Role of Sequential Monitoring of WT1 Gene Expression in Patients With Acute Myeloid Leukemia for the Early Detection of Leukemia Relapse

Wilms' tumor gene 1 in hematological malignancies: friend or foe?

Wilms' tumor gene 1 (WT1) is a transcription and post-translational factor that has a crucial role in the biological and pathological processes of several human malignancies. For hematological malignancies, WT1 overexpression or mutation has been found in leukemia and myelodysplastic syndrome. About 70-90% of acute myeloid leukemia patients showed WT1 overexpression, and 6-15% of patients carried WT1 mutations. WT1 has been widely regarded as a marker for monitoring minimal residual disease in acute myeloid leukemia. Many researchers were interested in developing WT1 targeting therapy. In this review, we summarized biological and pathological functions, correlation with other genes and clinical features, prognosis value and targeting therapy of WT1 in hematological features.

Prognostic value of combined WT1 and multiparameter flow cytometry assessment for measurable residual disease after induction in non-APL acute myeloid leukemia

The objective of this study was to investigate the expression pattern of Wilms tumor 1 (WT1) gene at diagnosis, complete remission (CR) and relapse status in non-acute promyelocytic leukemia (non-APL) acute myeloid leukemia (AML) patients, and further explore the prognostic value of measurable residual disease (MRD) assessment by WT1 gene and multiparameter flow cytometry (MFC). Our results showed that the average expression level of WT1 was 4026 ± 616.1 copies/104 ABL at diagnosis, 155.3 ± 36.03 copies/104 ABL at CR, and 1766 ± 238.8 copies/104 ABL at relapse, with statistically significant differences (p = .000). ROC analysis showed that WT1 expression levels were 118.1 copies/104 ABL and MFC-MRD was 0.155%, which had good predictive efficacy for relapse of patients during consolidation therapy. Both WT1-MRD and MFC-MRD had a significant impact on relapse-free survival (RFS) and overall survival (OS). Patients with WT1-MRD positive or MFC-MRD positive were associated with worse RFS (HR 3.840, 95% CI 1.582-9.320, p = .003), (HR 4.464, 95% CI 1.841-10.984, p = .001) and worse OS (HR 2.963, 95% CI 1.058-8.295, p = .039), (HR 3.590, 95% CI 1.254-10.280, p = .017). Besides, compared with patients who were negative for both WT1-MRD and MFC-MRD, patients who were positive both WT1-MRD and MFC-MRD were associated with worse RFS (HR 6.200, 95% CI 2.206-17.430, p = .001) and worse OS (HR 4.886, 95% CI 1.388-17.197, p = .013). This study demonstrates that combined assessment of MRD by WT1 and MFC improves relapse and prognosis prediction in non-APL AML patients, and may help guide interventions for disease relapse.

Prognostic value of the WT-1 gene combined with recurrent cytogenetic genes in acute myeloid leukemia

Wilms tumor gene 1 (WT-1 gene) is overexpressed in most patients with acute myeloid leukemia (AML) and is an indicator for minimal residual disease (MRD) monitoring, but because the WT-1 gene has relatively low specificity, further studies of the prognostic value of a combination of the WT-1 and other genes are needed. The aim of this study was to explore the prognostic value of the WT-1 gene combined with recurrent cytogenetic genes in AML. In AML, the transcript expression of the WT-1 gene was closely related to leukemic tumor burden and acted as an accurate molecular indicator for MRD detection. Most patients with low expression levels of the WT-1 gene after induction and consolidation therapy were significantly associated with favorable relapse-free survival (RFS) and overall survival (OS), but 17.6% of patients relapsed and died of primary disease. However, when analyzing the WT-1 gene combined with recurrent cytogenetic genes, none of the patients with low expression levels of the WT-1 gene and recurrent cytogenetic genes negative relapsed and died in the median follow-up time of 19 months (range: 3-94 months). Thus, the combination of the WT-1 gene and recurrent cytogenetic genes is a more accurate indicator for MRD monitoring and prognosis evaluation in AML patients.

Measurable residual disease study through three different methods can anticipate relapse and guide pre-emptive therapy in childhood acute myeloid leukemia

PURPOSE

Although outcomes of children with acute myeloid leukemia (AML) have improved over the last decades, around one-third of patients relapse. Measurable (or minimal) residual disease (MRD) monitoring may guide therapy adjustments or pre-emptive treatments before overt hematological relapse.

METHODS

In this study, we review 297 bone marrow samples from 20 real-life pediatric AML patients using three MRD monitoring methods: multiparametric flow cytometry (MFC), fluorescent in situ hybridization (FISH) and polymerase chain reaction (PCR).

