Hematopoietic stem cell transplant in adults with acute lymphoblastic leukemia: the present state

Introduction: Allogeneic hematopoietic stem cell transplant (allo-HSCT) has an important role in management of acute lymphoblastic leukemia (ALL). Proper patient selection is central to ensure optimal outcomes. Areas covered: This review covers various aspects of HSCT in ALL patients, including indications, donor selection, conditioning regimens, and post-transplant management. Expert commentary: Allo-HSCT is important in post-remission management of ALL but proper risk-stratification is a major challenge. Incorporation of minimal residual disease (MRD) and molecular testing will improve patient allocation. Patients receiving pediatric-inspired induction who achieve molecular remission might not need allo-HSCT in first remission. Allo-HSCT should be considered in patients who don’t achieve MDR negativity, didn’t receive intensive induction, or have high risk cytogenetic and molecular features. Despite improved responses with tyrosine kinase inhibitors (TKIs) in Philadelphia positive (Ph+) ALL, allo-HSCT remains standard. Matched sibling donors are the optimal graft source, but other sources are valid alternatives. There is no single optimal conditioning regimen and retrospective studies found myeloablative and reduced intensity regimens to be comparable. Following allo-HSCT, there is no role for maintenance therapy in Philadelphia-negative ALL. In Ph+ ALL, maintenance TKIs improve outcomes. The integration of targeted and immunotherapies in the peri-transplant period holds potential for improved outcomes.