Background and Importance Allogeneic haematopoietic cell transplantation (allo-HCT) is a potentially curative therapeutic modality for acute myeloid leukaemia (AML), but it still carries high morbidity and mortality; there are limited data regarding outcomes, so it is important to research its results, and the factors that influence them.

Aim and Objectives To assess the survival of allo-HCT in AML patients age <60 years, describe its characteristics, and identify factors that are related to the best outcomes.

Retrospective observational study. We included all patients with AML, aged <60 years, who underwent allo-HCT performed at our centre between 2016-2019.

We analysed their age, sex, cytogenetic risk group, disease status at the time of transplantation, Karnofsky performance status (KPS) score, comorbidity indexes (HCT-CI and EBMTscore), donor type, source, conditioning regimens, graft-versus-host disease (GVHD) prophylaxis, retransplantation, donor age, donor sex, CMV-mismatch, ABO-mismatch, development of GVHD, related hospitalisations, progression, and death.

Overall survival (OS) and progression-free survival (PFS) were analysed using Kaplan-Meier and Log-Rank test.

Thirty-seven patients were included. Mean age was 44.81 ± 12.26 [18-59] years. 64.9% were women. 51.4% intermediate-risk and 43.2% high-risk. 70.3% in first complete remission (CR). 91.9% patients had a KPS score over 90% at the time of transplantation. 54.1% HCT-CI between 0-2, 81.1% EBMT score ≤4. 64.8% related donor (43.2% HLA-identical and 21.6% haploidentical), 35.1% unrelated donor (21.6% HLA-identical, 10.8% HLA 9/10, and 2.7% HLA 8/10). 70.3% allogeneic peripheral blood stem cell transplantation. 64.9% reduced-intensity conditioning. 16.2% retransplantation. Most donors were men >30 years. 37.8% received post-transplantation treatment with cyclophosphamide, tacrolimus, and mycophenolate mofetil. 18.9% CMV-mismatch (patient pos/ donor neg), 56.8% ABO-compatible, 54.1% development chronic GVHD and 40.5% acute GVHD. 43.2% did not require related hospitalisation.

PFS at 12 months was 72% (95% CI, 55-84%), and 51% (95% CI, 34-66%) at 24 months. OS at 12 months was 78% (95% CI, 61-89%) and 62% (95% CI, 45-76%) at 24 months. Median PFS and OS were not reached. The median follow-up for PFS was 33 months [1-69] and 34 months [1-69] for OS.

PFS was significantly higher in patients in 1st CR, EBMTscore ≤4, and lower-risk.

Conclusion and Relevance Patients undergoing allo-HCT show encouraging survival, although more extended follow-up is required to define more accurately their prognosis.

Conflict of Interest No conflict of interest