Significance of WT1 and multiparameter flow cytometry assessment in patients with chronic myelomonocytic leukemia receiving allogeneic hematopoietic stem cell transplantation

Introduction The objective of this study was to investigate the clinical significance of minimal residual disease (MRD) monitoring through Wilms tumor 1 (WT1) gene expression and multicolor flow cytometry (FCM) in patients with chronic myelomonocytic leukemia (CMML) after allogeneic hematopoietic stem cell transplantation (allo-HSCT). Methods For this purpose, WT1 gene expression and the CMML-related abnormal immunophenotype were examined using real-time quantitative polymerase chain reaction and FCM, respectively. Results In total, 59 patients with CMML who underwent allo-HSCT were enrolled in this study. Thirteen cases (22.0%) developed hematological relapse, and 15 patients (25.4%) expired during the follow-up period. Thirty-four patients (37.6%) were positive for WT1 (WT1+), and 44 patients (74.6%) were positive for FCM prior to allo-HSCT. After allo-HSCT, there were 21 WT1+ patients (35.6%) and 10 patients (16.9%) who were positive in FCM (FCM+). Post-transplant WT1+ (post-WT1 0.6+; 50.7% vs. 7.6%, p < .001) and post-transplant FCM+ (post-FCM+; 90.0% vs. 8.8%, p < .001) indicated a higher 3-year cumulative incidence of relapse (CIR) compared with the WT1- or FCM-patients. Multivariate analysis of event-free survival (EFS), overall survival (OS), and CIR showed that the FCM status after transplantation was an independent prognostic factor for relapse (p < .05). Conclusion Both FCM and WT1 after HSCT were identified as important predictors of recurrence of CMML following transplantation and may be useful in guiding interventions against disease relapse.