Avastin Slows Growth of Metastatic Breast Cancer

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Women diagnosed with metastatic breast cancer who got Avastin (chemical name: bevacizumab) in combination with one of three standard chemotherapy regimens lived 1 to 3 months longer without the cancer growing compared to women who only got chemotherapy according to a study published online in the Journal of Clinical Oncology.

Still, the women in the study (called RIBBON-1) who got Avastin didn't live longer overall than the women who didn't get Avastin. This means overall survival was the same for both groups.

Avastin is a targeted therapy medicine that's given intravenously. Avastin 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.

In RIBBON-1, 1,237 women diagnosed with HER2-negative, metastatic breast cancer were treated with one of three standard chemotherapy regimens either with or without Avastin. The chemotherapy regimens were:

  • an anthracycline-based combination: Adriamycin (chemical name: doxorubicin) or Ellence (chemical name: epirubicin)
  • a taxane: Taxotere (chemical name: docetaxel) or Abraxane (chemical name: albumin-bound paclitaxel)
  • Xeloda (chemical name: capecitabine)

This was the first treatment for metastatic breast cancer the women received.

The time until the cancer grew (progression-free survival) was 1.2 months longer for the 622 women treated with Avastin and either an anthracycline-based or taxane chemotherapy (9.2 months) compared to women who got only chemotherapy (8 months).

Progression-free survival was 2.9 months longer for the 615 women treated with Avastin and Xeloda (8.6 months) compared to women treated only with Xeloda (5.7 months).

The proportion of women who responded to treatment -- called response rate -- was higher for women treated with Avastin and chemotherapy compared to women who only got chemotherapy:

  • 51.3% of women who got Avastin and either an anthracycline or taxane chemotherapy responded to treatment compared to 37.9% of women who got only chemotherapy
  • 35.4% of women who got Avastin and Xeloda responded to treatment compared to 23.6% of women who got only Xeloda

Still, overall survival was the same for all the women in RIBBON-1. So the women treated with Avastin didn't live longer than women who weren't treated with Avastin.

In December 2010 the U.S. Food and Drug Administration (FDA) recommended removing the indication for Avastin (chemical name: bevacizumab) in combination with Taxol (chemical name: paclitaxel) to treat metastatic, HER2-negative breast cancer that hasn't been treated with chemotherapy. In early 2011 the British agency similar to the FDA, the National Institute for Health and Clinical Excellence (NICE), also decided not to approve using Avastin to treat metastatic breast cancer. Still, the European Medicines Agency (EMA), a European regulatory agency similar to the FDA, still approves using Avastin in combination with Taxol (chemical name: paclitaxel) to treat certain metastatic breast cancers.

Based on RIBBON-1 results and four similar studies, the FDA and NICE have the following concerns about using Avastin to treat metastatic, HER2-negative breast cancer:

  • Although the research shows that using Avastin with one of several chemotherapy medicines improved progression-free survival, this benefit was small and overshadowed by the risk of serious side effects.
  • Research hasn't shown that adding Avastin to chemotherapy increases overall survival -- this means that women lived for about the same amount of time whether or not they got Avastin. The FDA feels that the small improvement in progression-free survival with no improved overall survival isn't a meaningful benefit, especially when the risk of serious side effects was considered.
  • Adding Avastin to chemotherapy didn't ease metastatic breast cancer symptoms.

Side effects of Avastin include high blood pressure, bleeding (nosebleeds, for example), and extra protein in the urine. People treated with Avastin also may have weakness, pain, and diarrhea. Avastin also may cause other serious side effects, including a higher risk of stroke or heart problems, kidney malfunction, and reduced white blood cell count (neutropenia), which can increase the risk of serious infection.

Many doctors -- including doctors involved in the RIBBON-1 study -- believe that the benefits of Avastin for certain women diagnosed with metastatic breast cancer are worth the risks and cost of treatment. U.S. doctors can choose to use Avastin to treat metastatic breast cancer whether or not that particular use is officially approved by the FDA. Still, loss of approval can make it less likely that insurers in the United States will pay for Avastin to treat breast cancer. In England, health care is covered by the British National Health Service (NHS). The NICE decision means it's likely that the NHS will no longer pay for Avastin to treat breast cancer.

In the United States, removing the breast cancer indication from Avastin will be a process. The medicine itself is not being removed from the market and the FDA recommendation will not have any immediate effect on using Avastin to treat breast cancer. Genentech, the company that makes Avastin, has asked for a full FDA hearing to again present available research results on Avastin and to review plans for future research that could help both the FDA and doctors better understand who would most benefit from Avastin to treat advanced-stage breast cancer. That hearing is scheduled for June 2011. Some of Genentech's proposed new research will try to find genetic or other factors that might help doctors figure out which women diagnosed with advanced-stage breast cancer could benefit most from Avastin.

The FDA's recommendation to remove the breast cancer indication will not affect Avastin's approvals to treat advanced-stage cancers of the lung, colon, and rectum.

If you've been diagnosed with metastatic breast cancer, you and your doctor will develop a treatment plan that will likely include chemotherapy and possibly hormonal therapy and/or targeted therapy medicines. No matter which treatments are recommended for you, you may want to talk to your doctor about:

  • why each treatment is recommended (including any combinations)
  • treatment timing and sequence
  • expected benefits, risks, and side effects of each treatment

If you're already getting Avastin and responding to treatment, you may want to ask your doctor about the RIBBON-1 study results and about the FDA and NICE decisions. It's likely that your doctor will recommend that you stick with your treatment plan unless it stops being effective or you have severe side effects.

Stay tuned to Breastcancer.org Research News for updates on the FDA Avastin hearings.

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