Pharmacokinetics of Mitoxantrone in Plasma and Leukemic Cells During Treatment of Patients with Acute Non-Lymphocytic Leukemia

High single dose of mitoxantrone and cytarabine in acute non-lymphocytic leukemia: a pharmacokinetic and clinical study

In a phase I-II study, the authors evaluated the intracellular pharmacokinetics, toxicity, and efficiency of a high dose of mitoxantrone given as first induction in acute non-lymphocytic leukemia. Twenty-two patients with previously untreated de novo ANLL were included and received 30 or 40 mg/m2 mitoxantrone on day 1 by intravenous infusion over 1 hour and 500 mg/m2 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-mg/m2 group and 25 days in the 40-mg/m2 group. Two patients had fatal lung complications probably unrelated to mitoxantrone. A third patient had a possible mitoxantrone-induced reversible lung complication. In the leukemic cells, we found a high accumulation of mitoxantrone which, in contrast to the plasma concentration, remained stable during the 48 hours studied. Compared with previous results with 12 mg/m2 mitoxantrone, the AUC for intracellular concentrations versus time for the first 20 hours studied was increased by 150% to 0.638 nmol/mg cell protein x hour with 30 mg/m2 mitoxantrone and by 260% to 1.103 nmol/mg cell protein x hour with 40 mg/m2 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.

Effects of intrapleural mitoxantrone and mepacrine on malignant pleural effusion--a randomised study

30 patients with malignant pleuritis were randomised to be treated, either with intrapleural instillation of mepacrine chloride or with mitoxantrone. The patients were evaluated with chest X-ray and a symptom questionnaire during a follow-up period of 12 weeks. Mitoxantrone levels in the pleural space and plasma were measured at different time points in some of the patients. High concentrations of mitoxantrone were found in the pleural fluid while the plasma concentrations were low, giving a plasma/intracavity ratio generally of less than 1:60. The chest X-rays showed excellent results for both treatment modalities. However, the patients treated with mepacrine chloride experienced greater discomfort with fever and pain, and those treated with mitoxantrone reported significantly less dyspnoea and less asthenia after 4 weeks. We conclude that both treatments are equally effective in preventing the recurrence of malignant effusion. However, mitoxantrone seems to have further advantages when it comes to improving the quality of life.

Pharmacokinetics of mitoxantrone, etoposide and cytosine arabinoside in leukemic cells during treatment of acute myelogenous leukemia--relationship to treatment outcome and bone marrow toxicity

Twenty-seven patients with acute myelogenous leukemia (AML) were given remission induction treatment with mitoxantrone, etoposide and cytosine arabinoside (ara-C). The pharmacokinetics in leukemic blood cells of mitoxantrone, etoposide and the active metabolite of ara-C, ara-CTP, were determined during the first day of treatment. There was a large interpatient variability of the area under the time versus concentration curve (AUC) for all three drugs. On the individual level, there was no correlation between the AUCs of the different drugs. Neither did the AUC of any individual drug nor the calculated total intracellular drug exposure have any association with the outcome of treatment or hematological toxicity, measured as duration of leukopenia/thrombocytopenia. In conclusion, when combination chemotherapy with mitoxantrone, etoposide and ara-C is given to patients with AML, intracellular drug concentrations, achieved after the first dose of each drug, do not seem to be predictive for treatment response or hematological toxicity.

In vivo accumulation of etoposide in peripheral leukemic cells in patients treated for acute myeloblastic leukemia; relation to plasma concentrations and protein binding

Since etoposide interacts with the nuclear enzyme topoisomerase II, the drug concentrations in the malignant cells during chemotherapy may have clinical correlates. Plasma protein binding of etoposide is extensive (94%) and alterations of the non-proteinbound fraction affect pharmacokinetic behavior of the drug. The pharmacokinetics of etoposide was therefore studied in plasma, total and non-proteinbound concentrations, and in leukemic cells isolated from peripheral blood samples from 22 patients after the first dose of the induction treatment for acute myelocytic leukemia. Fourteen patients received 100 mg/m2 and eight patients 200 mg/m2 as a 1 h infusion. The mean area under the concentration versus time curve AUC(0-infinity) in plasma was at the lower dose level 78.4 +/- 29.1 (mean +/- S.D.) micrograms/ml x h and 201.0 +/- 56.5 micrograms/ml x h at the higher dose level. The fraction of non-proteinbound etoposide in plasma was 5.2 +/- 3.4 and 5.4 +/- 2.1% in the two treatment groups. AUC(0-16h) in leukemic cells was 8.4 +/- 8.7 and 22.4 +/- 12.1 micrograms/ml x h at the two dose levels, respectively. The cellular etoposide concentration was 12.1 +/- 7.9 and 14.7 +/- 5.1% of the plasma concentration at the end of the infusion. The interpatient variability in cellular drug levels was considerable and exceeded the variability in plasma concentrations. Cellular accumulation of etoposide could be important for treatment outcome.

Intracellular concentrations of mitoxantrone in leukemic cells in vitro vs in vivo

The aim of this study was to determine the intracellular pharmacokinetics of mitoxantrone in vivo and to use these results to establish how leukemic cells should be incubated to perform clinically relevant in vitro studies of this drug. Blood samples were obtained from 11 patients with acute nonlymphoblastic leukemia at certain intervals up to 20 h after the infusion of mitoxantrone 12 mg/m2. Plasma and leukemic cells were separated and the drug concentrations were determined with HPLC. Before treatment, leukemic cells from 12 patients were incubated with 0.02, 0.05, 0.1, 0.2 and 1.0 microM mitoxantrone for 1-4 h and thereafter cultured in suspension culture for 20 h; during this time cell samples were taken at certain intervals for drug determination. In cells incubated with 0.05 and 0.2 microM mitoxantrone the cytotoxic effect was measured with the DiSC assay after cultivation for 4-5 days. In vivo, the intracellular levels exceeded the plasma concentrations already at the end of infusion and after 2 h the intracellular concentrations were 200-300 times higher than in plasma. In vitro, the intracellular steady state level of mitoxantrone was reached after 1-2 h and there was a pronounced intracellular retention even after 20 h culture in drug-free medium. Incubation with 0.05 microM during 1 h gave intracellular concentrations of mitoxantrone similar to those achieved in vivo. This incubation concentration gave a mean cytotoxic effect of 53% living cells measured with the DiSC assay, which gives good possibilities to discriminate between mitoxantrone-sensitive and unsensitive cells. We believe that exposing leukemic cells in vitro for in vivo mimicking mitoxantrone concentrations could increase the clinical relevance of predictive assays.