Haploidentical transplantation may be a feasible option for patients with relapsed/refractory acute myeloid leukemia

In a recent issue of Haematologica, Eolia Brissot from Hôpital Saint Antoine, APHP, Paris, France, and colleagues published the results of a retrospective, multicenter, registry-based study. The aim of the analysis was to evaluate whether haploidentical donor transplantation with post-transplant cyclophosphamide (Haplo PTCy) could replace 10/10 or 9/10 unrelated donor (UD) transplantation. Data was collected from the Acute Leukemia Working Party of the EBMT registry.

This analysis compared the outcomes of patients with acute myeloid leukemia (AML) with active disease who underwent allogeneic stem cell transplantation (allo-SCT) from a haploidentical donor with post-transplant cyclophosphamide (Haplo PTCy group, n = 199) versus from a 10/10 (UD 10/10 group, n = 1,111) or a 9/10 (UD 9/10 group, n = 383) unrelated donor between 2007 and 2014.

Key findings:

Data are given as Haplo PTCy vs UD 10/10 vs UD 9/10 cohorts, respectively

• No significant difference was found in the three cohorts regarding leukemia-free survival (LFS), overall survival (OS), relapse incidence (RI), non-relapse mortality (NRM), or graft-versus-host disease-free/relapse-free survival (GRFS):
  • 2-year LFS: 22.8% vs 28% vs 22.2 %, P = not significant
  • 2-year OS: 29.3% vs 34.7% vs 27.6%, respectively, P = not significant
  • 2-year RI: 52% vs 46.3% vs 51.1%, P = not significant
  • 2-year NRM: 25.3% vs 25.7% vs 26.7%, P = not significant
• Three factors showed a correlation with superior GRFS:
  • longer time from diagnosis until transplantation
  • RIC instead of MAC regimen
  • Karnofsky Performance Score ≥ 90
• Predictive factors that correlated with a higher relapse incidence:
  • First or second relapse compared to primary refractory acute myeloid leukemia
  • Poor cytogenetics

Taken together, this study indicates that transplantation with haploidentical donors is as beneficial as transplantation with HLA-identical sibling donors. As a result, haploidentical donor transplantation is a feasible therapy option for AML patients with active disease.

The researchers stated that “when an HLA-identical sibling donor is not available for an AML patient with active disease and who is, otherwise, a candidate for HSCT, a Haplo donor may be used with the expectation of similar rates of NRM, LFS, OS, and GRFS at two years, compared with 10/10 matched and 9/10 mismatched UD.”