title: Late phase II study of novel oral fluoropyrimidine anticancer drug S-1 (1 M tegafur-0.4 M gimestat-1 M otastat potassium) in advanced gastric cancer patients.
abstract: S-1 is a novel oral anticancer drug, composed of tegafur (FT), gimestat (CDHP) and otastat potassium (Oxo) in a molar ratio of 1:0.4:1, based on the biochemical modulation of 5-fluorouracil (5-FU). CDHP inhibits dihydropyrimidine dehydrogenase (DPD), an enzyme which degrades 5-FU, and maintains prolonged 5-FU concentrations in the blood and tumours. Oxo is distributed in the gastrointestinal tract at a high concentration after oral administration and alleviates gastrointestinal toxicity due to 5-FU. S-1 improves the tumour-selective toxicity of 5-FU by the actions of two modulators, CDHP and Oxo. We conducted a late phase II clinical trial of S-1 as an open trial in patients with advanced gastric cancer, to confirm its antitumour effect and adverse reactions. 51 patients with advanced gastric cancer were enrolled in the trial. S-1 was administered orally twice daily after meals, at a standard dose of 80 mg/m2/day. One course consisted of consecutive administration for 28 days and 14 days' rest. Administration was repeated over four courses. A complete response was obtained in 1 patient and partial responses in 24 patients, producing a response rate of 49% (25/51) (95% confidence interval (CI) 35.9-62.3%). The incidence of adverse reactions was 78% (40/51) and that of adverse reactions of grades 3 and 4 was 20%. Adverse reactions of grades 3 and 4 included a decrease in the haematocrit, leucopenia, granulocytopenia, diarrhoea, malaise and proteinuria. No serious unexpected adverse reactions were observed. In conclusion, S-1 was effective and well tolerated in patients with advanced gastric cancer.
authors.affiliation: Department of Gastroenterology, Aomori Prefectural Central Hospital, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Sakata
authors.forename: A
authors.initials: A
authors.lastname: Ohtsu
authors.forename: N
authors.initials: N
authors.lastname: Horikoshi
authors.forename: K
authors.initials: K
authors.lastname: Sugimachi
authors.forename: Y
authors.initials: Y
authors.lastname: Mitachi
authors.forename: T
authors.initials: T
authors.lastname: Taguchi
mesh_terms: D000284:Administration, Oral; D000328:Adult; D000368:Aged; D000964:Antimetabolites, Antineoplastic / Q000008:administration & dosage* / Q000009:adverse effects; D004338:Drug Combinations; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010094:Oxonic Acid / Q000008:administration & dosage* / Q000009:adverse effects; D011725:Pyridines / Q000008:administration & dosage* / Q000009:adverse effects; D013274:Stomach Neoplasms / Q000188:drug therapy* / Q000473:pathology; D016019:Survival Analysis; D005641:Tegafur / Q000008:administration & dosage* / Q000009:adverse effects; D016896:Treatment Outcome
chemical_list: D000964:Antimetabolites, Antineoplastic; D004338:Drug Combinations; D011725:Pyridines; C079198:S 1 (combination); D005641:Tegafur; D010094:Oxonic Acid