Wilms tumour gene 1 overexpression in bone marrow as a marker for minimal residual disease in acute myeloid leukaemia

Low WT1 Expression Identifies a Subset of Acute Myeloid Leukemia with a Distinct Genotype

Background: Wilms' tumor gene 1 (WT1) is a critical player in acute myeloid leukemia (AML), often serving as a biomarker for measurable residual disease (MRD). The WT1 gene is overexpressed in the majority of AML cases at diagnosis, with apparently no correlation with prognosis, and in the meantime, its role in patients with low-level expression is still undefined. This study investigates the mutational landscape and clinical outcomes of AML patients with low WT1 expression at diagnosis. Methods: We analyzed 34 AML patients with low WT1 expression (WT1/ABL1 < 250) diagnosed and treated from 2013 to 2017 at three institutions. Next-generation sequencing (NGS) was employed to investigate the mutational status of 32 genes commonly mutated in AML. The presence of specific mutations, as well as clinical outcomes, was compared to the general AML population. Results: Patients with low WT1 expression showed a significantly higher mutational burden, with a median of 3.4 mutations per patient, compared to the general AML population. Notably, clonal hematopoiesis (CHIP) or myelodysplasia-related (MR) mutations, particularly in ASXL1, TET2, and SRSF2, were present in most patients with low WT1 expression. All but one case of NPM1- or FLT3-mutant AML in the low-WT1 cohort harbored more CHIP or MR mutations. Patients with low WT1 expression had an overall survival (OS) that was superimposable to the OS expected in MR AML. Conclusions: Low WT1 expression in AML is associated with a distinct and complex mutational profile, marked by frequent CHIP and MR mutations.

Clinical Outcomes of Early WT1 mRNA Reduction After Remission Induction in Newly Diagnosed Acute Myeloid Leukemia Undergoing Allogeneic Hematopoietic Stem Cell Transplantation

Wilms' Tumor 1 (WT1) mRNA is a non-specific marker of measurable residual disease in acute myeloid leukemia (AML). Few studies have focused on the prognostic value of WT1 mRNA after initial remission induction of patients with AML who have received transplant treatments. Thus, we retrospectively analyzed the clinical features and prognostic impact of WT1 mRNA reduction in patients with AML after initial remission induction at our hospital. We classified the reduction in WT1 mRNA levels using logarithmic stratification, with particular focus on the prognostic impact of a 3-log reduction after initial remission induction. This single-center, retrospective, observational study included 71 consecutive patients with AML who underwent allogeneic hematopoietic stem cell transplantation (allo-HSCT) between April 2013 and June 2023 and had WT1 mRNA quantified. Patients were grouped based on whether a 3-log reduction was observed during follow-up (N=30) or not (N=41). Among patients who did not achieve a 3-log reduction, European Leukemia Net (ELN) 2022 adverse risk was more common, and fewer patients showed complete hematological responses at transplantation. Patients who reached a 3-log reduction in WT1 mRNA after the initial remission induction had significantly longer overall survival (OS) and progression-free survival (PFS) and a lower relapse rate than patients who had not reached a 3-log reduction (2-year OS: 79.7% vs. 27.5%, 2-year PFS: 83.1% vs. 11.7% and 2-year cumulative relapse rate: 5.9% vs. 81.2%). In multivariate analysis, a 3-log reduction in WT1 mRNA after initial remission induction and ELN 2022 adverse risk by genetics were significantly associated with OS and PFS. We identified that patients with AML undergoing HSCT with an early and deep 3-log reduction in WT1 mRNA after initial remission induction were associated with low relapse rates and better long-term prognosis. Our data highlight the importance of WT1 mRNA reduction after initial remission induction.

Use of Wilms Tumor 1 Gene Expression as a Reliable Marker for Prognosis and Minimal Residual Disease Monitoring in Acute Myeloid Leukemia With Normal Karyotype Patients

BACKGROUND

Acute myeloid leukemia with normal karyotype (AML-NK) represents the largest group of AML patients classified with an intermediate prognosis. A constant need exists to introduce new molecular markers for more precise risk stratification and for minimal residual disease (MRD) monitoring.

PATIENTS AND METHODS

Quantitative assessment of Wilms tumor 1 (WT1) gene transcripts was performed using real-time polymerase chain reaction. The bone marrow samples were collected at the diagnosis from 104 AML-NK patients and from 34 of these patients during follow-up or disease relapse.

