Chlorozotocin: results in colorectal carcinoma treated with high and low doses. A Southwest Oncology Group study

Clorozotocin was evaluated in patients with advanced colorectal cancer at 225 mg/m2 every six weeks in 14 patients with no prior treatment, at 200 mg/m2 in 43 patients with normal tolerance of prior chemotherapy, and at 100 mg/m2 in 38 patients with extensive or poorly tolerated prior therapy. Median survival for the respective groups was 192, 107 and 79 days; these differences are best explained as a function of performance status. Partial response was reported for one patient, 15 had disease stabilization and two had improvement short of partial remission. Myelotoxicity was acceptable at all doses, with thrombocytopenia being dose limiting at 225 mg/m2. Four patients developed azotemia during or after chlorozotocin treatment. Chlorozotocin has minimal activity against colorectal carcinomas and no dose-response relationship is evident.