Intensive single-agent mitoxantrone for metastatic breast cancer

Toxicity of the topoisomerase II inhibitors

Topoisomerase II inhibitors represent a broad class of antineoplastic agents with a wide spectrum of activity against malignancies. Topoisomerase II inhibitors include the anthracyclines, mitoxantrone and epipodophyllotoxins. Short-term toxicity includes myelosuppression and gastrointestinal toxicity. Long-term survivors are at risk of cardiac toxicity and secondary leukaemia. This article discusses these toxicities in detail, including administration of these agents to patients with hepatic and/or renal insufficiency, and the need for dose adjustments in selected patient populations.

Stem-cell transplant preparative regimens

Owing to the relatively high probability of recurrent disease in patients receiving hematopoietic stem-cell transplantation (HSCT) for malignancies, further development of new preparative regimens is warranted. Based on the data presented, one can predict that it will continue to be difficult to identify HSCT regimens that are more effective. Incremental improvements are expected to be small, difficult to measure, and will require inclusion of very large numbers of patients. Controlled trials to evaluate the effectiveness of specific treatment regimens for specific groups of patients will require only centers with large numbers of patients or co-operative groups to successfully conduct these studies. Development of HSCT regimens with low mortality and a minimum of morbidity without compromising efficacy are needed. This may be accomplished through the use of agents to protect normal, non-hematopoietic tissues from regimen-related toxicity (RRT), further exploration and expansion of applications of targeted radiolabeled antibody approaches and mixed chimerism approaches. The future holds much work, but great promise, in the development of new HSCT regimens.

Phase I/II trial of high dose mitoxantrone in metastatic breast cancer: the M.D. Anderson Cancer Center experience

Anthracyclines are among the most active agents in metastatic breast cancer. Mitoxantrone demonstrated a different toxicity profile when compared to doxorubicin. We performed a phase I/II study of single-agent high-dose mitoxantrone therapy for advanced breast cancer. Nineteen patients who had a diagnosis of metastatic breast cancer received treatment at the M.D. Anderson Cancer Center between June 1986 and December 1987. The patients received escalating doses of mitoxantrone until a maximum tolerated dose (MTD), defined as grade 3 or 4 nonhematologic toxicity or infection, was obtained. The starting dose of 25 mg/m2, given by short intravenous infusion, was escalated by 25% in each five-patient cohort if each patient in the previous cohort tolerated the initial course and 2 or fewer patients reached the MTD. The median cumulative dose of mitoxantrone was 93 mg/m2 (range, 25-205) and the maximum single dose was 39 mg/m2. Myelosuppression was the dose limiting toxicity. The median duration of granulocyte count < or = 250/microl was 5-7 days. Four patients (22%) had infections that required hospitalization, 3 patients (17%) had cardiac toxicity. One patient (6%) achieved a complete response, and 3 (17%) had a partial response, with an overall response rate of 22.3%. No apparent dose-response relationship was observed in our study. The mitoxantrone dosage recommended for phase II studies is 25 mg/m2 every 3-4 weeks. We conclude that high-dose mitoxantrone therapy for metastatic breast cancer was relatively well tolerated but was not associated with a higher response rate than that of standard dose mitoxantrone.

Phase I trial of mitoxantrone and granulocyte-macrophage colony-stimulating factor (GM-CSF) in patients with advanced solid malignancies

PURPOSE

To determine the maximally tolerated dose (MTD) and pharmacokinetics of high-dose mitoxantrone and document the toxicities and side effects of mitoxantrone when administered with GM-CSF.

PATIENTS AND METHODS

Twenty-three patients with advanced solid tumors were entered into a phase I and pharmacokinetic study. Mitoxantrone was administered at doses of 12, 21, 28, 32, 37, and 48 mg/m2 on day 1; GM-CSF (5 micrograms/kg once or twice daily) was administered on days 2 to 14. Therapy was repeated every 3 weeks. Dose escalation continued in sets of three patients until the dose limiting toxicity (DLT) was observed. The DLT was based on hematologic, non-hematologic, and cardiac toxicity, and delay of therapy by more than 1 week due to toxicity. Plasma samples were assayed for mitoxantrone concentrations using high performance liquid chromatography (HPLC).

RESULTS

Twelve patients required either mitoxantrone dose reductions or delays. DLT of neutropenia was observed at a mitoxantrone dose of 48 mg/m2/day. Therefore, we conclude the MTD was 37 mg/m2/day. Myelosuppression appeared to be cumulative. Two patients were withdrawn from the study due to a drop in left ventricular ejection fraction (LVEF). Two of 23 patients experienced a partial response. The mean area under the curve (AUC) and peak mitoxantrone levels increased linearly with dose; triexponential elimination of mitoxantrone was observed. No statistically significant correlation was observed between either peak mitoxantrone level or AUC and duration of absolute neutrophil count (ANC) < 500/mm3.

CONCLUSION

The use of GM-CSF allows administration of mitoxantrone at a dose greater than three times that given in standard therapy; treatment is well tolerated. Further studies are needed to determine whether mitoxantrone has cumulative cardiac or hematologic toxicity.

