Secondary failure of platelet recovery after allogeneic hematopoietic stem cell transplantation in pediatric acquired aplastic anemia: Incidence, risk factors, and clinical outcomes.

Secondary failure of platelet recovery (SFPR) poses a significant risk for life-threatening complications following hematopoietic stem cell transplantation (HSCT). However, the incidence, clinical outcomes, and risk factors associated with SFPR in the context of allogeneic HSCT (allo-HSCT) for pediatric patients with acquired aplastic anemia (AA) remain unclear. We conducted a retrospective review of 86 consecutive acquired AA children who underwent allo-HSCT at our center from December 2017 to November 2023. The 1-year cumulative incidence of SFPR was found to be 11.6% (95% confidence interval [CI]: 6.2%-21.1%). The median time to SFPR was 2 months (range: 1-5 months) post-transplantation. To clarify the risk factors for SFPR, 9 SFPR cases and 69 non-SFPR cases were further analyzed. Multivariable analyses revealed that age, pre-transplantation body mass index (BMI) and a history of grade Ⅲ-Ⅳ acute graft-versus-host disease (aGVHD) were the most significant predictors for SFPR post-transplantation (p < 0.05). Additionally, we found that the 2-year overall survival rate was significantly lower in children with SFPR compared to those without (74.1% vs. 96.7%; p < 0.005). Ultimately, 4 patients achieved full platelet count recovery, with 2 patients becoming transfusion-independent. However, 1 patient still requires periodic platelet transfusions, and 2 patients unfortunately died.Among the 6 patients who received thrombopoietin receptor agonist therapy, an overall response rate of 66.6% was observed, suggesting the potential efficacy of this treatment approach in managing SFPR. This study underscores the need for vigilant monitoring of platelet recovery in pediatric HSCT recipients and highlights the need for further research into the etiology of SFPR to improve clinical outcomes.