Long‐term follow‐up of haploidentical hematopoietic stem cell transplantation without in vitro T cell depletion for the treatment of leukemia

Abstract

BACKGROUND: Many patients who require allogeneic hematopoietic stem cell transplantation (allo-HSCT) lack a human leukocyte antigen (HLA)-matched donor. Recently, a new strategy was developed for HLA-mismatched/haploidentical transplantation from family donors without in vitro T cell depletion (TCD). METHODS: Over the past 9 years, 756 patients underwent haploidentical transplantation using a protocol developed by the authors, which combines granulocyte-colony stimulating factor-primed bone marrow (G-BM) and peripheral blood stem cells without in vitro TCD. The long-term outcome with this treatment modality was reported, and a risk-factor analysis was provided. RESULTS: Of these patients, 752 (99%) achieved sustained, full donor chimerism. The incidence of grades 2 through 4 acute graft-versus-host disease (GVHD) was 43%, and the 2-year cumulative incidence of total chronic GVHD was 53%. The 3-year cumulative incidence of nonrelapse mortality was 18%. The 2-year cumulative incidences of relapse were 15% and 26% in the standard-risk and high-risk groups, respectively. Of the 756 patients, 480 survived throughout the follow-up period of 1154 days (range: 335-3511 days) with the 3-year leukemia-free survival rates of 68% and 49% in the standard-risk and high-risk groups, respectively. Lower leukemia-free survival was associated with high-risk disease status (P = .001), chronic myelogenous leukemia disease type (P = .004), neutrophil engraftment beyond 13 days after transplant (P = .012), and the occurrence of grades 2 through 4 acute GVHD (P = .019). CONCLUSIONS: The results from the authors' 9-year experience showed that G-BM combined with peripheral blood stem cells from haploidentical donors, without in vitro TCD, is a reliable source of stem cells for transplantation by using the protocol developed by the authors.