therapy Afinitor (chemical name: everolimus).

The results were presented at the 2011 San Antonio Breast Cancer Symposium.

Afinitor is 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. 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.

This study looked at 395 women diagnosed with HER2-negative breast cancer that was treated with the neoadjuvant chemotherapy combination of epirubicin (brand name: Ellence) and cyclophosphamide (brand name: Cytoxan) before this study (some of the women also got Avastin). None of the women showed any response to that treatment. Half the women were randomly chosen to get more neoadjuvant treatment with paclitaxel in combination with Afinitor. The other half got only paclitaxel.

When the women had surgery, the researchers determined the response to the paclitaxel with or without Afinitor treatment by seeing if there was a pathologic complete response. A pathologic complete response means that the researchers found no active cancer cells when they looked at the tissue removed during surgery. The researchers wanted to know if more women had a pathologic complete response with Afinitor and paclitaxel or with paclitaxel alone.

The study found that adding Afinitor to paclitaxel didn't improve the response to neoadjuvant treatment with paclitaxel.

Whether or not they got Afinitor with paclitaxel, very few women had a pathologic complete response to neoadjuvant treatment:

  • 3.6% of women who got paclitaxel and Afinitor had a pathologic complete response
  • 5.6% of women who got only paclitaxel had a pathologic complete response

Most women had a partial response to neoadjuvant treatment, but adding Afinitor didn't improve the likelihood of a partial response:

  • 52.2% of women who got paclitaxel and Afinitor had a partial response
  • 62.1% of women who got only paclitaxel had a partial response

Although these results on using Afinitor as a neoadjuvant treatment for HER2-negative breast cancer were disappointing, other research has shown that some women may benefit from adding Afinitor to other treatments for advanced-stage HER2-negative breast cancer.

Stay tuned to Breastcancer.org's Research News for more information on the potential of Afinitor to treat breast cancer.

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