Background: Three different therapeutic regimens of irinotecan (CPT-11) in combination with 5-fluorouracil (5-FU) and folinic acid (FA) were evaluated for efficacy and safety in the first-line therapy of advanced colorectal cancer.
Patients and methods: Patients were randomly assigned to receive intravenously either: CPT-11 125 mg/m(2), FA 20 mg/m(2) followed by 5-FU 500 mg/m(2) bolus, weekly for 4 weeks (arm A, Saltz regimen); or CPT-11 180 mg/m(2) day 1 then FA 200 mg/m(2) over 2 h and 5-FU 400 mg/m(2) bolus and 5-FU 600 mg/m(2) 22-h infusion on days 1 and 2, every 2 weeks (arm B, Douillard regimen); or CPT-11 350 mg/m(2) (days 1 and 43) alternating with FA 20 mg/m(2)/day followed by 5-FU bolus 425 mg/m(2)/day during 5 days (days 22-26) (arm C, Mayo Clinic regimen).
Results: A total of 154 patients were included in the study (arm A, 51 patients; arm B, 53; arm C, 50). Overall response rates for the intention-to-treat populations were 33% [95% confidence interval (CI) 21% to 48%], 42% (95% CI 28% to 56%) and 30% (95% CI 18% to 45%) for arms A, B and C, respectively. Median times to progression were 6, 8 and 7 months for arms A, B and C, respectively. Median survival times were 15, 12 and 17 months for arms A, B and C, respectively. Overall response rates for the evaluable patient populations were 40% (95% CI 24% to 58%) in arm A, 44% (95% CI 29% to 60%) in arm B and 31% (95% CI 17% to 47%) in arm C. Neutropenia was the main serious adverse event in arms A (30% of patients) and C (22% of patients) but occurred in only 8% of patients in arm B. Delayed diarrhea was the main severe adverse event for the three regimens, from 15% to 22%.
Conclusion: All three regimens were highly active. The biweekly combination of CPT-11 and 5-FU/FA (arm B) was notable for its low incidence of grade 3/4 neutropenia. The incidence of grade 3/4 delayed diarrhea was equivalent for the three treatment arms.