Optimal time-points for minimal residual disease monitoring change on the basis of the method used in patients with acute myeloid leukemia who underwent allogeneic stem cell transplantation: A comparison between multiparameter flow cytometry and Wilms' tumor 1 expression

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.