Phase I evaluation of semustine in a weekly schedule

A phase I study of weekly semustine was conducted in 32 patients with advanced cancer. Doses were escalated from 18 to 36 mg/m2/week. At a dose of 36 mg/m2/week, 43% of the patients developed platelet counts less than 100,000/mm3 after a median of 20 weeks on study, and 25% developed wbc counts less than 3000/mm3 after a median of 16 weeks on study. Drug-related nausea was reported by only one patient and was the only subjective toxic effect reported. Tumor regressions were noted in patients with adenocarcinoma of the colon, melanoma, and mixed adenocarcinoma and squamous cell lung cancer. A reasonable starting dose for phase II studies is 36 mg/m2/week, with dose adjustments based on platelet and wbc counts.