The Gruppo Oncologico Nord Ovest (GONO) conducted a phase III study comparing fluorouracil, leucovorin, oxaliplatin, and irinotecan (FOLFOXIRI [irinotecan 165 mg/m2 day 1, oxaliplatin 85 mg/m2 day 1, leucovorin 200 mg/m2 day 1, fluorouracil 3,200 mg/m2 48-hour continuous infusion starting on day 1, every 2 weeks]) with infusional fluorouracil, leucovorin, and irinotecan (FOLFIRI).

Selection criteria included unresectable metastatic colorectal cancer, age 18 to 75 years, and no prior chemotherapy for advanced disease. The primary end point was response rate (RR).

A total of 244 patients were randomly assigned. An increase of grade 2 to 3 peripheral neurotoxicity (0% v 19%; P < .001), and grade 3 to 4 neutropenia (28% v 50%; P < .001) were observed in the FOLFOXIRI arm. The incidence of febrile neutropenia (3% v 5%) and grade 3 to 4 diarrhea (12% v 20%) were not significantly different. Responses, as assessed by investigators, were, for FOLFIRI and FOLFOXIRI, respectively, complete, 6% and 8%; and partial, 35% and 58%, (RR, 41% v 66%; P = .0002). RR confirmed by an external panel was 34% versus 60% (P < .0001). The R0 secondary resection rate of metastases was greater in the FOLFOXIRI arm (6% v 15%; P = .033, among all 244 patients; and 12% v 36%; P = .017 among patients with liver metastases only). Progression-free survival (PFS) and overall survival (OS) were both significantly improved in the FOLFOXIRI arm (median PFS, 6.9 v 9.8 months; hazard ratio [HR], 0.63; P = .0006; median OS, 16.7 v 22.6 months; HR, 0.70; P = .032).

The FOLFOXIRI regimen improves RR, PFS, and OS compared with FOLFIRI, with an increased, but manageable, toxicity in patients with metastatic colorectal cancer with favorable prognostic characteristics. Further studies of FOLFOXIRI in combination with targeted agents and in the neoadjuvant setting are warranted.