How to Change the Role of Allogeneic Hematopoietic Cell Transplantation in Adults with B-Cell Acute Lymphoblastic Leukemia.

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) has long constituted a cornerstone of post-remission consolidation therapy for adults with high-risk B-cell acute lymphoblastic leukemia (B-ALL), offering potent graft-versus-leukemia activity at the expense of significant treatment-related toxicity (TRT) and non-relapse mortality (NRM). Over the past two decades, however, outcomes following allo-HSCT have improved substantially. This progress has been driven primarily by a marked reduction in NRM, translating into improved overall survival (OS), as consistently documented by large cooperative group analyses and single-center series. Advances in supportive care, infectious prophylaxis, donor selection, and graft-versus-host disease (GvHD) prevention have contributed substantially to this improvement. In parallel, transplant decision-making has been profoundly reshaped by refined disease biology-based risk stratification and the systematic evaluation of measurable residual disease (MRD). Moreover, the advent of highly effective immunotherapeutic approaches-including blinatumomab, inotuzumab ozogamicin, and chimeric antigen receptor (CAR) T-cell therapies-has enabled the achievement of deeper molecular remissions prior to transplantation, both in first and subsequent complete remissions. Taken together, these developments have shifted allo-HSCT from a widely applied strategy to a more individualized, risk-adapted therapeutic approach. This review examines how the indications, timing, and objectives of allo-HSCT are evolving in the contemporary treatment landscape of adult B-ALL, with particular emphasis on Philadelphia chromosome-negative, Philadelphia-like, and Philadelphia chromosome-positive disease subsets.