Expression patterns of WT1 and PRAME in acute myeloid leukemia patients and their usefulness for monitoring minimal residual disease

Immune-dysregulation harnessing in myeloid neoplasms

Myeloid malignancies arise in bone marrow microenvironments and shape these microenvironments in favor of malignant development. Immune suppression is one of the most important stages in myeloid leukemia progression. Leukemic clone expansion and immune dysregulation occur simultaneously in bone marrow microenvironments. Complex interactions emerge between normal immune system elements and leukemic clones in the bone marrow. In recent years, researchers have identified several of these pathological interactions. For instance, recent works shows that the secretion of inflammatory cytokines such as tumor necrosis factor-α (TNF-α), from bone marrow stromal cells contributes to immune dysregulation and the selective proliferation of JAK2V617F+ clones in myeloproliferative neoplasms. Moreover, inflammasome activation and sterile inflammation result in inflamed microenvironments and the development of myelodysplastic syndromes. Additional immune dysregulations, such as exhaustion of T and NK cells, an increase in regulatory T cells, and impairments in antigen presentation are common findings in myeloid malignancies. In this review, we discuss the role of altered bone marrow microenvironments in the induction of immune dysregulations that accompany myeloid malignancies. We also consider both current and novel therapeutic strategies to restore normal immune system function in the context of myeloid malignancies.

WT1 together with RUNX1::RUNX1T1 targets DUSP6 to dampen ERK activity in acute myeloid leukaemia

Wilms' tumour 1 (WT1) can function as an oncogene or a tumour suppressor. Our previous clinical cohort studies showed that low WT1 expression at diagnosis independently predicted poor outcomes in acute myeloid leukaemia (AML) with RUNX1::RUNX1T1, whereas it had an opposite role in AML with non-favourable cytogenetic risk (RUNX1::RUNX1T1-deficient). The molecular mechanism by which RUNX1::RUNX1T1 affects the prognostic significance of WT1 in AML remains unknown. In the present study, first we validated the prognostic significance of WT1 expression in AML. Then by using the established transfected cell lines and xenograft tumour model, we found that WT1 suppresses proliferation and enhances effect of cytarabine in RUNX1::RUNX1T1(+) AML but has opposite functions in AML cells without RUNX1::RUNX1T1. Furthermore, as a transcription factor, WT1 physically interacts with RUNX1::RUNX1T1 and acts as a co-factor together with RUNX1::RUNX1T1 to activate the expression of its target gene DUSP6 to dampen extracellular signal-regulated kinase (ERK) activity. When RUNX1::RUNX1T1-deficient, WT1 can activate the mitogen-activated extracellular signal-regulated kinase/ERK axis but not through targeting DUSP6. These results provide a mechanism by which WT1 together with RUNX1::RUNX1T1 suppresses cell proliferation through WT1/DUSP6/ERK axis in AML. The current study provides an explanation for the controversial prognostic significance of WT1 expression in AML patients.

Targeting PRAME for acute myeloid leukemia therapy

Despite significant progress in targeted therapy for acute myeloid leukemia (AML), clinical outcomes are disappointing for elderly patients, patients with less fit disease characteristics, and patients with adverse disease risk characteristics. Over the past 10 years, adaptive T-cell immunotherapy has been recognized as a strategy for treating various malignant tumors. However, it has faced significant challenges in AML, primarily because myeloid blasts do not contain unique surface antigens. The preferentially expressed antigen in melanoma (PRAME), a cancer-testis antigen, is abnormally expressed in AML and does not exist in normal hematopoietic cells. Accumulating evidence has demonstrated that PRAME is a useful target for treating AML. This paper reviews the structure and function of PRAME, its effects on normal cells and AML blasts, its implications in prognosis and follow-up, and its use in antigen-specific immunotherapy for AML.

