Estimation of molecular upper remission limit for monitoring minimal residual disease in peripheral blood of acute myeloid leukemia patients by WT1 expression

Identification and validation of STAT4 as a prognostic biomarker in acute myeloid leukemia

Acute myelogenous leukemia (AML) is a common malignancy and is supposed to have the ability to escape host immune surveillance. The present study aimed to identify key genes in AML that may affect tumor immunity and to provide prognosis biomarkers of AML. The Cancer Genome Atlas (TCGA) dataset was screened for transcription factors (TFs) involved in immunity and influencing survival, combining Gene Expression Omnibus (GEO) data to validate the impact on patient survival. A prognostic signature was established using four transcription factors, and these genes play an important role in the immune system, with higher regulatory T cell (Treg) scores in high-risk patients compared with the low-risk group. Analysis of individual genes showed that STAT4 and Treg are closely related, which may be due to STAT4 transcribing related genes that affect immunity. STAT4 expression was positively correlated with the proportion of abnormal cells and promoted AML recurrence as verified by AML clinical patient samples. In addition, silencing of STAT4 significantly slowed down the proliferation capacity of HL60 cells. In conclusion, these findings suggest that STAT4 may be a potential biomarker for AML prognosis. As a key gene affecting the prognosis of AML patients, STAT4 has the potential to be a candidate diagnostic and prognostic biomarker 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.

Dynamic changes in the level of WT1 as an MRD marker to predict the therapeutic outcome of patients with AML with and without allogeneic stem cell transplantation

Monitoring minimal residue disease (MRD) is an effective approach to evaluate the response to chemotherapy, and it is used to select the ideal therapeutic strategy and to predict the recurrence during therapy for hematological disorders. The Wilm's tumor 1 (WT1) gene, which is highly expressed in >80% of patients with acute myeloid leukemia (AML) and its increased expression level may cause poor clinical outcomes, is a potential MRD marker of hematological neoplasms. In the present study, the expression levels of WT1 and other molecular markers were retrospectively analyzed by reverse transcription‑quantitative PCR in 195 patients with AML. The expression level of WT1 was significantly lower in patients with remission compared with patients with early‑stage and recurrent AML. Moreover, WT1 expression was significantly decreased in patients with RUNX family transcription factor 1‑RUNX1 translocation partner 1 fusion, but higher in patients with promyelocytic leukemia‑retinoic acid receptor α fusion. WT1 expression was significantly reduced during remission. In patients with AML who underwent allogeneic hematopoietic stem cell transplantation (allo‑HSCT), the mortality rate 2 years after allo‑HSCT was significantly lower in patients with low expression level of WT1 compared with subjects presenting high expression level of WT1. Collectively, the upregulation of the expression level of WT1 in combination with the identification of other genetic abnormalities may be used as MRD markers of hematological neoplasms.

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

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

Quantitative assessment of Wilms tumor 1 expression by real-time quantitative polymerase chain reaction in patients with acute myeloblastic leukemia

BACKGROUND

The Wilms tumor 1 (WT1) gene is originally defined as a tumor suppressor gene and a transcription factor that overexpressed in leukemic cells. It is highly expressed in more than 80% of acute myeloid leukemia (AML) patients, both in bone marrow (BM) and in peripheral blood (PB), and it is used as a powerful and independent marker of minimal residual disease (MRD); we have determined the expression levels of the WT1 by real-time quantitative polymerase chain reaction (RQ-PCR) in PB and BM in 126 newly diagnosed AML patients.

MATERIALS AND METHODS

This study was done in molecular pathology and cancer research center from April 2014 to June 2015, RQ-PCR method was used to determine the WT1 gene expression in BM and/or PB samples from 126 patients of AML, we cloned both WT1 and ABL genes for creating a standard curve, and we calculate copy number of WT1 genes in patients.

RESULTS

A total of 126 AML patients consist of 70 males (55.6%) and 56 females (44.4%), with a median age of 26 years; 104 (81%) patients out of 126 show overexpression of WT1 gene. We also concomitant monitoring of fusion transcripts (PML RARa, AML1-ETO, MLL-MLL, CBFb-MYH11, or DEK-CAN) in our patients, the AML1-ETO group showing remarkably low levels of WT1 compared with other fusion transcript and the CBFB-MYH11 showing high levels of WT1.

