Early phase II study of S-1, a new oral fluoropyrimidine, for advanced non-small-cell lung cancer

The efficacy and safety of S-1, a new oral fluoropyrimidine, were evaluated in patients with non-small-cell lung cancer (NSCLC). The objective of this study was to determine whether the drug should be investigated in a late phase II study.

Each treatment course consisted of an oral dose of S-1, 50 mg/body or 75 mg/body, twice a day for 28 days followed by a 2-week washout period.

Fifty-six eligible patients were enrolled. Five of the 40 previously untreated patients (12.5%; 90% confidence interval, 6.2%-23.5%) showed a partial response (PR), and no tumor response was observed in the 16 previously treated patients. The median survival duration in all eligible patients was 8.4 months, with a 1-year survival rate of 27.3%. The incidences of grade 3 or more severe adverse effects were: anemia, 5.4%; leukopenia, 5.4%; neutropenia, 5.4%; thrombocytopenia, 1.8%; anorexia, 3.6%; diarrhea, 3.6%; and general fatigue, 5.4%. These effects disappeared after cessation of the drug or appropriate treatment. One patient died as a result of aggravated interstitial pneumonitis, but the relationship of this event to S-1 was not clear.

S-1 showed modest activity with mild toxicity in the treatment of non-small-cell lung cancer. Based on this result, we will progress to the next stage of a late phase II study for advanced NSCLC, and a phase II study of S-1 and cisplatin for advanced gastric cancer. Final results will be reported as they are obtained.