Real world outcome analysis of treosulfan-based conditioning prior to allo-HCT in patients with MDS compared to clinical trial data

Allogeneic hematopoietic cell transplantation (alloHCT) is the only curative therapy for myelodysplastic syndrome (MDS), particularly in patients with higher risk MDS, resulting in superior survival compared to non-transplant approaches in transplant eligible patients [ 1 , 2 ]. Various studies demonstrated that treosulfan in combination with fludarabine showed a favorable acute toxicity profile, allowing donor cell engraftment with complete and sustained donor hematopoietic chimerism after alloHCT combined with good tolerability also for MDS patients [ 3 , 4 , 5 , 6 ]. To compare treosulfan- versus busulfan-based conditioning in elderly and/or comorbid patients, we performed an analysis on the MDS subgroup of a randomized phase 3 trial, which evaluated both conditioning regimens in patients with acute myeloid leukemia and MDS. In addition, to demonstrate transition of the clinical efficacy of treosulfan-based conditioning from the clinical trial setting to the real-world, the trial data was combined with data obtained from 2 large transplant centers (real-world data [RWD]).