A phase II study of chlorozotocin in metastatic malignant melanoma

Thirty-five patients with metastatic malignant melanoma underwent treatment with chlorozotocin administered as a single dose of 120 mg/m2 by means of rapid intravenous infusion every six weeks. There were 1 complete and 4 partial remissions with an overall response rate of 14%. The median duration of response was 18 weeks; the patient in complete remission continues disease-free in excess of 42 weeks. The sites of response included: lung, 2; subcutaneous, 2; and lymph node, 1. There was minimal myelotoxicity: for the first cycle, the median white blood cell count nadir was 5400/mm3, and the platelet nadir was 210,000/mm3. No evidence of cumulative platelet toxicity was observed. Chlorozotocin is active against metastatic melanoma to the same degree as other chloroethylnitrosoureas in clinical use, but without causing bone marrow toxicity. These data suggest that chlorozotocin should be evaluated in combination with other agents active against melanoma.