[Antitumor effect of FU-O-G, new antitumor agent, following long term administration].

FU-O-G, the O-glucuronide methylester of 5-fluorouracil (5-FU), is a compound with a unique chemical structure. It is an antitumor agent of the prodrug type which exerts its activity by enzymatically liberating 5-FU in tumor tissues. It has been reported that the antitumor activity of this compound is superior to those of 5-FU and Tegafur (FT-207) in the treatment of various transplantable tumors. In this study, long-term administration of FU-O-G to mice bearing relatively slow-growing tumors such as Lewis lung carcinoma, mammary tumor FM3 A and hepatoma MH-134 was carried out. Consequently, FU-O-G was shown to be remarkably effective against those tumors, whereas 5-FU and FT-207 were hardly effective. Long-term daily administration was shown to be more effective than intermittent dosage in the treatment of Lewis lung carcinoma. In combination therapies of FU-O-G with other antitumor drugs, FU-O-G exhibited a synergistic effect against Lewis lung carcinoma when combined with Carboquone (CQ) or Nimustine hydrochloride (ACNU).