Combined effects of S-1, a new form of oral tegafur, plus modulators on ovarian cancer in nude rats.

We evaluated the efficacy of S-1 as a new oral antitumor agent in ovarian cancer-bearing nude rats. This drug consists of tegafur, 5-chloro-2,4-dihydroxypyridine, and oxonic acid in a molar ratio of 1:0.4:1.S-1 was given alone or in combination with cisplatin. When administered alone at a daily dose of 20 mg/ kg, S-1 produced a significant inhibition of tumor growth [inhibition rate (IR) 89%] in the treated versus the control animals (p < 0.05). The effects of S-1 resembled those of cisplatin-treated groups. The consecutive daily administration of S-1, 20 mg/kg, combined with cisplatin, 1 mg/kg, markedly inhibited cell growth (IR 99%), a significant difference relative to cisplatin alone (p < 0.05). The daily administration of S-1 combined with low-dose cisplatin induced tumor regression with a low toxicity.