Toxicity of WR-2721 administered in single and multiple doses.
Two hundred forty-three patients have received WR-2721 in Phase I-II studies. Separate studies were conducted in which patients with advanced malignancies received WR-2721 before single or multiple doses of radiotherapy or in single doses prior to cyclophosphamide, nitrogen mustard or cis-platinum. Single doses were escalated from 25 to 1330 mg/m2. An Acceptable Tolerated Dose (ATD) of 740 mg/m2 infused in 15 minutes has been established and is currently used in Phase II studies. Significant persistent hypotension (greater than 20 torr systolic) as a dose-limiting toxicity has occurred in 5% of patients in the single dose study. Fifty-five patients have been entered in the multiple dose trial. Dose levels of 340 mg/m2, four times a week for three weeks, and 250 mg/m2, four times a week for six weeks have been reached. There were five idiosynchratic reactions (fever, chills, rash, hypotension), one of which was severe. Some patients withdrew from the multiple dose study because of vomiting after each injection, or fear. No deaths nor any long-term untoward effects were observed. There is no suggestion of tumor protection.