FATE and Role of Peripheral Blood CD26+ Leukemia STEM CELLS at Diagnosis in Chronic Myeloid Leukemia Patients: FINAL Results of Prospective Flowers Study

• Published in: Blood 2024-11, Vol.144 (Supplement 1), p.995-995
• Main Authors: Sicuranza, Anna, Santoni, Adele, Pacelli, Paola, Freducci, Sara, Pacini, Emanuele, Abruzzese, Elisabetta, Cattaneo, Daniele, Iurlo, Alessandra, Luciano, Luigiana, Galimberti, Sara, Giai, Valentina, Mulas, Olga, Caocci, Giovanni, Sorà, Federica, Capodanno, Isabella, Crugnola, Monica, Gozzini, Antonella, Russo, Sabina, Annunziata, Mario, Fozza, Claudio, Liberati, Anna Marina, Cartocci, Alessandra, Zappone, Elisabetta, Cencini, Emanuele, Sammartano, Vincenzo, Bestoso, Elena, Marzano, Cristina, Tocci, Dania, Miracapillo, Teresa, Turriziani, Camilla, Raspadori, Donatella, Bocchia, Monica
• Format: Article
• Language: English
• ISSN: 0006-4971; 1528-0020
• DOI: 10.1182/blood-2024-204689

Background: In a cross-sectional study we previously demonstrated that in peripheral blood (PB) of chronic myeloid leukemia (CML) patients leukemia stem cells (LSCs) CD26+ are detectable by flow-cytometry at diagnosis, during TKI therapy and during treatment free remission (TFR). No prospective data are available regarding the behavior of PB CD26+LSCs from diagnosis and the correlation, if any, between the bulk of this staminal compartment at diagnosis with the attainment of molecular response. Methods: We here present final results of a prospective Italian multicenter study including newly diagnosed chronic phase (CP) CML patients centrally monitored by flow-cytometry for PB CD26+LSCs quantification from diagnosis up to 24 months of TKI treatment. Results: 242 consecutive CP-CML patients were enrolled (132 imatinib, 72 nilotinib and 38 dasatinib). The bulk of CD26+LSCs at diagnosis varied between patients with a median value of 7,1454 cells/µl (range 0,0126-698,746 cells/µl; IQR 2,18-33,26 cells/µl). During TKI treatment, we observed a consistent and rapid reduction of them achieving median values of 0,0132 cells/µl (IQR 0-0,034 cells/µl), 0,011 cells/µl (IQR 0-0,031 cells/µl) and 0,0071 cells/µl (IQR 0-0,0259 cells/µl) at 3, 12 and 24 months, respectively. No statistically significant differences in terms of CD26+LSCs log-reduction were noted according to the type of TKI treatment at any time points evaluated. However, a significant correlation between a low amount of CD26+LSCs at diagnosis and an optimal molecular response at 3, 12 and 24 months (BCR::ABL1