Clinical usefulness of WT1 mRNA expression in bone marrow detected by a new WT1 mRNA assay kit for monitoring acute myeloid leukemia: a comparison with expression of WT1 mRNA in peripheral blood

WT1-guided pre-emptive therapy after allogeneic hematopoietic stem cell transplantation in patients with acute myeloid leukemia

Measurable residual disease (MRD)-guided pre-emptive therapies are now widely used to prevent post-transplant hematological relapse in patients with acute myeloid leukemia (AML). This single-center retrospective study aimed to clarify the significance of pre-emptive treatment based on Wilms' tumor gene-1 mRNA (WT1) monitoring for MRD in patients with AML who underwent allogeneic hematopoietic stem cell transplantation (allo-HSCT). Patients with AML who received chemotherapy for hematological relapse or WT1 increase after allo-HSCT were eligible for inclusion. From January 2017 to June 2022, 30 patients with a median age of 57 (16-70) years were included and stratified into two groups: 10 with WT1 increase and 20 with hematological relapse. The median times from HCT to WT1 increase or hematological relapse were 309 days (range: 48-985) or 242 days (range: 67-1116), respectively. Less intensive chemotherapy using azacitidine or cytarabine was selected for all patients with WT1 increase and 12 (60%) with hematological relapse. The 1-year overall survival and event-free survival rates for WT1 increase and hematological relapse were 70% vs. 44% (P = 0.024) and 70% vs. 29% (P = 0.029), respectively. These real-world data suggest that WT1-guided pre-emptive therapy may be superior to therapy after hematological relapse in patients with AML who have undergone allo-HSCT.

Dynamic Relapse Prediction by Peripheral Blood WT1mRNA after Allogeneic Hematopoietic Cell Transplantation for Myeloid Neoplasms

Although various relapse prediction models based on pretransplant information have been reported, they cannot update the predictive probability considering post-transplant patient status. Therefore, these models are not appropriate for deciding on treatment adjustment and preemptive intervention during post-transplant follow-up. A dynamic prediction model can update the predictive probability by considering the information obtained during follow-up. This study aimed to develop and assess a dynamic relapse prediction model after allogeneic hematopoietic cell transplantation (allo-HCT) for acute myeloid leukemia (AML) and myelodysplastic syndrome (MDS) using peripheral blood Wilms' tumor 1 messenger RNA (WT1mRNA). We retrospectively analyzed patients with AML or MDS who underwent allo-HCT at our institution. To develop dynamic models, we employed the landmarking supermodel approach, using age, refined disease risk index, conditioning intensity, and number of transplantations as pretransplant covariates and both pre- and post-transplant peripheral blood WT1mRNA levels as time-dependent covariates. Finally, we compared the predictive performances of the conventional and dynamic models by area under the time-dependent receiver operating characteristic curves. A total of 238 allo-HCT cases were included in this study. The dynamic model that considered all pretransplant WT1mRNA levels and their kinetics showed superior predictive performance compared to models that considered only pretransplant covariates or factored in both pretransplant covariates and post-transplant WT1mRNA levels without their kinetics; their time-dependent areas under the curve were 0.89, 0.73, and 0.87, respectively. The predictive probability of relapse increased gradually from approximately 90 days before relapse. Furthermore, we developed a web application to make our model user-friendly. This model facilitates real-time, highly accurate, and personalized relapse prediction at any time point after allo-HCT. This will aid decision-making during post-transplant follow-up by offering objective relapse forecasts for physicians.

Quantitative Assessment of Bone Marrow Activity Using 18 F-FLT PET in Aplastic Anemia and Myelodysplastic Syndromes

PURPOSE

Peripheral cytopenias are typical of blood test abnormalities associated with a variety of conditions, including aplastic anemia (AA) and myelodysplastic syndromes (MDSs). We prospectively investigated the feasibility of quantitative analysis of whole-body bone marrow activity using PET with 3'-deoxy-3'- 18 F-fluorothymidine ( 18 F-FLT) in AA and MDS.

PATIENTS AND METHODS

Sixty-eight patients with cytopenia underwent 18 F-FLT PET/MRI scan, with simultaneous bone marrow aspiration and biopsy for hematopoiesis evaluation. SUVs were measured in the vertebrae (Th3, 6, and 9 and L3), bilateral iliac crests, and extremities. SUV and bone marrow pathology were compared between AA and MDS and analyzed in relation to severity of AA and prognosis of MDS.

