Initial clinical experience with the radiosensitizing nitroimidazole Ro 07-0582.

The 2-nitroimidazole derivate Ro 07-0582 is known from experimental studies to be a very efficient radiosensitizer of hypoxic cells. Experiences with its clinical use are very limited so far. This study reports the side effects observed in the use of this drug in 12 patients. Nine of these patients were suffering from brain tumors, 3 from extracerebral tumors. In 8 of our 12 patients a sensoric polyneuropathy occurred which was strongly related to the total dose of the drug administered. Polyneuropathy was observed on the average after a total dose of 26 grams, but was already noticed at doses as low as 22 grams. It showed a good tendency for remission after termination of the drug treatment and was reversible in all patients within 4 weeks. In one patient with a brain tumor a severe organic psychosyndrome occurred which is possibly related to the drug. This side effect was also reversible. In this small group of patients the critical dose limit seems to be 29 grams. This dose can be divided into 6 fractions of 60-80 mg/kg. Up to the present knowledge this single dose is likely to give an enhancement ratio of 1,5, which would be extremly valuable for the treatment of hypoxic tumor cells.