Mechanism of action of antitumor drug etoposide: a review.

Metabolism studies of the antitumor drug etoposide show the formation of metabolites in the lactone ring, which are probably not important for the drug's mechanism of action, and oxidative transformations in the dimethoxyphenol ring (E ring), which lead to products that can cause DNA damage and may play a role in the drug's mechanism of action. The cytotoxicity of etoposide is caused by the induction of DNA damage. The occurrence of the DNA lesions can be explained by the capacity of the drug to interfere with the scission-reunion reaction of mammalian topoisomerase II by stabilizing a cleavable complex.