Tolerability of An Effective Two Day Induction Regimen for Newly Diagnosed AML

Abstract Background: The standard remission induction regimen for treating Acute Myeloid Leukemia consists of seven days of continuous infusion cytarabine and three days of an anthracycline, the “7 + 3” regimen. We present a single institution, retrospective analysis of toxicity associated with a regimen that requires only two days of chemotherapy using high dose cytarabine and mitoxantrone. The regimen is based on the timed sequential therapy concept where two pulses of chemotherapy are given. The first pulse recruits cells into the cell cycle, while the second pulse is given at the time of peak recruitment. Methods: One hundred four patients with AML were treated with two days of chemotherapy given 96 hours apart from April 1997 to April 2008. Each day of chemotherapy consisted of two doses of cytarabine 2gm/m2 (at t=0 and t=12) followed by one dose of mitoxantrone 30 mg/m2 administered after the second cytarabine dose (t=15). Each patient's chart and electronic record were thoroughly reviewed, and toxicities associated with induction therapy were analyzed and graded according to the National Cancer Institute's Common Terminology Criteria for Adverse Events v3.0. Responses were defined per the Revised IWG Recommendations (Cheson, J Clin Onc 21: 4642, 2003). Results: One hundred four patients were eligible for toxicity evaluation. Hematologic toxicities were the most common toxicities seen with this induction therapy. Overall, all patients experienced hematologic toxicity of some grade with 98% of patients having one or more Grade 3/4 hematologic toxicity. The incidences of grade 3/4 hematologic toxicities are the following: Hemoglobin 65.3% (Gr 3 59.6%, Gr 4 5.7%), thrombocytopenia 93.2% (Gr 3 9.6%, Gr 4 83.6%), and neutropenia 89.4% (Gr 3 1.9%, Gr 4 87.5%). Febrile neutropenia occurred in 64% of the patients, and grade 3 and 4 infections occurred in 25%. Common non-hematologic toxicities included fatigue, nausea, vomiting, diarrhea, and electrolyte abnormalities. The vast majority of non-hematologic toxicities were grade 1 and 2. Three patients (2.9%) died within the first 30 days of induction therapy. One patient died before completing therapy due to massive hemoptysis. One died from complications of refractory disease, and the third patient died from disseminated fungal infection. An additional 10 patients (6 TF-RD, 1 TF-aplasia, 1 CR, 1 CRi, 1 CRp) died within the first 60 days. Of the 6 patients with refractory disease, 4 received re-induction therapy to which 3 did not have a response and the fourth died of sepsis while aplastic. Two patients had intracerebral hemorrhage (TF-aplasia and CRp). One patient died suddenly in CR of unknown causes and one patient (CRi) died from complications of pneumonia/ARDS. Conclusion: Although this regimen incorporating high dose cytarabine into remission induction presents a significantly higher dose intensity of cytarabine and mitoxantrone compared to that of the “7+3” regimen, the toxicity profile and 30-day mortality rate compare favorably to the “7 + 3” regimen. This regimen has been shown to produce a CR rate comparable to that of the “7+3” regimen with equal efficacy and better tolerance in elderly patients with AML. We conclude that this regimen effectively administers a high yet apt dosage of chemotherapy, and it can even be used for remission induction in elderly patients. This induction regimen could serve as a platform for future studies of maintenance and biologic therapies in the elderly AML patients.