Bevacizumab Plus Paclitaxel Increases Response and Progression-Free Survival in Metastatic Breast Cancer

Paula Moyer, MA

May 18, 2005

May 18, 2005 (Orlando) — Adding the monoclonal antibody bevacizumab (Avastin) to paclitaxel (Taxol), which targets vascular endothelial growth factor, significantly prolongs survival and increases the response rate in patients with metastatic breast cancer, according to investigators whose findings were presented here at the American Society of Clinical Oncology (ASCO) 2005 Annual Meeting.

"This is a positive study," said principal investigator Kathy D. Miller, MD, at a late-breaking session. "The addition significantly improved the progression-free survival from 6.1 months to nearly 11 months, with a hazard ratio of 0.498, which is highly significant." Dr. Miller is an associate professor of hematology and oncology at Indiana University in Indianapolis.

Dr. Miller and her coinvestigators wanted to see if bevacizumab would be effective in breast cancer based on positive findings seen in other solid tumors that had metastasized. Therefore, they commenced the Eastern Cooperative Oncology Group's Breast Cancer Intergroup Trial E-2100, a randomized phase 3 trial to compare weekly paclitaxel plus bevacizumab with weekly paclitaxel alone as first-line treatment of women with locally recurrent or metastatic breast cancer.

The paclitaxel dose was 90 mg/m2 and given on days 1, 8, and 15 of a 28-day cycle. The patients in the bevacizumab-containing treatment group received a dose of 10 mg/kg on days 1 and 15. The patients were a median of 55 years old. Approximately 40% of patients had progressed within two years of adjuvant therapy.

"The addition of bevacizumab to paclitaxel clearly improved the response rates, from 14.2% to 28.2%," Dr. Miller said. "It significantly improved the progression-free survival from 6.1 months to nearly 11 months, with a hazard ratio of 0.498, which is highly significant." When the investigators analyzed the overall survival data, the researchers found that the combination therapy had a hazard ratio of 0.67.

The adverse events were consistent with those known for both drugs, Dr. Miller said. For example, approximately 13% of bevacizumab-treated patients developed hypertension that required treatment, and approximately 2.5% developed proteinuria of 2 g or more of protein per day. Grade 3 neuropathy occurred in 13.6% of patients receiving paclitaxel alone and in 19.9% of those in the bevacizumab group.

"These findings are exciting because this is the first time an antiangiogenic agent has been found to be successful in breast cancer," said Gabriel N Hortobagyi, MD, in an interview seeking outside comment." Dr. Hortobagyi is the president-elect of ASCO and the chair of the breast medical oncology department at the University of Texas M. D. Anderson Cancer Center in Houston. "It is one of the few agents that has been proven to prolong survival in metastatic disease." Dr. Hortobagyi added that the adverse events, particularly the potential for cardiovascular events, needed to be carefully monitored, but pointed out the benefits clearly outweighed the risks.

ASCO 2005 Annual Meeting: Late-breaking session. Presented May 16, 2005.

Reviewed by Gary D. Vogin, MD

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