Comparison of Haploidentical Bone Marrow versus Matched Unrelated Donor Peripheral Blood Stem Cell Transplantation with Posttransplant Cyclophosphamide in Patients with Acute Leukemia

Abstract

Background: Post-transplant cyclophosphamide (PTCy) is increasingly being utilized as a principle graft-versus-host disease (GvHD) prophylaxis strategy in allogeneic hematopoietic cell transplantation (allo-HCT). A haploidentical (haplo) or matched unrelated donor (UD) are valid options in the absence of a matched related donor. Experimental design: We compared the outcomes of patients with acute leukemia who underwent haplo bone marrow (haplo-BM, N=401) versus UD mobilized peripheral blood stem cells (UD-PB, N=192) transplantation in the setting of PTCy. Results: The median follow-up duration was 36 months in the haplo-BM group and 16.6 months in the UD-PB group, respectively (p<0.01). Myeloablative conditioning was used in 64.6% and 42.7% of haplo-BM and UD-PB patients, respectively (p<0.01). Cumulative incidence of neutrophil engraftment at day 30 was 87% in haplo-BM versus 94% in UD-PB, respectively (p =0.21). In the multivariate analysis, the risk of grade II-IV acute GvHD (HR=0.53, p=0.01) and chronic GvHD (HR=0.50, p=0.02) was significantly lower in the haplo-BM group compared to the UD-PB group. There was no significant difference between the study groups, with respect to relapse incidence, non-relapse mortality, leukemia-fee survival, overall survival or, GvHD-free, relapse-free survival. Conclusion: The use of a haplo donor with a BM graft resulted in a lower incidence of GvHD compared to a UD-PB stem cell graft in the setting of PTCy for patients with acute leukemia. However, differences in GvHD did not translate into the difference in survival outcomes. Based upon these data, UD-PB or haplo-BM should be considered equally acceptable sources for allo-HCT.