Inhibiting the growth of blood vessels that supply tumors slows the progression of metastatic breast cancer according to results of a large clinical trial of Avastin, an anti-angiogenic therapy. The study, published in the December 27th issue of the New England Journal of Medicine, found that Avastin in combination with chemotherapy significantly prolongs progression-free survival for women with breast cancer compared to chemotherapy alone.
Rush University Medical Center participated in the clinical trial which was sponsored by the National Cancer Institute and conducted by a network of researchers led by the Eastern Cooperative Oncology Group (ECOG).
The study of 722 women with recurrent (metastatic) breast cancer found that the women who received Avastin in combination with standard chemotherapy had a doubling of delay in worsening of their cancer by approximately five months, on average, compared to patients treated with chemotherapy alone. Those on Avastin had progression-free survival of 11.3 months compared to 6 months on standard chemotherapy alone.
"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."
Avastin is a therapeutic antibody designed to specifically inhibit vascular endothelial growth factor (VEGF), a protein that plays an important role in angiogenesis and the maintenance of existing blood vessels throughout the lifecycle of a tumor. By inhibiting VEGF, Avastin is designed to interfere with the blood supply to a tumor, which is thought to be critical to a tumor's ability to grow and spread in the body.
Avastin not only slowed the growth of the tumor, it also doubled the remission rate (the shrinkage of tumors by 50 percent or more) compared with chemotherapy alone. With chemotherapy, 25% of tumors responded; with the combination of chemotherapy and bevacizumab, 49% did so.
Rush University Medical Center has been involved in the study of Avastin from the very beginning, participating in the Phase I, Phase II and Phase III studies of the drug. The next step is studying the drug in the adjuvant setting to determine if it can help decrease the risk of cancer recurrence.
"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.