A phase I study of combination S-1 plus cisplatin chemotherapy with concurrent thoracic radiation for locally advanced non-small cell lung cancer

A combination of S-1, a newly developed oral 5-fluorouracil derivative, and cisplatin is reported to show anti-tumour activity against advanced non-small cell lung cancer (NSCLC). Because S-1 shows synergistic effects with radiation, we conducted a phase I study to evaluate the maximum tolerated doses (MTDs), recommended doses (RDs), and dose-limiting toxicities (DLTs) of cisplatin and S-1 when combined with concurrent thoracic radiation (total dose of 60 Gy with 2 Gy per daily fraction) in patients with locally advanced NSCLC. Chemotherapy consisted of two 4-week cycles of cisplatin administered on days 1 and 8, and S-1 administered on days 1-14. S-1/cisplatin dosages (mg/m²/day) were escalated as follows: 60/30, 60/40, 70/40, 80/40 and 80/50. Twenty-two previously untreated patients were enrolled. The MTDs and RDs for S-1/cisplatin were 80/50 and 80/40, respectively. DLTs included febrile neutropaenia, thrombocytopaenia, bacterial pneumonia and delayed second cycle of chemotherapy. No patient experienced radiation pneumonitis > grade 2 and only one patient experienced grade 3 radiation oesophagitis. The overall response rate was 86.4% with a median survival time of 24.4 months. These results indicate that combination cisplatin-S-1 chemotherapy with concurrent thoracic radiation would be a feasible treatment option and a phase II study is currently under way.