The Role of Wilms' Tumor Gene (WT1) Expression as a Marker of Minimal Residual Disease in Acute Myeloid Leukemia

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.

Anticancer and cancer preventive activities of shogaol and curcumin from Zingiberaceae family plants in KG-1a leukemic stem cells

BACKGROUND

Leukemic stem cells (LSCs) present a significant challenge in the treatment of leukemia in patients because they exhibit a drug-resistant phenotype, making them difficult to eliminate. Searching for a new anticancer drug is crucial for improving leukemia treatment. Plants from the Zingiberaceae family are frequently used in traditional medicines due to their safety and accessibility. This study explores the anticancer activity, cancer preventive properties, and apoptosis inducing mechanisms of active compounds derived from these plants.

METHODS

Ten crude ethanolic extracts from each plant of the Zingiberaceae family were obtained using maceration techniques. The cytotoxicity of all extracts anticancer was assessed in comparison to anticancer drugs (cyclophosphamide, cytarabine, doxorubicin, and idarubicin) using MTT assay on cancer cell lines (KG-1a, K562, A549, MCF-7, and HeLa) and peripheral blood mononuclear cells (PBMCs). Cancer prevention properties of the effective extracts and their active compounds were evaluated by measuring the levels of tumor necrosis factor-alpha (TNF-α), interleukin-2 (IL-2), and nitric oxide (NO) using commercial kits. Cell cycle and cell death analyses were conducted using flow cytometry. Moreover, the effects of effective extracts and their active compounds on WT1 and CD34 expressions, as well as the apoptosis mechanism induced by the active compounds in KG-1a cells, were determined by Western blotting.

RESULTS

The cytotoxicity tests revealed that crude ethanolic extracts from Curcuma longa, C. zedoaria, and Zingiber officinale exhibited effective cytotoxicity against cancer cell lines while demonstrating lower impact on PBMCs. The active compounds of C. longa and C. zedoaria are curcuminoids, while those in Z. officinale are shogaol and gingerol. Notably, the IC20 values of curcuminoids and shogaol exhibited cancer prevention properties and reduced WT1 protein expression, thereby inhibiting cell proliferation. Furthermore, shogaol and curcumin demonstrated the ability to arrest the cell cycle at the G2/M phase and induce apoptosis through the Akt pathway.

CONCLUSION

These findings highlight shogaol and curcumin as promising compounds for leukemia treatment.

Finding potential targets in cell-based immunotherapy for handling the challenges of acute myeloid leukemia

Acute myeloid leukemia (AML) is a hostile hematological malignancy under great danger of relapse and poor long-term survival rates, despite recent therapeutic advancements. To deal with this unfulfilled clinical necessity, innovative cell-based immunotherapies have surfaced as promising approaches to improve anti-tumor immunity and enhance patient outcomes. In this comprehensive review, we provide a detailed examination of the latest developments in cell-based immunotherapies for AML, including chimeric antigen receptor (CAR) T-cell therapy, T-cell receptor (TCR)-engineered T-cell therapy, and natural killer (NK) cell-based therapies. We critically evaluate the unique mechanisms of action, current challenges, and evolving strategies to improve the efficacy and safety of these modalities. The review emphasizes how promising these cutting-edge immune-based strategies are in overcoming the inherent complexities and heterogeneity of AML. We discuss the identification of optimal target antigens, the importance of mitigating on-target/off-tumor toxicity, and the need to enhance the persistence and functionality of engineered immune effector cells. All things considered, this review offers a thorough overview of the rapidly evolving field of cell-based immunotherapy for AML, underscoring the significant progress made and the ongoing efforts to translate these innovative approaches into more effective and durable treatments for this devastating disease.

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.

Drug resistance in human cancers - Mechanisms and implications

Cancers have complex etiology and pose a significant impact from the health care perspective apart from the socio-economic implications. The enormity of challenge posed by cancers can be understood from the fact that clinical trials for cancer therapy has yielded minimum potential promises compared to those obtained for other diseases. Surgery, chemotherapy and radiotherapy continue to be the mainstay therapeutic options for cancers. Among the challenges posed by these options, induced resistance to chemotherapeutic drugs is probably the most significant contributor for poor prognosis and ineffectiveness of the therapy. Drug resistance is a property exhibited by almost all cancer types including carcinomas, leukemias, myelomas, sarcomas and lymphomas. The mechanisms by which drug resistance is induced include the factors within the tumor microenvironment, mutations in the genes responsible for drug metabolism, changes in the surface drug receptors and increased drug efflux. We present here comprehensively the drug resistance in cancers along with their mechanisms. Also, apart from resistance to regularly used chemotherapeutic drugs, we present resistance induction to new generation therapeutic agents such as monoclonal antibodies. Finally, we have discussed the experimental approaches to understand the mechanisms underlying induction of drug resistance and potential ways to mitigate induced drug resistance.

