Dose-finding study of weekly 24-h continuous infusion of 5-fluorouracil associated with alternating oxaliplatin or irinotecan in advanced colorectal cancer patients.

Purpose: To determine maximum tolerated dose, safety and efficacy of weekly 24 h infusional 5-fluorouracil (5-FU) combined alternately with oxaliplatin and irinotecan.
Patients and Methods: Advanced colorectal carcinoma patients in first- or second-line chemotherapy received increasing doses of 5-FU (weekly 24 h continuous intravenous infusion without leucovorin) on days 1, 8, 15 and 22, irinotecan days 1 and 15; and oxaliplatin days 8 and 22, every 35 days.
Results: Thirty-four patients received 175 cycles. The median age was 64 years (range 47-78). Eighteen per cent of patients had the primary tumor in the rectum, with a median of one disease site (range one to three), and liver involvement in 88% and lung in 38%. Six (18%) patients had chemotherapy for prior advanced disease. The most frequent grade 3-4 toxicity was neutropenia (41% of patients), but the regimen was well tolerated clinically, with febrile neutropenia in two patients and grade 4 neutropenia lasting >7 days in one; grade 3-4 diarrhea, nausea and vomiting in 6% of patients; grade 3-4 peripheral neuropathy in 9% of patients. Seventeen patients had a partial response (50%; 95% confidence interval 33%-67%), 13 had stable disease and one had progressive disease. Five patients underwent metastatic surgical resection after tumor shrinkage. Median response duration was 14 months (range 4.7-29.2+) and median time to progression was 11.3 months (range 1.1+-30.7+).
Conclusions: This combination three-drug regimen is feasible and well tolerated without toxicity overlap. Preliminary antitumor activity compares well with standard double combinations, with an unusually long median time to progression. The recommended dose is 5-FU 3000 mg/m(2), weekly for 4 weeks, irinotecan 100 mg/m(2) days 1 and 15, oxaliplatin 80 mg/m(2) days 8 and 22. Further assessment of antitumor activity and safety is warranted.