Late effects after hematopoietic stem cell transplantation in patients with HLH: A Histiocyte Society, PDWP, IEWP, and TCWP EBMT Study

Background: Hematopoietic stem cell transplantation (HCT) is the only curative treatment in primary hemophagocytic lymphohistiocytosis (pHLH). However, HCT is associated with a wide range of late effects (LEs). Objective: We sought to characterize the long-term outcome and LEs following HCT in pHLH. Methods: A total of 274 children with pHLH from the European Society for Blood and Marrow Transplantation registry who underwent allogeneic HCT between 2004 and 2015 were included. Multivariable logistic regression models were used to evaluate the adjusted impact of baseline variables on central nervous system and hormonal LEs, respectively. Results: A broad spectrum of LEs was identified, with neurologic (31%) and hormonal (34.8%) complications being the most prevalent. Chemotherapy (HLH-1994/HLH-2004) before HCT was identified as a significant risk factor for endocrinological LEs (P = .03), highlighting a novel aspect not previously reported. The presence of neurologic abnormality at diagnosis was an independent risk factor for neurologic LEs (P < .001) as was incomplete remission status at the time of HCT (P = .04). Conclusions: HCT has significantly improved survival in patients with pHLH. However, survivors still face significant risks of LEs.