Phase I and pharmacokinetic study of trans-N3P3Az2(NHMe)4

trans-N3P3Az2(NHMe)4, an aziridinyl-substituted cyclophosphazene, was tested for its toxicity, pharmacokinetic behavior, and cytostatic activity in a phase I study in 30 patients. A total of 66 courses of a single iv bolus injection were given in five dose steps. Toxicity consisted of leukocytopenia and thrombocytopenia, dose limiting at 70 mg/m2, mild anemia, and some nausea. Leukocyte and platelet count nadirs fell between 2 and 3 weeks, with recovery at 6 weeks. A tendency for cumulative thrombocytopenia was noticed in three of 13 patients at risk. A three-phase plasma elimination model was applicable with t1/2 alpha of 9.9 minutes, t1/2 beta of 78.5 minutes, and t1/2 gamma of 435.5 minutes; renal drug excretion was substantial. Three partial remissions in 21 evaluable patients suggest some clinical activity for this drug.