The Wilms' tumor gene WT1 is a good marker for diagnosis of disease progression of myelodysplastic syndromes

Modulating the immune system as a therapeutic target for myelodysplastic syndromes and acute myeloid leukemia

Modulating the immune system to treat diseases, including myeloid malignancies, has resulted in the development of a multitude of novel therapeutics in recent years. Myelodysplastic syndromes or neoplasms (MDS) and acute myeloid leukemia (AML) are hematologic malignancies that arise from defects in hematopoietic stem and progenitor cells (HSPCs). Dysregulated immune responses, especially in innate immune and inflammatory pathways, are highly associated with the acquisition of HSPC defects in MDS and AML pathogenesis. In addition to utilizing the immune system in immunotherapeutic interventions such as chimeric antigen receptor T cell therapy, vaccines, and immune checkpoint inhibitors, mitigating dysregulation of innate immune and inflammatory responses in MDS and AML remains a priority in slowing the initiation and progression of these myeloid malignancies. This review provides a comprehensive summary of the current progress of diverse strategies to utilize or modulate the immune system in the treatment of MDS and AML.

Molecular Drivers of Myelodysplastic Neoplasms (MDS)-Classification and Prognostic Relevance

Myelodysplastic neoplasms (MDS) form a broad spectrum of clonal myeloid malignancies arising from hematopoietic stem cells that are characterized by progressive and refractory cytopenia and morphological dysplasia. Recent advances in unraveling the underlying pathogenesis of MDS have led to the identification of molecular drivers and secondary genetic events. With the overall goal of classifying patients into relevant disease entities that can aid to predict clinical outcomes and make therapeutic decisions, several MDS classification models (e.g., French-American-British, World Health Organization, and International Consensus Classification) as well as prognostication models (e.g., International Prognostic Scoring system (IPSS), the revised IPSS (IPSS-R), and the molecular IPSS (IPSS-M)), have been developed. The IPSS-M is the first model that incorporates molecular data for individual genes and facilitates better prediction of clinical outcome parameters compared to older versions of this model (i.e., overall survival, disease progression, and leukemia-free survival). Comprehensive classification and accurate risk prediction largely depend on the integration of genetic mutations that drive the disease, which is crucial to improve the diagnostic work-up, guide treatment decision making, and direct novel therapeutic options. In this review, we summarize the most common cytogenetic and genomic drivers of MDS and how they impact MDS prognosis and treatment decisions.

Clinical significance of the increased expression of the WT1 gene in peripheral blood of patients with acquired aplastic anemia

To determine the significance of increased Wilms tumor 1 (WT1) gene expression in the peripheral blood of patients with acquired aplastic anemia (AA), we analyzed serial changes in WT1 mRNA copy number (WT1cn) in 63 patients with AA as well as in five patients with myelodysplastic syndromes (MDS) and seven patients with paroxysmal nocturnal hemoglobinuria (PNH). WT1cn was higher than the cut-off (≥50 copies/μg RNA) at the time of the first measurement in 41% of untreated (60-190 copies/μg RNA [median 130]) and 59% of treated (59-520 copies/μg RNA [median 150]) AA patients. Although WT1cns gradually increased in most AA patients during the 2-105 months follow-up period, they did not lead to clonal evolution except in three patients in whom the maximum change ratio of WT1cn (WT1cn-change max), defined as the ratio of WT1cn at the first examination to that of the maximum value, exceeded 20.0 and who developed MDS at 2, 46, and 105 months. Increased WT1 gene expression was enriched in granulocytes rather than in mononuclear cells in most WT1-positive AA patients and did not correlate with mutations of genes associated with myeloid malignancy. WT1cns were high at 690-5700 (median 2000) in MDS patients and remained high thereafter, while WT1cns in PNH patients (77-200; median 96) were similar to those in AA. Thus, moderate increases in WT1cns up to 600 are common in AA patients in stable remission. An increase in the WT1cn-change max over 20.0 may portend transformation from AA to MDS.

Dynamic change in peripheral blood WT1 mRNA levels within three cycles of azacitidine predict treatment response in patients with high-risk myelodysplastic syndromes

Azacitidine (AZA) improves overall survival (OS) in patients with high-risk myelodysplastic syndromes (MDS). However, predictive factors for response to AZA remain largely unknown. To elucidate whether dynamic change in peripheral blood (PB) Wilms' Tumor 1 (WT1) mRNA levels could predict response to AZA, we retrospectively identified 75 treatment-naïve patients with high-risk MDS who received at least 3 cycles of AZA. We classified patients into 4 groups, low-increase (LI), low-stable (LS), high-decrease (HD), and high-stable (HS) based on the dynamic change in PB WT1 mRNA levels within 3 cycles of AZA. Cumulative incidence of overall response after 10 cycles of AZA was significantly higher in LS/HD than in HS/LI (75.5% vs 4.5%, P < 0.001). The median OS for LS/HD was 18.2 months (95% CI, 12.8-28.1 months), whereas it was 11.6 months for HS/LI (95% CI, 6.6-14.1 months; P < 0.001). Multivariate analysis demonstrated that poor-/very poor-IPSS-R cytogenetic risk and HS/LI were independently associated with poor OS (poor-/very poor-IPSS-R cytogenetic risk: HR, 2.26; 95% CI, 1.10-4.68, P = 0.03, HS/LI: HR, 2.32; 95% CI, 1.21-4.46, P = 0.01). Patients with HS/LI did not show any further response to continuous AZA, and they should be considered for alternative therapy from earlier cycles.

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.

Is Myelodysplasia a Consequence of Normal Aging?

PURPOSE OF REVIEW

To review available data on the relationship of MDS and aging and to address the question if biological changes of (premature) aging are a prerequisite for the development of MDS.

