Phase 2 Study of S-1 in Advanced or Metastatic Pancreatic Cancer

Locally advanced or metastatic pancreatic cancer is relatively unresponsive to chemotherapy. This is true for the nucleoside analogue gemcitabine, with a response rate of approximately 10%, as well as for 5-fluorouracil (5-FU). Even when gemcitabine is combined with other chemotherapeutic drugs or biological agents, the overall tumor response rate remains basically unchanged. S-1 is a new generation oral fluoropyrimidine that combines Tegafur (5-fluoro-1-(tetrahydro-2-furanyl)-2,4(1H,3H)-pyrimidinedione \[FT\]), an oral prodrug of 5-FU, with two modulators, Gimeracil (5-chloro-2,4-dihydroxypyridine \[CDHP\]), which inhibits 5-FU degradation by dihydropyrimidine dehydrogenase (DPD) inhibition, and Oteracil potassium (Oxo), which inhibits 5-FU phosphorylation in the digestive tract. This combination of 3 compounds is designed to achieve enhanced antitumor activity while decreasing gastrointestinal toxicity.