Role of WT1 in Measurable Residual Disease Follow-Up in the Post Allogeneic Stem Cell Transplant Setting

Objectives: The Wilms' tumor gene 1 (WT1) plays a critical role in cell development and the regulation of essential genes involved in cell growth and metabolism. In the context of hematopoietic tumors, including acute myeloid leukemia (AML), WT1 has been identified as a potential marker for measurable residual disease (MRD) assessment. Relapse after allogeneic hematopoietic stem cell transplantation (allo-SCT) remains a significant challenge in AML treatment, highlighting the importance of MRD monitoring for risk stratification and treatment decisions. This study aimed to investigate the clinical significance of WT1 as a molecular marker for MRD and its correlation with chimerism in AML patients post-allo-SCT setting. Methods: We have included 58 patients with WT1-expression-positive acute myeloid leukemia (AML) who received allo-SCT in our center between 2016-2022. The exclusion criteria are as follows: not having WT1 polymerase chain reaction (PCR) measurement at diagnosis, not receiving allo-SCT, and not having a serial measurement of WT1 post-transplant. Pre- and post-transplant assessments were made with flow cytometry, WT1 PCR, and bone marrow morphological evaluations. Statistical analyses were carried out to explore correlations between WT1 levels, MRD markers, and chimerism post-transplantation. Results: We found that WT1 had a significant correlation with flow cytometry and bone marrow morphological evaluation, but not with chimerism. Interestingly, high WT1 expressors exhibited a more robust correlation with chimerism compared to the general cohort. The negative predictive value for post-allo-SCT relapse was 91.8% for the whole WT1 cohort; for high WT1 expressors, it was similar, at 87.5%. The negative predictive value for post-allo-SCT relapse was high for the whole WT1 cohort; for high WT1 expressors, it was similar. The WT1 MRD assay showed a high negative predictive value for post-allo-SCT relapse, consistent across both the entire cohort (91.8%) and high WT1 expressors (87.5%). Conclusions: WT1 expression levels may serve as a valuable ancillary marker in MRD assessment and relapse prediction post-allo-SCT in AML patients, particularly for those lacking specific fusion genes or mutations. However, further large-scale, controlled studies are needed to standardize WT1 MRD assays and establish clear guidelines for their clinical application.

Efficacy of WT1 geneguided preemptive therapy for prevention of relapse in acute myeloid leukemia after transplantation and its optimal intervention threshold

OBJECTIVES

Monitoring minimal residual disease (MRD) and timely intervention are effective strategies for preventing relapse after allogeneic hematopoietic stem cell transplantation (allo-HSCT) in adult acute myeloid leukemia (AML). The WT1 gene, a pan-leukemia marker, can be used as an indicator for MRD monitoring in AML patients. Currently, there is no unified standard for the intervention timing or treatment threshold based on WT1 gene detection after transplantation. This study aims to evaluate the clinical value of WT1 gene-guided preemptive therapy and further explore its optimal intervention threshold.

METHODS

Data of adult AML patients with intermediate or high-risk cytogenetics who underwent allo-HSCT between January 2014 and June 2020 at the Department of Hematology, Xiangya Hospital, Central South University, were retrospectively collected. All patients had WT1 gene expression data within three years post-transplantation. We compared the outcomes of WT1-positive patients who received preemptive therapy with those who did not, and both groups with WT1-negative patients. The endpoints analyzed included cumulative incidence of relapse (CIR), disease-free survival (DFS) rate, overall survival (OS) rate, and non-relapse mortality (NRM) rate. Data of patients who did not receive any intervention were included to analyze factors that might influence prognosis. Univariate analysis was performed using factors such as age, gender, transplantation type,cytogenetic risk stratification, pre-transplant disease status, pre- and post-transplant WT1 levels, and donor gender; factors with P<0.10 in univariate analysis were further included in a Cox regression model for multivariate analysis. Receiver operating characteristic (ROC) curve analysis was used to determine the optimal cut-off value of WT1 gene expression for predicting relapse.

