Age- and comorbidity-adjusted busulfan, fludarabine, cytarabine, and low-dose TBI-based conditioning regimen is effective for myelodysplastic syndromes with excess blasts undergoing allogeneic peripheral blood stem cell transplantation.

The optimal intensity of conditioning regimens for allogeneic hematopoietic stem cell transplantation (allo-HSCT) in patients diagnosed with myelodysplastic syndromes with excess blasts (MDS-EB) remains debated. We retrospectively analyzed the clinical outcomes of 102 MDS-EB patients who received an individualized conditioning protocol based on age and comorbidity, including busulfan, fludarabine, cytarabine, and low-dose total body irradiation (TBI). All patients achieved successful engraftment, with a median time to neutrophil and platelet engraftment of 12 and 13 days, respectively. The cumulative incidence of grade II-IV acute graft-versus-host disease (GVHD) at 180 days was 16.9%, while moderate-to-severe chronic GVHD at 2 years occurred in 15.0% of patients. After a median follow-up of 23 months, the 2-year relapse incidence was 11.5%. The 2-year overall survival (OS), progression-free survival (PFS), and GVHD-free/relapse-free survival (GRFS) were 81.9%, 77.3%, and 66.4%, respectively. The very high-risk subgroup of the International Prognostic Scoring System for MDS (IPSS-M) exhibited significantly higher relapse rates compared with the lower-risk groups (17.8% vs 2.4%, P = 0.03). Multivariate analysis identified IPSS-M as the only independent predictor of PFS (hazard ratio (HR) = 3.30, P = 0.04), whereas transplant conditioning intensity (TCI) showed no association with survival outcomes. These findings suggest that the age- and comorbidity-adjusted conditioning regimen achieves high engraftment rates, low relapse, and favorable survival in MDS-EB patients, with disease biology (IPSS-M) outweighing conditioning intensity in prognostic relevance.