Usefulness of KIT mutant transcript levels for monitoring measurable residual disease in t (8;21) acute myeloid leukemia

In addition to RUNX1::RUNX1T1 transcript levels, measurable residual disease monitoring using KIT mutant (KITmut ) DNA level is reportedly predictive of relapse in t (8; 21) acute myeloid leukemia (AML). However, the usefulness of KITmut transcript levels remains unknown. A total of 202 bone marrow samples collected at diagnosis and during treatment from 52 t (8; 21) AML patients with KITmut (D816V/H/Y or N822K) were tested for KITmut transcript levels using digital polymerase chain reaction. The individual optimal cutoff values of KITmut were identified by performing receiver operating characteristics curve analysis for relapse at each of the following time points: at diagnosis, after achieving complete remission (CR), and after Course 1 and 2 consolidations. The cutoff values were used to divide the patients into the KITmut -high (KIT_H) group and the KITmut -low (KIT_L) group. The KIT_H patients showed significantly lower relapse-free survival (RFS) and overall survival (OS) rates than the KIT_L patients after Course 1 consolidation (p = 0.0040 and 0.021, respectively) and Course 2 consolidation (p = 0.018 and 0.011, respectively) but not at diagnosis and CR. The <3-log reduction in the RUNX1::RUNX1T1 transcript levels after Course 2 consolidation was an independent adverse prognostic factor for RFS and OS. After Course 2 consolidation, the KIT_H patients with >3-log reduction in the RUNX1::RUNX1T1 transcript levels (11/45; 24.4%) had similar RFS as that of patients with <3-log reduction in the RUNX1::RUNX1T1 transcript levels. The combination of KITmut and RUNX1::RUNX1T1 transcript levels after Course 2 consolidation may improve risk stratification in t (8; 21) AML patient with KIT mutation.

High WT1 expression predicted induction chemotherapy failure in acute myeloid leukemia patients with non-favorable cytogenetic risk

The prognostic significance of WT1 expression at diagnosis in acute myeloid leukemia (AML) remains obscure, and subgroup analysis is the way for clarification. We previously reported the results in t(8;21) AML. In this study, 437 consecutive adult AML patients with non-favorable cytogenetic risk were enrolled. All patients were tested WT1 transcript levels using real-time quantitative PCR at diagnosis; AML-related common fusion genes, KMT2A-PTD, FLT3-ITD, NPM1, CEBPA and TP53 mutations were simultaneously tested. 92.4% of patients overexpressed WT1 compared to normal bone marrow. The existence of FLT3-ITD, NPM1 mutation and the absence of CEBPA biallelic mutation were significantly related to higher WT1 expression. The cutoff value for WT1 was determined by performing receiver operating characteristic curve analysis in regard to complete remission (CR) achievement and was used to categorize patients into low-expression (WT1-L) and high-expression (WT1-H) groups. In the entire cohort, WT1-H was significantly associated with a lower 1-course and 2-course CR rate (P < 0.0010 and P = 0.0060) but was not related to relapse-free survival (RFS). Multivariate analysis showed that WT1-H was an independent adverse prognostic factor for both 1-course and 2-course CR achievement. Subgroup analysis was further performed. WT1-H had a significant adverse impact on CR achievement within intermediate-cytogenetic risk, high-cytogenetic risk, ELN-defined-intermediate-risk, normal karyotype, KMT2A rearrangement, FAB-M2, FAB-M5 and NPM1 mutation (+) subgroups, whereas it had no impact within ELN-defined-low-risk, ELN-defined-high-risk, FAB-M4, FLT3-ITD mutation (+) and CEBPA biallelic mutation (+) subgroups. Moreover, WT1-H patients had a significantly lower RFS rate than WT1-L patients within both FAB-M5 and KMT2A rearrangement subgroups (P = 0.010 and 0.028), whereas WT1 had no impact on RFS within other subgroups mentioned above (all P > 0.05). Therefore, high WT1 expression at diagnosis independently predicted induction chemotherapy failure in AML patients with non-favorable cytogenetic risk, and it was related to relapse just within FAB-M5 and KMT2A rearrangement subgroups.

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.

Low IL7R Expression at Diagnosis Predicted Relapse in Adult Acute Myeloid Leukemia Patients With t(8;21)

Background

Acute myeloid leukemia (AML) with t(8;21) needs to be further stratified. In addition to leukemia cells, immune cells in tumor microenvironment participate in tumor initiation, growth and progression. Interleukins (ILs)/interleukin receptors (ILRs) interaction plays important roles in the antitumor immune response. IL7R is reported to be relevant to prognosis in solid tumor and acute lymphoblastic leukemia. However, the prognostic significance of IL7R in t(8;21) AML remains to be clarified.