RESULTS

We found that overexpression of the WT1 gene (WT1^high status), present in 25.5% of patients, was an independent unfavorable factor for achieving complete remission. WT1^high status was also associated with resistance to therapy and shorter disease-free survival and overall survival. Assessment of the log reduction value of WT1 expression, measured in paired diagnosis/complete remission samples, revealed that patients with a log reduction of < 2 had a tendency toward shorter disease-free survival and overall survival and a greater incidence of disease relapse. Combining WT1 gene expression status with NPM1 and FLT3-ITD mutational status, we found that the tumor behavior of intermediate patients (FLT3-ITD^-/NPM1^- double negative) with WT1^high status is almost the same as the tumor behavior of the adverse risk group.

CONCLUSION

WT1 expression status represents a good molecular marker of prognosis, response to treatment, and MRD monitoring. Above all, the usage of the WT1 expression level as an additional marker for more precise risk stratification of AML-NK patients could lead to more adapted, personalized treatment protocols.

Wilms Tumor 1 (WT1) mRNA Expression Level at Diagnosis Is a Significant Prognostic Marker in Elderly Patients with Myelodysplastic Syndrome

BACKGROUND/AIMS

A high expression of Wilms tumor 1 (WT1) mRNA occurs in most cases of acute leukemia and myelodysplastic syndrome (MDS). Although there are many reports suggesting that acute myeloid leukemia patients with high expression levels of WT1 mRNA have a relatively poor long-term survival, there are few reports addressing the relationship between WT1 levels and prognosis in MDS.

METHODS

We retrospectively analyzed 42 elderly patients with MDS whose WT1 levels at diagnosis were available, and we assessed the relationships between WT1 levels in peripheral blood and preexisting prognostic factors such as World Health Organization prognostic scores and Revised International Prognostic Scoring System risk categories, bone marrow blast percentages, and chromosomal abnormalities linked to a poor prognosis. We also evaluated the relationship between WT1 levels and prognosis.

RESULTS

WT1 levels were significantly different between high- and low-risk MDS patients (p < 0.05). There was a trend towards a significant difference between those with and those without poor prognostic chromosomal rearrangements (p = 0.051). Moreover, the overall survival and progression-free survival were significantly worse in elderly patients with higher levels of WT1 (p = 0.00039 and p = 0.00077, respectively).

CONCLUSIONS

The WT1 mRNA expression level at diagnosis may be a significant independent prognostic marker for elderly patients with MDS.

Prognostic significance of diagnosed WT1 level in acute myeloid leukemia: a meta-analysis

The Wilms' tumor 1 (WT1) expression has been recognized in a substantial number of acute myeloid leukemia (AML) patients. Some studies indicated the association of diagnosed WT1 higher expression (WT1(H)) and poor outcome in the AML patients, while other studies had different opinions. Therefore, we performed a meta-analysis to evaluate the controversial prognostic significance of diagnosed WT1(H) in AML. Eligible studies were identified from several databases including PubMed, Embase, Web of Science, and the Cochrane Library (up to September 2014). The primary end point was overall survival (OS) and disease-free survival (DFS) was chosen as secondary end point. If possible, we would pool estimate effects (hazard ratio [HR] with 95 % confidence interval [CI]) of outcomes in both fixed and random effects models. Eleven studies, covering 1497 AML patients, were included in this meta-analysis. Pooled HRs indicated that diagnosed WT1(H) had a poor impact on the survival of AML patients (HR for OS, 1.37; HR for DFS, 1.38). Furthermore, diagnosed WT1(H) appeared to be an adverse prognostic indicator in adult AML (HR for OS, 1.43; HR for DFS, 1.41) and non-promyelocytic AML (non-M3 AML) (HR for OS, 1.46; HR for DFS, 1.41). Diagnosed WT1(H) had slightly but significantly poor prognostic impact on OS and DFS of patients with AML in total population and some specific subgroups.

