Comparable outcomes for TBI-based versus treosulfan based conditioning prior to allogeneic hematopoietic stem cell transplantation in AML and MDS patients

This is the authors' abstract. We don't add key points for this paper.

Allogeneic hematopoietic stem cell transplantation (allo-HCT) is a standard treatment for patients with AML and MDS. The combination of fractionated total body irradiation(8GyTBI/Flu) with fludarabine is an established conditioning regimen, but fludarabine/treosulfan(Flu/Treo) constitutes an alternative in older/comorbid patients. We conducted a retrospective analysis of 215 AML(in CR) and 96 MDS patients undergoing their first allo-HCT between 2011 and 2022, identifying 53 matched Flu/Treo and 8GyTBI/Flu patients through propensity score matching. Median follow-up of survivors was 3.3 years and 4.1 years. For the Flu/Treo group, 1-year non-relapse mortality (2% vs. 10%, p = 0.03) was lower, while 1-year relapse incidence (16% vs. 13%, p = 0.81) was similar. Three-year outcomes, including relapse-free survival and graft-versus-host disease incidence, were comparable (OS: 81% vs. 74%, p = 0.70; RFS: 78% vs. 66%, p = 0.28; chronic GvHD: 34% vs. 36%, p = 0.97; acute GvHD (100 days): 11% vs. 23%, p = 0.11). Multivariable analysis, considering age, ECOG, HCT-CI, and MRD status, revealed no associations with main outcomes. Dose-reduced conditioning with Flu/Treo or 8GyTBI/Flu demonstrated favorable and comparable survival rates exceeding 70% at 3 years with 1-year NRM rates below 10% and low relapse rates in the matched cohort. These data underline the need for further evaluation of TBI and Treo-based conditionings in prospective trials.