CONCLUSION

We conclude that WT1 expression by RQ-PCR in AML patients may be employed as an independent tool to detect MRD in the majority of normal karyotype AML patients.

Effect of the microtransplantation of allogeneic hematopoietic stem cells as maintenance therapy for elderly patients with acute leukemia

The incidence of acute myeloid leukemia (AML) increases with age. Elderly patients with AML are less tolerant to high-intensity consolidation therapy than younger patients, with significantly worse prognoses. Induction and consolidation therapy combined with allogeneic hematopoietic stem cell microtransplantation may improve the prognosis of elderly patients with AML. The present study reports the effect of maintenance therapy with low-dose chemotherapy treatment combined with microtransplantation in elderly patients with AML following consolidation. Between January 2011 and April 2014, three elderly patients (>55 years old), including one 58-year-old patient with acute mixed lineage leukemia (AMLL) and two patients with AML aged 59 years and 62 years, underwent microtransplantation maintenance therapy. Following a complete response to induction chemotherapy and consolidation chemotherapy with two to four cycles of medium dose Ara-c (auto transplantation was performed in the patient with AMLL), maintenance therapy was performed using low-dose Ara-c combined with human leukocyte antigen haploidentical allogeneic hematopoietic stem cell microtransplantation, which was repeated every 3 to 6 months. The patients were followed up for 27, 20 and 16 months, respectively, and all three patients achieved disease-free survival. The bone marrow Wilms' tumor suppression gene (WT1) level of the case with AMLL was dynamically monitored. The results showed that the WT1 level was abnormally high prior to microtransplantation and gradually declined to normal levels subsequent to the process. None of the patients suffered from graft versus host disease during the microtransplantation process. In conclusion, microtransplantation maintenance therapy following consolidation therapy is feasible in elderly patients with AML, and is expected to be able to further remove residual lesions and improve treatment efficacy. A large-scale clinical trial is required to confirm the effect of maintenance therapy in elderly patients with AML.

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.

Peripheral blood WT1 expression predicts relapse in AML patients undergoing allogeneic stem cell transplantation

To evaluate if WT1 expression may predict relapse after allo-SCT, we analyzed WT1 levels on peripheral blood (PB) and bone marrow (BM) before and after allo-SCT in 24 AML patients with WT1 overexpression at diagnosis. Five copies of WT1/ABL × 10⁴ from PB were identified as the threshold value that correlated with relapse after allo-SCT. The same correlation was not identified when WT1 expression was assessed from bone marrow (BM). Eight out of 11 (73%) patients with a pre-allo-SCT PB-WT1 ≥ 5 and 4/13 (31%) patients with a pre-allo-SCT PB-WT1 < 5 relapsed, respectively (P = 0.04). The incidence of relapse was higher in patients with PB-WT1 ≥ 5 measured after allo-SCT, at the 3rd (56% versus 38%; P = 0.43) and at the 6th month (71% versus 20%; P = 0.03). Patients with pretransplant PB-WT1 < 5 had significantly better 2-year OS and LFS than patients with a PB-WT1 ≥ 5 (81% versus 0% and 63% versus 20%) (P = 0.02). Our data suggest the usefulness of WT1 monitoring from PB to predict the relapse in allotransplanted AML patients and to modulate the intensity of conditioning and/or the posttransplant immunosuppression in an attempt to reduce the posttransplant relapse risk.

Minimal residual disease in acute myeloid leukaemia

Technological advances in the laboratory have led to substantial improvements in clinical decision making through the introduction of pretreatment prognostic risk stratification factors in acute myeloid leukaemia (AML). Unfortunately, similar progress has not been made in treatment response criteria, with the definition of 'complete remission' in AML largely unchanged for over half a century. Several clinical trials have demonstrated that high-sensitivity measurements of residual disease burden during or after treatment can be performed, that results are predictive for clinical outcome and can be used to improve outcomes by guiding additional therapeutic intervention to patients in clinical complete remission, but at increased relapse risk. We review these recent trials, the characteristics and challenges of the modalities currently used to detect minimal residual disease (MRD), and outline opportunities to both refine detection and improve clinical use of MRD measurements. MRD measurement is already the standard of care in other myeloid malignancies, such as chronic myelogenous leukaemia and acute promyelocytic leukaemia (APL). It is our belief that response criteria for non-APL AML should be updated to include assessment for molecular complete remission and recommendations for post-consolidation surveillance should include regular monitoring for molecular relapse as standard of care.