Prognostic impact of the level of MRD before allo-HSCT in pediatric ALL: A 10-year single-center study

Results from a retrospective, 10-year, single-center study, evaluating the prognostic impact of pretransplant measurable residual disease (MRD) levels in pediatric patients with acute lymphoblastic leukemia (ALL) undergoing allogeneic hematopoietic stem cell transplantation (allo-HSCT; N = 104), were published in Clinical Lymphoma, Myeloma & Leukemia by Yang et al. MRD was assessed by multiparametric flow cytometry, using 0.01% (10⁻⁴) as the positivity threshold. The primary endpoint was cumulative incidence of leukemia relapse (CIR).

Key data: Pretransplant MRD-positive patients (n = 15) had a higher CIR rate (46.7% vs 28.1%; hazard ratio [HR], 3.65; 95% confidence interval [CI], 1.15–11.55; p = 0.028) and worse event-free survival (EFS; 33.3% vs 64.0%; HR, 3.92; 95% CI, 1.47–10.43; p = 0.006) compared with pretransplant MRD-negative patients (n = 89). Patients with pre-MRD ≥1 × 10⁻³ had worse EFS (HR, 6.00; 95% CI, 1.37–26.38; p = 0.017) and higher CIR (HR, 8.20; 95% CI, 1.44–46.86; p = 0.018) vs those with pre-MRD <1 × 10⁻⁴. Among patients who achieved MRD negativity before transplantation, 1 vs ≥2 negative assessments were not associated with significant differences in overall survival (OS), EFS, CIR, or non-relapse mortality (NRM).

Key learning: Pretransplant MRD status is a strong predictor of outcomes after allo-HSCT in pediatric ALL, highlighting the importance of pretransplant disease control to optimize outcomes in this setting.