Pharmacokinetic and Pharmacodynamic Study of S-1 and Its Effects in Patients With the Digestive Organ Cancer With Reference to Genetic Polymorphism and Activity of CYP2A6 and DPD

S-1 is a novel oral fluorouracil antitumor drug that consists of tegafur which is a prodrug of 5-fluorouracil (5-FU); 5-chloro-2,4-dihydropyridine (CDHP), which inhibits dihydropyrimidine dehydrogenase (DPD) activity; and potassium oxonate (Oxo), which reduces gastrointestinal toxicity. 5-FU is metabolized by CYP2A6 and DPD. In this study, the researchers investigate the influences of differences in activities of CYP2A6 and DPD on pharmacokinetics and pharmacodynamics of S-1 and clinical outcomes in digestive organ cancer patients treated with S-1.