The discovery of taxol: Wall, Horwitz, Holton

Taxol is a widely employed drug for chemotherapy of breast cancer and finds use for ovarian and lung cancer as well as for Kaposi’s syndrome. Getting from the discovery of taxol to approval for treatment of cancer took 30 years. The molecule was discovered in the Pacific yew tree, where it occurs in very small amounts. Early studies proved encouraging but not striking enough to generate real enthusiasm for pushing taxol forward. Then Susan Horwitz discovered its mechanism of action—it prevents the dissolution of microtubules—and enthusiasm strengthened. The problem at that stage was getting enough taxol to treat patients. Environmentalists were concerned that harvesting trees for taxol would destroy basically all of the Pacific yew trees in old forests, a legitimate concern. The discovery of a taxol precursor in the English yew, where it occurs in substantial amounts, coupled with the synthesis of taxol from that precursor solved the supply issue. It is now made by total synthesis. Determination by a few scientists over decades brought this important cancer drug into practice.