RESULTS

Of the 68 patients with cytopenia, 12 were diagnosed with AA, 27 with MDS, 12 with bone marrow neoplasia, 2 with myelofibrosis, and 15 with other conditions. Iliac 18 F-FLT SUVs were significantly correlated with bone marrow cell numbers and cell density ( r = 0.47, P < 0.001 and ρ = 0.65, P < 0.001, respectively). There was a significant positive correlation between iliac and vertebral SUVs in AA and MDS ( r = 0.65, P < 0.05 and r = 0.70, P < 0.001, respectively), and the slope of the regression line was significantly steeper in AA than in MDS ( P < 0.05). In AA patients, vertebral 18 F-FLT SUVs significantly decreased with disease progression, and in MDS patients, higher whole-body 18 F-FLT uptake was associated with shorter overall survival (hazards ratio, 3.18; 95% confidence interval, 1.07-9.47; P = 0.037).

CONCLUSIONS

Quantitative whole-body bone marrow imaging using 18 F-FLT PET helps distinguish AA from MDS and assess the severity of AA and prognosis of MDS.

Frequency and clinical impact of WT1 mutations in the context of CEBPA-mutated acute myeloid leukemia

INTRODUCTION

Several studies have confirmed that mutations in the Wilms tumor 1 (WT1) gene occur in adult acute myeloid leukemia (AML). However, few data are available regarding the incidence of WT1 mutations in CEBPA^mut AML and their impact.

METHODS

We retrospectively analyzed the frequency and clinical impact of WT1 mutations in 220 newly diagnosed AML patients with CEBPA mutations(CEBPA^mut). Chromosome karyotype analysis was performed by R or G banding method and further confirmed either by fluorescence in situ hybridization (FISH) and/or by multiple reverse transcription polymerase chain reaction (multiple RT-PCR). Mutations were detected with a panel of 112mutational genes using next-generation sequencing (NGS).

RESULTS

Overall, 30 WT1 mutations were detected in 29 of the 220 CEBPA^mut AML patients (13.18%) screened. These mutations clustered overwhelmingly in exon 7 (n=16). WT1 mutations were found to be significantly more frequent in AML patients with double-mutated CEBPA (CEBPA^dm) than in AML patients with single-mutated CEBPA (17.36%vs. 8.08%, P = 0.043). Among WT1-mutated patients, the most common co-mutation was FLT3-ITD (n = 7, 24.14%), followed by NRAS (n = 5, 17.24%), CSF3R (n = 4, 13.79%), GATA2 (n = 4, 13.79%), and KIT (n = 4, 13.79%). The most frequent functional pathway was signaling pathways inas many as 62.07% of cases. Notably,the concomitant mutations in epigenetic regulatorswere inversely correlated with WT1 mutations(P = 0.003). CEBPA^dm AML patients with WT1 mutations had inferior relapse-free survival, event-free survival and overall survival compared with patients CEBPA^dm AML without WT1 mutations (P = 0.002, 0.004, and 0.010, respectively).

CONCLUSION

Our data showed that WT1 mutations are frequently identified in CEBPA^mut AML, especially in CEBPA^dm AML. CEBPA^mut AML patients with WT1 mutations show distinct spectrum of comutations. In the context of CEBPA^dm AML, WT1 mutations predict a poor prognosis.

Possible prognostic impact of WT1 mRNA expression at day + 30 after haploidentical peripheral blood stem cell transplantation with posttransplant cyclophosphamide for patients with myeloid neoplasm: a multicenter study from the Okayama Hematological Study Group

BACKGROUND

Previous studies have revealed that relapse of myeloid neoplasms after allogeneic hematopoietic stem cell transplantation (allo-HSCT) could be predicted by monitoring Wilms' tumor 1 (WT1) mRNA expression. However, only a few studies have investigated patients who received human leukocyte antigen-haploidentical stem cell transplantation with posttransplant cyclophosphamide (PTCY-haplo). In this study, we investigated the relationship between WT1 mRNA levels and clinical outcomes in the PTCY-haplo group, and compared them with those in the conventional graft-versus-host disease prophylaxis group (conventional group).

METHODS

We retrospectively analyzed 130 patients who received their first allo-HSCT between April 2017 and December 2020, including 26 who received PTCY-haplo.

RESULTS

The WT1 mRNA expression level at day + 30 after allo-HSCT associated with increased risk of 1-year cumulative incidence of relapse (CIR) was ≥ 78 copies/μg RNA in the conventional group (p < 0.01) and ≥ 50 copies/μg RNA in the PTCY-haplo group (p = 0.03).

CONCLUSIONS

The appropriate cutoff level of WT1 mRNA at day + 30 after allo-HSCT for predicting prognosis in patients treated with PTCY-haplo may be < 50 copies/μg RNA.

