Breast Cancer

About Taxol^TM

What is Taxol^TM?

Taxol, or paclitaxel, is a drug used for treating certain women who have advanced breast or ovarian cancer. Paclitaxel is a compound extracted from the bark of the Pacific yew tree (Taxus brevifolia).

Paclitaxel's was discovered in the 1960s during a large-scale plant-screening program sponsored by the National Cancer Institute (NCI). Interest in developing the drug increased in 1979 after scientists found that paclitaxel has a unique mechanism for preventing the growth of cancer cells.

In 1983, NCI began conducting clinical trials (research studies in humans) of paclitaxel's safety and its effectiveness against various types of cancer. Demand for paclitaxel increased in 1989 after NCI-supported investigators at The Johns Hopkins Oncology Center reported that the drug produced successful treatment in 30 percent of previously treated patients with advanced ovarian cancer.

Although the responses to paclitaxel were not permanent (they lasted 4 months on average, some up to 9 months), it was clear that ovarian cancer patients with few other options benefited from the treatment. In December 1992, FDA approved the use of paclitaxel for treatment-resistant ovarian cancer.

Subsequently, clinical trials using paclitaxel for the treatment of advanced breast cancer demonstrated that the drug is effective against this disease. In April 1994, FDA approved the use of paclitaxel for breast cancer that has recurred within 6 months after the completion of initial chemotherapy and for metastatic breast cancer that is not responding to combination chemotherapy.

Like most cancer drugs, paclitaxel has certain side effects, some of which can be serious. However, the risks associated with paclitaxel are believed to be outweighed by the drug's potential benefits for many patients with advanced breast or ovarian cancer, according to the National Cancer Institute and the American Cancer Society.

Current clinical trials:

Researchers continue to look for new and better ways to use paclitaxel in the treatment of cancer. They are studying paclitaxel's effectiveness when used to treat breast and ovarian cancer earlier in the course of these diseases and when used in combination with other drugs.

Trials to test the effectiveness of paclitaxel against many other types of cancer, including leukemia, lymphoma, and cancers of the lung, head and neck, and colon, also are in progress.

Early research using paclitaxel was limited by a restricted supply due to several difficulties in obtaining the drug. For example, the concentration of the compound in yew bark is low, and paclitaxel extraction is complex and expensive. In addition, bark collection was restricted because the Pacific yew is a limited resource located in old-growth forests that are the habitat of the endangered spotted owl.

As demand for paclitaxel increased, NCI, with the help of industry and other Government agencies, moved aggressively to increase the availability of paclitaxel, and a semi-synthetic form of the drug is undergoing clinical evaluation.

A promising alternative is docetaxel, a compound that resembles paclitaxel in chemical structure. Docetaxel, like the semi-synthetic paclitaxel, is produced by altering a compound extracted from the needles of the yew tree. The drug has shown promise in early clinical trials.

Breast Cancer

About TaxolTM

About Taxol^TM