Purpose: To investigate the side effects, determine the maximum-tolerated dose (MTD), and study the pharmacokinetics of S-1, an oral flouropyrimidine-based antineoplastic agent consisting of the fluorouracil (5-FU) prodrug tegafur combined with two modulators, 5-chloro-2,4-dihydroxypryridine and potassium oxanate. Patients and Methods: Patients with advanced solid tumors received S-1 bid for 28 days, followed by 1 week of rest. 5-FU pharmacokinetics were investigated after a single initial dose of S-1 during the first 24 hours and weekly thereafter. Results: Twenty-eight patients received S-1 at the four consecutive dose levels of 25, 45, 35, and 40 mg/m2. The MTD was initially found at 45 mg/m2, with diarrhea as the dose- limiting toxicity (DLT). Diarrhea was also the DL at the dose of 40 mg/m2, which was the MTD for patients exposed to extensive prior chemotherapy. Other toxicities were generally mild. Two patients had a reduction of more than 50% in tumor dimensional. Plasma pharmacokinetics of 5-FU were linear; at the highest S-1 dose level, 5-FU plasma peak concentrations reached 1 to 2 μmol/L, and the half-life of 5-FU was 3 to 4 hours. A statistically significant relationship was observed between the severity of diarrhea and pharmacokinetic parameters of 5-FU. Conclusion: The recommended dose of 5-1 in chemotherapy-naive or minimally chemotherapy-exposed patients is 40 mg/m2 bid on 28 consecutive days, every 5 weeks. In heavily pretreated patients, the recommended dose is 35 mg/m2 bid. Phase II trials are warranted in tumors known to be responsive to 5-FU treatment. (C) 2000 by American Society of Clinical Oncology.
|Original language||English (US)|
|Number of pages||8|
|Journal||Journal of Clinical Oncology|
|State||Published - Jul 2000|
ASJC Scopus subject areas
- Cancer Research