Second allogeneic haematopoietic stem cell transplantation for non‐malignant diseases

Summary We retrospectively analysed clinical outcomes of 152 patients with non‐malignant diseases (NMDs) who underwent a second allogeneic haematopoietic stem cell transplantation (HSCT), using a composite end‐point, graft‐versus‐host disease (GVHD)‐free, relapse (i.e. graft failure)‐free and subsequent transplant‐free survival (GRSFS), to assess major failure events. The 5‐year overall survival (OS) and GRSFS rates were 67.0% and 52.1%, respectively. Graft failure (GF) was the most frequent GRSFS failure event, occurring in 24.5% of patients. In multivariate analysis, use of a human leucocyte antigen 0–1 antigen mismatch unrelated bone marrow (BM)/peripheral blood stem cell (PBSC) donor, unrelated cord blood (CB) donor and no donor change were associated with lower incidence of engraftment ( p < 0.01). In addition to conditioning and human leucocyte antigen (HLA) compatibility in second HSCT, disease group was identified as an independent risk factor for GRSFS. Specifically, patients with haemophagocytic lymphohistiocytosis had the poorest outcome ( p = 0.04), while those with inherited metabolic diseases (IMDs) tended towards more favourable outcome ( p = 0.06). Among the 51 deaths, 44 (86.6%) were attributed to causes other than the original disease, with variation across disease groups. GRSFS may be a useful metric to quantify the clinical impact of major failure events and to inform strategies for second HSCT in NMDs.