RESULTS

A total of 165 AML patients were included, of whom 86 had WT1 gene positivity within three years post-transplantation. Among these, 58 received preemptive therapy and 28 did not. Compared with WT1-negative patients, those WT1-positive patients who did not receive preemptive therapy had significantly higher 5-year CIR (42.9% vs 10.5%, P<0.001), lower 5-year DFS (50.0% vs. 80.7%, P=0.001), and lower 5-year OS (60.7% vs 82.8%, P=0.018), while the 5-year NRM rates were not significantly different (7.1% vs 8.9%, P=0.744). For patients who received preemptive therapy, no significant differences in these outcomes were observed (all P>0.05). Multivariate analysis revealed that post-transplantation WT1 gene positivity was a poor prognostic factor for AML patients (CIR: HR=6.24, P=0.000 1; DFS: HR=2.77, P=0.009 6). ROC curve analysis indicated that the area under the curve (AUC) for WT1 gene expression predicting post-transplantation relapse within 3 years was 0.727 (95% CI 0.582 to 0.873), with an optimal cut-off value of 122 copies, sensitivity of 60.0%, and specificity of 89.9%.

CONCLUSIONS

sequential monitoring of WT1 gene expression in intermediate- or high-risk AML patients after allo-HSCT within 3 years, with timely preemptive therapy for those who become WT1-positive, can effectively reduce relapse and improve prognosis. A WT1 gene expression level of 120 copies may be a more precise and reliable intervention threshold for preemptive therapy.

Prognostic impact of peripheral blood WT1 mRNA dynamics in patients with acute myeloid leukemia treated with venetoclax combination therapy

BACKGROUND

Wilms' tumor gene 1 (WT1) mRNA quantification is a useful marker of measurable residual disease in acute myeloid leukemia (AML). However, whether monitoring the WT1 mRNA levels may predict the outcome of venetoclax (VEN) combination therapy in AML is not reported. This study aims to elucidate whether WT1 mRNA dynamics could predict long-term prognosis.

METHODS

33 patients with untreated or relapsed/refractory AML evaluated for peripheral blood WT1 dynamics in VEN combination therapy were analyzed.

RESULTS

The median age was 73 years (range 39-87). Azacitidine was combined with VEN in 91% of patients. Overall, the median overall survival (OS) was 334 days (95% CI 210-482), and the complete remission (CR) plus CR with incomplete hematologic recovery rate was 59%. A 1-log reduction of WT1 mRNA values by the end of cycle 2 of treatment was associated with significantly better OS and event-free survival (EFS) (median OS 482 days vs. 237 days, p = 0.049; median EFS 270 days vs. 125 days, p = 0.02). The negativity of post-treatment WT1 mRNA value during the treatment was associated with significantly better OS and EFS (median OS 482 days vs. 256 days, p = 0.02; median EFS not reached vs. 150 days, p = 0.005). Multivariate analysis confirmed the significance of these two parameters as strong EFS predictors (HR 0.26, p = 0.024 and HR 0.15, p = 0.013, respectively). The increase in WT1 mRNA values was correlated with relapse.

CONCLUSION

This study demonstrates that WT1 mRNA dynamics can be a useful marker for assessing long-term prognosis of VEN combination therapy for AML.

WT1 and TP53 as valuable diagnostic biomarkers for relapse after hematopoietic stem cell transplantation in acute myeloid leukemia

BACKGROUND

Relapse following hematopoietic stem cell transplantation (HSCT) occurs relatively frequently and is a significant risk factor for mortality in patients with acute myeloid leukemia (AML). Early diagnosis is, therefore, of utmost importance and can provide valuable guidance for appropriate and timely intervention. Here, the diagnostic value of two molecular markers, Wilms tumor 1 (WT1) and tumor suppressor protein p53 (TP53), were studied.

METHODS AND RESULTS

Twenty AML patients undergoing HSCT participated in this investigation. Some had relapsed following HSCT, while others were in remission. Peripheral blood (PB) and bone marrow (BM) samples were collected following relapse and remission. WT1 and TP53 messenger RNA (mRNA) expression was evaluated using reverse transcription-quantitative polymerase chain reaction (RT‒qPCR). The diagnostic value of genes was evaluated by utilizing receiver-operating characteristic (ROC) curve analysis. ROC analysis showed WT1 and TP53 as diagnostic markers for relapse after HSCT in AML patients. The mRNA expression level of WT1 was elevated in individuals who experienced relapse compared to those in a state of remission (p value < 0.01). Conversely, the expression level of TP53 mRNA was lower in individuals who had relapsed compared to those in remission (p value < 0.01).

