Ts-1 Teysuno, S-1

What it is

TS-1 (tegafur/gimeracil/oteracil) is an oral fluoropyrimidine-based chemotherapy agent that combines three active components to enhance antitumor efficacy while reducing toxicity. It is used as both first-line and second-line treatment for advanced and metastatic colorectal cancer, often in combination with other agents such as irinotecan or oxaliplatin. The formulation provides sustained 5-fluorouracil levels through tegafur while gimeracil inhibits 5-FU degradation and oteracil reduces gastrointestinal toxicity.

How it works

TS-1 works through its primary component tegafur, which is converted to 5-fluorouracil (5-FU) in tumor tissues, where it inhibits thymidylate synthase and disrupts DNA synthesis and repair. Gimeracil inhibits dihydropyrimidine dehydrogenase (DPD), the enzyme responsible for 5-FU catabolism, thereby maintaining therapeutic drug levels. Oteracil selectively inhibits 5-FU phosphorylation in the gastrointestinal tract, reducing dose-limiting diarrhea and mucositis.

Molecular targets

Common side effects

Not all are listed, and everyone experiences them differently. If you notice any, tell your care team.