Purpose: The goals of this study were to determine the maximum-tolerated dose and describe the toxicities of the combination of irinotecan and docetaxel administered every 3 weeks to patients with advanced malignancies and, also, to evaluate the effect of irinotecan on the disposition of docetaxel and describe preliminary evidence of antitumor activity.
Patients and methods: Eighteen patients received 85 courses (median, two courses; range, one to 15 courses) of treatment with irinotecan, administered over 90 minutes by intravenous infusion, followed by docetaxel, administered over 60 minutes by intravenous infusion. Four escalating dose levels of irinotecan/docetaxel (160/50 mg/m(2), 160/65 mg/m(2), 200/65 mg/m(2), and 200/75 mg/m(2)) were studied. Pharmacokinetic analyses were performed to evaluate the effect of irinotecan on the disposition of docetaxel.
Results: The most common and dose-limiting toxicity was myelosuppression, which consisted of neutropenia that was severe (National Cancer Institute common toxicity criteria [NCI CTC] grade 4) but brief (< 5 days) in 11 patients, with three episodes of febrile neutropenia. Nonhematologic toxicities of anorexia, nausea, and stomatitis were mild to moderate (NCI CTC grades 1 and 2), but there was one incidence each of both CTC grade 3 anorexia and nausea. All patients had total alopecia. Diarrhea was dose-dependent and severe in four patients who failed to take adequate antidiarrhea therapy. Five out of 16 assessable patients, one with cholangiocarcinoma, one with leiomyosarcoma, and three with non-small-cell lung cancer, achieved partial remissions.
Conclusion: The combination of irinotecan and docetaxel causes significant reversible myelosuppression, which was dose limiting but led to no serious sequelae. There was no evidence of a clinically significant interaction using these two agents in this sequence. The combination showed antitumor activity at all the dose levels tested and should be further studied in a number of tumor types. The recommended phase II dose on this schedule is irinotecan 160 mg/m(2) and docetaxel 65 mg/m(2).