Adding Avastin Slows Growth of Metastatic, HER2-Positive Disease

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A study has found that adding Avastin (chemical name: bevacizumab) to a combination of Herceptin (chemical name: trastuzumab) and Taxotere (chemical name: docetaxel) increased the likelihood of responding to treatment and the time women diagnosed with locally advanced and metastatic HER2-positive breast cancer lived without the cancer growing (progression-free survival) compared to women treated with only Herceptin and Taxotere.

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

Herceptin, a targeted therapy medicine, and Taxotere, a chemotherapy medicine, are both used to treat early-stage and advanced-stage/metastatic HER2-positive breast cancer. Locally advanced breast cancer is cancer that has spread to the chest wall below or the skin above 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.

HER2-positive breast cancers make too much of the HER2 protein. The HER2 protein sits on the surface of cancer cells and receives signals that tell the cancer to grow and spread. About one out of every four breast cancers is HER2-positive. HER2-positive breast cancers tend to be more aggressive and harder to treat than HER2-negative breast cancers. Herceptin works against HER2-positive breast cancers by blocking the cancer cells' ability to receive growth signals.

Both Herceptin and Taxotere are given intravenously.

Avastin is a targeted therapy medicine that works by blocking the growth of new blood vessels that cancer cells need to grow and function. A protein called vascular endothelial growth factor (VEGF) makes new blood vessels grow in cancer cells. Avastin blocks the VEGF protein. Avastin also is given intravenously.

Avastin had been approved by the U.S. Food and Drug Administration (FDA) to be used in combination with Taxol (chemical name: paclitaxel) to treat metastatic, HER2-negative breast cancer that hadn't yet been treated with chemotherapy. In November 2011, the FDA removed the breast cancer indication because it believed:

  • Women diagnosed with metastatic breast cancer treated with Avastin risk potentially life-threatening side effects with no proof that Avastin will offer benefits.
  • There was no convincing evidence at the time the indication was removed that treating women diagnosed with metastatic breast cancer with Avastin will help them live longer or improve their quality of life.

Still, some doctors believe that the benefits of Avastin for certain women diagnosed with advanced-stage breast cancer are worth the risks and cost of treatment. Doctors are continuing to investigate using Avastin to treat advanced-stage breast cancer and this study is one example of that research.

Called AVEREL, this study included 424 women diagnosed with either locally advanced or metastatic HER2-positive breast cancer. While the women may have received treatment previously for early-stage breast cancer, none had yet been treated for advanced-stage breast cancer.

The women were randomly assigned to get one of two treatment regimens. Half got a combination of Herceptin, Taxotere, and Avastin and the other half got a combination of only Herceptin and Taxotere.

The women got their assigned treatment until the cancer showed signs of growing; they also stopped treatment if they developed unacceptable side effects. When the results were reported, half the women had been followed for about 2 years and half had been followed for shorter times.

An independent analysis of the results done by an outside panel of experts (not the researchers who did the study) found that 76.5% of women who got Herceptin, Taxotere, and Avastin had some response to the treatment (called response rate) compared to 65.9% of women who got only Herceptin and Taxotere. Response means that either the cancer showed signs of being weakened by treatment or at least remained stable without growing for a period of time.

Progression free-survival was almost 3 months longer for women treated with Herceptin, Taxotere, and Avastin compared to women treated only with Herceptin and Taxotere (16.8 months compared to 13.9 months). Half of all the women treated with Herceptin, Taxotere, and Avastin lived without the cancer growing for more than 16.8 months and half lived with no cancer growth for shorter periods of time. Half of all the women treated with only Herceptin and Taxotere lived without the cancer growing for more than 13.9 months and half lived with no cancer growth for shorter periods of time.

The researchers need to follow the women for more time to see if overall survival -- the time a woman lives with or without the cancer growing -- is better when Avastin is added to Herceptin and Taxotere.

Because of the uncertainty about the value of Avastin as a breast cancer treatment and concerns raised when the FDA removed the breast cancer approval, doctors are interested in ways to identify the women most likely to benefit from Avastin. In the AVEREL study, the researchers measured VEGF levels in all of the women in the study to see if there was a link between VEGF levels and the likelihood of responding to Avastin. Overall, women who had high VEGF levels got the most benefit from Avastin.

There will be more results from the AVEREL study in the future, once longer follow-up information is available.

If you're being treated for locally advanced or metastatic HER2-positive breast cancer, you and your doctor may be considering a number of treatment options. If you're willing to participate in a clinical trial you may have even more options, possibly including Avastin in combination with other treatments. Talk to your doctor about any role for Avastin in your treatment plan, and about any clinical trials that might be a good fit for you and your unique situation.

You can learn more about both Herceptin and Avastin, including their side effects, in the Breastcancer.org Targeted Therapies pages.

Stay tuned to Breastcancer.org Research News for updates on the AVEREL study.

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