Adoptive T-cell therapy for Leukemia

Allogeneic stem cell transplantation (alloSCT) is the most robust form of adoptive cellular therapy (ACT) and has been tremendously effective in the treatment of leukemia. It is one of the original forms of cancer immunotherapy and illustrates that lymphocytes can specifically recognize and eliminate aberrant, malignant cells. However, because of the high morbidity and mortality that is associated with alloSCT including graft-versus-host disease (GvHD), refining the anti-leukemia immunity of alloSCT to target distinct antigens that mediate the graft-versus-leukemia (GvL) effect could transform our approach to treating leukemia, and possibly other hematologic malignancies. Over the past few decades, many leukemia antigens have been discovered that can separate malignant cells from normal host cells and render them vulnerable targets. In concert, the field of T-cell engineering has matured to enable transfer of ectopic high-affinity antigen receptors into host or donor cells with greater efficiency and potency. Many preclinical studies have demonstrated that engineered and conventional T-cells can mediate lysis and eradication of leukemia via one or more leukemia antigen targets. This evidence now serves as a foundation for clinical trials that aim to cure leukemia using T-cells. The recent clinical success of anti-CD19 chimeric antigen receptor (CAR) cells for treating patients with acute lymphoblastic leukemia and chronic lymphocytic leukemia displays the potential of this new therapeutic modality. In this review, we discuss some of the most promising leukemia antigens and the novel strategies that have been implemented for adoptive cellular immunotherapy of lymphoid and myeloid leukemias. It is important to summarize the data for ACT of leukemia for physicians in-training and in practice and for investigators who work in this and related fields as there are recent discoveries already being translated to the patient setting and numerous accruing clinical trials. We primarily focus on ACT that has been used in the clinical setting or that is currently undergoing preclinical testing with a foreseeable clinical endpoint.

Minimal residual disease testing to predict relapse following transplant for AML and high-grade myelodysplastic syndromes

Evaluation of: Lange T, Hubmann M, Burkhardt R et al. Monitoring of WT1 expression in PB and CD34(+) donor chimerism of BM predicts early relapse in AML and MDS patients after hematopoietic cell transplantation with reduced-intensity conditioning. Leukemia 25, 498-505 (2011). Early detection of relapse is critical for patients who have undergone hematopoietic stem cell transplantation (HSCT) for acute myeloid leukemia (AML) or high-grade myelodysplastic syndromes (MDS), since therapy can be initiated while disease burden remains low. As these neoplasms represent a heterogeneous group of malignancies with distinct underlying mutations, no single genetic marker exists that both defines AML/MDS and can be exploited for sensitive detection of neoplastic cells prior to overt hematologic relapse. Conversely, the Wilms' tumor gene (WT1) expression level is increased in blasts of most AML/MDS patients, and quantitative analysis of WT1 expression has been used to predict relapse following myeloablative HSCT. In this article, we review a recently published study evaluating the usefulness of multiple markers, including WT1 expression, for predicting relapse in AML/MDS patients following reduced-intensity conditioning nonmyeloablative HSCT.

Persistence of cytogenetic abnormalities at complete remission after induction in patients with acute myeloid leukemia: prognostic significance and the potential role of allogeneic stem-cell transplantation

PURPOSE

To determine the prognostic impact of persistent cytogenetic abnormalities at complete remission (CR) on relapse-free survival (RFS) and overall survival (OS) in patients with acute myeloid leukemia (AML) and to examine the potential role of allogeneic stem-cell transplantation (SCT) in this setting.

PATIENTS AND METHODS

Data from 254 adult patients with AML (excluding acute promyelocytic leukemia) who achieved CR after induction chemotherapy on various first-line protocols were examined.

RESULTS

Median follow-up for surviving patients was 43 months. Patients with cytogenetic abnormalities at CR (n = 71) had significantly shorter RFS (P = .001) and OS (P < .001) compared with patients with normal cytogenetics at CR (n = 183); 3-year RFS was 15% and 45%, and 3-year OS was 15% and 56%, respectively. Among the patients with persistent cytogenetic abnormalities at CR, those who underwent SCT in first CR (CR1; n = 15) had better RFS and OS compared to those without SCT (n = 56; P = .04 and .06, respectively). In multivariate analysis, persistent cytogenetic abnormalities at CR was an independent predictor for RFS (P < .001) and OS (P = .001), but among patients with persistent cytogenetic abnormalities at CR, no significant differences in OS (P = .25) was observed between those who did or did not receive SCT with a trend favoring SCT for RFS (P = .08).

CONCLUSION

Persistent cytogenetically abnormal cells at CR predict a significantly shorter RFS and OS. SCT in CR1 may improve the clinical outcome of patients lacking cytogenetic remission after induction although this depends on patient selection.

Expression and distribution of PPP2R5C gene in leukemia

BACKGROUND

Recently, we clarified at the molecular level novel chromosomal translocation t(14;14)(q11;q32) in a case of Sézary syndrome, which caused a rearrangement from TRAJ7 to the PPP2R5C gene. PPP2R5C is one of the regulatory B subunits of protein phosphatase 2A (PP2A). It plays a crucial role in cell proliferation, differentiation, and transformation. To characterize the expression and distribution of five different transcript variants of the PPP2R5C gene in leukemia, we analyzed the expression level of PPP2R5C in peripheral blood mononuclear cells from 77 patients with de novo leukemia, 26 patients with leukemia in complete remission (CR), and 20 healthy individuals by real-time PCR and identified the different variants of PPP2R5C by RT-PCR.

