tegafur, gimeracil and oteracil

S-1 is an oral fluoropyrimidine chemotherapy agent consisting of three components: tegafur, gimeracil, and oteracil potassium in a molar ratio of 1:1:0.4. Tegafur is a prodrug of 5-fluorouracil (5-FU), which inhibits thymidylate synthase to disrupt DNA synthesis. Gimeracil (5-chloro-2,4-dihydroxypyridine) is a potent inhibitor of dihydropyrimidine dehydrogenase (DPD), the enzyme responsible for 5-FU degradation, thereby increasing 5-FU plasma levels and enhancing its efficacy. Oteracil potassium (monopotassium 1,2,4-triazine-3,5-dione-6-carboxylate) selectively inhibits the phosphorylation of 5-FU in the gastrointestinal tract, thereby reducing gastrointestinal toxicity. Originally developed by Taiho Pharmaceutical, it is approved in the European Union (as Teysuno) for advanced gastric cancer in combination with cisplatin and is widely used in Asia for various solid tumors. It is currently being investigated in combination with novel immunotherapies, such as rilvegostomig, for the adjuvant treatment of biliary tract cancer.

Other names

tegafur + oteracil + gimeraciltegafur-gimeracil-oteracil potassium