Pharmacology of chlorozotocin Nsc-178248), a new nitrosourea antitumor agent.

Structure-activity studies of nitrosourea pharmacology have resulted in the synthesis of a new water-soluble agent,chlorozotocin, which has significant antitumor activity against the L1210 leukemia system and produces only a minor degree of inhibition of mouse and human bone marrow DNA synthesis compared to BCNU. It is important to emphasize that the bone marrow sparing feature of chlorozotocin is relative and that if the drug is administered at lethal dose levels in mice, myelosuppression is observed. The potential importance of these studies is the identification of a new and active nitrosourea antiumor agent with modified bone marrow toxicity. If aminoglucose modification of nitrosourea bone marrow toxicity can be confirmed in man without significant loss of antitumor activity, the use of such a compound could facilitate treatment of patients with neoplastic disease who have pre-existing abnormal bone marrow function. It would also allow the more effective use of a nitrosourea agent in combination with anticancer agents possessing more potent myelosuppressive properties.