CONCLUSIONS

WT1 and TP53 possess the potential to serve as invaluable biomarkers in the identification of molecular relapse after HSCT in patients with AML. Further studies for a definitive conclusion are recommended.

Expression analysis, clinical significance and potential function of PLXNB2 in acute myeloid leukaemia

BACKGROUND

The overall survival (OS) rate of adult patients suffering from acute myeloid leukaemia (AML) remains unsatisfactory at less than 40%. Current risk stratification systems fail to provide accurate guidelines for precise treatment. Novel biomarkers for predicting prognosis are urgently needed. Plexin B2 (PLXNB2), a functional receptor of angiogenin (ANG), has been found to be aberrantly expressed in multitudinous tumours. We detected overexpression of PLXNB2 mRNA in AML via transcriptome microarray analysis. This study aims to explore the potential role of PLXNB2 as a biomarker of prognosis and a prospective target of AML.

METHODS

qRT‒PCR was conducted to verify the expression of PLXNB2 mRNA in bone marrow mononuclear cells from AML patients. Immunohistochemical and immunofluorescence staining were performed and confirmed increased expression of PLXNB2 protein in AML bone marrow tissues. Data on PLXNB2 expression, prognosis and clinical features were accessed from multiple bioinformatic databases, including The Cancer Genome Atlas (TCGA). Genes coexpressed and correlated with PLXNB2 were identified and analysed in the TCGA AML cohort. Metascape was applied for functional and pathway enrichment analysis of genes related to PLXNB2. Small molecular agents and traditional Chinese medicines potentially targeting genes related to PLXNB2 were screened via the Connectivity Map, TCMSP and HIT databases.

RESULTS

PLXNB2 mRNA and protein levels are higher in AML samples than in normal controls. Overexpression of PLXNB2 is associated with worse OS in AML. Patients with high PLXNB2 expression might benefit more from haematopoietic stem cell transplantation (HSCT) (indicated by prolonged OS) than those with only chemotherapy treatment. Differentially expressed genes between the high and low PLXNB2 expression groups were overlapped with PLXNB2-coexpressed genes, and genes that overlapped were enriched in immune functions, endothelial cell regulation and cell interaction gene sets, indicating the potential function of PLXNB2 in AML. A total of 36 hub genes were identified from the differentially expressed genes, and MRC1, IL10, CD163 and CCL22 had significant prognostic value for AML. Analysis of the connectivity map and traditional agents revealed that honokiol, morphines, triptolide and paeoniflorin could be potential treatment regimens.

CONCLUSIONS

The overexpression of PLXNB2 is an adverse prognostic factor in adult AML patients and could be used as a potential biomarker. PLXNB2 might exert an oncogenic role by modulating immune functions, endothelial cell functions and cell interactions. AML patients with high PLXNB2 expression could benefit more from HSCT.

WT1 and PRAME RNA-loaded dendritic cell vaccine as maintenance therapy in de novo AML after intensive induction chemotherapy

Intensive induction chemotherapy achieves complete remissions (CR) in >60% of patients with acute myeloid leukemia (AML) but overall survival (OS) is poor for relapsing patients not eligible for allogeneic hematopoietic stem cell transplantation (allo-HSCT). Oral azacytidine may be used as maintenance treatment in AML in first remission, but can be associated with substantial side effects, and less toxic strategies should be explored. Twenty AML patients in first CR (CR1) ineligible for allo-HSCT were treated with FDC101, an autologous RNA-loaded mature dendritic cell (mDC) vaccine expressing two leukemia-associated antigens (LAAs). Each dose consisted of 2.5-5 × 106 mDCs per antigen, given weekly until week 4, at week 6, and then monthly, during the 2-year study period. Patients were followed for safety and long-term survival. Treatment was well tolerated, with mild and transient injection site reactions. Eleven of 20 patients (55%) remained in CR, while 4 of 6 relapsing patients achieved CR2 after salvage therapy and underwent allo-HSCT. OS at five years was 75% (95% CI: 50-89), with 70% of patients ≥60 years of age being long-term survivors. Maintenance therapy with this DC vaccine was well tolerated in AML patients in CR1 and was accompanied by encouraging 5-year long-term survival.