RECENT FINDINGS

Whereas the association of MDS with advanced age and some common biologic features of aging and MDS are well established, additional evidence for both, especially on the role of stem cells, the stem cell niche, and inflammation, has been recently described. Biologically, many but not all drivers of aging also play a role in the development and propagation of MDS and vice versa. As a consequence, aging contributes to the development of MDS which can be seen as an interplay of clonal disease and normal and premature aging. The impact of aging may be different in specific MDS subtypes and risk groups.

A machine learning approach to predicting risk of myelodysplastic syndrome

BACKGROUND

Early myelodysplastic syndrome (MDS) diagnosis can allow physicians to provide early treatment, which may delay advancement of MDS and improve quality of life. However, MDS often goes unrecognized and is difficult to distinguish from other disorders. We developed a machine learning algorithm for the prediction of MDS one year prior to clinical diagnosis of the disease.

METHODS

Retrospective analysis was performed on 790,470 patients over the age of 45 seen in the United States between 2007 and 2020. A gradient boosted decision tree model (XGB) was built to predict MDS diagnosis using vital signs, lab results, and demographics from the prior two years of patient data. The XGB model was compared to logistic regression (LR) and artificial neural network (ANN) models. The models did not use blast percentage and cytogenetics information as inputs. Predictions were made one year prior to MDS diagnosis as determined by International Classification of Diseases (ICD) codes, 9th and 10th revisions. Performance was assessed with regard to area under the receiver operating characteristic curve (AUROC).

RESULTS

On a hold-out test set, the XGB model achieved an AUROC value of 0.87 for prediction of MDS one year prior to diagnosis, with a sensitivity of 0.79 and specificity of 0.80. The XGB model was compared against LR and ANN models, which achieved an AUROC of 0.838 and 0.832, respectively.

CONCLUSIONS

Machine learning may allow for early MDS diagnosis MDS and more appropriate treatment administration.

Galinpepimut-S (GPS): an investigational agent for the treatment of acute myeloid leukemia

Introduction: Acute myeloid leukemia (AML) is a disorder wherein clonal expansion of undifferentiated myeloid precursors results in compromised hematopoiesis and bone marrow failure. Even though numerous AML patients respond to induction chemotherapy, relapse is common and hence new therapeutic approaches are needed. Wild-type Wilms tumor gene (WT1) is greatly expressed in numerous blood disorders and so this has led to development of galinpepimut-S, a WT1 vaccine as a modality to maintain remission in patients with AML.Areas covered: We summarize and examine the structure, key features, safety, and efficacy data of galinpepimut-S (GPS) for AML. GPS has been shown to be safe and tolerable in phase 1 and phase 2 studies and is now being evaluated in a phase 3 study.Expert opinion: Given the unmet need in the treatment of relapsed and refractory AML, especially among the elderly and patients with comorbidities who are not fit enough to undergo traditional salvage treatments, GPS could potentially fill the gap for this subset of patients. Future clinical trials utilizing GPS in second complete remission 2 (CR2) compared to best available therapy in AML and in combination with other immunotherapeutic agents (like pembrolizumab) for treatment for various malignancies are underway.

WT1 Expression Levels Combined with Flow Cytometry Blast Counts for Risk Stratification of Acute Myeloid Leukemia and Myelodysplastic Syndromes

Wilm's tumor 1 (WT1), a zinc-finger transcription factor and an epigenetic modifier, is frequently overexpressed in several hematologic disorders and solid tumors, and it has been proposed as diagnostic and prognostic marker of acute myeloid leukemia (AML) and myelodysplastic syndrome (MDS). However, the exact role of WT1 in leukemogenesis and disease progression remains unclear. In this real-world evidence retrospective study, we investigated prognostic role of WT1-mRNA expression levels in AML and MDS patients and correlations with complete blood counts, flow cytometry counts, and molecular features. A total of 71 patients (AML, n = 46; and MDS, n = 25) were included in this study, and WT1 levels were assessed at diagnosis, during treatment and follow-up. We showed that WT1 expression levels were inversely correlated with normal hemopoiesis in both AML and MDS, and positively associated with blast counts. Flow cytometry was more sensitive and specific in distinguishing normal myeloid cells from neoplastic counterpart even just using linear parameters and CD45 expression. Moreover, we showed that a simple integrated approach combining blast counts by flow cytometry, FLT3 mutational status, and WT1 expression levels might be a useful tool for a better prognostic definition in both AML and MDS patients.

Association between the Wilms tumor-1 rs16754 polymorphism and acute myeloid leukemia: A MOOSE-compliant meta-analysis

The Wilms tumor-1 (WT1) protein is an important regulator of malignant hematopoiesis and has been implicated in the pathogenesis of acute myeloid leukemia (AML). Recently special attention has been paid to the relationship of the WT1 single nucleotide polymorphism (SNP) rs16754 with AML risk and outcome, but the conflicting results made it difficult to draw definitive conclusions. In the present study, we systematically reviewed the literature and performed a meta-analysis of existing evidence. We searched Embase, Pubmed, Web of Science, Medline, Cochrane Library, Wanfang, and China National Knowledge Infrastructure databases using predefined search methodology for relevant studies. We pooled odd ratio (OR) with 95% confidence intervals (95% CI) to evaluate the association between SNP rs16754 and AML risk. In addition, we analyzed hazard ratio (HR) with 95% CI for overall survive, relapse-free survival, and disease-free survival. Q-statistic was used to assess the homogeneity and Egger test was used to evaluate publication bias. Eleven studies met the inclusion criteria for analysis. The results of fixed-effect meta-analyses revealed no association between SNP rs16754 and AML risk (AA + GA vs GG: OR = 0.92, 95% CI: 0.71-1.19, P = .518; AA vs GA + GG: OR = 1.23, 95% CI: 0.86-1.76, P = .262; AA vs GG: OR = 1.05, 95% CI: 0.68-1.63, P = .820; AG vs AA: OR = 0.77, 95% CI: 0.53-1.13, P = .186; AG vs GG: OR = 0.89, 95% CI: 0.68-1.16, P = .376). In subgroup analysis by race, age, and disease type, we did not find any significant association. However, the presence of rs16754 GA/GG genotype was associated with improved overall survive (HR = 0.48, 95% CI: 0.26-0.91, P = .024) and relapse-free survival (HR = 0.82, 95% CI: 0.68-1.00, P = .048) compared with the rs16754 AA. In summary, the WT1 SNP rs16754 was not associated with AML risk, but it had a significant impact on clinical outcome in AML patients.

