Phase II study of S-1 monotherapy in patients with previously treated, advanced non-small-cell lung cancer

Background In this phase II clinical trial, we evaluated the efficacy and safety of S-1 monotherapy in patients with previously treated advanced non-small-cell lung cancer (NSCLC). We also measured plasma concentrations of 5-fluorouracil (5-FU) and 5-chloro-2,4-dihydroxypyridine components of S-1 and examined correlation with effectiveness and toxicity. Methods S-1 was given orally at a dose of 80 mg/m(2)/day for 14 consecutive days, followed by a 7-day rest period. This treatment course was repeated until disease progression or intolerable toxicity. Results We enrolled 30 patients. The response rate was 26.7% (8/30), and the disease control rate was 70% (21/30). Median progression-free survival (PFS) was 3.1 months, and median overall survival (OS) was 11.2 months. Mutations in the epidermal growth factor receptor (EGFR) gene were analyzed in 27 patients. The response rate was higher in patients with mutant EGFR (50.0%) than in those with wild-type EGFR (11.8%, P = 0.0288). Median PFS was 4.8 and 2.5 months (P = 0.038), and median OS was 22.4 and 8.4 months (P = 0.071). There was no grade 4 toxicity in this study. Five patients had grade 3 non-hematologic toxicity, and there was a trend toward higher plasma concentrations of 5-FU in those patients than in another patients. Conclusions S-1 monotherapy is effective and well-tolerated treatment for previously treated advanced NSCLC.