Minimal residual disease in high-risk neuroblastoma shows a dynamic and disease burden-dependent correlation between bone marrow and peripheral blood

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Bone marrow is the most frequent site of metastasis and relapse for neuroblastoma.

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Minimal residual disease has been identified in bone marrow and peripheral blood (BM-MRD and PB-MRD) by quantifying several sets of neuroblastoma-associated mRNAs.

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BM-MRD has significant prognostic information for high-risk neuroblastoma.

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BM-MRD and PB-MRD show a dynamic and disease burden-dependent correlation in high-risk neuroblastoma.

Neuroblastoma (NB) is the most common extracranial solid tumor in children and originates from sympathoadrenal or Schwann cell precursors derived from neural crest. These neural crest derivatives also constitute the hematopoietic and mesenchymal stem cells in bone marrow (BM) that is the most frequent site of NB metastasis and relapse. In NB patients, NB cells have been pathologically detected in BM and peripheral blood (PB), and minimal residual disease (MRD) in BM and PB (BM-MRD and PB-MRD) can be monitored by quantitating several sets of NB-associated mRNAs (NB-mRNAs). Although previous studies have shown varying degrees of correlation between BM-MRD and PB-MRD, the underlying factors and/or mechanisms remains unknown. In the present study, we determined the levels of BM-MRD and PB-MRD by quantitating seven NB-mRNAs in 133 pairs of concurrently collected BM and PB samples from 19 high-risk NB patients with clinical disease evaluation, and examined their correlation in overall and subgroups of sample pairs. The levels of BM-MRD and PB-MRD were moderately (r = 0.418, p < 0.001) correlated with each other in overall sample pairs. The correlation became strong (r = 0.725, p < 0.001), weak (r = 0.284, p = 0.008), and insignificant (p = 0.194) in progression, stable, and remission subgroups of sample pairs, respectively. It also became stronger in subgroups of sample pairs with poor treatment responses and poor prognostic factors. Present study suggests that MRD in high-risk NB shows a dynamic and disease burden-dependent correlation between BM and PB.

Prognostic impact of peripheral blood Wilms' tumour 1 mRNA expression levels in response to azacytidine in MDS: A single-centre analysis

To determine the impact of peripheral blood (PB) Wilms' tumour 1 (WT-1) mRNA levels in patients with primary myelodysplastic syndromes (MDS), we analysed the relationships between several clinical variables at the time of diagnosis and the haematological response of patients treated with azacytidine. We observed overall responses in 20 (63%) patients; there were no significant differences in clinical variables, including bone marrow blast counts, IPSS scores and IPSS-R risk scores, between responders and non-responders. The responders' PB WT-1 mRNA levels were significantly lower than those of non-responders (P = 0.03). PB WT-1 mRNA expression could be a marker for predicting the response to azacytidine in patients with de novo MDS.

The Proportional Relationship Between Pretransplant WT1 mRNA Levels and Risk of Mortality After Allogeneic Hematopoietic Cell Transplantation in Acute Myeloid Leukemia Not in Remission

BACKGROUND

The relationship between the expression levels of Wilms' tumor-1 gene (WT1) mRNA in peripheral blood before allogeneic hematopoietic cell transplantation (allo-HCT) and risk of mortality in acute myeloid leukemia (AML) patients in noncomplete remission (non-CR) remains quite elusive.

METHODS

We retrospectively assessed the impact of the pretransplant WT1 mRNA level on survival after allo-HCT in non-CR AML patients.

RESULTS

A total of 125 AML patients, including 46 non-CR patients (36.8%), were analyzed. On multivariate analysis of non-CR AML patients, WT1 mRNA ≥5000 copies/μg RNA was significantly related to increased risk of mortality (hazard ratio, 2.7; 95% confidence interval, 1.3-5.5; P = 0.008). Furthermore, in the entire cohort, log10-transformed WT1 mRNA before allo-HCT was found to be significantly associated with the increased risk of mortality irrespective of whether the disease status was CR or non-CR, using Akaike's information criterion. As the pretransplant WT1 mRNA level elevated, the hazard ratio of mortality monotonically increased in a nonlinear manner regardless of remission status, suggesting that WT1 mRNA level in peripheral blood might reflect tumor burden.

CONCLUSIONS

This study demonstrated that the pretransplant WT1 mRNA level was a powerful prognostic factor in allo-HCT even for non-CR AML patients, and there may be a WT1 mRNA threshold in non-CR patients for benefiting from allo-HCT.

