SarCNU, a Nitrosourea Analog on a Day 1, 5, and 9 Oral Schedule: A Phase I and Pharmacokinetic Study in Patients With Advanced Solid Tumors

Abstract

Purpose: 2-Chloroethyl-3-sarcosinamide-1-nitrosourea (SarCNU) is a novel chloroethylnitrosourea that demonstrates selective cytotoxicity in athymic mice bearing human glioma. SarCNU demonstrates selective cytotoxicity in vitro against human glioma at least in part because of the selective SarCNU uptake by the extraneuronal monoamine transporter. The purpose of this phase I study was to determine the maximum-tolerated dose (MTD), the toxicity profile, the pharmacokinetics profile, and recommended phase II dose. Patients and Methods: Forty-three eligible patients with advanced solid tumors were enrolled. SarCNU was administered orally on days 1,5, and 9 every 28 days. The dose ranged from 30 to 1,075 mg/m2. Pharmacokinetic evaluation was done on the first cycle (one dose was given intravenously on day 1 or 5 of the first cycle to determine bioavailability). Results: Delayed myelosuppression (thrombocytopenia and neutropenia occurring 4 to 6 weeks after administration) was the dose-limiting toxicity (DLT). Anemia occurred but was mild. Nonhematologic toxicity was generally mild, but one patient died with pulmonary toxicity that was probably secondary to SarCNU. There were no partial or complete responses, but eight patients had stable disease for 19 to 46 weeks. The oral bioavailability of SarCNU was 80% ± 37%. The terminal phase half-life was similar after intravenous (58.4 ± 23.5 minutes) or oral (64.0 ± 34.8 minutes) administration. The total plasma clearance was 20.4 ± 8.8 L/h/m2, and the apparent volume of distribution was 29.9 ± 17.6 L/m2. The area under the plasma concentration–time profile increased proportionally with the dose, and the pharmacokinetics seemed to be independent of the route of administration and the number of doses. Conclusion: SarCNU was well tolerated and the MTD was 1,075 mg/m2. The recommended starting dose for phase II trials is 860 mg/m2 orally on days 1, 5, and 9 every 6 weeks.