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.

Intraocular infiltration of Philadelphia chromosome-positive acute lymphoblastic leukemia diagnosed by polymerase chain reaction from the aqueous humor: A case report

RATIONALE

Intraocular manifestation of hematopoietic tumors is rare and often difficult to distinguish from inflammation. We report a patient with acute lymphoblastic leukemia (ALL) who developed intraocular infiltration during the remission period.

PATIENT CONCERNS

A 40-year-old man presented with hypopyon in his right eye. Three months later, extensive subretinal infiltration and the elevation of intraocular pressure were observed. Fourteen months prior to this, he had been diagnosed with Philadelphia chromosome-positive ALL, and had received chemotherapy and bone marrow transplantation that resulted in complete remission.

DIAGNOSIS

The breakpoint cluster region-Ableson (BCR/ABL) chimera was detected by polymerase chain reaction (PCR) analysis in the patient's aqueous humor. Additionally, a high expression of WT1 (Wilms tumor gene) mRNA in the aqueous humor was discovered. A bone marrow examination yielded a high expression of BCR/ABL fusion gene, and it was determined the patient had experienced a relapse of ALL.

INTERVENTIONS

The dasatinib was administered orally to the patient.

OUTCOMES

The intraocular infiltration disappeared, and intraocular pressure was normalized.

LESSONS

Intraocular infiltration in leukemia patients may be an indication of relapse regardless of systemic conditions. Analyzing mRNA expression of BCR/ABL and WT1 of ocular fluid in patients with hypopyon is beneficial in diagnosing topical relapses in leukemia.

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.

[Changes of WT1 mRNA expression level in patients with myelodysplastic syndromes after hypomethylating agents and its prognostic significance]

目的

监测骨髓增生异常综合征（MDS）患者去甲基化治疗后WT1 mRNA水平的变化，评估WT1 mRNA水平变化在判断患者疗效、区分不同疾病稳定（stable disease, SD）状态中的意义。

方法

以2009年11月至2018年3月56例在广东省人民医院接受去甲基化治疗（≥4个疗程）的MDS患者为研究对象，实时定量PCR检测其骨髓或外周血WT1 mRNA的表达，观察WT1 mRNA表达水平的动态变化与患者临床疗效和预后的相关性。

结果

去甲基化治疗3个疗程后，MDS患者WT1 mRNA水平较治疗前显著降低。20例疾病进展患者病情进展或转为急性髓系白血病（AML）后WT1 mRNA表达水平较治疗前明显升高。45例SD的MDS患者，根据SD期间WT1 mRNA表达水平变化分为WT1升高与未升高两组，SD期间WT1 mRNA表达水平升高的患者中病情进展或转AML的比例为95.65%（22/23），而SD期间WT1 mRNA表达水平未升高的患者中病情进展或转为AML的比例为9.09%（2/22）（χ²=33.852，P<0.001）。与SD期间WT1 mRNA表达水平未升高的患者相比，SD期间WT1 mRNA表达水平升高的患者的总生存期[17（95%CI 11~23）个月对未达到，P<0.001]和无进展生存期[13（95%CI 8~18）个月对未达到，P<0.001]明显缩短。

结论

WT1 mRNA表达水平是评估MDS患者去甲基化治疗后疗效变化有效的实验室指标，尤其对于SD的患者，动态检测WT1 mRNA表达水平，可预测病情演变，从而指导临床治疗。

A double-blind randomized comparative clinical trial to evaluate the safety and efficacy of dendritic cell vaccine loaded with WT1 peptides (TLP0-001) in combination with S-1 in patients with advanced pancreatic cancer refractory to standard chemotherapy

BACKGROUND

Pancreatic cancer is a refractory malignancy, and the development of a new effective treatment strategy is needed. We generated a dendritic cell vaccine by culturing monocytes obtained by apheresis of blood from each patient, inducing their differentiation into dendritic cells, and pulsing with tumor antigen peptides. However, the clinical efficacy of the vaccine has not been established. We therefore decided to conduct an exploratory clinical trial of dendritic cell vaccine loaded with Wilms' tumor gene 1 peptides (TLP0-001) as a potential new treatment for patients with advanced pancreatic cancer refractory to standard chemotherapy.

METHODS

This is an investigator-initiated, double-blind, comparative trial. The patients were allocated to two groups in a 1:1 ratio through a central registration by dynamic allocation. A total of 185 patients with inoperable or metastatic pancreatic cancer who were refractory or intolerant to standard primary chemotherapy with gemcitabine plus nab-paclitaxel will be allocated to secondary treatment either with placebo in combination with S-1 (the control group) or TLP0-001 in combination with S-1 (the investigational product group). The primary objective of this trial is to evaluate the safety and efficacy (as measured by overall survival) of the investigational product by comparing the two groups. This clinical trial will be performed in accordance with Japanese Good Clinical Practice guidelines.

