P148 | CHRONIC MYELOID LEUKEMIA (CML): THE ROLE OF ALLOGENEIC-HEMOPOIETIC STEM CELL TRANSPLANT IN ASCIMINIB PATIENTS’ COHORT

In the last decades, major molecular response (MMR) achieved by tyrosine kinase inhibitors (TKIs) in CML patients has significantly reduced the indication for allo-HSCT. However, a small percentage of patients are resistant or intolerant to multiple TKI lines, resulting in worse outcome and subsequent indication for allo-HSCT. Asciminib, a selective BCR::ABL1 allosteric inhibitor, has recently been approved for chronic-Phase (crP) CML with resistance or intolerance to at least two previous TKIs. Therefore, the safety and efficacy of allo-HSCT after Asciminib treatment is still an unexplored issue. With this aim, we retrospectively collected data of 12 CML patients treated with Asciminib as >3rd line TKIs, across 8 Italian allo-HSCT Program. The baseline clinical characteristics of the patients are summarized in Table 1. During Asciminib treatment, 6 patients discontinued the therapy due to grade 3/4 Adverse Events, followed by a definitive stop in 2 cases. At 3 months, Complete Hematological (CHR), cytogenetic (CcyR), Molecular (MMR) and no (NR) Response were observed in 3, 2, 1 and 6 patients, respectively. All patients but one underwent allo-HSCT in crP. The disease status and allo-HSCT features are detailed in Table 1. All patients engrafted as PMN and PLTS. At 90 days after allo-HSCT, all crP patients showed a full donor chimerism and a deep molecular response, while the patient in accelerated phase (aP) had a mixed chimerism and did not reach any response. Cumulative incidence of aGVHD was 18% (all the 3 patients with maximum grade 1 aGVHD) and no patients developed cGVHD. With a median follow up of 19.27 months from allo-HSCT, OS, DFS and 1 year NRM were respectively 83%, 92% and 8%. Overall, 2 patients died: one for persistence of aP disease and one for encephalitis. In conclusion, in TKIs resistant CML, allo-HSCT remains the best clinical option, with excellent results in terms of deep molecular response and limited incidence of complications. In our cohort of advanced-lines patients, the use of Asciminib seems to be a potential bridge strategy for allo-HSCT, inducing and maintaining until allo-HSCT a satisfying response. Further studies in larger cohorts are warranted in order to confirm these results and drive clinical decisions.