IDENTIFICATION OF LEUKEMIC STEM CELLS IN AML PATIENTS BY USING NEXT-GENERATION FLOW: A PERSONALIZED BIOMARKER OF PROGNOSIS AND PROGRESSION

Acute Myeloid Leukemia (AML) is a biologically heterogeneous disease characterized by high rates of relapse: about 30% of AML patients achieving Minimal Residual Disease (MRD) negativity undergo a relapse, underlining the limitations of current MRD detection approaches and suggesting the persistence of leukemic cell populations that escape conventional monitoring, causing relapse in AML patients. Leukemic Stem Cells (LSCs) represent a rare subpopulation within the CD34⁺CD38⁻ compartment and share several features with normal hematopoietic stem cells (HSCs). However, LSCs aberrantly express lineage and surface markers associated with leukemia, allowing their identification by Next Generation Flow (NGF). This project aims to identify and characterize LSCs at baseline and to monitor them after induction therapy and after relapse, if any. Furthermore, this study tries to find a personalized LSCs MRD using NGF in order to investigate its prognostic value. AML LSCs have been evaluated in bone marrow samples in AML patients using a combination of cytometry antigens (CD45, CD34, CD38, CD90, CD45RA, CD123, CD366 and CD371). 58 AML patients have been analyzed: 40/58 (69%) AML patients have been studied from diagnosis, confirming that, beside the bulk of leukemic clone, LSCs and residual HSCs can be identified and characterized using NGF. 29/40 (72,5%) AML patients were analyzed post induction therapy, monitoring AML- LSCs presence alongside treatment by using their specific LSCs-MRD panel: 20/29 (69%) still presented LSCs, instead 9/29 (31%) didn’t show LSCs after the first course. Furthermore, we explored the role of LSCs persistence by comparing “LSCs MRD” to the residual AML clone using standard flow MRD and the gold standard molecular MRD markers in small specific clusters of patients. Finally, we explored also HSCs role after induction therapy, demonstrating that HSCs reappear only in some AML patients, suggesting a possible role as prognostic marker. This is an exploratory pilot study confirming the possibility to detect AML LSCs using NGF, suggesting their role as possible biological MRD marker to monitor AML patients