Prognostic Impact of the Level of Minimal Residual Disease Prior to Allogeneic Hematopoietic Stem Cell Transplantation on Pediatric Patients With Acute Lymphoblastic Leukemia: A 10-Year Single-Center Study.

[PURPOSE] This study evaluated the impact of different levels of pretransplantation minimal residual disease (pre-MRD) on the prognosis of pediatric patients with acute lymphoblastic leukemia (ALL) who underwent allogeneic hematopoietic stem cell transplantation (allo-HSCT).

[METHODS] A retrospective study from January 2014 to April 2025 including 104 pediatric patients with ALL was performed. MRD was determined using multiparametric flow cytometry.

[RESULTS] Compared to patients with pre-MRD positive, patients with pre-MRD negative had better event-free survival (EFS) rate (33.3% vs. 64.0%, P = .006) and lower cumulative incidence of relapse (CIR) rate (46.7% vs. 28.1%, P = .028). In the subgroup whose MRD turned negative before transplantation, the number of times of MRD negativity (1 time vs. ≥2 times) had no significant effect on the long-term survival rate and the recurrence rate of leukemia after transplantation (P > .05). We found that among patients in the study, those with MRD≥1.0 × 10 had a poorer prognosis. The Cox multivariate regression analysis showed that besides MRD, complete remission(CR)1 or≥2, transplantation type, chronic graft-versus-host disease(cGVHD), hepatic veno-occlusive disease (VOD), and transplant-associated thrombotic microangiopathy (TA-TMA) also influence the prognosis of pediatric patients with ALL who received allo-HSCT.

[CONCLUSIONS] Patients with positive pre-MRD experienced a significant decrease in survival after transplantation. For children with leukemia whose MRD turned negative before transplantation, it is not necessary to consolidate chemotherapy again, and it may be possible to bridge transplantation as soon as possible to treat the leukemia.