Allogeneic hematopoietic cell transplantation for myelodysplastic syndrome in young adults: A retrospective study on behalf of the EBMT Chronic Malignancies Working Party.

Myelodysplastic syndromes (MDS) in young adults are uncommon and underrepresented in transplant cohorts. We evaluated 697 patients aged 18-40 years who underwent first allogeneic hematopoietic cell transplantation (allo-HCT) reported to the EBMT between 2016 and 2021. The primary endpoint was overall survival (OS); secondary endpoints included progression-free survival (PFS), cumulative incidence of relapse (CIR), non-relapse mortality (NRM), and graft-versus-host disease (GVHD). With a median follow-up of 2.8 years, 3-year OS and PFS were 69% (95% CI, 65-73) and 62% (58-66), respectively. At 3 years, CIR and NRM were 20% (16-23) and 18% (15-21). Grade II-IV acute GVHD occurred in 28% (25-32) by day +100, while chronic GVHD and extensive chronic GVHD occurred in 38% (34-42) and 18% (14-21) at 3 years. In multivariable analysis, very-poor cytogenetic risk was associated with inferior OS (HR 2.81, 95% CI 1.77-4.45). Haploidentical donors and reduced-intensity conditioning were also associated with inferior survival. Patients younger than 30 years had superior PFS, whereas outcomes with matched sibling and matched unrelated donors were comparable. These findings support the feasibility of allo-HCT in young adults with MDS and may help inform risk-adapted transplant approaches.