Experimental Combo of Herceptin and Omnitarg Helps Treat Advanced-Stage HER2-Positive Disease

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Treatment given to weaken and destroy breast cancer before surgery is called neoadjuvant treatment. Neoadjuvant treatment is typically used for:

  • cancer that has spread outside the breast to other tissue in the breast area (locally advanced)
  • inflammatory breast cancer; this aggressive form of breast cancer is characterized by a feeling of thickness or heaviness in the breast, or red, inflamed breast skin

One or more chemotherapy medicines are typically used for neoadjuvant treatment. Doctors are starting to study how certain targeted therapies might be best used with chemotherapy in neoadjuvant regimens to treat early-stage, HER2-positive breast cancer.

A study shows that neoadjuvant regimens that include the targeted therapies Herceptin (chemical name: trastuzumab) and Omnitarg (chemical name: pertuzumab) and the chemotherapy medicine Taxotere (chemical name: docetaxel) or just Herceptin and Omnitarg alone, weakened and destroyed cancer cells in women diagnosed with locally advanced or inflammatory HER2-positive breast cancer. The regimen that included Herceptin, Omnitarg, and Taxotere was the most effective. These results were presented at the 2010 San Antonio Breast Cancer Symposium (SABCS).

HER2-positive breast cancers have too many copies of the HER2/neu gene, which makes too much of the HER2 protein. HER2-positive breast cancers tend to be aggressive, so neoadjuvant treatment may be recommended. Herceptin and Omnitarg work against HER2-positive breast cancers by blocking the cancer cells' ability to receive growth signals. Both medicines are given intravenously.

Herceptin is approved by the FDA to treat advanced-stage, HER2-positive breast cancer and to lower the risk of recurrence (the cancer coming back) of early-stage, HER2-positive breast cancer with a high risk of recurrence.

Omnitarg is an experimental medicine that is not currently approved by the FDA to treat breast cancer. Doctors have been studying how Omnitarg could be used to treat several types of cancer, including breast cancer.

Lab research suggests that Omnitarg can improve Herceptin's ability to weaken or destroy HER2-positive breast cancers. So doctors have been studying how these two medicines could be used together to treat HER2-positive breast cancer.

In this study, 400 women diagnosed with either locally advanced or inflammatory HER2-positive breast cancer that hadn't been treated with any chemotherapy got one of four neoadjuvant regimens:

  • Herceptin and Omnitarg
  • Herceptin and Taxotere
  • Omnitarg and Taxotere
  • Herceptin, Omnitarg, and Taxotere

After neoadjuvant treatment was done, the women had surgery to remove the cancer. The researchers recorded how many women had no active cancer cells in the tissue removed during surgery. When there are no cancer cells in the tissue removed, doctors call it a "pathologic complete response." Some doctors believe a pathologic complete response to neoadjuvant treatment means the cancer is less likely to come back.

In each treatment group, some women had a pathologic complete response. Still, more women had a complete pathologic response in the Herceptin, Omnitarg, and Taxotere group. The proportion of women who had a complete pathologic response was:

  • 16.8% with Herceptin and Omnitarg
  • 29% with Herceptin and Taxotere
  • 24% with Omnitarg and Taxotere
  • 63.2% with Herceptin, Omnitarg, and Taxotere

The proportion of women who had some response to treatment (either a complete or a partial pathologic response) was more than 90% for all of the neoadjuvant treatment regimens evaluated. This is called the clinical benefit rate.

After surgery, most of the women were treated with chemotherapy and Herceptin. The women who got the neoadjuvant Herceptin and Omnitarg regimen were treated with Taxotere and Herceptin after surgery. Doctors call treatments given after surgery adjuvant treatments. Adjuvant treatments are given to lower the risk of the cancer coming back.

Both chemotherapy and targeted therapy medicines can cause serious side effects, including low white blood cell counts (neutropenia, which increases the risk of serious infection), severe diarrhea, and neuropathy (nerve damage in the hands and feet). Particularly serious side effects are classified as grade 3 or grade 4.

In this study, most of the serious side effects during neoadjuvant treatment were related to Taxotere. The most common serious side effect in the women who got the neoadjuvant regimen of only Herceptin and Omnitarg was neutropenia and it was seen in less than 1% of the women. About 2% of the women in the Herceptin-Omnitarg group had a reaction to the medicines that was similar to an allergic reaction. Women treated with anti-HER2 medicines sometimes have heart problems. One woman in the Herceptin-Omnitarg group had heart failure during treatment.

While these results are promising, more research is needed to better understand how anti-HER2 targeted therapies such as Herceptin and Omnitarg can be best used as neoadjuvant treatments.

If you've recently been diagnosed with HER2-positive breast cancer and haven't had surgery yet, you might want to talk to your doctor about this study and whether treatment before surgery makes sense for you.

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