Safety and Pharmacokinetics of Escalated Doses of Weekly Intravenous Infusion of CCI-779, a Novel mTOR Inhibitor, in Patients With Cancer

Abstract

Purpose To establish the safety, tolerability, and pharmacokinetic parameters of CCI-779, a selective inhibitor of the mammalian target of rapamycin, in patients with advanced cancer. Patients and Methods Using a modified continuous reassessment method, we performed a phase I with pharmacokinetic study of CCI-779 given as a weekly 30 minutes intravenous (IV) infusion. Results Twenty-four patients received CCI-779 at doses ranging 7.5 to 220 mg/m². No immunosuppressive effect was reported. Dose-limiting thrombocytopenia occurred in two patients at 34 or 45 mg/m². At 220 mg/m², dose-limiting toxicities consisted of manic-depressive syndrome, stomatitis, and asthenia in two of nine patients, preventing further dose escalation. The most frequent drug-related toxicities were acne-like, maculopapular rashes and mucositis or stomatitis. All toxicities were reversible on treatment discontinuation. Maximum concentration and area under the concentration-time curve increase sub-proportionally with dose. Mean steady-state volume of distribution ranged from 127 to 385L. Sirolimus was a major metabolite (metabolite-to-parent ratio range, 2.5 to 3.5). Whole blood clearance was nonlinear, ranging from 19 to 51 L/h (34 to 220 mg/m²). Variability predicted with flat doses appears comparable with data based on body-surface area–normalized treatment. Partial responses were observed in one patient with renal clear-cell carcinoma and in one patient with breast adenocarcinoma. Conclusion CCI-779 displayed no immunosuppressive effects with manageable and reversible adverse events at doses up to 220 mg/m², the highest dose tested. Based on our results, weekly doses of 25, 75, and 250 mg CCI-779 not based on classical definitions of maximum-tolerated dose are being tested in phase II trials in patients with breast and renal cancer.