Objective: To evaluate preliminarily the significance of detecting the Wilms' tumor (WT1) gene level on monitoring minimal residual disease (MRD) and predicting the clinical outcome in patients of acute leukemia following hematopoietic stem cell transplantation (HSCT).
Methods: The mRNA expression levels of WT1 and house-keeping gene ABL were dynamically measured with Real-time quantitative reverse transcription polymerase chain reaction (RQ-RT-PCR) on 326 bone marrow samples from 63 post-HSCT patients in our hospital from December 2001 to September 2009. After comparing the WT1 levels of patients with different post-transplantation outcomes, the investigators used the receiver operating characteristic (ROC) curve to determine the WT1 threshold so as to predict their clinical relapses. Then different prognoses of WT1 positive and negative patients were analyzed.
Results: The levels of WT1 expression showed significant difference between the 19 relapsing and 44 non-relapsing patients with the median expression levels of 1270 (55 - 47 596) and 132 (0 - 2959) respectively (P < 0.01). In 19 relapsing patients, except for 1 patient discontinuing the detection of WT1, 10 mortality cases due to recurrence had higher levels of WT1 expression than other 8 patients (P > 0.05). According to the ROC curve, the cut-off value of WT1 at 585 could separate 63 patients into the WT1-positive group (> 585) and the WT1-negative group (≤ 585). The WT1-negative group was found to have a longer relapse-free survival (RFS) and overall survival (OS) than the positive group (all P < 0.01). Twenty-one WT1-positive patients were followed up for 3, 4 - 6, 7 - 9 and 9 months respectively. The cumulative post-HSCT recurrence rates in those WT1-positive cases were 8/8, 2/4, 2/4 and 3/5 (P = 0.063) respectively. And the intervention was ineffective.
Conclusion: WTl gene may be an independent factor of monitoring MRD. And WT1 > 585 is a poor post-HSCT prognostic factor for the patients of acute leukemia.