Allogeneic hematopoietic cell transplantation in patients with myelodysplastic syndrome using treosulfan based compared to other reduced-intensity or myeloablative conditioning regimens. A report of the chronic malignancies working party of the EBMT

Allogeneic haematopoietic-cell transplantation (allo-HCT) is a potentially curative therapy for high-risk myelodysplastic syndrome (MDS). Reduced-intensity conditioning (RIC) is usually associated with lower non-relapse mortality (NRM), higher relapse rate and similar overall-survival (OS) as myeloablative-conditioning (MAC). Fludarabine/treosulfan (FT) is a reduced-toxicity regimen with intense anti-leukaemia activity and a favourable toxicity profile. We investigated post-transplant outcomes in 1722 MDS patients following allo-HCT with FT (n = 367), RIC (n = 687) or MAC (n = 668). FT and RIC recipients were older than MAC recipients, median age 59, 59 and 51 years, respectively (P < 0 center dot 001) but other disease characteristics were similar. The median follow-up was 64 months (1-171). Five-year relapse rates were 25% (21-30), 38% (34-42) and 25% (22-29), after FT, RIC and MAC, respectively, (P < 0 center dot 001). NRM was 30% (25-35), 27% (23-30) and 34% (31-38, P = 0 center dot 008), respectively. Five-year OS was 50% (44-55), 43% (38-47), and 43% (39-47), respectively (P = 0 center dot 03). In multivariate analysis, FT was associated with a lower risk of relapse (HR 0 center dot 55, P < 0 center dot 001) and better OS (HR 0 center dot 72, P = 0 center dot 01). MAC was associated with higher NRM (HR 1 center dot 44, P = 0 center dot 001). In conclusion, FT is associated with similar low relapse rates as MAC and similar low NRM as RIC, resulting in improved OS. FT may be the preferred regimen for allo-HCT in MDS.