FINDINGS

Significantly higher expression of PPP2R5C was found in AML, CML, T-ALL, and B-CLL groups in comparison with healthy controls. High expression of PPP2R5C was detected in the B-ALL group; however, no significant difference was found compared with the healthy group. The expression level of PPP2R5C in the CML-CR group decreased significantly compared with that in the de novo CML group and was not significantly different from the level in the healthy group. By using different primer pairs that covered different exons, five transcript variants of PPP2R5C could be identified. All variants could be detected in healthy samples as well as in all the leukemia samples, and similar frequencies and distributions of PPP2R5C were indicated.

CONCLUSIONS

Overexpression of PPP2R5C in T-cell malignancy as well as in myeloid leukemia cells might relate to its proliferation and differentiation. Investigation of the effect of target inhibition of this gene might be beneficial to further characterization of molecular mechanisms and targeted therapy in leukemia.

Quantitative monitoring of single nucleotide mutations by allele-specific quantitative PCR can be used for the assessment of minimal residual disease in patients with hematological malignancies throughout their clinical course

BACKGROUND

Monitoring of minimal residual disease (MRD) in patients with hematological malignancies is important for evaluating the patients' therapeutic response and risk of relapse. Single nucleotide mutations associated with leukemogenesis can be considered as applicable MRD markers.

METHODS

We developed an allele-specific quantitative polymerase chain reaction (AS-qPCR) for FLT3 2503G>T, KIT 2446G>T, and KIT 2447A>T and compared the change in the expression levels of the FLT3 or KIT mutations assessed by AS-qPCR to those of the RUNX1-RUNX1T1 fusion gene and WT1 by conventional quantitative PCR.

RESULTS

The AS-qPCR using primers including template-mismatched nucleotide or template-mismatched nucleotide plus locked nucleic acid substituted nucleotide provided higher selectivity for mutant nucleotides. The change in the expression levels of the FLT3 or KIT mutations at the time of relapse and just after hematopoietic stem cell transplantation correlated well with that of the RUNX1-RUNX1T1 fusion gene and WT1. Moreover, during complete remission, only AS-qPCR could detect low-level expression of residual mutations.

CONCLUSIONS

The AS-qPCR for analyzing single nucleotide mutations contributes to the monitoring of MRD in patients without recurrent fusion gene throughout the clinical course and thus broadens the spectrum of patients in whom MRD can be monitored.

NCI First International Workshop on the Biology, Prevention, and Treatment of Relapse after Allogeneic Hematopoietic Stem Cell Transplantation: report from the Committee on Disease-Specific Methods and Strategies for Monitoring Relapse following Allogeneic Stem Cell Transplantation. Part I: Methods, acute leukemias, and myelodysplastic syndromes

Relapse has become the major cause of treatment failure after allogeneic stem cell transplantation. Outcome of patients with clinical relapse after transplantation generally remains poor, but intervention prior to florid relapse improves outcome for certain hematologic malignancies. To detect early relapse or minimal residual disease, sensitive methods such as molecular genetics, tumor-specific molecular primers, fluorescein in situ hybridization, and multiparameter flow cytometry (MFC) are commonly used after allogeneic stem cell transplantation to monitor patients, but not all of them are included in the commonly employed disease-specific response criteria. The highest sensitivity and specificity can be achieved by molecular monitoring of tumor- or patient-specific markers measured by polymerase chain reaction-based techniques, but not all diseases have such targets for monitoring. Similar high sensitivity can be achieved by determination of donor chimerism, but its specificity regarding detection of relapse is low and differs substantially among diseases. Here, we summarize the current knowledge about the utilization of such sensitive monitoring techniques based on tumor-specific markers and donor cell chimerism and how these methods might augment the standard definitions of posttransplant remission, persistence, progression, relapse, and the prediction of relapse. Critically important is the need for standardization of the different residual disease techniques and to assess the clinical relevance of minimal residual disease and chimerism surveillance in individual diseases, which in turn, must be followed by studies to assess the potential impact of specific interventional strategies.

The clinical relevance of Wilms Tumour 1 (WT1) gene mutations in acute leukaemia

Recurrent genetic aberrations are important predictors of outcome in acute myeloid leukaemia (AML). Numerous novel molecular abnormalities have been identified and investigated in recent years adding to the risk stratification and prognostication of conventional karyotyping. Mutations in the Wilms Tumour 1 (WT1) gene were first described more than a decade ago but their clinical significance has only recently been evaluated. WT1 mutations occur in approximately 10% of adult AML patients at diagnosis and are most frequent in the cytogenetically normal (CN) AML subgroup. These mutations appear to confer a negative prognostic outcome by increasing the risk of relapse and death. Mutation frequency is higher in pediatric patients and also appears to confer a negative impact on relapse and survival. Herein, we discuss the importance of WT1 mutations in AML.

