High Complete Remission (CR) Rates and Reduced Early Mortality with High Dose Ara-c (HiDAC) and Mitoxantrone (MITO) Induction Chemotherapy for Older (age>60) High Risk Patients with Acute Myeloid Leukemia (AML)

Patients with high risk AML, defined as those with age > 60 years or multiple medical co-morbidities determined by Charleston comorbidity index (CCI) carry a poor prognosis and inferior outcomes after 7+3 induction chemotherapy. CR rates tend to range from 6–51% and induction death rates between 9–48%. We present here a single institution experience of high risk AML patients treated with an induction regimen consisting of high dose mitoxantrone and cytarabine (HiDAC/MITO).

We performed a retrospective analysis of all patients with AML who received HiDAC/MITO induction from January 2009- January 2010 at our institution. Patients with age ≥60 or age <60 with high CCI received HiDAC at 3gm/m2 over three hours on days 1 to 5 plus MITO 80mg/m2 once on day 2. Effect of other high risk features including poor risk cytogenetics, therapy related AML (t-AML), AML with prior antecedent hematological disorder (AHD) and relapsed AML on treatment outcome were also evaluated. The primary endpoints of the study were CR (defined as bone marrow blasts <5%) at day 30 and treatment related mortality within 30 days of initiation of treatment. End of follow-up was June 30, 2010.

20 AML had received HiDAC/MITO for remission induction. The median age was 66.5 years (range 47 to 78), those with age ≥ 70 was 8 (40%). CCI was ≥ 5 in 18 (90%) patients. Other high risk features included high risk cytogenetics in 8 (40%) and non-denovo AML (AML with AHD, t-AML or relapsed AML) in 11 (55%). Overall CR rate was 17 (85%, CI: 61%-96%) and 3 (15%) patients had refractory disease. There was no treatment related mortality. Median time to neutrophil recovery (>1000/ul) was 27 (range 19 to 37) days and median time to platelet recovery (>100,000/ul) was 28 days (range 23 to 44) days. Patients with non–denovo AML were more likely to be refractory to treatment or relapse after day 30. Median follow up of the entire cohort is 288 (range 29 to 530) days. 3 month and 6 month overall survival (OS) was 94.7% and 73.3% and progression free survival (PFS) 93.8% and 87.5%, respectively. The median OS was 410 days (CI: 243-*); (denovo 410 vs. others 381 days). Median PFS is 524 days (CI: 381-*); (denovo *not reached vs. others 381 days). 11(55%) patients were able to proceed to autologous (4) or allogeneic (7) stem cell transplantation (SCT) after receiving HiDAC/MITO. The time to transplant ranged from 44 to 195 days. Median OS of the patients who underwent SCT is 524 days versus 269 days for the non transplant group (p =0.0038). The HiDAC/MITO induction regimen was well tolerated. Cardiac toxicity defined by symptomatic CHF was noted in 6/20 patients. Of the six patients 2 had prior cardiac history and 1 had prior anthracycline exposure and 1 had both anthracycline exposure and cardiac history. Cardiac toxicity was delayed and identified by echo at a median of 90 range (42 to139) days after induction chemotherapy. None of these patients died from cardiac toxicity.

In this high risk AML population, HiDAC/MITO induction was well tolerated and demonstrated an overall response rate of 85% and no induction deaths, allowing a substantial number (55%) of patients to proceed to SCT. Contrary to our expectations advanced age or multiple medical co-morbidities did not affect CR rate or survival, thus high lighting the utility of this regimen for high risk newly diagnosed elderly patients with AML.

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No relevant conflicts of interest to declare.