WT1 molecular assessment combined with flow cytometry increases the prognostic value of pre transplant MRD in AML

The presence of Minimal Residual Disease (MRD) before allogeneic Stem Cell Transplantation (SCT) has been shown to be associated with poor outcomes in patients with Acute Myeloid Leukemia (AML).¹ Multicolor Flow Cytometry (MFC) is recognized as a reliable tool for evaluation of MRD. Furthermore, Wilms Tumor 1 (WT1) gene expression is the most standardized molecular MRD marker in AML.

In a Letter to the Editor of Haematologica on 11^th May 2017, Fabio Guolo, University of Genoa, Genoa, and colleagues discuss results from their retrospective study which analyzed the role of pre-transplant combined MFC-molecular MRD assessment as a predictor of post-transplant relapse risk.^2,3

WT1 gene expression and MRD evaluation by MFC was analyzed in bone marrow samples from 224 consecutive AML patients who received allogenic-SCT in either First or Second Complete Remission (CR1/2) at the IRCCS AOU San Martino-IST, University of Genoa between January 2004 and January 2014.

The key results of the study were:

• 3-year Cumulative Incidence (CI) of relapse in patients that were MFC negative/WT1 negative (24/224), MFC positive/ WT1 negative (150/224) and MFC positive/ WT1 positive (50/224) were 8.7%, 23.1% and 51.9% respectively; P < 0.0001
• 3-year Overall Survival (OS) in patients that were MFC/WT1 negative, MFC positive/ WT1 negative and MFC positive/ WT1 positive were 73.5%, 60% and 36.7% respectively; P < 0.0001

In summation, combined molecular (WT1- based) and MFC assessment of pre-transplant MRD can accurately predict relapse risk in AML patients.