Superior Graft-versus-Leukemia Effect Associated with Transplantation of Haploidentical Compared with HLA-Identical Sibling Donor Grafts for High-Risk Acute Leukemia: An Historic Comparison

The outcomes of an historic comparison of 117 consecutive, high-risk, acute leukemia patients undergoing hematopoietic stem cell transplantation (HSCT) from HLA-mismatched/haploidentical donors (HID, n = 81) or HLA-identical sibling donors (ISD, n = 36) without the use of in vitro T cell depletion (TCD), between the period of January 2005 and April 2009 were compared. Full engraftment was achieved in 98% of patients in the HID group and 97% in the ISD group. The cumulative incidences of grades II-IV acute graft-versus-host disease (aGVHD) in the HID and ISD cohorts were 49% and 24%, respectively (P = .014) with a relative risk (RR) of 2.99 (1.25-7.21) (P = .014). The incidence of chronic GVHD (cGVHD) did not differ significantly between the 2 cohorts. The 2-year cumulative incidence of relapse was significantly lower in HID (26%) than in ISD patients (49%) (P = .008). The 2-year cumulative incidence of nonrelapse mortality (NRM) was comparable in recipients of HID (34%) and ISD grafts (38%) (P = .85). The 3-year probability of overall survival (OS) was higher in HID patients (42%) than in ISD (20%) (P = .048) patients. Our comparisons suggest that HID transplants can achieve a stronger graft-versus-leukemia (GVL) effect than ISD for high-risk acute leukemia patients.