Factors predicting outcome after allogeneic transplant in refractory acute myeloid leukemia: a retrospective analysis of Gruppo Italiano Trapianto di Midollo Osseo (GITMO)

The clinical outcome of primary refractory (PRF) AML patients is poor and only a minor proportion of patients is rescued by allogenic hematopoietic stem cell transplantation (HSCT). The identification of pre-HSCT variables may help to determine PRF AML patients who can most likely benefit from HSCT. We analyzed PRF AML patients transplanted between 1999 and 2012 from a sibling, unrelated donor or a cord blood unit. Overall, 227 patients from 26 Gruppo Italiano Trapianto di Midollo Osseo e Terapia cellulare centers were included in the analysis. At 3 years, the overall survival was 14%. By multivariate analysis, the number of chemotherapy cycles, (hazard ratio (HR): 1.87; 95% confidence interval (CI): 1.24–2.85; P=0.0028), the percentage of bone marrow or peripheral blood blasts (HR: 1.75; 95% CI: 1.16–2.64; P=0.0078), the adverse cytogenetic (HR: 1.44; 95% CI: 1.00–2.07; P=0.0508) and the age of patients (HR: 1.77; 95% CI: 1.08–2.88; P=0.0223) remained significantly associated with survival. Thus, we set up a new score predicting at 3 years after transplantation, an overall survival probability of 32% for patients with score 0 (no or 1 prognostic factor), 10% for patients with score 1 (2 prognostic factors) and 3% for patients with score 2 (3 or 4 prognostic factors).