High prognostic value of pre-allogeneic stem cell transplantation minimal residual disease detection by WT1 gene expression in AML transplanted in cytologic complete remission

•MRD in AML has become one of the most important factors to determine prognosis and therapeutic choices.•We analyzed the prognostic value of pre-SCT MRD, evaluated by WT1 expression.•Cases with cCR and MRD-WT1 negativity pre-SCT have lower Relapse Rate and better OS.•Pre-SCT WT1 expression is a powerful predictor of post-SCT outcome in AML undergoing SCT in cCR. We analyzed the outcome of allogeneic stem cell transplantation (allo-SCT) in acute myeloid leukemia (AML) patients according to molecular Minimal Residual Disease (MRD) status prior to allo-SCT. MRD was assessed by the quantitative expression of the pan-leukemic marker Wilms' tumor (WT1) gene, according to the validated LeukemiaNet method. Between 2005 and 2016, 122 consecutive AML patients, WT1 positive at diagnosis, received allo-SCT in cytologic complete remission (cCR). The median age at SCT was 53 years (range 18–70). Quantitative analysis of WT1 gene expression (bone marrow samples) was available in all cases both at diagnosis (100% of samples overexpressed WT1 with a mean of 8607±8187 copies/104 Abelson) and immediately before allo-SCT. Eighty one cases (66%) were MRD-WT1 negative (WT1 250 copies) prior to allo-SCT. We evaluated post-SCT overall survival (OS), disease free survival (DFS) and relapse rate (RR), according to MRD-WT1 status pre-SCT. Both post-allo-SCT OS and DFS were significantly improved in patients who were MRD-WT1 negative at the time of SCT compared with those who were MRD-WT1 positive, with a median OS and DFS not reached in the MRD-WT1 negative group and 9 and 8 months, respectively, in the WT1 positive group (OS log-rank p