Outcomes of Measurable Residual Disease in Pediatric Acute Myeloid Leukemia before and after Hematopoietic Stem Cell Transplant: Validation of Difference from Normal Flow Cytometry with Chimerism Studies and Wilms Tumor 1 Gene Expression

We enrolled 150 patients in a prospective multicenter study of children with acute myeloid leukemia undergoing hematopoietic stem cell transplantation (HSCT) to compare the detection of measurable residual disease (MRD) by a "difference from normal" flow cytometry (ΔN) approach with assessment of Wilms tumor 1 (WT1) gene expression without access to the diagnostic specimen. Prospective analysis of the specimens using this approach showed that 23% of patients screened for HSCT had detectable residual disease by ΔN (.04% to 53%). Of those patients who proceeded to transplant as being in morphologic remission, 10 had detectable disease (.04% to 14%) by ΔN. The disease-free survival of this group was 10% (0 to 35%) compared with 55% (46% to 64%, P < .001) for those without disease. The ΔN assay was validated using the post-HSCT specimen by sorting abnormal or suspicious cells to confirm recipient or donor origin by chimerism studies. All 15 patients who had confirmation of tumor detection relapsed, whereas the 2 patients with suspicious phenotype cells lacking this confirmation did not. The phenotype of the relapse specimen was then used retrospectively to assess the pre-HSCT specimen, allowing identification of additional samples with low levels of MRD involvement that were previously undetected. Quantitative assessment of WT1 gene expression was not predictive of relapse or other outcomes in either pre- or post-transplant specimens. MRD detected by ΔN was highly specific, but did not identify most relapsing patients. The application of the assay was limited by poor quality among one-third of the specimens and lack of a diagnostic phenotype for comparison.

Monitoring of fusion gene transcripts to predict relapse in pediatric acute myeloid leukemia

BACKGROUND

In acute myeloid leukemia (AML), accurate detection of minimal residual disease (MRD) enables better risk-stratified therapy. There are few studies, however, on the monitoring of multiple fusion transcripts and evaluation of their accuracy as indicators of MRD at multiple time points.

METHODS

We retrospectively examined RNA obtained from 82 pediatric AML patients enrolled in the Japanese Pediatric Leukemia/Lymphoma Study Group (JPLSG) AML-05 study. The expression of six important fusion transcripts (AML1(RUNX1)-ETO, CBFB-MYH11, MLL(KMT2A)-AF9, MLL-ELL, MLL-AF6, and FUS-ERG) was analyzed at five time points 30-40 days apart following diagnosis.

RESULTS

In patients with AML1-ETO (n = 36 at time point 5), all six patients with >3,000 copies and four of 30 patients with ≤3,000 copies relapsed. AML1-ETO transcripts persisted during treatment even in patients without relapse, as well as CBFB-MYH11 transcripts. In contrast, in patients with MLL-AF9 (n = 9 at time point 5), two patients were positive for MLL-AF9 expression (>50 copies) and both relapsed. Only one of seven MLL-AF9-negative patients relapsed. In the AML1-ETO group, MRD-positive patients (>3,000 copies at time point 5) had significantly lower relapse-free survival (RFS; P < 0.0001) and overall survival (OS; P = 0.009) than MRD-negative patients. Similarly, in the MLL-AF9 group, MRD-positive patients (>50 copies at time point 5) had significantly lower RFS (P = 0.002) and OS (P = 0.002) than MRD-negative patients.

CONCLUSIONS

Detection of MLL-AF9 transcripts on real-time quantitative polymerase chain reaction is a promising marker of relapse in pediatric AML. In contrast, the clinical utility of detecting AML1-ETO and CBFB-MYH11 expression is limited, although higher AML1-ETO expression can be a potential predictor of relapse when assessed according to an optimal threshold.

[Prediction of outcome in acute myeloid leukemia by measurement of WT1 expression as a basic marker of minimal residual disease]