Quantitative assessment of PTPN11 or RAS mutations at the neonatal period and during the clinical course in patients with juvenile myelomonocytic leukaemia

To evaluate minimal residual disease (MRD) after chemotherapy and haematopoietic stem cell transplantation in juvenile myelomonocytic leukaemia (JMML), a locked nucleic acid-allele specific quantitative polymerase chain reaction (LNA-AS-qPCR) was developed for 13 patients (four types of PTPN11 mutation and four types of RAS mutation). The post-transplant MRD detected by LNA-AS-qPCR analysis was well correlated with chimerism assessed by short tandem repeat PCR analysis. Non-intensive chemotherapy exerted no substantial reduction of the tumour burden in three patients. There was no significant difference in the quantity of RAS mutant DNA after spontaneous haematological improvement in 4 patients with NRAS or KRAS 34G > A during a 2- to 5-year follow-up. PTPN11, NRAS, or KRAS mutant DNA was detected from Guthrie card dried blood in five of seven patients (who were aged <2 years at diagnosis) at a level of 1.0-6.5 x 10(-1) of the values at diagnosis. Accordingly, these five patients might have already reached a subclinical status at birth. Considering the negative correlation between mutant DNA level in neonatal blood spots and age at diagnosis, JMML patients with a larger tumour burden at birth appeared to show earlier onset.

Development of a Wilms' tumor antigen-specific T-cell receptor for clinical trials: engineered patient's T cells can eliminate autologous leukemia blasts in NOD/SCID mice

BACKGROUND

The Wilms' tumor antigen (WT1) is an attractive target for immunotherapy of leukemia. In the past, we isolated and characterized the specificity and function of a WT1-specific T-cell receptor. The goal of this translational study was to develop a safe and efficient WT1-T-cell receptor retroviral vector for an adoptive immunotherapy trial with engineered T cells.

DESIGN AND METHODS

We generated a panel of retroviral constructs containing unmodified or codon-optimized WT1-T-cell receptor alpha and beta genes, linked via internal ribosome entry sites or 2A sequences, with or without an additional inter-chain disulfide bond in the T-cell receptor constant domains. These constructs were functionally analyzed in vitro, and the best one was tested in an autologous primary leukemia model in vivo.

RESULTS

We identified a WT1-T-cell receptor construct that showed optimal tetramer staining, antigen-specific cytokine production and killing activity when introduced into primary human T cells. Fresh CD34(+) cells purified from a patient with leukemia were engrafted into NOD/SCID mice, followed by adoptive immunotherapy with patient's autologous T cells transduced with the WT1-T-cell receptor. This therapeutic treatment evidently decreased leukemia engraftment in mice and resulted in a substantial improvement of leukemia-free survival.

CONCLUSIONS

This is the first report that patient's T cells, engineered to express the WT1-T-cell receptor, can eliminate autologous leukemia progenitor cells in an in vivo model. This study provides a firm basis for the planned WT1-T-cell receptor gene therapy trial in leukemia patients.

Standardization of WT1 mRNA quantitation for minimal residual disease monitoring in childhood AML and implications of WT1 gene mutations: a European multicenter study

A standardized, sensitive and universal method for minimal residual disease (MRD) detection in acute myeloid leukemia (AML) is still pending. Although hyperexpression of Wilms' tumor (WT1) gene transcript has been frequently proposed as an MRD marker in AML, wide comparability of the various methods used for evaluating WT1 expression has not been given. We established and standardized a multicenter approach for quantifying WT1 expression by quantitative reverse transcriptase PCR (qRT-PCR), on the basis of a primer/probe set combination at exons 6 and 7. In a series of quality-control rounds, we analyzed 69 childhood AML samples and 47 normal bone marrow (BM) samples from 4 participating centers. Differences in the individual WT1 expressions levels ranged within <0.5 log of the mean in 82% of the cases. In AML samples, the median WT1/1E+04 Abelson (ABL) expression was 3.5E+03 compared with that of 2.3E+01 in healthy BM samples. As 11.5% of childhood AML samples in this cohort harbored WT1 mutations in exon 7, the effect of mutations on WT1 expression has been investigated, showing that mutated cases expressed significantly higher WT1 levels than wild-type cases. Hence, our approach showed high reproducibility and applicability, even in patients with WT1 mutations; therefore, it can be widely used for the quantitation of WT1 expression in future clinical trials.