DISCUSSION

Clinical trials of the standard regimen, including gemcitabine, for advanced pancreatic cancer are ongoing worldwide. However, a strategy for after the primary treatment has not been established. We therefore decided to conduct this study to evaluate the safety and efficacy of TLP0-001 as a secondary treatment for pancreatic cancer in anticipation of the approval of this new drug in Japan. This trial is conducted with full consideration of safety, as it is the first-in-human clinical trial of TLP0-001; thus, the trial will be conducted only at the Second Department of Surgery at Wakayama Medical University until the safety is confirmed by interim analysis. We plan to conduct a multicenter trial at 18 institutions in Japan after confirmation of the safety.

TRIAL REGISTRATION

University Hospital Medical Information Network Clinical Trials Registry, UMIN000027179 . Registered on 9 April 2017.

c-MYB and DMTF1 in Cancer

The c-Myb gene encodes a transcription factor that regulates cell proliferation, differentiation, and apoptosis through protein-protein interaction and transcriptional regulation of signaling pathways. The protein is frequently overexpressed in human leukemias, breast cancers, and other solid tumors suggesting that it is a bona fide oncogene. c-MYB is often overexpressed by translocation in human tumors with t(6;7)(q23;q34) resulting in c-MYB-TCRβ in T cell ALL, t(X;6)(p11;q23) with c-MYB-GATA1 in acute basophilic leukemia, and t(6;9)(q22-23;p23-24) with c-MYB-NF1B in adenoid cystic carcinoma. Antisense oligonucleotides to c-MYB were developed to purge bone marrow cells to eliminate tumor cells in leukemias. Recently, small molecules that inhibit c-MYB activity have been developed to disrupt its interaction with p300. The Dmp1 (cyclin D binding myb-like protein 1; Dmtf1) gene was isolated through its virtue for binding to cyclin D2. It is a transcription factor that has a Myb-like repeat for DNA binding. The Dmtf1 protein directly binds to the Arf promoter for transactivation and physically interacts with p53 to activate the p53 pathway. The gene is hemizygously deleted in 35-42% of human cancers and is associated with longer survival. The significances of aberrant expression of c-MYB and DMTF1 proteins in human cancers and their clinical significances are discussed.

Pilot trial of K562/GM-CSF whole-cell vaccination in MDS patients

Myelodysplastic syndromes (MDS) are a heterogeneous group of clonal hematopoietic stem cell malignancies. Currently, approved drugs are given with non-curative intent as the only known cure is allogeneic bone marrow transplantation, which relies on the donor's immune system driving an allogeneic effect. Previous efforts to harness the endogenous immune system have been less successful. We present the results of a pilot study of K562/GM-CSF (GVAX) whole-cell vaccination in MDS patients. The primary objective of safety was met as there were no serious adverse events. One patient had a decrease in transfusion requirements and another demonstrated hematologic improvement suggesting a signal for clinical activity. In vitro correlative studies indicated biological effects on immune cells following vaccination. Although only a pilot study, results are encouraging that an immunotherapeutic approach with a whole-cell vaccine may be feasible in MDS patients.

Bone marrow fibrosis in myelodysplastic syndromes: a prospective evaluation including mutational analysis

The biological and molecular events that underlie bone marrow fibrosis in patients with myelodysplastic syndromes are poorly understood, and its prognostic role in the era of the Revised International Prognostic Scoring System (IPSS-R) is not yet fully determined. We have evaluated the clinical and biological events that underlie bone marrow fibrotic changes, as well as its prognostic role, in a well-characterized prospective patient cohort (n=77) of primary MDS patients. The degree of marrow fibrosis was linked to parameters of erythropoietic failure, marrow cellularity, p53 protein accumulation, WT1 gene expression, and serum levels of CXCL9 and CXCL10, but not to other covariates including the IPSS-R score. The presence of bone marrow fibrosis grade 2 or higher was associated with the presence of mutations in cohesin complex genes (31.5% vs. 5.4%, p=0.006). By contrast, mutations in CALR, JAK2, PDGFRA, PDGFRB,and TP53 were very rare. Survival analysis showed that marrow fibrosis grade 2 or higher was a relevant significant predictor for of overall survival, and independent of age, performance status, and IPSS-R score in multivariate analysis.

Wilms tumor 1 mutations in the pathogenesis of acute myeloid leukemia

Wilms tumor 1 (WT1) has long been implicated in acute myeloid leukemia. It has been described to be both overexpressed and mutated in different forms of acute myeloid leukemia, and overexpression has been reported to play a prognostic role in this disease. However, the precise mechanism through which WT1 may play a role in leukemogenesis has remained elusive. In recent years, new evidence has emerged that points towards a novel role of WT1 mutations in the deregulation of epigenetic programs in leukemic cells through its interaction with TET proteins. Herein we review the current status of the field and its therapeutic and prognostic implications in acute myeloid leukemia.

Myelodysplastic syndromes: advantages of a combined cytogenetic and molecular diagnostic workup

In this study we present a new diagnostic workup for the myelodysplastic syndromes (MDS) including FISH, aCGH, and somatic mutation assays in addition to the conventional cytogenetics (CC). We analyzed 61 patients by CC, FISH for chromosome 5, 7, 8 and PDGFR rearrangements, aCGH, and PCR for ASXL1, EZH2, TP53, TET2, RUNX1, DNMT3A, SF3B1 somatic mutations. Moreover, we quantified WT1 and RPS14 gene expression levels, in order to find their possible adjunctive value and their possible clinical impact. CC analysis showed 32% of patients with at least one aberration. FISH analysis detected chromosomal aberrations in 24% of patients and recovered 5 cases (13.5%) at normal karyotype (two 5q- syndromes, one del(7) case, two cases with PDGFR rearrangement). The aGCH detected 10 "new" unbalanced cases in respect of the CC, including one with alteration of the ETV6 gene. After mutational analysis, 33 patients (54%) presented at least one mutation and represented the only marker of clonality in 36% of all patients. The statistical analysis confirmed the prognostic role of CC either on overall or on progression-free-survival. In addition, deletions detected by aCGH and WT1 over-expression negatively conditioned survival. In conclusion, our work showed that 1) the addition of FISH (at least for chr. 5 and 7) can improve the definition of the risk score; 2) mutational analysis, especially for the TP53 and SF3B1, could better define the type of MDS and represent a "clinical warning"; 3) the aCGH use could be probably applied to selected cases (with suboptimal response or failure).

