Older matched sibling donor vs young haploidentical donor for older patients with acute myeloid leukemia

Abstract

Selection of a suitable donor for allogeneic hematopoietic stem cell transplantation (allo-HCT) has mainly relied on HLA matching and, to date, a matched sibling donor (MSD) remains the first choice. However, patients with acute myeloid leukemia (AML) are older and therefore tend to have older siblings. Haploidentical donors (HIDs) are easily available, and offspring are younger than siblings. As donor age has been associated with worse outcomes, a younger HID might be a better choice than an older MSD for older patients with AML who receive transplantation in first complete remission (CR1). From the European Society for Blood and Marrow Transplantation registry database, we selected patients with AML aged ≥60 years who received transplantation in CR1, either from MSD aged ≥50 years or HID ≤40 years. HIDs received posttransplant cyclophosphamide as graft-versus-host disease (GVHD) prophylaxis, and MSDs received in vivo T-cell depletion. A total of 1247 patients were identified, including 721 MSDs and 526 HIDs. In univariate analysis, HID was associated with lower relapse incidence (P = .01), higher nonrelapse mortality (NRM; P = .01). The 2-year probability of overall survival (OS), leukemia-free survival (LFS), and GVHD-free and relapse-free survival (GRFS) were 62.5%, 56%, and 47%, respectively for the all population. In multivariate analysis, we confirmed that HID was associated with less relapse but more NRM, which translated into similar OS, LFS, and GRFS. Based on this retrospective study, young HIDs led to less relapse but higher NRM than older MSDs after allo-HCT in an older population with AML in CR1.

Graphical abstract

Figure 1.

GRFS by donor type. The 2-year probability of GRFS was 46.8% (95% CI, 42.8-50.7) for older MSDs and 46.2% (95% CI, 41.2-51) for young HIDs (P = .76).

Figure 2.

RI, NRM, LFS, and OS by donor type. The 2-year RI was 28.6% (95% CI, 25.1-32.2) for older MSDs, significantly higher than for young HIDs (20.1% [95% CI, 16.4-24.2]; P < .001) (A). The 2-year cumulative incidence of NRM was lower for older MSDs (14.7% [95% CI, 12-17.6]) than for young HIDs (24.4% [95% CI, 20.4-28.6]; P < .001) (B). The 2-year probability of LFS was 56.7% (95% CI, 52.7-60.5) for older MSDs vs 55.5% (95% CI, 50.5-60.3) for young HIDs (P = .73) (C). The 2-year probability of OS was 62.9% (95% CI, 58.9-66.7) for older MSDs vs 62% (95% CI, 57-66.6) for young HIDs (P = .29) (D).