The objective of the present phase I study was to define the dose-limiting toxicities (DLTs) and maximum tolerated dose (MTD) of irinotecan, capecitabine, and oxaliplatin given in combination (IXO regimen) to patients with previously untreated, unresectable advanced or metastatic colorectal cancer (CRC).
PATIENTS AND METHODS
Patients received oxaliplatin followed by irinotecan as intravenous infusions on day 1, with oral capecitabine taken twice daily (BID) on days 2 to 15 of a 3-week cycle. The dose ranges were explored as follows: oxaliplatin, 75 to 120 mg/m2; irinotecan, 160 to 230 mg/m2; capecitabine, 750 to 1000 mg/m2 BID. Dose escalation was performed individually for each drug at each dose level according to the type and severity of toxicity encountered in the previous cohort.
A total of 39 patients were enrolled at 7 dose levels and the MTD. The recommended doses for phase II evaluation were oxaliplatin 100 mg/m2, irinotecan 160 mg/m2, and capecitabine 950 mg/m2 BID. Diarrhea and febrile neutropenia were DLTs. Of the 39 enrolled patients, 26 (67%) had confirmed objective responses. The median progression-free survival was 11 months, and the median overall survival was 25 months. The survival rate at 5 years was 23%.
The IXO regimen has a manageable toxicity profile with promising antitumor activity as first-line treatment of advanced and metastatic CRC.
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