Long‐term follow‐up of haploidentical haematopoietic stem cell transplantation in paediatric patients with high‐risk acute myeloid leukaemia: Report from a single centre

Summary

Data from 200 children with high‐risk acute myeloid leukaemia who underwent their first haploidentical haematopoietic stem cell transplantation (haplo‐HSCT) between 2015 and 2021 at our institution were analysed. The 4‐year overall survival (OS), event‐free survival (EFS) and cumulative incidence of relapse (CIR) were 71.9%, 62.3% and 32.4% respectively. The 100‐day cumulative incidences of grade II–IV and III–IV acute graft‐versus‐host disease (aGVHD) were 41.1% and 9.5% respectively. The 4‐year cumulative incidence of chronic GVHD (cGVHD) was 56.1%, and that of moderate‐to‐severe cGVHD was 27.3%. Minimal residual disease (MRD)‐positive (MRD+) status pre‐HSCT was significantly associated with lower survival and a higher risk of relapse. The 4‐year OS, EFS and CIR differed significantly between patients with MRD+ pre‐HSCT (n = 97; 63.4%, 51.4% and 41.0% respectively) and those with MRD‐negative (MRD‐) pre‐HSCT (n = 103; 80.5%, 73.3% and 23.8% respectively). Multivariate analysis also revealed that acute megakaryoblastic leukaemia without Down syndrome (non‐DS‐AMKL) was associated with extremely poor outcomes (hazard ratios and 95% CIs for OS, EFS and CIR: 3.110 (1.430–6.763), 3.145 (1.628–6.074) and 3.250 (1.529–6.910) respectively; p‐values were 0.004, 0.001 and 0.002 respectively). Thus, haplo‐HSCT can be a therapy option for these patients, and MRD status pre‐HSCT significantly affects the outcomes. As patients with non‐DS‐AMKL have extremely poor outcomes, even with haplo‐HSCT, a combination of novel therapies is urgently needed.