Outcomes of allogeneic hematopoietic stem cell transplantation for primary hemophagocytic lymphohistiocytosis in adults

Allogeneic hematopoietic stem cell transplantation (HSCT) is the only curative approach for primary hemophagocytic lymphohistiocytosis (pHLH), but data on adult patients are scarce. Here we present an 8-year experience on HSCT for adult pHLH to reveal the benefits and risks in this population. A total of 29 adult pHLH patients entered this study, at a median follow-up of 29 months (3-112 months), the 5-year probability of survival was 60%. Six patients rejected HSCT, of whom 1 alive in complete response (CR). In 23 patients who underwent HSCT, 5-year survival post-HSCT overall was 73%, and in haploidentical HSCT (haplo-HSCT) cases, 71%. Patients who achieved CR at HSCT had a better outcome than those of partial response (92% vs. 47%, p = 0.013). Neither the use of HLA mismatched donor (75% vs. 72%, p = 0.996) nor the use of donor with monoallelic mutation (74% vs. 71%, p = 0.901) affected the prognosis. Hemophagocytic lymphohistiocytosis status of CR at HSCT was a positive prognostic factor. We concluded that HSCT is a promising method to cure adult-onset pHLH. Achieving CR before HSCT contributes to better outcome. Haplo-HSCT is safe and effective for adult pHLH patients, donors with monoallelic mutations in pHLH related genes but normal cytotoxic functions are reliable.