RESULTS

Patients showed a 3-year overall survival of 73% and a 3-year event-free survival of 68%. Global relapse rate was of 25%. All relapses were preceded by the reappearance of MRD detection by: (1) MFC (p = 0.001), (2) PCR and/or FISH in patients with an identifiable chromosomal translocation (p = 0.03) and/or (3) one log increase of Wilms tumor gene 1 (WT1) expression in two consecutive samples (p = 0.02). The median times from MRD detection to relapse were 26, 111, and 140 days for MFC, specific PCR and FISH, and a one log increment of WT1, respectively.

CONCLUSIONS

MFC, FISH and PCR are complementary methods that can anticipate relapse of childhood AML by weeks to several months. However, in our series, pre-emptive therapies were not able to prevent disease progression. Therefore, more sensitive MRD monitoring methods that further anticipate relapse and more effective pre-emptive therapies are needed.

Peripheral blood marker of residual acute leukemia after hematopoietic cell transplantation using multi-plex digital droplet PCR

Background

Relapse remains the primary cause of death after hematopoietic cell transplantation (HCT) for acute leukemia. The ability to identify minimal/measurable residual disease (MRD) via the blood could identify patients earlier when immunologic interventions may be more successful. We evaluated a new test that could quantify blood tumor mRNA as leukemia MRD surveillance using droplet digital PCR (ddPCR).

Methods

The multiplex ddPCR assay was developed using tumor cell lines positive for the tumor associated antigens (TAA: WT1, PRAME, BIRC5), with homeostatic ABL1. On IRB-approved protocols, RNA was isolated from mononuclear cells from acute leukemia patients after HCT (n = 31 subjects; n = 91 specimens) and healthy donors (n = 20). ddPCR simultaneously quantitated mRNA expression of WT1, PRAME, BIRC5, and ABL1 and the TAA/ABL1 blood ratio was measured in patients with and without active leukemia after HCT.

Results

Tumor cell lines confirmed quantitation of TAAs. In patients with active acute leukemia after HCT (MRD+ or relapse; n=19), the blood levels of WT1/ABL1, PRAME/ABL1, and BIRC5/ABL1 exceeded healthy donors (p<0.0001, p=0.0286, and p=0.0064 respectively). Active disease status was associated with TAA positivity (1+ TAA vs 0 TAA) with an odds ratio=10.67, (p=0.0070, 95% confidence interval 1.91 - 59.62). The area under the curve is 0.7544. Changes in ddPCR correlated with disease response captured on standard of care tests, accurately denoting positive or negative disease burden in 15/16 (95%). Of patients with MRD+ or relapsed leukemia after HCT, 84% were positive for at least one TAA/ABL1 in the peripheral blood. In summary, we have developed a new method for blood MRD monitoring of leukemia after HCT and present preliminary data that the TAA/ABL1 ratio may may serve as a novel surrogate biomarker for relapse of acute leukemia after HCT.

WT1 Gene Expression in Peripheral Blood Before and After Allogeneic Stem Cell Transplantation is a Clinically Relevant Prognostic Marker in AML - A Single-center 14-year Experience

BACKGROUND

This work summarizes our experience with WT1 monitoring before and after allogeneic hematopoietic stem cell transplantation (allo-HSCT).

PATIENTS AND METHODS

The expression of WT1 gene was measured by real-time polymerase chain reaction in peripheral blood according to the European Leukemia Net recommendations. Between May 2005 and August 2019, we analyzed 147 consecutive patients with acute myeloid leukemia with high WT1 expression at diagnosis, transplanted in first (CR1) or second (CR2) complete remission.

RESULTS

At the time of allo-HSCT, 107 patients had WT1-normal expression (WT1 ≤ 50 copies), and 40 patients had WT1-high expression. The median follow-up was 21 months. The estimated 5-year overall survival and event-free survival was significantly better in the WT1-normal cohort (65% and 57% vs. 37% and 25%; P = .0003 and P < .0001, respectively) and 5-year cumulative incidence of relapse was significantly lower in the WT1-normal group (19% vs. 53%; P < .0001). Five-year non-relapse mortality was not significantly different (20% and 23%). Multivariate analysis revealed WT1-high expression and acute graft-versus-host disease grade 3/4 as significantly negative prognostic factors for OS. Overall, 49 patients developed WT1 molecular relapse in the post-transplant period; in 14 cases, the therapeutic intervention was done. In all but 1 relapsed patient where WT1 minimal residual disease (MRD) was monitored (38 patients), we detected WT1-high levels (sensitivity of 97%).

