Peripheral blood stem cell versus bone marrow graft for patients ≥60 years undergoing reduced intensity conditioning haploidentical transplantation for acute myeloid leukemia in complete remission: An analysis of the Acute Leukemia Working Party of the European Society for Blood and Marrow Transplantation

Abstract In the context of T‐cell replete haploidentical stem cell transplantation (Haplo‐SCT) using post‐transplantation cyclophosphamide (PT‐Cy), it is still unknown whether peripheral blood (PB) or bone marrow (BM) is the best graft source. While PB is associated with a higher incidence of graft‐versus‐host disease (GVHD), it may induce a stronger graft‐versus‐leukemia effect compared to BM, notably in acute myeloid leukemia (AML). From the EBMT registry database, we compared T‐cell replete PB ( n = 595) versus BM ( n = 209) grafts in a large cohort of 804 patients over the age of 60 years who underwent Haplo‐SCT with PT‐Cy for an AML in first or second complete remission. The risk of acute GVHD was significantly higher in the PB group (Grade II‐IV: HR = 1.67, 95% CI [1.10–2.54], p = 0.01; Grade III‐IV: HR = 2.29, 95% CI [1.16–4.54], p = 0.02). No significant difference was observed in chronic GVHD or non‐relapse mortality. In the PB group, the risk of relapse was significantly lower in the PB group (HR = 0.65, 95% CI [0.45–0.94], p = 0.02) and leukemia‐free survival was significantly better (HR = 0.76, 95% CI [0.59–0.99], p = 0.04), with a trend toward better overall survival (HR = 0.78, 95% CI [0.60–1.01], p = 0.06). We conclude that in the specific context of Haplo‐SCT with PT‐Cy, PB grafts represent a valid option to decrease the risk of relapse and improve outcome of older AML patients who usually do not benefit from conditioning intensification.