Highly positive results are reported from the first nationwide clinical study showing the benefits of an antiangiogenic agent in breast cancer therapy.
The study with Avastin showed the biggest improvement in metastatic breast cancer ever reported in a chemotherapy-based clinical trial. It nearly doubled the time between initiation of chemotherapy for metastatic disease and progression of the breast cancer tumors.
"This therapy is a one-two punch! You hit the tumor with the chemo and sabotage new blood vessel growth by restricting its oxygen supply with Avastin," said Dr. Melody Cobleigh, co-author of the study and director of the Coleman Foundation Comprehensive Breast Center at Rush. "This is a noteworthy advance in cancer treatment."
The study was coordinated by the Eastern Cooperative Oncology Group (ECOG) and Kathy Miller, M.D., associate professor of medicine and Sheila D. Ward Scholar at the Indiana University School of Medicine, is the lead author.
Dr. Miller said she found the results exciting because this was the first study to show that an antiangiogenic agent can delay progression of advanced breast cancer. The study looked at Taxol (paclitaxel), which is one of the standard agents for metastatic disease, with and without the addition of Avastin (bevacizumab).
"This study not only achieved the longest progression-free survival in advanced disease but the therapy achieved that improvement without adding to the day-to-day treatment burden and with only minor increases in toxicity," said Dr. Miller.
The study enrolled 722 women with metastatic disease from the United States, Canada, Peru and South Africa. Patients were randomized to one of two arms of the phase III study -- Taxol alone or Taxol with Avastin. The patients, who joined the study from December 2001 through May 2004, represented a balance of age, disease-free interval, estrogen-positive receptors and sites of disease.
The results show that treatment with Taxol and Avastin increased the period patients went without progression of their disease from 5.9 months to 11.8 months.
Avastin is a human monoclonal antibody that acts to reduce the development of blood vessels that feed tumors. Cancer tumors need an increasing supply of blood to grow and the development of the blood vessels to supply the tumor is a process called angiogenesis. Avastin already has been approved by the Food and Drug Administration for treatment of colorectal and lung cancer.
"The tumor can't grow bigger than the size of a sesame seed without an oxygen supply," said Cobleigh. "And patients can stay on Avastin as long at it works. It is not a chemotherapy drug so it has minimal toxicity. "
According to the American Cancer Society, an estimated 178,000 women will be diagnosed with breast cancer and approximately 40,000 will die from the disease in the United States in 2007.
"The next step is to move Avastin into the initial treatment of breast cancer in hopes that it will prevent recurrence in the first place," said Dr. Miller.
Full results are reported in the Dec. 27 issue of the New England Journal of Medicine.
The first clinical study with Avastin in humans was done in 1997 at Indiana University School of Medicine by George W. Sledge Jr., M.D., a pioneer in the field of antiangiogenic research. Dr. Sledge, a breast cancer specialist and the Ballve-Lantero Professor of Oncology, also conducted a 1998 Avastin study for breast cancer patients. Both early studies produced positive results.
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