Haploidentical transplant in adult patients with acute lymphoblastic leukemia in Argentina: a comparison with matched related and unrelated donors

We aimed at analyzing the outcome of allogeneic stem cell transplant (ASCT) in adult patients with acute lymphoblastic leukemia (ALL), comparing Haploidentical (Haplo) with HLA-matched (sibling and unrelated) donors. Between 2008 and 2017, we collected data from 236 patients (median age 31 years; range 16–64; 90% HCT-CI 0–1) who underwent unmanipulated ASCT in first complete remission and subsequent remissions in 15 Argentinian centers. Donors were HLA-matched ( n = 175; 74%) and Haplo ( n = 61; 26%). Two-year overall survival (OS) was 55% (95% CI 47–63) for the HLA-matched group and 49% (95% CI 34–62) for the Haplo group ( p = 0.351). For OS, crude HR, adjusted HR for covariates (HR 1.24; 95% CI 0.77–1.99; p = 0.363) and HR including a propensity score in the model (HR 1.22; 95% CI 0.71–2.08; p = 0.414) showed no impact of donor category on the OS. No difference was found in terms of nonrelapse mortality, relapse, leukemia-free survival, and grade 3–4 acute graft-versus-host disease (GVHD); 2-year incidence of chronic GVHD was higher in HLA-matched vs Haplo group ( p = 0.028). Patients with ALL who underwent ASCT were young subjects with low HCT-CI. In this setting, a Haplo donor represents an alternative widely available in the absence of an HLA-matched donor. Relapse remains a challenge for all donor categories.