Paclitaxel (Taxol) in breast cancer.

Paclitaxel (Taxol) is a diterpine plant compound that was isolated initially from the bark of the western yew tree, Taxus brevifolia, but can now be produced by semisynthesis from a renewable source. Paclitaxel is the first new agent in the past decade to have confirmed single agent activity in breast cancer in excess of 50%. A 28% response rate has been reported in doxorubicin-refractory patients. Ongoing studies include attempts to combine paclitaxel with other drugs used for breast cancer treatment and with radiation.