Haploidentical hematopoietic stem cell transplantation in pediatric and adolescent patients: A study of the Spanish hematopoietic stem cell transplantation group (GETH)

Introduction: The main advantages of haploidentical hematopoietic stem cell transplantation (haplo-HSCT) are the immediate availability of donors, the possibility of developing cell therapy approaches with different novel transplant platforms, and the procedure's cost savings. Methodology: We retrospectively analyzed the pediatric haplo-HSCT activity of the Spanish hematopoietic stem-cell transplantation group (GETH) between 1999 and 2016, aiming to study clinical characteristics and outcomes by describing patient groups with non-malignant disease (NMD) or malignant disease (MD) and the impact of 2 different periods (1999-2009 and 2010-2016) on long-term outcomes. Results: Twelve centers performed 232 haplo-HSCTs in 227 children, representing 10% of all pediatric allogeneic HSCT activity in Spain from 1999 to 2016, with a notable increase since 2013. Most haplo-HSCTs (86.7%) were performed in patients with MD; 95% received peripheral blood stem cells from donors, and 78.9% received ex vivo T-cell depleted grafts. Non-manipulated grafts using post-transplantation cyclophosphamide have been incorporated since 2012. We observed a higher percentage of graft failure in NMD versus MD (32% vs. 15.6%; p = 0.029). Relapse and transplant-related mortality were the procedure's main limitations in MD and NMD, respectively. Five-year overall survival was 48.5% (SE 3.9), with no statistically significant difference when comparing the MD and NMD cohorts. Patients who received previously a HSCT the overall survival was significantly decreased. We observed no survival improvement over time. Conclusions: Although haplo-HSCT is an increasingly employed treatment option, our patients' results need improvement. We need to develop reference centers, especially for NMD whose rarity makes it difficult to gain experience. (C) 2022 Elsevier Espana, S.L.U. All rights reserved.