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.

Analysis of pre-chemotherapy WBC, PLT, monocyte, hemoglobin, and MPV levels in acute myeloid leukemia patients with WT1, FLT3, or NPM gene mutations

Effects of mutations on AML (acute myeloid leukemia) patients have been an area of clinical interest. The aim of this study was to analyze pre-chemotherapy WBC (white blood cell), platelet, monocyte, hemoglobin, and mean platelet volume (MPV) levels in acute myeloid leukemia patients with Wilms tumor 1 (WT1), FMS-like tyrosine kinase 3 (FLT3), or nucleophosmin (NPM) gene mutations, attempting to detect and compare possible differences in these values.The study included 71 patients with acute myeloid leukemia known to have WT1, FLT3, or NPM gene mutations. The patients were divided into 3 groups: FLT3-mutated AML patients without any accompanying known mutations other than WT1 at the time of diagnosis (Group 1), NPM-mutated AML patients without any accompanying known mutations other than WT1 at the time of diagnosis (Group 2), WT1-mutated AML patients with no other accompanying known mutations at the time of diagnosis (Group 3). We carried out intergroup comparisons of WBC, platelet (PLT), monocyte, hemoglobin, and MPV levels before chemotherapy.There was a statistically significant difference between the groups in terms of WBC parameters (P = .001). There were no statistically significant differences between the groups with respect to hemoglobin, platelet, and monocyte levels.Higher white blood cell counts could be observed in patients with FLT3-mutated AML.

Prognostic impact of peripheral blood WT1-mRNA expression in patients with MDS

Few reports suggested a prognostic impact of Wilms'Tumor-1 (WT1)-mRNA overexpression in MDS, but translation into clinical routine was hampered by limited patients numbers, differing sample sources, non-standardized methods/cut-offs. To evaluate whether WT1-mRNA expression yields additional prognostic information, we measured peripheral blood (PB) WT1-mRNA expression in 94 MDS using a standardized assay offering a validated cut-off to discriminate between normal and WT1-mRNA overexpression. Overall, 54 patients (57%) showed WT1-mRNA overexpression, while 40 patients (43%) had normal WT1-mRNA expression. This enabled discrimination between MDS and both healthy controls and non-MDS cytopenias. Furthermore, WT1-mRNA expression correlated with WHO 2016 subcategories and IPSS-R as indicated by mean WT1-mRNA expression and frequency of WT1-mRNA overexpressing patients within respective subgroups. Regarding the entire group, PB WT1-mRNA expression was associated with prognosis, as those patients showing WT1-mRNA overexpression had higher risk for disease progression and AML transformation and accordingly shorter progression-free, leukemia-free and overall survival in univariate analysis. In multivariate analysis, prognostic impact of PB WT1-mRNA expression status was independent of IPSS-R and enabled more precise prediction of PFS, but not OS, within IPSS-R very low/low and intermediate risk groups. Overall, measuring PB WT1-mRNA appears valuable to support diagnostics and refine prognostication provided by the IPSS-R.

Assessment of WT1 Expression as a Marker of Treatment Outcome in Karyotype Normal Acute Myeloid Leukemia Patients in Pakistan

Currently, there is an effort to predict relapse by follow-up monitoring of MRD and subsequently to begin the treatment of the patients during their clinical and hematological remission prior to overt hematological relapse. Expression of WT1 in AML is known to be independently associated with significant inferior response to therapy and short survival outcome. Follow-up monitoring of WT1 gene expression during or after therapy would be a valuable predictive marker for early recurrence or relapse of AML disease. This pilot study evaluated newly diagnosed and post-induction or consolidation chemotherapy of AML patients who were registered with the Oncology Clinics of the Aga Khan University Hospital, Karachi. High WT1 burden (> 5000 copies/ml) in 2 patients was indicative of early recurrence of the disease along with shorter disease-free and overall survival. Low WT1 expression (< 200 copies/ml) in 2 patients after induction and consolidation therapy, respectively, was suggestive of better prognosis.

A 4-gene expression score associated with high levels of Wilms Tumor-1 (WT1) expression is an adverse prognostic factor in acute myeloid leukaemia

Wilms Tumor-1 (WT1) expression level is implicated in the prognosis of acute myeloid leukaemia (AML). We hypothesized that a gene expression profile associated with WT1 expression levels might be a good surrogate marker. We identified high WT1 gene sets by comparing the gene expression profiles in the highest and lowest quartiles of WT1 expression in two large AML studies. Two high WT1 gene sets were found to be highly correlated in terms of the altered genes and expression profiles. We identified a 17-probe set signature of the high WT1 set as the optimal prognostic predictor in the first AML set, and showed that it was able to predict prognosis in the second AML series after adjustment for European LeukaemiaNet genetic groups. The gene signature also proved to be of prognostic value in a third AML series of 163 samples assessed by RNA sequencing, demonstrating its cross-platform consistency. This led us to derive a 4-gene expression score, which faithfully predicted adverse outcome. In conclusion, a short gene signature associated with high WT1 expression levels and the resultant 4-gene expression score were found to be predictive of adverse prognosis in AML. This study provides new clues to the molecular pathways underlying high WT1 states in leukaemia.

