Pilot study of simplified low-dose S-1 plus CPT-11 as first-line chemotherapy for patients with advanced colorectal cancer

Abstract

Background: 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. S-1 plus irinotecan (CPT-11) administered for advanced colorectal cancer could be expected to show as equally good results as the infusional 5-fluorouracil/leucovorin (5-FU/LV) with CPT-11 (FOLFIRI) regimen. When toxicity is too severe preventing patients from receiving an intensive chemotherapeutic regimen, survival benefit might be forfeited. A pilot study of low-dose S-1 plus CPT-11 therapy with constant doses without consideration of body surface area (BSA) was therefore performed.

Patients and methods: Twenty-two patients were enrolled in this study. S-1 was given orally at 40 mg b.i.d. for 21 consecutive days followed by a 14-day rest period. CPT-11 was administered as a 90-minute intravenous infusion at a dose of 80 mg on days 1 and 15. Courses of treatment were repeated every 35 days.

Results: The median age was 62.5 years (26-74). The median cycles were 8.5 (3-20). The overall response rate was 45.5% (complete response (CR), 1; partial response (PR), 9). Median progression-free survival (PFS) and median overall survival time (MST) were 9.0 and 20.2 months respectively. No grade 3 or 4 toxicities were observed. Eight patients (36.4%) did not have any sign or symptom of toxicity throughout all the treatment courses. The response, survival and toxicity were not significantly different according to BSA.

Conclusion: These results suggest that simplified low-dose S-1 plus CPT-11 treatment might be of considerable advantage as first-line chemotherapy for patients with advanced colorectal cancer who would like to avoid toxicity.