Methods

Bone marrows collected from 156 newly diagnosed t(8;21) AML patients were used for testing IL7R transcript level by TaqMan-based real-time quantitative PCR (RQ-PCR), and RNAseq were performed in 15 of them. Moreover, IL7R expression at diagnosis were measured by RQ-PCR and flow cytometry (FCM) simultaneously in other 13 t(8;21) AML patients.

Results

t(8;21) AML patients had varied IL7R transcript levels and were categorized into low-expression (IL7R-L) and high-expression (IL7R-H) groups; IL7R-L was significantly associated with a lower relapse-free survival (RFS) rate (P=0.0027) and KITD816/D820 mutation (P=0.0010). Furthermore, IL7R-L was associated with a lower RFS rate in KITD816/D820 group (P=0.013) and IL7R-H/KITD816/D820 patients had similar RFS to KITN822/e8/WT patients (P=0.35). GO analysis enrichment showed that down-regulated genes were predominantly involved in the regulation of T cell and leukocyte activation, proliferation and differentiation in IL7R-L group. IL7R-L had significantly lower levels of Granzymes A/B, CCR7, CD28 and CD27 than IL7R-H group (all P&lt;0.05). FCM analysis showed IL7R protein was primarily expressed in CD4+ T and CD8+ T cell subset. A significant association was found between the transcript level of IL7R and the percentage of CD8+ T cells in nucleated cells (P=0.015) but not CD4+ T cells (P=0.47).

Conclusion

Low IL7R transcript level of bone marrow at diagnosis predicted relapse in t(8;21) AML, which might be caused by the difference in the amount, status and function of T cells.

Correlation of preferentially expressed antigen of melanoma (PRAME) gene expression with clinical characteristics in acute leukemia patients

Background

Preferentially expressed antigen of melanoma (PRAME) gene is regularly overexpressed in acute leukemia (AL) and other malignant diseases which are recognized by human leucocyte antigen (HLA-24) located in the human chromosome of 22q11 coded by 509 amino acids. To rule out the PRAME gene expression in AL patients and its correlation with clinical characteristics in the Indian population set up by RT-qPCR.

Results

A total of 42 samples collected, 29 (69.4%) were males, and 13 (30.95%) were females, with a mean and standard deviation for age were 39.07 ± 22.22 years. Of which AML were of 22 (52.38%) cases, ALL were of 14 (33.33%) cases, and 6 (14.2%) cases which included other forms of leukemia. PRAME gene expression was highly expressed in thirty-three 27 (64.28%) AL patients compared to the least expression in healthy individuals. No significant difference between the different forms of AL (p=0.3203) was observed. Cytogenetic analysis of normal karyotype (NK), abnormal karyotype (Ab. K), and culture failure (CF) displayed statistical non-significance (p=0.5801). Among cytogenetic abnormalities obtained, no significant differences between the groups were observed (p=0.8507). Chloride, potassium, and absolute lymphocyte count (ALC) was found to be statistically significant with p=0.0038**, p=0.0358*, and p=0.0216*, respectively, between all other clinical characteristics. There was no correlation between the PRAME gene expression and clinical parameters.

Conclusion

PRAME gene expression in AL patients was highly expressed, comparable to studies reported globally with significant cytogenetic results. PRAME gene could be used as a potential diagnostic marker for monitoring the malignancies and minimal residual disease in AL.

[Clinical features and prognosis of childhood B-lineage acute lymphoblastic leukemia expressing the PRAME gene]

OBJECTIVES

To study the clinical and prognostic significance of the preferentially expressed antigen of melanoma (PRAME) gene in the absence of specific fusion gene expression in children with B-lineage acute lymphoblastic leukemia (B-ALL).

METHODS

A total of 167 children newly diagnosed with B-ALL were enrolled, among whom 70 were positive for the PRAME gene and 97 were negative. None of the children were positive for MLL-r, BCR/ABL, E2A/PBX1, or ETV6/RUNX1. The PRAME positive and negative groups were analyzed in terms of clinical features, prognosis, and related prognostic factors.