Wilms' tumor-1 transcript in peripheral blood helps diagnose acute myeloid leukemia and myelodysplastic syndrome in patients with pancytopenia

BACKGROUND/AIM

Pancytopenia is caused by acute myeloid leukemia (AML), myelodysplastic syndrome (MDS), aplastic anemia (AA), or by non-hematological diseases. Because Wilms' tumor-1 (WT1) is overexpressed in patients with AML and MDS, its expression level may be helpful for diagnosing these hematological malignancies.

PATIENTS AND METHODS

We retrospectively investigated the WT1 transcripts in peripheral blood (PB) from 47 patients with decreased blood cell counts.

RESULTS

The final diagnoses included AML, MDS, AA, drug poisoning, and non-hematological diseases. PB WT1 mRNA was overexpressed in AML and MDS, whereas the patients with other diseases mostly tested negatively for the transcript. The patients with MDS with higher marrow blast counts had higher PB WT1 mRNA levels. The sensitivity of the PB WT1 transcript in detecting AML and MDS was 78%, and the specificity was 90%.

CONCLUSION

The WT1 mRNA level in PB may help diagnose AML and MDS in patients with pancytopenia.

Identification of a Set of Seven Genes for the Monitoring of Minimal Residual Disease in Pediatric Acute Myeloid Leukemia

BACKGROUND

Monitoring of minimal residual disease (MRD) has become a strong diagnostic tool in acute lymphoblastic leukemia. It is used for risk-adapted therapy and for the recognition of pending relapses. In acute myeloid leukemia (AML), there is still a need for more suitable MRD markers.

EXPERIMENTAL DESIGN

A stepwise approach which combined genome-wide expression profiling, TaqMan low density arrays, and a TaqMan real-time PCR-based screening was used to identify new markers for the monitoring of MRD in AML. Leukemic cells from 52 children with AML and 145 follow-up samples from 25 patients were analyzed.

RESULTS

Seven genes were identified which are vastly overexpressed in many patients with AML compared with healthy bone marrow: CCL23, GAGED2, MSLN, SPAG6, and ST18 as well as the previously described markers WT1 and PRAME. The expression of all genes decreased to normal levels in patients who achieved a continuous complete remission. Elevated levels of at least one gene were found prior to relapse in 7 out of 10 patients who relapsed.

CONCLUSIONS

This set of genes should allow a sensitive and specific monitoring of MRD in AML. Notably, some of these markers could also serve as therapeutic targets or might be involved in leukemogenesis. MSLN is already used as a target for immunotherapy in clinical trials in other malignancies.

Significant correlation between the degree of WT1 expression and the International Prognostic Scoring System Score in patients with myelodysplastic syndromes

PURPOSE

To determine whether pattern of WT1 gene expression is a useful marker for establishing prognosis and tracking disease progression in patients with myelodysplastic syndromes (MDS).

PATIENTS AND METHODS

We performed a quantitative assessment of the WT1 transcript amount by real-time quantitative polymerase chain reaction (RQ-PCR) in 173 samples (131 bone marrow samples and 42 peripheral-blood samples) from 131 patients with MDS (79 patients with refractory anemia [RA], 31 with RA with excess blasts [RAEB], 18 with secondary acute myeloid leukemia [s-AML] evolved from MDS, and three with deletion of 5q as the sole cytogenetic abnormality). Values obtained were correlated with the blast percentage and International Prognostic Scoring System (IPSS) score.

RESULTS

Sixty-five percent of BM and 78% of PB samples for RA and 100% of BM and PB samples of RAEB and s-AML expressed WT1 transcript amounts greater than the level observed in healthy volunteers. The degree of WT1 expression was highly correlated with the type of MDS, was much higher in RAEB and s-AML compared with RA, and increased during disease progression. Moreover, a significant correlation was found between WT1 expression levels, blast cell percentage, and the presence of cytogenetic abnormalities. Therefore, we found a significant correlation between the amount of WT1 transcripts and the IPSS score, which currently represents the most reliable risk index of disease progression available for MDS patients.

CONCLUSION

WT1 is a useful molecular marker for risk assessment in MDS patients.