Phase III randomized study of two fluorouracil combinations with either interferon alfa-2a or leucovorin for advanced colorectal cancer. Corfu-A Study Group.

PURPOSE: To compare the efficacy and toxicity profiles of a combination of fluorouracil (5-FU) with recombinant human interferon alfa-2a (Roferon-A; Hoffman La-Roche AG, Basel, Switzerland) versus the combination of 5-FU with leucovorin (LV) in the treatment of advanced colorectal cancer. PATIENTS AND METHODS: A total of 496 previously untreated colorectal cancer patients were randomized to receive either Roferon-A (9 MIU) subcutaneously three times per week, with 5-FU (750 mg/m2/d) by continuous intravenous (i.v.) infusion (CIV) on days 1 to 5, then, after a 9-day hiatus, as a weekly i.v. bolus at the same dose (IFN/5-FU); or LV (200 mg/m2/d) by i.v. infusion plus 5-FU (370 mg/m2/d) by i.v. bolus on days 1 to 5, repeated every 4 weeks (LV/5-FU). RESULTS: There were no significant differences between IFN/5-FU and LV/5-FU in the overall response rate (21% v 18%), duration of response (7.3 v 6.2 months), or survival time (median, 11.0 v 11.3 months). Toxicity profiles differed; constitutional symptoms and myelosuppression were more frequent and more severe with IFN/5-FU, and gastrointestinal symptoms with LV/5-FU. More patients interrupted treatment for adverse events (AEs) with IFN/5-FU than with LV/5-FU. Five treatment-related deaths occurred with each regimen. CONCLUSION: The combination IFN/5-FU produced response rates, response durations, and survival times similar to those with LV/5-FU. Biochemical modulation of 5-FU by either IFN or LV appears to result in equivalent efficacy; however, fewer patients were able to tolerate the specified IFN/5-FU combination used in this study.