Paclitaxel

Paclitaxel

　　Paclitaxel is a complex secondary metabolite found in plants of the genus Taxus, and it is currently the only known drug that can promote microtubule polymerization and stabilize already polymerized microtubules. Isotope tracing has shown that paclitaxel binds only to polymerized microtubules and does not react with unpolymerized tubulin dimers. When cells are exposed to paclitaxel, they accumulate large amounts of microtubules inside the cell. This accumulation interferes with various cellular functions, particularly causing cell division to halt at the mitotic phase, thereby blocking normal cell division. Through Phase II–III clinical studies, paclitaxel has been found to be primarily effective against ovarian cancer and breast cancer, and also shows certain efficacy against lung cancer, colorectal cancer, melanoma, head and neck cancer, lymphoma, and brain tumors.