Efficacy of imatinib maintenance after stem cell transplantation for Ph+/ BCR :: ABL1 positive ALL: long-term outcome of a randomized trial and impact of peritransplant minimal residual disease

Tyrosine kinase inhibitors are recommended as maintenance therapy following allogeneic stem cell transplantation (HSCT) for Philadelphia chromosome–positive (Ph+) acute lymphoblastic leukemia (ALL), but optimal medication, dose, and duration remain a subject of ongoing study. We provide the final analysis of a prospective randomized trial comparing prophylactic and minimal residual disease (MRD)-triggered imatinib maintenance. The two patient cohorts did not differ significantly in terms of cumulative incidence of relapse (CIR; 14% vs. 18%), non-relapse mortality (NRM; 12% vs. 11%), leukemia-free survival (LFS) 64% vs. 69%, and overall survival (OS) at 10 years (68% vs. 71%). Endpoints were assessed every 6 weeks within the trial from 4 weeks after SCT until EOS at week 55 and after that according to local standards. In summary, this provides a framework for MRD-based treatment of patients for maintenance after HSCT with excellent long-term outcome after 10 years in both groups.