Investigation of Minimal Residual Disease in Acute Myeloid Leukemia by Immunophenotyping

Current treatment strategies for patients with acute myeloid leukemia (AML) result in a high complete remission (CR) rate (60-80%). However, relapses due to the persistence of low numbers of residual neoplastic cells which are undetectable by conventional morphological techniques (minimal residual disease [MRD]), still occur in most patients; in fact, only around one-third of patients with AML are leukemia-free at 5 yr. Owing to this, patients are indiscriminately subjected to consolidation treatments, including conventional chemotherapy and autologous and allogeneic stem cell transplantation, in order to eradicate possible MRD. Therefore, more sensitive techniques are needed to lay the foundations for the design of patient-adapted consolidation therapies that would reduce the risk of both: toxic deaths resulting from overtreatment in patients that could be cured with conventional chemotherapy and relapses resulting from insufficiently intensive consolidation treatment in patients at high risk of relapse because of persistence of residual leukemic cells. In addition, such sensitive methods for MRD detection can contribute to the assessment of the efficacy of ex vivo purging protocols for autologous stem cells prior to reinfusion and to a more precise evaluation of the effectiveness of new treatment strategies.