Trial of paclitaxel with or without bevacizumab as first-line therapy for locally recurrent or metastatic breast cancer

Mar 23 2006

Results from a large, randomised clinical trial for patients with breast cancer show that those who received bevacizumab (Avastin.) in combination with paclitaxel (Taxol.) survived without the disease getting worse for almost twice as long as patients who received paclitaxel alone. The results were announced today at the 5th European Breast Cancer Conference (EBCC-5).

A total of 722 patients with locally recurrent or metastatic breast cancer were enrolled in the study. Patients were randomised into two treatment groups. One group received the standard treatment, paclitaxel alone and the second group received the new drug combination of paclitaxel with bevacizumab. Researchers found that patients who received bevacizumab in combination with paclitaxel had significantly improved progression free survival of 11.4 months, compared to 6.11 months with paclitaxel alone - a statistically significant difference. Initial overall survival data is also promising and shows a trend towards improved overall survival (28.4 vs 25.2 months) with the new drug combination.

"These results are good news for people with breast cancer," said the study author Dr. R. Zon, Michiana Hematology Oncology, P.C. USA, adding, "A drug with a novel mode of action on the blood vessels within the cancer has not added side effects for patients and those who received the test drugs kept their cancer under control for almost twice as long as patients who received the standard regimen. The next step will be introducing the new drug in patients whose breast cancer has not progressed to metastasis."

The clinical trial was sponsored by the National Cancer Institute (NCI) and conducted by a network of researchers led by the Eastern Cooperative Oncology Group (ECOG), one of the largest clinical cancer research organisations in the U.S. The promising trial results showed only a minimal increase in toxicity when bevacizumab was added to paclitaxel. Manageable side effects of the drug combination included high blood pressure and bleeding.

The antibody drug bevacizumab works by blocking angiogenesis - the formation and growth of new blood vessels - by targeting a protein called vascular endothelial growth factor (VEGF). Cancerous tumours form a network of blood vessels in order to assist their growth, so by blocking the formation of new blood vessels to the tumour it will stop growing and eventually suffocate to death. The drug paclitaxel works by slowing or stopping the division of cancer cells in the body. It affects the cell structures called microtubules, which play an important role in cell function. The combination of the two drugs bevacizumab and paclitaxel enable the cancer cells themselves to be attacked as well as the cancer cell's support system, (the blood vessels that feed the tumour).