Clinical Impact of Continuous Dasatinib Administration on the Prognosis of Patients With BCR::ABL1 Acute Lymphoblastic Leukemia: Result of the Prospective MRD2014 Study Conducted by Fukuoka Blood and Marrow Transplantation Group (FBMTG)

To assess the efficacy of continuous dasatinib in improving outcomes for adult patients with BCR::ABL1 ALL. The prospective, multicenter ALL/MRD2014 trial introduced a modified protocol compared to the MRD2008 trial, incorporating continuous dasatinib use and reduced chemotherapy intensity. Among the 164 adult ALL patients enrolled (2014-2019), 61 were Philadelphia-positive (Ph+) (median age 50 years; 38 males, 23 females). Post-induction, 96.7% achieved complete remission (CR). The 3-year event-free survival (EFS) and overall survival (OS) were 51% and 76%, respectively. Patients undergoing allo-HSCT in CR1 had improved outcomes, with a 3-year EFS of 64% and OS of 87%. MRD-negative patients before transplantation exhibited superior survival (EFS: 71% vs. 29%; OS: 94% vs. 57%). Comparison with the MRD2008 trial revealed similar outcomes, with the MRD2014 trial achieving a 3-year EFS of 51% and OS of 76% vs. 52% and 84% in MRD2008. Although not statistically significant, the MRD2014 trial showed trends of increased relapse (CIR: 39% vs. 26%, p = 0.305) and reduced non-relapse mortality (NRM: 10% vs. 21%, p = 0.181). The ALL/MRD2014 trial underscores the importance of MRD status and allo-HSCT in Ph+ ALL. Continuous dasatinib-based regimens offer favorable outcomes in MRD-negative patients. This study was registered with the UMIN Clinical Trials Registry (UMIN-CTR), number UMIN000012382.