S-1 (Teysuno^®): A Review of Its Use in Advanced Gastric Cancer in Non-Asian Populations

S-1 (Teysuno^®) is an oral anticancer agent comprising the 5-fluorouracil (5-FU) prodrug tegafur and targeted modulators, gimeracil and oteracil. S-1 in combination with cisplatin is a recommended first-line treatment for gastrointestinal cancers in Japan and has recently been approved in the EU for the treatment of advanced gastric cancer. This article reviews S-1 pharmacology from an EU perspective. In a randomized, open-label trial in 24 non-Asian countries in patients with advanced gastric cancer, there were no significant differences between S-1 plus cisplatin and 5-FU plus cisplatin groups in median overall survival (OS) [primary endpoint], progression-free survival or overall response rate. In a post hoc analysis of OS, S-1 plus cisplatin was noninferior to 5-FU plus cisplatin. There were no significant between-group differences in patient quality of life, according to the Functional Assessment of Cancer Therapy (Gastric) Trial Outcome Index, except that S-1 plus cisplatin recipients had a significantly longer time to worsening in physical well-being than 5-FU plus cisplatin recipients. Overall, S-1 plus cisplatin was better tolerated than 5-FU plus cisplatin, with significantly lower rates of haematological, some gastrointestinal tract and other adverse events, serious adverse events and deaths resulting from toxicity, along with significantly fewer haematological and renal function abnormalities. Compared with 5-FU, S-1 plus cisplatin recipients had significantly higher rates of hand-foot syndrome and hyperbilirubinaemia, although there were no between-group differences in the proportions of patients with increased liver enzymes. S-1 is a useful alternative to 5-FU for patients with advanced gastric cancer.