Efficacy of Mitoxantrone and Etoposide in Patients with Acute Myeloid Leukemia Refractory to Initial Standard Induction Therapy.

The most effective reinduction regimen for acute myeloid leukemia (AML) patients who do not achieve complete remission (CR) after one cycle of cytarabine combined with an anthracycline is not well established. In an effort to search for new synergistic and non-cross resistant antileukemic regimens different chemotherapeutic combinations have been investigated in refractory AML patients. Multiple regimens including high dose cytarabine, anthracyclines, fludarabine and etoposide have been used with CR rates up to 40%. Mitoxantrone and etoposide have activity in AML as induction agents but their role in reinduction in patients not responding to first line therapy has not been fully established. In the current retrospective study we evaluated the efficacy and toxicity of mitoxantrone and etoposide in AML patients treated at our institution who did not respond to first induction therapy with cytarabine and an anthracycline. A total of fifty seven AML patients were treated with mitoxantrone and etoposide (mean age 55 years, range 18–75 years). Twenty four patients were treated with mitoxantrone 10 mg/m2/d and etoposide 100 mg/m2/d both administered intravenously, days 1 to 5 (regimen 5+5) and thirty three patients were treated with mitoxantrone 10 mg/m2/d administered intravenously days 1 to 3 and etoposide 100 mg/m2/d administered intravenously, days 1 to 5 (regimen 3+5). Twenty six of fifty seven patients (46%) achieved CR. CR was achieved in 38% of patients (9/24) treated with the 5+5 regimen and 52% of patients (17/33) treated with the 3+5 regimen. Mean blast percentage before treatment with mitoxantrone and etoposide was 25% in patients who achieved CR vs 40% in patients who did not achieve CR (p < 0.03). Grade 3/4 hepatic toxicities were seen in 5% (3/57) of patients and there were no grade 3 or 4 renal toxicities. The median duration of neutropenia in patients achieving CR was 29 days after reinduction. 10% (6/57) of the patients died from infectious complications. Cytogenetic analyses were performed prior to first-line therapy in all patients. Patients with favorable cytogenetics treated with etoposide and mitoxantorne had 100% CR (3/3), patients with standard cytogenetics had 58% CR (19/33) and patients with unfavorable cytogenetics had 19% CR (4/21). Overall CR was achieved in 61% (22/36) of patients with favorable and standard cytogenetics. Our data suggest that the combination of etoposide and mitoxantorne is an active and well tolerated regimen, especially in patients with favorable and standard cytogenetics, and warrants further studies in prospective trials.