Phase II trial of PCNU in advanced colorectal carcinoma. An Eastern Cooperative Oncology Group pilot study

PCNU, a chloroethylnitrosourea with high alkylating activity, low carbamoylating activity, optimal octanol: water partition coefficient, and broad activity in animal systems was administered to 30 evaluable patients with measurable advanced colorectal carcinoma by brief intravenous infusions every 6 weeks. The initial dose was 75 or 100 mg/m2, with escalation or reduction for toxicity, and a total of 64 evaluable courses were given. Half of the patient population had received no prior chemotherapy. Two objective partial responses occurred. The response rate was 6.7% with a 95% confidence interval of 0.8-22.1%. Thrombocytopenia was dose-limited and leukopenia was relatively mild. Gastrointestinal toxicity was less severe than expected for clinically available nitrosoureas. In colorectal carcinoma, PCNU has limited clinical activity that does not appear to be superior to that of other nitrosoureas.