Objective: To probe the potential utility of Wilms tumor 1 (WT1) as a marker of minimal residual disease (MRD) in acute myeloid leukemia (AML) to estimate the relapse-predicting cut-off value. Methods: Quantitative assessment of bone marrow WT1 mRNA level was preformed using real-time quantitative reverse transcription polymerase chain reaction (RQ-RT-PCR) assay. The expression levels of WT1 dynamically measured with RQ-RT-PCR were retrospectively analyzed in 121 AML cases (not including acute promyelocytic leukemia) achieving complete remission (CR) after induction therapy followed by consolidation therapy. By comparing WT1 levels of patients with different post-therapy outcomes, the investigators used the receiver operating characteristic (ROC) curve to determine WT1 threshold so as to predict their clinical relapses. Then prognoses and the significance of intervention were analyzed between WT1 positive and negative patients according to the cut-off value of WT1. Results: According to ROC curve, WT1 level higher than 2.98% predicted the possibility of relapse. For simplicity and clinical application, 3.00% was used as the cut-off value of WT1 level for relapse. WT1 levels in 41 patients at diagnosis were detected, meanwhile 3 patients whose WT1 levels at diagnosis below 3.00% were excluded, then the median WT1 level of the rest 38 patients at diagnosis was 44.09% (range 7.19%-188.06%) . The median WT1 level in remission was 0.48% (352 samples, range 0-8.41%) . The median WT1 level at diagnosis was higher than that in remission. Excluding the 3 patients with WT1 level at diagnosis under 3.00%, the relapse rate of WT1 positive group (>3.00% during consolidation phase and follow-up) and WT1 negative group (≤3.00%) was 70.0% (14/20) and 12.2% (12/98) respectively (P<0.001) . The median time from WT1 positivity to clinical relapse was 58 days. Conclusions: WT1 expression level above 3.00% was associated with markedly high risk of relapse, which could be as a useful marker for monitoring MRD following consolidation therapy.

Enhancing acute myeloid leukemia therapy - monitoring response using residual disease testing as a guide to therapeutic decision-making

INTRODUCTION

Current standards for monitoring the response of acute myeloid leukemia (AML) are based on morphologic assessments of the bone marrow and recovery of peripheral blood counts. A growing experience is being developed to enhance the detection of small amounts of AML, or minimal residual disease (MRD). Areas covered: Available techniques include multi-color flow cytometry (MFC) of leukemia associated immunophenotypes (LAIP), quantitative reverse transcriptase polymerase chain reaction (QRT-PCR) for detecting fusion and mutated genes (RUNX1-RUNX1T1, CBFB-MYH11, and NPM1), overexpression of genes such as WT1, and next generation sequencing (NGS) for MRD. Expert commentary: While MRD monitoring is standard of care in some leukemia subsets such as acute promyelocytic leukemia, this approach for the broader AML population does not universally predict outcomes as some patients may experience relapse in the setting of undetectable leukemia while others show no obvious disease progression despite MRD positivity. However, there are instances where MRD can identify patients at increased risk for relapse that may change recommended therapy. Currently, prospective investigations to define clinically relevant MRD thresholds are ongoing. Risk-adapted trials are needed to best define the use of MRD in the follow up of AML patients after initial induction therapy.

ESSENTIALS OF THE MOLECuLAR DIAGNOSIS OF ONCOHEMATOLOGICAL DISEASES

Molecular genetic and molecular biology methods enable one to reveal pathogenetic basis of oncohematological diseases, they are particular useful for diagnostic purpouses, to control and evaluate treatment efficiency. In leukemia patients there are two different types of chromosomal anomalities: some of them give rise for chimeric oncogenes, others activate hyperexpression of regulatory genes. It is necessary to take into account this difference in order to proparely develop molecular genetic tests. Molecular tests are more sensitive to compare with other approaches, due to this fact they are especially useful to monitor residual leukemia cells and for early detection of relapse.

[Expression of WT1 gene in children with acute myeloid leukemia]

OBJECTIVE

To study WT1 gene expression in children with acute myeloid leukemia (AML) and its possible correlations to clinical outcomes.

METHODS

Bone marrow samples were collected from 45 children with AML (excluding acute promyelocytic leukemia, AML-M3) at different time points of AML treatment and follow-up. WT1 gene expression levels in bone marrow mononuclear cells were assayed by real-time fluorescence quantitative PCR. The correlation between WT1 expression and prognosis was retrospectively analyzed.

RESULTS

The WT1 expression level in AML children with bone marrow blast cell percentage of >60% was significantly higher than in those with bone marrow blast cell percentage of ≤ 60% (p<0.05). The lower WT1 expression level was documented in children with AML-M2 compared with in children with other non-M2 subtypes (p<0.05). WT1 expression level in patients in complete remission was significantly lower than that in patients at diagnosis or relapse (p<0.01). The 2-year disease-free survival (DFS) in patients with higher WT1 expression was significantly lower than in those with lower WT1 expression at the end of induction chemotherapy (p<0.05). The 2-year overall survival (OS) and DFS in patients with ≥1 log WT1 reduction range were significantly higher than those with <1 log reduction of WT1 expression level at the end of induction chemotherapy (p<0.05). WT1 expression levels tended to rise 2-3 months prior to bone marrow relapse.

CONCLUSIONS

WT1 expression level is closely correlated prognosis in children with AML. Dynamic monitoring of WT1 expression level is of great clinical importance in terms of individualized management, prognosis evaluation and relapse prediction.