HIGH SINGLE-DOSE OF MITOXANTRONE AND CYTARABINE IN ACUTE NONLYMPHOCYTIC LEUKEMIA - A PHARMACOKINETIC AND CLINICAL-STUDY

In a phase I-II study, the authors evaluated the intracellular pharmac okinetics, toxicity, and efficiency of a high dose of mitoxantrone giv en as first induction in acute non-lymphocytic leukemia. Twenty-two pa tients with previously untreated de novo ANLL were included and receiv ed 30 or 40 mg/m(2) mitoxantrone on day 1 by intravenous infusion over 1 hour and 500 mg/m(2) ara-C twice a day for 5 days. If there was no complete remission (CR), a second induction with ara-C, etoposide, and amsacrine was given. The CR rate after two courses with this regimen was 77%. Median duration of severe neutropenia was 18 days in the 30-m g/m(2) group and 25 days in the 40-mg/m(2) group. Two patients had fat al lung complications probably unrelated to mitoxantrone. A third pati ent had a possible mitoxantrone-induced reversible lung complication. In the leukemic cells, we found a high accumulation of mitoxantrone wh ich, in contrast to the plasma concentration, remained stable during t he 48 hours studied. Compared with previous results with 12 mg/m(2) mi toxantrone, the AUC for intracellular concentrations versus time for t he first 20 hours studied was increased by 150% to 0.638 nmol/mg cell protein x hour with 30 mg/m(2) mitoxantrone and by 260% to 1.103 nmol/ mg cell protein x hour with 40 mg/m(2) mitoxantrone. In conclusion, a high dose of mitoxantrone results in a high intracellular exposure of the leukemic cells, which may be an advantage in improving survival of these patients.