Shorter duration of venetoclax administration to 14 days has same efficacy and better safety profile in treatment of acute myeloid leukemia

Venetoclax (VEN) is now widely used in the treatment of acute myelogenous leukemia (AML) in elderly patients who are not eligible for intensive remission induction therapy. Prolonged myelosuppression, increased incidence of infection, and long duration of hospital stay were major concerns for VEN treatment cases, and we thought that shortening the duration of VEN administration during induction therapy might solve these problems. Thirteen newly diagnosed AML patients who underwent VEN+azacitidine (AZA) induction therapy from March 2021 to June 2022 at Kushiro Rosai Hospital were analyzed retrospectively. The median age was 79 (range, 68-86) years, and 8 of the patients (61.5%) were classified as high risk according to the ELN 2017 risk stratification. Eight patients received VEN for 14 days (VEN14 group), and 5 patients received VEN for 28 days (VEN28 group). The composite complete remission (CRc) rate was 76.9% in total, and the CRc rates in the VEN14 and VEN28 groups were almost the same (75.0% and 80.0%, respectively). The median overall survival (OS) was not reached in the VEN14 group and was 254 days in the VEN28 group. The median event-free survival (EFS) was not reached in the VEN14 group and was 178 days in the VEN28 group. The VEN14 group might have a possibility to reduce febrile neutropenia (37.5% vs. 80%) and reduce the duration of hospital stay (median, 21.5 vs. 31 days) compared with the VEN28 group. VEN14 produced the same CRc rate and survival rate, safer profile, and shorter duration of hospital stay than VEN28.

Bone marrow CD34+ molecular chimerism as an early predictor of relapse after allogeneic stem cell transplantation in patients with acute myeloid leukemia

Background

Minimal residual disease (MRD) monitoring is an important tool to optimally address post-transplant management of acute myeloid leukemia (AML) patients.

Methods

We retrospectively analyzed the impact of bone marrow CD34+ molecular chimerism and WT1 on the outcome of a consecutive series of 168 AML patients submitted to allogeneic stem cell transplantation.

Results

The cumulative incidence of relapse (CIR) was significantly lower in patients with donor chimerism on CD34+ cells ≥ 97.5% and WT1 < 213 copies/ABL x 10^4 both at 1^st month (p=0.008 and p<0.001) and at 3^rd month (p<0.001 for both). By combining chimerism and WT1 at 3^rd month, 13 patients with chimerism < 97.5% or WT1 > 213 showed intermediate prognosis. 12 of these patients fell in this category because of molecular chimerism < 97.5% at a time-point in which WT1 was < 213.

Conclusions

Our results confirm that lineage-specific molecular chimerism and WT1 after allo-SCT (1^st and 3^rd month) are useful MRD markers. When considered together at 3^rd month, CD34+ molecular chimerism could represent an earlier predictor of relapse compared to WT1. Further studies are necessary to confirm this preliminary observation.

Clinical Impact of Measurable Residual Disease in Acute Myeloid Leukemia

Simple Summary

Advances in immunophenotyping and molecular techniques have allowed for the development of more sensitive diagnostic tests in acute leukemia. These techniques can identify low levels of leukemic cells (quantified as 10⁻⁴ to 10⁻⁶ ratio to white blood cells) in patient samples. The presence of such low levels of leukemic cells, termed “measurable/minimal residual disease” (MRD), has been shown to be a marker of disease burden and patient outcomes. In acute lymphoblastic leukemia, new agents are highly effective at eliminating MRD for patients whose leukemia progressed despite first line therapies. By comparison, the role of MRD in acute myeloid leukemia is less clear. This commentary reviews select data and remaining questions about the clinical application of MRD to the treatment of patients with acute myeloid leukemia.

Abstract

Measurable residual disease (MRD) has emerged as a primary marker of risk severity and prognosis in acute myeloid leukemia (AML). There is, however, ongoing debate about MRD-based surveillance and treatment. A literature review was performed using the PubMed database with the keywords MRD or residual disease in recently published journals. Identified articles describe the prognostic value of pre-transplant MRD and suggest optimal timing and techniques to quantify MRD. Several studies address the implications of MRD on treatment selection and hematopoietic stem cell transplant, including patient candidacy, conditioning regimen, and transplant type. More prospective, randomized studies are needed to guide the application of MRD in the treatment of AML, particularly in transplant.