Prognostic significance of Wilms tumor 1 mRNA expression levels in peripheral blood and bone marrow in patients with myelodysplastic syndromes

BACKGROUND

This present study was designed to follow up 82 patients among 115 MDS patients registered in study ODK-0801 for 5 years, to analyze the relationship between the WT1 mRNA expression level and prognosis.

OBJECTIVE

This study aimed to investigate the clinical utility of WT1 mRNA expression levels.

METHODS

After study ODK-0801, we investigated the conditions of the same patients once a year, including any clinical and laboratory findings supporting the diagnosis, and treatment among the living patients.

RESULTS

When we assessed the survival time of 82 MDS patients by WT1 mRNA expression level, there were significant differences between the < 500 and ≥ 104 copies/μ g RNA groups and between the 500-104 and ≥ 104 copies/μ g RNA groups for BM levels (p < 0.01). Examination of the time of freedom from acute myeloid eukemia (AML) transformation indicated that a high WT1 mRNA expression level (> 104 copies/μ g RNA) was a strong prognostic factor for a short time to AML transformation.

CONCLUSION

The results indicate that the tumorigenesis of MDS is likely to originate at the stem cell level, suggesting that the WT1 mRNA level measurement in the BM is an effective prognostic marker in patients with MDS.

Assessment of Relationship between Wilms' Tumor Gene (WT1) Expression in Peripheral Blood of Acute Leukemia Patients and Serum IL-12 and C3 Levels

BACKGROUND

Leukemia is a common cancer among children and adolescents. Wilms' tumor gene (WT1) is highly expressed in patients with acute leukemia. It is found as a tumor associated antigen (TAA) in various types of hematopoietic malignancies and can be employed as a useful marker for targeted immunotherapy and monitoring of minimal residual disease (MRD). In this regard, WT1 is a transcription factor that promotes gene activation or repression depending on cellular and promoter context. The purpose of this study was assessment of WT1 gene expression in patients with acute leukemia, measurement of IL-12 and C3 levels in serum and evaluation of the relationship between them.

MATERIALS AND METHODS

We evaluated the expression of WT1 mRNA using real-time quantitative RT-PCR and serum levels of IL-12 and C3 using ELISA and nephelometry in peripheral blood of 12 newly diagnosed patients with acute leukemia and 12 controls.

RESULTS

The results of our study showed that the average wT1 gene expression in patients was 7.7 times higher than in healthy controls (P <0.05). In addition, IL-12 (P = 0.003) and C3 (P <0.0001) were significantly decreased in the test group compared to controls.

CONCLUSIONS

WT1 expression levels are significantly higher in patients compared with control subjects whereas serum levels of interleukin-12 and C3 are significantly lower in patients. Wt1 expression levels in patients are inversely related with serum levels of IL-12 and C3.

Mechanisms of leukemia resistance to antibody dependent cellular cytotoxicity

Specific immunotherapy for acute leukemia remains a great unmet need. Native unmodified monoclonal antibody therapies, while promising, are inadequately effective for these malignancies, and multiple mechanisms for failure have been described. Antibody-dependent cellular cytotoxicity or phagocytosis is the primary modality of mAb-mediated cell killing in vivo, but ultimately leads to relapse of the leukemias, in model systems and in humans. By use of a T-cell receptor mimic mAb ESKM, derived against a WT1 peptide expressed in complex with HLA-A*02:01, whose only mechanism of therapeutic action is ADCC, we evaluated the mechanisms of leukemic relapse from its potent therapeutic action in mouse xenograft models of human leukemia. Leukemia escape was not associated with loss of the antigenic target, downregulation of cell surface HLA, antibody pharmacokinetic or biodistribution issues, or development of leukemia cell-intrinsic resistance to ADCC. Interestingly, the rapidity of leukemic growth determined whether leukemia was able to evade cytotoxicity independent of the presence of sufficient effector cells. By engineering leukemia cells with upregulated p27^Kip1 and slower cell cycling times, we show that relapse was inversely correlated with growth rates resulting in the eventual inadequacy of effector to target ratio. Moreover, lack of migration of effector cells into lymphomatous pockets of ALL also allowed local escape. Successful leukemia therapy with mAb might therefore be improved in similar situations by combination with measures to reduce burden and slow leukemia cell growth.

Minimal residual disease monitoring and preemptive immunotherapy in myelodysplastic syndrome after allogeneic hematopoietic stem cell transplantation

This study investigated the efficacy of minimal residual disease (MRD) monitoring and MRD-directed preemptive immunotherapy in high-risk myelodysplastic syndrome (MDS) patients who received allogeneic hematopoietic stem cell transplantation (HSCT). MRD assessment consisted of Wilms' tumor gene 1 (WT1) detection with PCR and leukemia-associated immunophenotypic pattern examination with multiparameter flow cytometry (FCM). Post-HSCT, 31 patients were positive for WT1, and 8, for FCM; positivity for WT1 (18.6 vs. 6.1 %, P = 0.040) or FCM (62.5 vs. 3.6 %, P < 0.001) indicated a higher 2-year relapse rate. Twenty-one patients met our combined criteria for MRD, and the presence of MRD was associated with a higher 2-year relapse rate (27.3 vs. 4.5 %, P = 0.003). Preferentially expressed antigen of melanoma (PRAME) expression alone was not an appropriate MRD marker; however, it suggested that the MRD-positive patients may fail to respond to preemptive immunotherapy. In patients positive for both PRAME and MRD, the relapse rate was 60 % despite preemptive immunotherapy. Multivariate analysis confirmed the association between the increased relapse rate and positivity for both PRAME and MRD (hazard ratio = 42.8, P = 0.001). MRD monitoring predicted relapse in high-risk MDS post-HSCT patients, and PRAME- and MRD-positive patients did not benefit from preemptive immunotherapy.

