Efficacy and safety of low-dose TBI combined MAC regimen for HSCT in high-risk AML patients with active disease.

Background: The management of high-risk acute myeloid leukaemia (AML) remains challenging, highlighting the need for innovative conditioning strategies beyond current regimens.

Methods: In the present single-arm study, a FACT regimen comprised of low-dose total body irradiation (TBI) with fludarabine, cytarabine and cyclophosphamide was employed to treat cytogenetically high-risk AML patients exhibiting pre-transplant active disease. This clinical trial is registered in the Chinese Clinical Trial Registry with the registration number ChiCTR2000035111.

Results: In this study, 21 high-risk AML patients with pre-transplant disease statuses including primary induction failure, relapse and measurable residual disease positivity, were enrolled to undergo FACT conditioning. The FACT group demonstrated a 1-year non-relapse mortality (NRM) rate of 9.5%, indicating a similar level of safety and tolerability among the conditioning regimens. The estimated cumulative incidence of grade 2-4 acute graft-versus-host disease (GVHD) at one year was 30.7%. Additionally, the cumulative incidence of chronic GVHD was 36.0% at one year and increased to 43.0% at two years.

Conclusions: The FACT regimen is an effective myeloablative conditioning (MAC) strategy for high-risk AML patients, potentially reducing relapse risk without increasing NRM, warranting further research.