Impact of Cytogenetic Risk on Outcomes of Non-T-Cell-Depleted Haploidentical Hematopoietic Cell Transplantation in Patients with Relapsed or Refractory Acute Myeloid Leukemia

Baseline cytogenetics and disease status are key factors predicting the outcomes of allogeneic hematopoietic cell transplantation (HCT) in patients with acute myeloid leukemia (AML). The importance of cytogenetic risk in patients with primary refractory or relapsed (R/R) AML undergoing haploidentical (Haplo) HCT is unknown. We studied the impact of cytogenetic risk in patients with R/R de novo AML with active disease who underwent non-T-cell-depleted Haplo-HCT with post-transplantation cyclophosphamide from 2010 to 2020. Four hundred forty patients with active disease at transplantation from the European Society for Blood and Marrow Transplantation database were analyzed (291 [66.1%] with intermediate-risk [AMLint] and 149 [44.1%] with adverse-risk cytogenetics [AMLadv]). Impact of baseline cytogenetic risk on various transplantation outcomes was evaluated. Pre-transplantation disease status was relapse in 48.1% and 26.8% and primary refractory in 51.9% and 73.2% of the patients with AMLint and AMLadv, respectively (P < .0001). Two-year leukemia-free survival (LFS, 35.5% versus 15.5%, P = .001) and overall survival (OS, 39.2% versus 20.1%, P = .001) were better in AMLint versus AMLadv. In multivariate analysis, the relapse rate was significantly higher (hazard ratio [HR] = 2.17 [95% confidence interval {CI} 1.57-3.0]) and LFS (HR = 1.71 [95% CI, 1.31-2.22]) and OS (HR = 1.69 [95% CI, 1.29-2.22]), significantly lower for patients with AMLadv compared to AMLint, conditioning intensity did not affect leukemia relapse rate. Non-relapse mortality (HR = 1.1 [95% CI, 0.7-1.74]) and graft-versus-host disease-free, relapse-free survival (HR = 1.37 [95% CI, 1.06-1.77]) did not differ significantly between the risk groups. Disease status before transplant (primary refractory versus relapsed) or conditioning intensity did not impact main transplant outcomes. Baseline cytogenetic risk remains a key prognostic factor for patients with R/R AML with persistent disease before non-T-cell-depleted Haplo-HCT.