Changes in expression of WT1 during induced differentiation of the acute myeloid leukemia cell lines by treatment with 5-aza-2'-deoxycytidine and all-trans retinoic acid

The aim of the present study was to investigate the effect of 5-aza-2'-deoxycytidine (decitabine; DAC) and all-trans retinoic acid (ATRA) on Wilms' tumor 1 (WT1) in acute myeloid leukemia (AML) in vitro. The methylation status of the WT1 promoter was analyzed using methylation-specific polymerase chain reaction (MSP). The expression level of WT1 was detected by reverse transcription-quantitative polymerase chain reaction. The effect of DAC and ATRA on cell differentiation was evaluated by flow cytometry. The WT1 gene was methylated in U937 cells, but unmethylated in SHI-1 and K562 cells; the U937 cells did not express the WT1 gene, but the SHI-1 and K562 cells highly expressed the WT1 gene. DAC and ATRA, alone or in combination, exhibited no effect on the expression level of WT1 in the U937 cells and on the differentiation of the K562 cells. The combined treatment of DAC and ATRA markedly decreased the WT1 expression levels of the SHI-1 and K562 cells, and induced the differentiation of the SHI-1 and U937 cells. In the SHI-1 cells, WT1 expression changed inversely to the dynamic changes of cluster of differentiation 11b-positive rates. In conclusion, the combined treatment of DAC and ATRA has clinical therapeutic potential in acute monocytic leukemia patients with high WT1 expression and a poor response to standard induction chemotherapy.

T-cell depleted allogeneic hematopoietic cell transplants as a platform for adoptive therapy with leukemia selective or virus-specific T-cells

Allogeneic hematopoietic cell transplants adequately depleted of T-cells can reduce or prevent acute and chronic GVHD in both HLA-matched and haplotype-disparate hosts, without post-transplant prophylaxis with immunosuppressive drugs. Recent trials indicate that high doses of CD34+ progenitors from G-CSF mobilized peripheral blood leukocytes isolated and T-cell depleted by immunoadsorption to paramagnetic beads, when administered after myeloablative conditioning with TBI and chemotherapy or chemotherapy alone can secure consistent engraftment and abrogate GVHD in patients with acute leukemia without incurring an increased risk of a recurrent leukemia. Early clinical trials also indicate that high doses of in vitro generated leukemia-reactive donor T-cells can be adoptively transferred and can induce remissions of leukemia relapse without GVHD. Similarly, virus-specific T-cells generated from the transplant donor or an HLA partially matched third party, have induced remissions of Rituxan-refractory EBV lymphomas and can clear CMV disease or viremia persisting despite antiviral therapy in a high proportion of cases. Analyses of treatment responses and failures illustrate both the advantages and limitations of donor or banked, third party-derived T-cells, but underscore the potential of adoptive T-cell therapy in the absence of ongoing immunosuppression.

Risk-Reducing Genetic Variant of Wilms Tumor 1 Gene rs16754 in Korean Patients With BCR-ABL1-Negative Myeloproliferative Neoplasm

The genetic variant rs16754 of Wilms tumor gene 1 (WT1) has recently been described as an independent prognostic factor in AML patients. It is of great interest to test whether WT1 single nucleotide polymorphism can be used as a molecular marker in other types of cancer, to improve risk and treatment stratification. We performed sequencing analysis of exons 7 and 9 of WT1, which are known mutational hotspots, in a total of 73 patients with BCR-ABL1-negative myeloproliferative neoplasm (MPN) and 93 healthy controls. No previously reported WT1 mutations were identified in the present study. In Korean patients with BCR-ABL1-negative MPN, WT1 genetic variant rs16754 had no significant impact on clinical outcomes. We observed a significant difference in the allelic frequencies of WT1 rs16754 in Koreans between BCR-ABL1-negative MPN cases and healthy controls. Individuals carrying variant G alleles of WT1 rs16754 showed a relatively low prevalence of BCR-ABL1-negative MPN, compared with those carrying wild A alleles of WT1 rs16754 (Hazard ratio 0.10-0.65, P<0.05). Therefore, possession of the variant G allele of WT1 rs16754 may reduce the risk of developing BCR-ABL1-negative MPN.

Review of the Results of WT1 Peptide Vaccination Strategies for Myelodysplastic Syndromes and Acute Myeloid Leukemia from Nine Different Studies

We performed a systematic review of data from nine clinical trials of WT1 peptide vaccination in patients with myelodysplastic syndromes and/or acute myeloid leukemia (MDS/AML), published between 2004 and 2012. A total of 51 patients were eligible for analysis. Vaccination with WT1 peptides proved safe and feasible in patients with MDS/AML, in studies from different institutions. Additionally, clinical responses and clinical benefit were observed, with some patients achieving and maintaining remission long-term (more than 8 years). A significant correlation between induction of WT1-specific T cells and normalization/reduction of WT1 mRNA levels and progression-free survival was noted in a number of studies. However, larger studies are warranted to confirm these results. Interestingly, the majority of trials reported the presence of WT1-specific T cells with limited or absent functionality prior to vaccination, which increased in frequency and function after vaccination. In conclusion, WT1 peptide vaccination strategies were safe in this heterogeneous group of patient with MDS/AML. Larger and more homogeneous studies or randomized clinical trials are needed to quantify the contribution of WT1 peptide vaccines to clinical responses and long-term survival.

