Treosulfan or busulfan plus fludarabine as conditioning treatment before allogeneic haemopoietic stem cell transplantation for older patients with acute myeloid leukaemia or myelodysplastic syndrome (MC-FludT.14/L): a randomised, non-inferiority, phase 3 trial

Summary Background Further improvement of preparative regimens before allogeneic haemopoietic stem cell transplantation (HSCT) is an unmet medical need for the growing number of older or comorbid patients with acute myeloid leukaemia or myelodysplastic syndrome. We aimed to evaluate the efficacy and safety of conditioning with treosulfan plus fludarabine compared with reduced-intensity busulfan plus fludarabine in this population. Methods We did an open-label, randomised, non-inferiority, phase 3 trial in 31 transplantation centres in France, Germany, Hungary, Italy, and Poland. Eligible patients were 18–70 years, had acute myeloid leukaemia in first or consecutive complete haematological remission (blast counts ClinicalTrials.gov ( NCT00822393 ). Findings Between June 13, 2013, and May 3, 2016, 476 patients were enrolled (240 in the busulfan group received treatment and transplantation, and in the treosulfan group 221 received treatment and 220 transplanation). At the second preplanned interim analysis (Nov 9, 2016), the primary endpoint was met and trial was stopped. Here we present the final confirmatory analysis (data cutoff May 31, 2017). Median follow-up was 15·4 months (IQR 8·8–23·6) for patients treated with treosulfan and 17·4 months (6·3–23·4) for those treated with busulfan. 2-year event-free survival was 64·0% (95% CI 56·0–70·9) in the treosulfan group and 50·4% (42·8–57·5) in the busulfan group (HR 0·65 [95% CI 0·47–0·90]; p Interpretation Treosulfan was non-inferior to busulfan when used in combination with fludarabine as a conditioning regimen for allogeneic HSCT for older or comorbid patients with acute myeloid leukaemia or myelodysplastic syndrome. The improved outcomes in patients treated with the treosulfan–fludarabine regimen suggest its potential to become a standard preparative regimen in this population. Funding medac GmbH.