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Minimal residual disease (MRD) of 30 adult AML patients was monitored by multiparameter flow cytometry (MFC) and WT1 expression before and after allogeneic stem cell transplantation (allo-SCT). Diagnostic performance of pre-transplant MRD measured by MFC was higher than that obtained by WT1 expression. Comparable results were displayed at day +30 post-transplant, while better values by WT1 compared to MFC were found at day +90. Positive MRD by MFC predicted a shorter disease free survival (DFS) before and 1 month after transplant ( p = 0.006 and p = 0.005), while only high WT1 levels at 1 month from the transplant significantly impacted on DFS ( p = 0.010). Our results support the idea that MRD monitoring by MFC should be suggested before and 30 days after the transplant, while WT1 expression should be preferred after this procedure. The assessment of MRD at day +30 from allo-SCT is recommended as post transplant check-point for the predictive role displayed, independently of the method used. [ABSTRACT FROM AUTHOR]

Abstract: Despite a high remission rate, a significant number of patients with acute myeloid leukemia (AML) relapse. Thus, the evaluation of minimal residual disease (MRD) in AML is an important strategy to better identify high risk patients. Most sensitive methodology to detect MRD is molecular polymerase chain reaction (PCR) but its applicability is restricted to AML with leukemia-specific molecular targets (e.g. AML1-ETO, CBFB-MYH11, MLL, FLT-3). In our study, MRD was monitored at different time points with both MFC and WT1-RNA quantification in 23 AML patients who did not present specific molecular targets. As previously published, we considered values of 10−3 (0.1%) in MFC and 90 WT1-RNA ×104 ABL copies as optimal thresholds. Receiver operating characteristics (ROC) analysis was used to confirm these data. To realize the methodology that better identify high risk patients, an analysis of sensitivity, specificity, predictive values (PV) and likelihood ratio (LR) was provided and similar results were showed. MRD levels ≥10−3 in MFC as well MRD levels ≥90 WT1-RNA copies in RQ-PCR, identify risk groups of patients with poor prognosis. Therefore, MFC and WT1-RNA quantification showed a comparable capacity in terms of technical performance and clinical significance to identify high risk patients who eventually relapsed. [Copyright &y& Elsevier]