Purpose: We conducted a phase I trial of carboxyamidotriazole (CAI, NSC 609974), designed to determine the maximum-tolerated dose (MTD), toxicity profile, and pharmacokinetic characteristics of CAI gelatin capsule (gelcap) formulation administered daily as a single oral dose.
Patients and methods: Twenty-nine patients with advanced malignancy who met standard eligibility criteria were treated with once-daily CAI given in cycles of 28 days. Pharmacokinetic sampling was performed on days 1 and 29 and trough plasma CAI levels were assessed weekly.
Results: Patients were entered at dose levels of 50, 75, and 100 mg/m2. All three patients at the 100-mg/m2 level experienced dose-limiting neurocerebellar toxicity. Other neurotoxicities were mild. Gastrointestinal side effects were common, but generally mild, with 23 patients experiencing nausea and/or vomiting of any grade. Fatigue was a frequent complaint, with 19 patients experiencing mild to moderate symptoms. Six patients with nausea and vomiting and five with fatigue experienced relief of symptoms with a change to nocturnal administration of CAI. Peak plasma concentrations (Cp) occurred at 2.4 +/- 1.5 hours after administration of the oral gelcap dose. Patients approached steady-state trough plasma concentrations (Css) by days 8 to 15 and maintained a relatively constant Css throughout the course of treatment. For all patients, the mean variation in weekly CAI Cp was 12.4% +/- 5.3%.
Conclusion: The MTD for the gelcap formulation was 75 mg/m2 with dose-limiting neurocerebellar toxicity (ataxia) seen at 100 mg/m2. Other prominent side effects, including nausea, vomiting, and fatigue, were partially alleviated through altering the administration schedule to nighttime dosing.