Phase I and pharmacologic studies of pyrazoloacridine, a novel DNA intercalating agent, on single-dosing and multiple-dosing schedules.

PURPOSETo determine the maximum-tolerated doses (MTDs), principal toxicities, and pharmacologic behavior of pyrazoloacridine (PZA), a novel DNA intercalator with a unique mechanism of action, on single- and multiple-dosing schedules.PATIENTS AND METHODSPZA was administered on a single-dosing schedule as a 1- to 3-hour infusion and on a multiple-dosing schedule as a 1-hour infusion daily for 5 days to cancer patients at doses ranging from 400 to 935 mg/m2 and 40 to 180 mg/m2/d every 3 weeks, respectively.RESULTSOn the single-dosing 1-hour schedule, CNS toxicity, characterized by neuropsychiatric and neuromotor effects, prompted prolongation of the infusion duration to 3 hours and led to a study of PZA on a multiple-dosing schedule. Both measures resulted in lower incidence of CNS toxicity. Neutropenia was the principal toxicity and precluded dose escalation to levels greater than 750 mg/m2 on the single-dosing (3-hour) schedule and 150 mg/m2/d x 5 (total dose, 750 mg/m2) on the multiple-dosing schedule. Th...