Matched sibling versus matched unrelated allogeneic hematopoietic stem cell transplantation in children with severe acquired aplastic anemia: experience of the polish pediatric group for hematopoietic stem cell transplantation.

In the study, 48 children with severe acquired aplastic anemia (SAA) transplanted from matched sibling donor (MSD) between 1991 and 2009, and 38 children with SAA transplanted from matched unrelated donor (MUD) between 2000 and 2009 were evaluated. Engraftment was achieved in 45 (93.75 %) patients after MSD-hematopoietic stem cell transplantation (HSCT) and in 33 (86.8 %) after MUD-HSCT. Transplant-related mortality rate after MSD-HSCT was 8 %, while 37 % after MUD-HSCT. After MSD-HSCT 44 (91.7 %) patients are alive for 1-216 months (median: 85 months), while after MUD-HSCT 24 (63.2 %) patients for 1-84 months (median: 16 months). The 5-year probability of event-free survival after MSD-HSCT and MUD-HSCT was 87 and 53 %, respectively, while 5 years of overall survival was 91 and 64 %, respectively. It was concluded that MSD-HSCT as the first line treatment for children with SAA is a safe therapeutic approach with a low rate of treatment failures and excellent outcome. Results of MUD-HSCT in pediatric patients with SAA who failed to respond to immunosuppressive therapy are still inferior than those of MSD-HSCT. Treatment failures of MUD-HSCT are mainly related to infectious complications and graft failure. It seems, however, that HLA-matching of unrelated donors at allelic level along with early MUD-HSCT after FCA (FLUDA, low-dose cyclophosphamide, and anti-thymocyte globulin) conditioning, perhaps using lower Thymoglobulin dose could enable further improvement of long-term results in children with SAA who lack MSD.