LAUSR

BACKGROUND Leukemia stem cells (LSCs) have been demonstrated to be more therapy-resistant than leukemic blast cells reflecting measurable residual disease (MRD). CD34+CD38- cell frequency is an independent factor for relapse prediction and could therefore be used in the future to improve MRD assessment in acute myeloid leukemia (AML). This protocol is designed to enable accurate and reproducible immunophenotypic detection of measurable residual stem cell disease necessary for proper therapeutic decision and report their prognostic value in AML patients. METHODS Fifty-four Novo AML adult patients diagnosed in the onco-hematology service of the "20 August 1953" Hospital in Casablanca. We analyzed phenotype and frequency of CD45dim CD34+CD38- cells in bone marrow samples from patients with AML and non-myeloid malignancies using six-color flow cytometry and a simple one-tube essay. RESULTS For evaluation of leukemic stem cells, our gate strategy was based on the selection of CD34+CD38 - stem cells and leukemia associated immunophenotype approach. Positivity of CD123 or/and aberrant expression of primitive markers CD117 and HLA DR on stem cells discriminate leukemia stem cells from normal hematopoietic stem cells. We reported a statistically significant difference between expressions of primitive markers (CD117 and HLA DR) on leukemic stem cells. In addition, the frequency of LSCs after complete remission in post-induction was persistent in 50% of AML patients. CONCLUSIONS Overall, we show that CD34+CD38-CD123+ as a basic phenotype, with aberrant phenotype detection of HLA DR and CD117 markers on stem cells, contributes to detecting LSCs which indicates the poor prognosis.