[590-S].

590-S (1-phthalidyl-5-fluorouracil) is a derivative of 5-fluorouracil and shows a several characteristics in experimental studies. That is, good absorption from the intestine, high blood levels of 5-fluorouracil, its rapid clearance, low toxicities, excellent tumor inhibition and broad anticancer spectrum, etc. From preliminary studies and phase I studies, MTD is thought to be 750-800 mg/m2 in daily administration. Mild G.I. toxicities was encountered in a few cases. However, CNS toxicities were not experienced in any of our cases.