Celecoxib and mucosal protection: translation from an animal model to a phase I clinical trial of celecoxib, irinotecan, and 5-fluorouracil.

PURPOSE Chemotherapy-induced diarrhea occurs secondary to mucosal inflammation and may be cyclooxygenase-2 mediated. Cyclooxygenase-2 inhibitors may ameliorate chemotherapy-induced mucosal toxicity and enhance its antitumor effect. We investigated this hypothesis in the Ward colorectal cancer rat model and in a phase I clinical study. EXPERIMENTAL DESIGN In the Ward rat model, irinotecan was given daily x 3 or weekly x 4 with or without celecoxib. In the phase I clinical study, we planned to escalate the dose of irinotecan in the FOLFIRI regimen (irinotecan, 5-fluorouracil, and leucovorin) with a fixed dose of celecoxib. Irinotecan was escalated in four dose levels: 180, 200, 220, and 260 mg/m2. Celecoxib was administered as 400 mg, twice daily starting on day 2 of cycle 1. Pharmacokinetics of irinotecan, SN-38, and SN-38G were obtained on days 1 and 14. A standard 3+3 dose escalation scheme was used. Plasma concentrations of irinotecan, SN-38, and SN-38G were measured using high-pressure liquid chromatography. RESULTS Celecoxib ameliorated diarrhea, weight loss, and lethality and resulted in synergistic antitumor effect in the rat model. Twelve patients with advanced cancers were enrolled and evaluable for dose-limiting toxicity (DLT). Diarrhea was the cause for discontinuation in one. Grade 2 and 3 diarrhea occurred in three and two patients, respectively. One patient had DLT at dose level 2 (grade 3 diarrhea). Two had a DLT at DL3 (G3 emesis and myocardial infarct). Celecoxib had limited influence on the pharmacokinetics of irinotecan in this data set. CONCLUSIONS Maximum tolerated dose of irinotecan in FOLFIRI schedule with celecoxib is 200 mg/m2.