RESULTS

Compared with the PRAME negative group, the PRAME positive group had a significantly higher proportion of children with the liver extending >6 cm below the costal margin (P<0.05). There was a significant reduction in the PRAME copy number after induction chemotherapy (P<0.05). In the minimal residual disease (MRD) positive group after induction chemotherapy, the PRAME copy number was not correlated with the MRD level (P>0.05). In the MRD negative group, there was also no correlation between them (P>0.05). The PRAME positive group had a significantly higher 4-year event-free survival rate than the PRAME negative group (87.5%±4.6% vs 73.5%±4.6%, P<0.05), while there was no significant difference between the two groups in the 4-year overall survival rate (88.0%±4.4% vs 85.3%±3.8%, P>0.05). The Cox proportional-hazards regression model analysis showed that positive PRAME expression was a protective factor for event-free survival rate in children with B-ALL (P<0.05).

CONCLUSIONS

Although the PRAME gene cannot be monitored as MRD, overexpression of PRAME suggests a good prognosis in B-ALL.

The Role of T Cell Immunotherapy in Acute Myeloid Leukemia

Acute myeloid leukemia (AML) is a heterogeneous disease associated with various alterations in T cell phenotype and function leading to an abnormal cell population, ultimately leading to immune exhaustion. However, restoration of T cell function allows for the execution of cytotoxic mechanisms against leukemic cells in AML patients. Therefore, long-term disease control, which requires multiple therapeutic approaches, includes those aimed at the re-establishment of cytotoxic T cell activity. AML treatments that harness the power of T lymphocytes against tumor cells have rapidly evolved over the last 3 to 5 years through various stages of preclinical and clinical development. These include tissue-infiltrated lymphocytes (TILs), bispecific antibodies, immune checkpoint inhibitors (ICIs), chimeric antigen receptor T (CAR-T) cell therapy, and tumor-specific T cell receptor gene-transduced T (TCR-T) cells. In this review, these T cell-based immunotherapies and the potential of TILs as a novel antileukemic therapy will be discussed.

Trial Watch: Adoptive TCR-Engineered T-Cell Immunotherapy for Acute Myeloid Leukemia

Simple Summary

Acute myeloid leukemia (AML) is a type of blood cancer with an extremely grim prognosis. This is due to the fact that the majority of patients will relapse after frontline treatment. Overall survival of relapsed AML is very low, and treatment options are few. T lymphocytes harnessed with antitumor T-cell receptors (TCRs) can produce objective clinical responses in certain cancers, such as melanoma, but have not entered the main road for AML. In this review, we describe the current status of the field of TCR-T-cell therapies for AML.

Abstract

Despite the advent of novel therapies, acute myeloid leukemia (AML) remains associated with a grim prognosis. This is exemplified by 5-year overall survival rates not exceeding 30%. Even with frontline high-intensity chemotherapy regimens and allogeneic hematopoietic stem cell transplantation, the majority of patients with AML will relapse. For these patients, treatment options are few, and novel therapies are urgently needed. Adoptive T-cell therapies represent an attractive therapeutic avenue due to the intrinsic ability of T lymphocytes to recognize tumor cells with high specificity and efficiency. In particular, T-cell therapies focused on introducing T-cell receptors (TCRs) against tumor antigens have achieved objective clinical responses in solid tumors such as synovial sarcoma and melanoma. However, contrary to chimeric antigen receptor (CAR)-T cells with groundbreaking results in B-cell malignancies, the use of TCR-T cells for hematological malignancies is still in its infancy. In this review, we provide an overview of the status and clinical advances in adoptive TCR-T-cell therapy for the treatment of AML.

Prognostic significance of TIM-3 expression pattern at diagnosis in patients with t(8;21) acute myeloid leukemia

Acute myeloid leukemia (AML) with t(8;21) is a heterogeneous disease and needs to be stratified. Both, cancer cells and immune cells participate in tumor initiation, growth and progression and might affect clinical outcomes. TIM-3 (T cell immunoglobulin and mucin domain-containing protein 3), an immune checkpoint molecule, is expressed not only on immune cells but also on leukemic stem cells (LSCs) in AML. This prompted us to investigate the prognostic significance of TIM-3 in t(8;21) AML. A total of 47 t(8;21) AML patients were tested for TIM-3 expression by multi-parameter flow cytometry at diagnosis. 35 of these, who received chemotherapy alone or along with allogeneic hematopoietic stem cell transplantation were followed up. The expression pattern of TIM-3 on T-cells and NK (natural killer) cells as a whole (T + NK) and LSCs were evaluated independently. High percentage of T + NK - TIM-3⁺ and CD34⁺CD38^-TIM-3⁺ cells were significantly associated with a high 2-year cumulative incidence of relapse (CIR) (p = 0.028, 0.016). Further, concurrent high frequencies of T + NK-TIM-3⁺ and CD34⁺CD38^-TIM-3⁺ cells at diagnosis were significantly associated with a high 2-year CIR (p < 0.0001) and this together with c-KIT D816 mutation were the independent adverse prognostic factors for relapse (hazard ratio (HR)=2.5, [95% confidence interval (CI), 1.1-6.0], p = 0.04; HR = 46.5, [95% CI, 2.7-811.5], p = 0.009). In conclusion, the expression pattern of TIM-3 on both T and NK cells and LSCs at diagnosis had prognostic significance in t (8;21) AML.