Transplant for MDS: challenges and emerging strategies

Allogeneic hematopoietic stem cell transplantation is the only curative treatment for myelodysplastic syndrome. Major improvements in the field of allogeneic stem cell transplantation have made it a better tolerated treatment that can be offered to older patients and patients with co-morbidities. However, treatment related toxicities, graft versus host disease, infectious complications and relapse remain major problems post transplant. With better understanding of disease biology and prognosis and with different types of conditioning regimens as well as different graft sources, a transplant strategy should be tailored to the individual host to maximize the benefits of this procedure.

Real-time assessment of relapse risk based on the WT1 marker in acute leukemia and myelodysplastic syndrome patients after hematopoietic cell transplantation

Relapse is the major cause of treatment failure after allogeneic hematopoietic cell transplantation (alloHCT) for acute leukemia and myelodysplastic syndrome (MDS). Wilms' tumor Ag (WT1) is overexpressed in the majority of acute leukemia and MDS patients and has been proposed as a universal diagnostic marker for detection of impending relapse. Comprehensive studies have shown that WT1 transcript levels have predictive value in acute leukemia patients in CR after chemotherapy. However, the focus of this study is the period after alloHCT for predicting relapse onset. We analyzed the accumulation of WT1 mRNA transcripts in PB of 82 leukemia and MDS patients and defined specific molecular ratios for relapse prediction. The extensively validated WT1/c-ABL ratio was used to normalize increases in WT1 transcript levels. The observed lead time of crossing or exceeding set WT1 levels is presented along with linear interpolation to estimate the calculated day the WT1 thresholds were crossed. The WT1/c-ABL transcript ratio of 50 or above yielded 100% specificity and 75% sensitivity reliably predicting future relapse with an observed average of 29.4 days (s.d.=19.8) and a calculated average of 63 days (s.d.=29.3) lead time before morphologic confirmation. A lower ratio of 20 or above gave lower specificity, but higher sensitivity (84.8% and 87.5%, respectively) identified more patients who relapsed, at earlier times, providing an earlier warning with actual average lead time of 49.1 days (s.d.=30.8) and calculated average of 78 days (s.d.=28.8). WT1 transcript levels serve as a diagnostic relapse test with greater sensitivity than the morphologic approach used in the clinic as a readout.

Prognostic impact of WT1 expression prior to hematopoietic stem cell transplantation in children with malignant hematological diseases

PURPOSE

Malignant hematological diseases represent the most common pediatric cancer. As they cannot always be cured by chemotherapy alone, leukemia and myelodysplastic syndrome (MDS) are frequent medical indications for hematopoietic stem cell transplantation, yet even this treatment is not capable of preventing relapse for certain. Therefore, molecular markers are used to monitor minimal residual disease (MRD) to be enabled to react early to an impeding relapse. As specific markers are not always available, Wilms' tumor gene 1 (WT1) has been suggested as a universal marker, but has not yet been established clinically.

METHODS

We determined the level of WT1 gene expression in 130 children, adolescents and young adults with malignant hematological diseases prior to transplantation and evaluated its impact on patients' outcome. A real-time quantitative RT-PCR was used for this purpose.

RESULTS

The relationship between a high level of WT1 and the cumulative incidence of relapse, event-free survival and overall survival proved to be highly significant in univariate and multivariate analyses. Forty-eight percent of all patients with high WT1 levels suffered from a relapse, whereas only eight percent showing normal WT1 levels before transplantation relapsed. The most convincing result was found for acute myeloid leukemia (AML) and MDS.

CONCLUSION

We conclude that WT1 expression prior to transplantation qualifies as an independent prognostic factor and should be further evaluated for MRD monitoring. It might especially be useful for patients with AML or MDS missing specific markers.

A TCR-mimic antibody to WT1 bypasses tyrosine kinase inhibitor resistance in human BCR-ABL+ leukemias

Acute and chronic leukemias, including CD34(+) CML cells, demonstrate increased expression of the Wilms tumor gene 1 product (WT1), making WT1 an attractive therapeutic target. However, WT1 is a currently undruggable, intracellular protein. ESKM is a human IgG1 T-cell receptor mimic monoclonal antibody directed to a 9-amino acid sequence of WT1 in the context of cell surface HLA-A*02. ESKM was therapeutically effective, alone and in combination with tyrosine kinase inhibitors (TKIs), against Philadelphia chromosome-positive acute leukemia in murine models, including a leukemia with the most common, pan-TKI, gatekeeper resistance mutation, T315I. ESKM was superior to the first-generation TKI, imatinib. Combination therapy with ESKM and TKIs was superior to either drug alone, capable of curing mice. ESKM showed no toxicity to human HLA-A*02:01(+) stem cells under the conditions of this murine model. These features of ESKM make it a promising nontoxic therapeutic agent for sensitive and resistant Ph(+) leukemias.

WT1 Peptide-Based Immunotherapy for Patients with Lung Cancer: Report of Two Cases

The Wilms' tumor gene WT1 is overexpressed in various types of solid tumors, including lung and breast cancer and WT1 protein is a tumor antigen for these malignancies. In phase I clinical trials of WT1 peptide-based cancer immunotherapy, two patients with advanced lung cancer were intradermally injected with 0.3 mg of an HLA-A*2402-restricted, 9-mer WT1 peptide emulsified with Montanide ISA51 adjuvant. Consecutive WT1 vaccination at 2-week intervals resulted in a reduction in tumor markers such as chorio-embryonic antigen (CEA) and sialyl Lewis (x) (SLX) and by a transient decrease in tumor size. No adverse effects except for local erythema at the injection sites of WT1 vaccine were observed. These results provided us with the first clinical evidence demonstrating that WT1 peptide-based immunotherapy should be a promising treatment for patients with lung cancer.

