Japanese scientists have made a novel prodrug they claim could improve cancer chemotherapy by avoiding the side effects associated with the parent drug. 

Cytarabine is a widely used anticancer drug but it can cause serious side effects, such as damage to the nerves in the brain. Kazuhito Tanabe and colleagues at Kyoto University added a 2-oxopropyl group to a nitrogen atom in cytarabine to form an inactive form of the drug, know as a prodrug. When they irradiated the prodrug with X-rays, they found that the 2-oxopropyl group fell off to give the parent drug. 

Tanabe explains that because irradiation can be used to convert the prodrug to the active form at exactly the right time, dosage and site in the body, healthy cells are not affected by the drug. 'The prodrug does not exhibit cytotoxicity without irradiation and thereby side effects were adequately diminished,' he says. 

The prodrug is currently being tested in animals and Tanabe says he expects it to selectively kill tumour cells when irradiated. 'The problem which we have to consider next is whether the prodrug can exhibit its cytotoxicity in human trials,' he says. 

Joanne Thomson