Phase I-II study of irinotecan in combination with mitomycin C in patients with advanced gastrointestinal cancer.

This phase I-II study was conducted to determine the maximum tolerated dose and optimal schedule of a combination of irinotecan (CPT 11) and mitomycin C (MMC) in a population of previously treated patients with gastrointestinal malignancies. Four cohorts of patients were recruited with MMC given at 8 mg/m2 for the first 3 levels together with irinotecan at 300 mg/m2, 325 mg/m2, and 350 mg/m2; the fourth dose level was given with MMC at 10 mg/m2 and irinotecan at 325 mg/m2. All treatment was repeated at 21-day intervals. The dose-limiting toxicity was hematologic (thrombocytopenia at level 4), and the recommended doses for subsequent phase II studies are MMC 8 mg/m2 with irinotecan 325 mg/m2. Evidence of efficacy was seen at all dose levels examined and justifies further exploration of this combination in a less heavily pretreated patient population.