Impact of Wilms' tumor 1 expression on outcome of patients undergoing allogeneic stem cell transplantation for AML.

The monitoring of the minimal residual disease by Wilms' tumor 1 expression (MRD) is a standardized test, which can be used in over 80% of patients with AML. To investigate the prognostic value of MRD in patients undergoing allogeneic stem cell transplantation (allo-SCT) for AML, MRD was monitored 3 months after transplantation in 139 patients. MRD positivity did not lead to any therapeutic intervention. Median follow-up was 39.3 (6.4-99.8) months. Patients with positive MRD at 3 months experienced more often post-transplant relapse (27/30, 90%) than those with negative MRD (16/109, 14.7%) (P<0.0001). Similarly, a shorter 3-year event-free survival (EFS) was observed in MRD-positive patients (10% vs 72.3% in MRD-negative patients, P<0.0001). The correlation between relapse and MRD was stronger in blood than in bone marrow samples. Multivariate analysis confirmed the detrimental role of 3-month positive MRD for relapse (hazard ratio (HR): 15.42; 95% confidence interval (CI): 7.53-31.59; P<0.0001) and EFS (HR: 10.71; 95% CI: 5.41-21.21; P<0.0001). Interestingly, 3-month chimerism was less predictive of relapse than positive MRD. In conclusion, our results demonstrate the usefulness of peripheral blood MRD monitoring in identifying very high-risk patients, who could benefit from an early preemptive treatment, and those who do not need such an intervention.