Cardiac complications of intensive dose mitoxantrone and cyclophosphamide with autologous bone marrow transplantation in metastatic breast cancer

Fifteen women with metastatic breast cancer undergoing autologous bone marrow transplantation were treated with an intensive induction regimen including cyclophosphamide and mitoxantrone in a phase I-II study. The cardiotoxicity of these two drugs in combination have not been previously reported. Three patients developed deeply inverted T-waves during or shortly following conclusion of high-dose chemotherapy with associated declines in ejection fraction of 0.04, 0.19 and 0.27. One patient developed a brief episode of congestive heart failure which resolved with supportive care. These three patients were the only ones to have received previous left chest wall radiotherapy during the course of their disease, prior to treatment with autologous bone marrow rescue. No patient developed dysrhythmia or QRS changes during a mean hospital stay of 33.7 days (range 27-40 days).

Mitoxantrone. A review of its pharmacodynamic and pharmacokinetic properties, and therapeutic potential in the chemotherapy of cancer

Mitoxantrone is a dihydroxyanthracenedione derivative which as intravenous mono- and combination therapy has demonstrated therapeutic efficacy similar to that of standard induction and salvage treatment regimens in advanced breast cancer, non-Hodgkin's lymphoma, acute nonlymphoblastic leukaemia and chronic myelogenous leukaemia in blast crisis; it appears to be an effective alternative to the anthracycline component of standard treatment regimens in these indications. Mitoxantrone is also effective as a component of predominantly palliative treatment regimens for hepatic and advanced ovarian carcinoma. Limited studies suggest useful therapeutic activity in multiple myeloma and acute lymphoblastic leukaemia. Regional therapy of malignant effusions, hepatic and ovarian carcinomas has also been very effective, with a reduction in systemic adverse effects. Mitoxantrone inhibits DNA synthesis by intercalating DNA, inducing DNA strand breaks, and causing DNA aggregation and compaction, and delays cell cycle progression, particularly in late S phase. In vitro antitumour activity is concentration- and exposure time-proportional, and synergy with other antineoplastic drugs has been demonstrated in murine tumour models. Leucopenia may be dose-limiting in patients with solid tumours, whereas stomatitis may be dose-limiting in patients with leukaemia. Other adverse effects are usually of mild or moderate severity although cardiac effects, particularly congestive heart failure, may be of concern, especially in patients with a history of anthracycline therapy, mediastinal irradiation or cardiovascular disease. Mitoxantrone displays an improved tolerability profile compared with doxorubicin and other anthracyclines, although myelosuppression may occur more frequently. Thus, mitoxantrone is an effective and better tolerated alternative to the anthracyclines in most haematological malignancies, in breast cancer and in advanced hepatic or ovarian carcinoma. Further studies may consolidate its role in the treatment of these and other malignancies.

Comparison of short-term and continuous chemotherapy (mitozantrone) for advanced breast cancer

132 patients with advanced recurrent breast cancer were treated with four courses of mitozantrone 14 mg/m2 intravenously every 3 weeks (9 weeks). Patients showing disease stabilisation or objective response were randomised to stop chemotherapy or to continue until disease progression. At that stage 27% showed partial responses, 3% complete responses, and 10% disease stabilisation. 22 patients were randomised to continue chemotherapy and 21 to stop. There was no difference in time to disease progression, response duration, or survival between the two groups. Toxicity was mild during the first four courses of therapy. Thus, short courses of single-agent chemotherapy can produce similar therapeutic results to long-term chemotherapy, which has major implications for cost, resource allocation, and toxicity of therapy. Stopping chemotherapy early in responders did not cause rapid relapse. Since drug resistance apparently develops early during therapy, new approaches to modify resistance should be more useful than continuous chemotherapy.

Redox cycling in MCF-7 human breast cancer cells by antitumor agents based on mitozantrone

In a series of hydroxyethylaminoalkylaminoanthraquinones (AQ's) based on mitozantrone, 1-AQ (340%) and 1,8-AQ (137%) stimulated basal rate NADPH oxidation (72 + 18 pmol min-1 mg S9 protein-1) whilst 1,4-AQ, 1,5-AQ and mitozantrone had no effect. A similar trend was observed for O2.- generation (measured as nmol acet. cyt c reduction min-1 mg protein-1) by these compounds in MCF-7 S9 fraction: 1-AQ (9.5) and 1,8-AQ (7.9), whilst 1,5-AQ, 1,4-AQ and mitozantrone showed no significant effect. All the AQ's including mitozantrone were cytotoxic to MCF-7 cells in a dose dependent manner with EC50 values as follows: 1-AQ (0.01 micron) greater than doxorubicin (0.4 microM) greater than mitozantrone (0.6 microM) greater than 1,8-AQ (2.0 microM) greater than 1,5-AQ (4.0 microM) greater than 1,4-AQ (8.0 microM). Thus the redox active AQ's were also the most cytotoxic. Mitozantrone however was not redox active but was more cytotoxic than all but 1-AQ hence it would appear that factors other than free radical generation contribute to the antitumor activity of this group of compounds.