Salvage allogeneic stem cell transplantation in patients with pediatric myelodysplastic syndrome and myeloproliferative neoplasms

Background: Allogeneic hematopoietic stem cell transplantation (HSCT) is the only curable approach for myelodysplastic syndrome (MDS) and myeloproliferative neoplasms (MPN); however, the event-free survival rate of patients with pediatric MDS and MPN is still only approximately 60%. Although salvage HSCT is the only curative approach for patients with the failure of previous HSCT, its safety and efficacy have yet to be determined. Procedures: We retrospectively analyzed 51 pediatric MDS or MPN who received salvage HSCT for relapse or graft failure following HSCT using registry data of the Japan Society for Hematopoietic Cell Transplantation. The indications used for salvage HSCT were relapse in 22 patients and graft failure in 29 patients. Results: The overall survival (OS) rate for salvage HSCT in relapsed patients was 49.0±10.8% at 3 years. The cumulative incidence of relapse following salvage HSCT was 29.8±10.7% at 3 years, whereas the incidence of non-relapse mortality (NRM) was 28.6±10.2%. No significant differences were observed in the OS after salvage HSCT between disease types. Twenty-four of 29 patients who received salvage HSCT for graft failure achieved engraftment, resulting in an engraftment probability of 81.5±8.0% on day 100. The OS rate after salvage HSCT for graft failure was 56.8±9.6% at 3 years. Conclusions: Second HSCT should be considered as a valuable option for the patients with relapse and graft failure in patients with pediatric MDS or MPN after HSCT, but high NRM is an important issue that needs to be addressed.