Purpose: In metastatic colorectal cancer, phase III studies have demonstrated the superiority of fluorouracil (FU) with leucovorin (LV) in combination with irinotecan or oxaliplatin over FU + LV alone. This phase III study investigated two sequences: folinic acid, FU, and irinotecan (FOLFIRI) followed by folinic acid, FU, and oxaliplatin (FOLFOX6; arm A), and FOLFOX6 followed by FOLFIRI (arm B).
Patients and methods: Previously untreated patients with assessable disease were randomly assigned to receive a 2-hour infusion of l-LV 200 mg/m(2) or dl-LV 400 mg/m(2) followed by a FU bolus 400 mg/m(2) and 46-hour infusion 2,400 to 3,000 mg/m(2) every 46 hours every 2 weeks, either with irinotecan 180 mg/m(2) or with oxaliplatin 100 mg/m(2) as a 2-hour infusion on day 1. At progression, irinotecan was replaced by oxaliplatin (arm A), or oxaliplatin by irinotecan (arm B).
Result: Median survival was 21.5 months in 109 patients allocated to FOLFIRI then FOLFOX6 versus 20.6 months in 111 patients allocated to FOLFOX6 then FOLFIRI (P =.99). Median second progression-free survival (PFS) was 14.2 months in arm A versus 10.9 in arm B (P =.64). In first-line therapy, FOLFIRI achieved 56% response rate (RR) and 8.5 months median PFS, versus FOLFOX6 which achieved 54% RR and 8.0 months median PFS (P =.26). Second-line FOLFIRI achieved 4% RR and 2.5 months median PFS, versus FOLFOX6 which achieved 15% RR and 4.2 months PFS. In first-line therapy, National Cancer Institute Common Toxicity Criteria grade 3/4 mucositis, nausea/vomiting, and grade 2 alopecia were more frequent with FOLFIRI, and grade 3/4 neutropenia and neurosensory toxicity were more frequent with FOLFOX6.
Conclusion: Both sequences achieved a prolonged survival and similar efficacy. The toxicity profiles were different.