WT1 (Wilms' Tumor 1) Peptide Immunotherapy for Renal Cell Carcinoma

Tumor-specific immunotherapy with a Wilms' tumor 1 (WT1) peptide has been on clinical trial for leukemia, myelodysplastic syndrome, breast and lung cancers and is producing promising results. In this study, we treated three patients with renal cell carcinoma with an anchor modified, HLA-A*2402 binding WT1 peptide which was emulsified in Freund's incomplete adjuvant. In two patients tumor growth was suppressed and clinical response was evaluated as stable disease by the RECIST criteria after 3 months of weekly immunizations. Notably, development of new metastases has stopped in these patients for a prolonged period. No deleterious side effects were observed. Peptide-specific T cells were expanded in PBMCs of the patients and a substantial fraction of them bore the surface phenotype consistent with a CD8+ cytotoxic effector population. Although established tumors did not regress further, considering the component of the vaccine, i.e. peptide alone, the stabilization effect suggested the potential of WT1 peptide to develop into a more effective vaccine. To our knowledge, this is the first report of WT1 immunotherapy for renal cell carcinoma. Hopefully, the results will stimulate more extensive clinical studies.

Identification of gene expression-based prognostic markers in the hematopoietic stem cells of patients with myelodysplastic syndromes

PURPOSE

The diagnosis of patients with myelodysplastic syndromes (MDS) is largely dependent on morphologic examination of bone marrow aspirates. Several criteria that form the basis of the classifications and scoring systems most commonly used in clinical practice are affected by operator-dependent variation. To identify standardized molecular markers that would allow prediction of prognosis, we have used gene expression profiling (GEP) data on CD34+ cells from patients with MDS to determine the relationship between gene expression levels and prognosis.

PATIENTS AND METHODS

GEP data on CD34+ cells from 125 patients with MDS with a minimum 12-month follow-up since date of bone marrow sample collection were included in this study. Supervised principal components and lasso penalized Cox proportional hazards regression (Coxnet) were used for the analysis.

RESULTS

We identified several genes, the expression of which was significantly associated with survival of patients with MDS, including LEF1, CDH1, WT1, and MN1. The Coxnet predictor, based on expression data on 20 genes, outperformed other predictors, including one that additionally used clinical information. Our Coxnet gene signature based on CD34+ cells significantly identified a separation of patients with good or bad prognosis in an independent GEP data set based on unsorted bone marrow mononuclear cells, demonstrating that our signature is robust and may be applicable to bone marrow cells without the need to isolate CD34+ cells.

CONCLUSION

We present a new, valuable GEP-based signature for assessing prognosis in MDS. GEP-based signatures correlating with clinical outcome may significantly contribute to a refined risk classification of MDS.

Recent advances in understanding the molecular pathogenesis of myelodysplastic syndromes

The advent of novel genomic sequencing technologies has aided the identification of somatically acquired genetic abnormalities up to 80% of myelodysplastic syndrome (MDS) patients. Novel recurrent genetic mutations in pathways such as RNA splicing, DNA methylation and histone modification and cohesion complexes, underscore the molecular heterogeneity seen in this clinically varied disease. Functional studies to establish a causative link between genomic aberrations and MDS biogenesis are still in their infancy. The deluge of this molecular information, once validated on a larger cohort, will be incorporated into prognostic systems and clinical practise, and also hopefully aid in MDS therapeutics, especially in guiding targeted therapy.

Detection and preliminary characterization of CD8+T lymphocytes specific for Wilms' tumor antigen in patients with non-Hodgkin lymphoma

Wilms' tumor antigen (WT1) is overexpressed in many different solid tumors and hematologic malignancies. However, little is known about WT1 expression or WT1-specific immune responses in patients with non-Hodgkin lymphoma (NHL). In a cross-sectional survey study, we investigated the immune recognition of WT1 by patients with NHL. Utilizing a WT1 overlapping peptide library, we discovered that a large percentage of patients with NHL of all grades maintain WT1-specific T cells. Ex vivo frequencies of these T cells measured from unfractionated samples by the CD137 activation marker assay were high in many patients (some > 1% CD8+). Using standard in vitro techniques we discovered that they were cytotoxic to WT1 peptide library-loaded T2 cells and WT1 antigen-primed autologous Epstein-Barr virus-transformed B cell lines (EBV-LCLs) and expressed interferon gamma (IFN-γ). In addition, we detected WT1 mRNA transcripts in diseased lymph node tissues of patients with NHL utilizing real-time quantitative polymerase chain reaction (RT-qPCR) technology. These results are the first example of strong T cell reactivity against WT1 in patients with NHL which also demonstrate strong cytotoxicity against peptide-loaded tumor cells. The potential for developing WT1 as a target for immunotherapy in NHL deserves further exploration.

Role of WT1-ZNF224 interaction in the expression of apoptosis-regulating genes

The transcription factor Wilms' tumor gene 1, WT1, is implicated both in normal developmental processes and in the generation of a variety of solid tumors and hematological malignancies. Physical interactions of other cellular proteins with WT1 are known to modulate its function. We previously identified the Krüppel-like zinc-finger protein, ZNF224, as a novel human WT1-associating protein that enhances the transcriptional activation of the human vitamin D receptor promoter by WT1. Here, we have analyzed the effects of WT1-ZNF224 interaction on the expression of apoptosis-regulating genes in the chronic myelogenous leukemia (CML) K562 cell line. The results demonstrated that ZNF224 acts in fine tuning of WT1-dependent control of gene expression, acting as a co-activator of WT1 in the regulation of proapoptotic genes and suppressing WT1 mediated transactivation of antiapoptotitc genes. Moreover, the DNA damaging drug cytosine arabinoside (ara-C) induces expression of ZNF224 in K562 cells and this induction enhances cell apoptotic response to ara-C. These findings suggest that ZNF224 can be a mediator of DNA damage-induced apoptosis in leukemia cells.