According to results presented at the 2003 San Antonio Breast Cancer Conference, a new form of paclitaxel, Abraxane™ (ABI-007) appears to nearly double anti-cancer response rates and significantly improve the duration of time to cancer progression compared to paclitaxel (Taxol®) in patients with metastatic breast cancer.
Metastatic breast cancer refers to cancer that has spread from the breast to distant sites in the body, often invading vital organs. Treatment for metastatic breast cancer is aimed at improving the duration of survival and/or quality of life for patients, but often not with the intent to cure. Paclitaxel is one of the most commonly used chemotherapy agents in the treatment of breast cancer. The formulation of paclitaxel includes agents so that proper storage and administration is possible. However, these agents are responsible for the development of many side effects associated with paclitaxel. Researchers tried to improve upon the outcomes achieved with paclitaxel by creating a new form of the drug. Abraxane™ is a form of paclitaxel that is bound with albumin, a type of protein normally found in the human body. It was thought that this form of paclitaxel will increase the capability of the drug to get into cancer cells and reduce the occurrences of side effects, compared to paclitaxel. Abraxane™ is not yet approved by the FDA but has completed the last phase of trials prior to FDA review.
A multi-institutional clinical trial was recently conducted directly comparing Abraxane™ to paclitaxel in the treatment of metastatic breast cancer. This trial included over 250 patients; approximately half of whom were treated with Abraxane™ and the other half with paclitaxel. Overall anti-cancer rates were achieved in 24% of patients treated with Abraxane™, compared with only 11% of patients treated with paclitaxel. The time to cancer progression was 21 weeks for patients treated with Abraxane™, compared to only 15.4 weeks for those treated with paclitaxel. Severe (grade IV) low white blood cell levels (neutropenia) occurred in 7% of patients treated with Abraxane™, compared with 19% of patients treated with paclitaxel. However, loss or reduction of sensation in the fingers and toes occurred in 10% of patients treated with Abraxane™, and 2% of patients treated with paclitaxel.
The researchers concluded that Abraxane™ appears superior to paclitaxel in the treatment of metastatic breast cancer, as anti-cancer responses and time to cancer progression were improved with Abraxane™. In addition, Abraxane™ reduced the incidence of neutropenia compared to paclitaxel. Patients with metastatic breast cancer may wish to speak with their physician about the risks and benefits of participating in a clinical trial further evaluating Abraxane™ or other novel therapeutic approaches. Sources of information regarding ongoing clinical trials include the National Cancer Institute (cancer.gov).
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Reference: O’Shaughnessy J, Tjulandin S, Davidson N, et al. ABI-007 (Abraxane™), a nanoparticle albumin-bound (nab) paclitaxel demonstrates superior efficacy vs. Taxol in MBC: a phase III trial. Proceedings from the 26th annual San Antonio Breast Cancer Symposium. December 2003. Abstract #44.