Retrospective analysis of treosulfan-based conditioning in comparison with standard conditioning in patients with myelodysplastic syndrome.

Myelodysplastic syndromes (MDSs) often occur in older adults with significant comorbidities. Therefore, a reduced-toxicity conditioning regimen may be more suitable than standard conditioning regimens before allogeneic blood stem cell transplantation. Here, we retrospectively compare the outcome of a treosulfan-based conditioning regimen with standard myeloablative TBI-based conditioning regimens in patients (pts) with MDS. A total of 48 pts with MDS were included in the study, of which 29 (60%) pts received TBI-based and 19 (40%) pts received a treosulfan-based conditioning regimen. A significantly lower relapse incidence (5% vs 34% at 3 years, P=0.019) resulting in a better, but not statistically significant relapse-free survival (RFS) (57% vs 31%, P=0.086) was observed after treosulfan-based conditioning. In pts with increased risk for significant side effects due to comorbidities (haematopoietic stem cell transplantation specific comorbidity index), the estimated 3-year RFS was significantly better in the treosulfan group: 54% (95% confidence interval (CI), 17-90%) compared with pts in the TBI group: 11% (95% CI, 0-44%; log-rank test P=0.0455). Treosulfan-based conditioning therapy is a feasible and effective regimen for pts with MDS, especially in pts with preexisting comorbidities.