Abstract
Primary refractory acute myeloid leukaemia (AML) remains a major clinical challenge, with poor outcomes despite salvage chemotherapy. Allogeneic haematopoietic cell transplantation (HCT) continues to be a potentially curative option for these patients. However, recent data on outcomes and prognostic factors specific to primary refractory AML remain limited. We conducted a retrospective analysis of 2600 adult patients with primary refractory AML who underwent their first allogeneic HCT between 2013 and 2022, using data from the Japanese national registry. The 3-year overall survival (OS) and leukaemia-free survival (LFS) rates were 28.5% and 24.4% respectively. The multivariate analysis identified older age (≥50 years), poor performance status (≥2), adverse cytogenetics, extramedullary disease at diagnosis and higher peripheral blood blast count at HCT (≥10%) as significant risk factors for worse OS and LFS. The cumulative incidences of relapse and non-relapse mortality at 3 years were 49.8% and 25.8% respectively. Based on the five significant risk factors, we developed a scoring system that effectively stratified patients into distinct prognostic groups for OS and LFS. This nationwide analysis demonstrated that allogeneic HCT offers the potential for long-term survival in adult patients with primary refractory AML. The proposed risk-scoring system may support clinical decision-making and patient counselling.