Diaziquone (AZQ).

Diaziquone is an aziridinylbenzoquinone with properties suggestive of an alkylating agent. The drug has shown broad antitumor activity against numerous transplantable murine tumors including curative activity against several intracerebrally implanted tumors. Parent diaziquone appears to have a t1/2 beta of approximately 30 min. The drug is rapidly and widely distributed to tissues as evidenced by a t1/2 alpha of approximately 1-3 min and a volume of distribution exceeding that of total body water. In addition, it rapidly penetrates the central nervous system, reaching peak concentrations (30-50%) of corresponding plasma levels) in approximately one hour. Diaziquone is rapidly and extensively metabolized by the liver. Diaziquone is a potent marrow suppressive agent inducing significant degrees of leukopenia, granulocytopenia, and thrombocytopenia in humans. Thrombocytopenia is often severe. Although myelosuppression is for the most part dose related, many patients had significant toxicity even at lower doses. Most investigators have attributed this to the extent of prior therapy. Diaziquone demonstrates a very steep dose-response relationship. Myelosuppression was the dose-limiting toxicity in all phase I trials. No nonhematologic dose-limiting toxicity has been identified to date. In phase I and preliminary phase II trials, diaziquone has demonstrated activity against primary brain tumors. Little activity has been seen in other tumor categories. It should be noted, however, that all studies to date have been carried out in heavily pretreated patients. Because of the broad spectrum of antitumor activity in experimental murine tumors, the lack of nonhematologic dose-limiting toxicity, the ability of this drug to attain significant levels in the central nervous system, and the activity of the drug in primary brain tumors, further studies examining its role in the management of patients with cancer are warranted. These studies should be conducted in patients who have had little or no prior therapy in order to better evaluate the efficacy of the drug.