CONCLUSION

The results of the analysis confirmed our previous experience that WT1 status before allo-HSCT is a strong prognostic factor for both OS and relapse risk. In addition, we confirmed the usefulness of this marker for MRD monitoring after allo-HSCT. The main advantage is the possibility of frequent MRD monitoring in peripheral blood and early bone marrow examination based on WT1-high expression.

WT1 Expression in Peripheral Blood at Diagnosis and During the Course of Early Consolidation Treatment Correlates With Survival in Patients With Intermediate and Poor-Risk Acute Myeloid Leukemia

BACKGROUND

Up to 55% of non-APL acute myeloid leukemias (AML) lack a molecular target suitable for standardized disease monitoring. We aimed to evaluate the prognostic significance of WT1 gene expression at early stages of intensive treatment.

PATIENTS AND METHODS

A total of 106 consecutive patients with intermediate and high-risk AML who had WT1 expression at diagnosis >500 copies/10⁴ABL and who achieved remission after 1 to 2 cycles of induction treatment were analyzed. WT1 expression was measured in peripheral blood using a standardized European LeukemiaNet method. Overexpression was defined as >50 copies/10⁴ABL. The median follow-up was 30 months.

RESULTS

Patients with normal versus high WT1 expression after 2 cycles of chemotherapy had overall survival (OS) at 3 years of 66% versus 41% (P = .01); event-free survival (EFS) 45% versus 22% (P = .01). Prognostic significance of WT1 expression after 2 cycles of treatment was maintained in the group of patients treated with chemotherapy alone without hematopoietic stem cell transplantation in first line treatment (OS 70% vs. 36%, P = .02; EFS 35% vs. 0%, P = .03). Significant prognostic factors for EFS on multivariate analysis were the achievement of molecular remission (<50 copies of WT1) at any time during treatment (hazard ratio [HR] 0.47, P = .04) and increased WT1 expression after 2 cycles of chemotherapy (HR 2.0, P = .03).

CONCLUSION

Increased WT1 expression after 2 cycles of chemotherapy is a negative prognostic factor for survival. WT1 remains a valuable molecular marker in AML without any leukemia-specific mutation, especially if next generation sequencing and/or digital polymerase chain reaction are not routinely available.

Wilms' tumor 1 gene in hematopoietic malignancies: clinical implications and future directions

The Wilms' tumor 1 (WT1) gene is an important regulatory molecule that plays a vital role in cell growth and development. Initially, knowledge of WT1 was mostly limited to Wilms' tumor. Over the past years, numerous studies have shown that WT1 is aberrant expressed or mutated in hematopoietic malignancies, including acute leukemia (AL), myelodysplastic syndrome (MDS) and chronic myelogenous leukemia (CML). Currently, many studies focus on exploring the role of WT1 in hematopoietic malignancies. Such studies improve the understanding of hematopoietic malignancies, and the collection of data about WT1 expression or mutation in hematopoietic malignancies over the past years can facilitate the risk stratification of hematopoietic malignancies. In this review, we highlight the important role of WT1 in hematopoietic malignancies, discuss its potential clinical applications as a minimal residual disease (MRD) and prognostic biomarker, and evaluate the possible therapy target of WT1 in hematopoietic malignancies.

Dynamic changes in the level of WT1 as an MRD marker to predict the therapeutic outcome of patients with AML with and without allogeneic stem cell transplantation

Monitoring minimal residue disease (MRD) is an effective approach to evaluate the response to chemotherapy, and it is used to select the ideal therapeutic strategy and to predict the recurrence during therapy for hematological disorders. The Wilm's tumor 1 (WT1) gene, which is highly expressed in >80% of patients with acute myeloid leukemia (AML) and its increased expression level may cause poor clinical outcomes, is a potential MRD marker of hematological neoplasms. In the present study, the expression levels of WT1 and other molecular markers were retrospectively analyzed by reverse transcription‑quantitative PCR in 195 patients with AML. The expression level of WT1 was significantly lower in patients with remission compared with patients with early‑stage and recurrent AML. Moreover, WT1 expression was significantly decreased in patients with RUNX family transcription factor 1‑RUNX1 translocation partner 1 fusion, but higher in patients with promyelocytic leukemia‑retinoic acid receptor α fusion. WT1 expression was significantly reduced during remission. In patients with AML who underwent allogeneic hematopoietic stem cell transplantation (allo‑HSCT), the mortality rate 2 years after allo‑HSCT was significantly lower in patients with low expression level of WT1 compared with subjects presenting high expression level of WT1. Collectively, the upregulation of the expression level of WT1 in combination with the identification of other genetic abnormalities may be used as MRD markers of hematological neoplasms.