Hematopoietic Stem Cell Transplantation in Children with Refractory Cytopenia of Childhood: Single-Center Experience Using High-Dose Cytarabine Containing Myeloablative and Aplastic Anemia Oriented Reduced-Intensity Conditioning Regimens

• Outcomes of HSCT in children with RCC were favorable.
• Early referral for HSCT might be preferred for RCC before disease progression.
• Reduced-intensity conditioning is promising for children with hypocellular RCC.

Refractory cytopenia of childhood (RCC) is the most common subtype of myelodysplastic syndrome in children, and the clinical course of RCC is heterogeneous. A certain proportion of RCC patients need allogeneic hematopoietic stem cell transplantation (HSCT); however, data on HSCT outcomes are not abundant, and the optimal intensity of a preparative conditioning regimen remains uncertain. In this study, we evaluated the outcomes of HSCT in 24 patients with RCC. Eleven patients received myeloablative conditioning (MAC) consisting of high-dose cytarabine, cyclophosphamide, and either total body irradiation (TBI) or busulfan. Nine patients (38%) received a reduced-intensity conditioning (RIC) regimen; of these, 7 received low-dose TBI and cyclophosphamide (200 mg/kg) with or without antithymocyte globulin or fludarabine, and 2 patients received low-dose TBI, fludarabine, and melphalan (140 mg/m2). The remaining 4 patients had disease progression before HSCT and received the MAC regimen. With a median follow-up of 91 months (range, 6 to 263), the probability of overall survival at 5 years was 81.1% (95% CI, 57.0 to 92.5). The 5-year overall survival for the 15 patients who received MAC was 73.3% (95% CI, 43.6 to 89.1), and all 9 patients with RIC are alive without any events. Further study is needed to evaluate the efficacy of RIC for children with RCC with an expectation for reduction of late effects such as growth retardation and infertility.