Comprehensive analysis of long-term outcomes in adult patients with acute lymphoblastic leukemia who received allogeneic stem cell transplantation: Real-world data of the Korean society of blood and marrow transplantation registry

Abstract Background/Aims Allogeneic stem cell transplantation (allo-SCT) is a curative option in adult patients with acute lymphoblastic leukemia (ALL) even in the era of immunotherapy. A successful transplant requires a suitable stem cell donor, and patients must overcome transplant-related mortality, including infections and graft-versus-host disease (GVHD). In this study, we investigated long-term survivals of the adult ALL patients who received allo-SCT. Factors affecting prognosis were also analyzed. Methods We retrospectively analyzed the adult patients with ALL who received allo-SCT between 2009 to 2022 years using the Korean Society of Blood and Marrow Transplantation registry. Event-free survival (EFS) was determined from the date of transplantation to the date of disease progression or death from any cause. Overall survival (OS) was determined from the date of allo-SCT to the date of death or last follow-up. Results A total of 756 ALL patients were enrolled in this study: 369 patients with Philadelphia chromosome (Ph) negative ALL, 267 patients with Ph-positive ALL, and 129 patients with T-ALL. At the time of transplantation, the median ages for Ph-negative ALL, Ph-positive ALL, and T-ALL were 41.2, 45.2, and 34.8 years, respectively. The 2-year EFS for Ph-negative ALL, Ph-positive ALL, and T-ALL were 49.2%, 57.2%, and 43.9%, respectively, and the 2-year OS were 53.5%, 63.1%, and 47.3%, respectively. In the Kaplan-Meier survival curve, long-term outcomes of the patients with complete remission (CR) 1 were significantly superior compared to the CR2. Significantly better outcomes for both EFS and OS were identified in patients with Human Leukocyte Antigens (HLA) full matched donors than those with haploidentical donors. Total body irradiation (TBI) was a favorable factor in patients with T-ALL. The intensity of conditioning regimen did not affect prognosis. The post-transplant cyclophosphamide strategy tended to be superior in terms of GVHD and early mortality in the haploidentical donor transplant group. Of the patients enrolled in this study, 64 underwent secondary transplantation, in which 38 patients were Ph-negative ALL, 15 were Ph-positive ALL, and 11 were T-ALL. The median EFS and OS for all patients who underwent secondary allo-SCT were 7.6 and 7.9 months, respectively. There was no significant survival difference in secondary transplant outcomes according to disease subtype. However, transplant outcomes in patients who achieved CR showed significantly superior EFS and OS compared to the group of patients transplanted with active disease status. Using TBI was identified as a favorable prognostic factor while, haploidentical donor was an adverse factor in secondary transplantation. Conclusion Allo-SCT could improve survival outcomes in patients who achieved CR1. Using HLA full-matched donor showed better outcomes in both patients with first- and secondary transplantation. In the secondary allo-SCT, TBI was a favorable prognostic factor.