Combination of mitoxantrone and etoposide in refractory acute myelogenous leukemia--an active and well-tolerated regimen.

Both mitoxantrone and etoposide have been shown to be active in monotherapy trials of relapsed and refractory acute myelogenous leukemia (AML). This phase II study was undertaken to assess the antitumor activity and toxicity of the combination in refractory and poor-risk AML. The regimen consisted of mitoxantrone, 10 mg/m2/d intravenously (IV), and etoposide, 100 mg/m2/d as short infusion, both on days 1 to 5. Sixty-one patients are evaluable for response and toxicity. Twenty-one were primarily refractory to conventional courses of cytarabine, daunorubicin, and thioguanine; 20 patients had poor-risk first relapse (relapse within 6 months of first complete remission [CR] or relapse under continuous maintenance therapy); 11 had second or subsequent relapses; and nine developed secondary AML after myelodysplastic phase or myelofibrosis. Twenty-six patients (42.6%) attained a CR and seven (11.5%) a partial remission (PR). The median duration of continuous CR was 4.7 months, with a range of 21 days to 14 months, excluding four patients who underwent autologous bone marrow transplantation. Severe myelosuppression was observed in all patients, with a median time to CR of 49 days. Nonhematologic toxicity included stomatitis (mainly grade 1 and 2) in 41 patients, nausea (mainly grade 1 and 2) in 44, infections (mainly grade 3) in 33, and fever of unidentified origin in 11. Other than transient, mild cardiac failure in nine patients, in some of them combined with grade 1 to 2 tachyarrhythmia, no other drug-related cardiac events were observed. Two cases of early death within the first 6 weeks of treatment were registered. Thus, the combination of mitoxantrone and etoposide is a highly active and well-tolerated regimen for refractory and poor-risk AML.