T-cell-based immunotherapy of acute myeloid leukemia: current concepts and future developments

Acute myeloid leukemia (AML) is a heterogeneous disease linked to a broad spectrum of molecular alterations, and as such, long-term disease control requires multiple therapeutic approaches. Driven largely by an improved understanding and targeting of these molecular aberrations, AML treatment has rapidly evolved over the last 3-5 years. The stellar successes of immunotherapies that harness the power of T cells to treat solid tumors and an improved understanding of the immune systems of patients with hematologic malignancies have led to major efforts to develop immunotherapies for the treatment of patients with AML. Several immunotherapies that harness T cells against AML are in various stages of preclinical and clinical development. These include bispecific and dual antigen receptor-targeting antibodies (targeted to CD33, CD123, CLL-1, and others), chimeric antigen receptor (CAR) T-cell therapies, and T-cell immune checkpoint inhibitors (including those targeting PD-1, PD-L1, CTLA-4, and newer targets such as TIM3 and STING). The current and future directions of these T-cell-based immunotherapies in the treatment landscape of AML are discussed in this review.

Re-Emergence of Minimal Residual Disease Detected by Flow Cytometry Predicts an Adverse Outcome in Pediatric Acute Lymphoblastic Leukemia

Purpose

While the role of minimal residual disease (MRD) assessment and the significance of achieving an MRD-negative status during treatment have been evaluated in previous studies, there is limited evidence on the significance of MRD re-emergence without morphological relapse in acute lymphoblastic leukemia (ALL). We sought to determine the clinical significance of MRD re-emergence in pediatric ALL patients.

Methods

Between 2005 and 2017, this study recruited 1126 consecutive patients newly diagnosed with ALL. Flow cytometry was performed to monitor MRD occurrence during treatment.

Results

Of 1030 patients with MRD-negative results, 150 (14.6%) showed MRD re-emergence while still on morphological complete remission (CR). Patients with white blood cell counts of ≥50 × 10⁹/L (p = 0.033) and MRD levels of ≥0.1% on day 33 (p = 0.012) tended to experience MRD re-emergence. The median re-emergent MRD level was 0.12% (range, 0.01–10.00%), and the median time to MRD re-emergence was 11 months (range, <1–52 months). Eighty-five (56.6%) patients subsequently developed relapse after a median of 4.1 months from detection of MRD re-emergence. The median re-emergent MRD level was significantly higher in the relapsed cohort than in the cohort with persistent CR (1.05% vs. 0.48%, p = 0.005). Of the 150 patients, 113 continued to receive chemotherapy and 37 underwent transplantation. The transplantation group demonstrated a significantly higher 2-year overall survival (88.7 ± 5.3% vs. 46.3 ± 4.8%, p < 0.001) and cumulative incidence of relapse (23.3 ± 7.4% vs. 64.0 ± 4.6%, p < 0.001) than the chemotherapy group.

Conclusions

MRD re-emergence during treatment was associated with an adverse outcome in pediatric ALL patients. Transplantation could result in a significant survival advantage for these patients.

The role of minimal residual disease in specific subtypes of pediatric acute lymphoblastic leukemia

Acute lymphoblastic leukemia (ALL) is a heterogeneous disease whose prognostic factors include minimal residual disease (MRD) and cytogenetic abnormalities. To explore the significance of MRD in ALL subtypes, we analyzed the outcomes of 1126 children treated with risk-stratified therapy based on sequential MRD monitoring. MRD distributions and treatment outcomes differed between distinct leukemia subtypes. Patients with ETV6-RUNX1 or hyperdiploidy had the best prognosis (5-year OS: 97 ± 1.5% and 89.2 ± 2.7%). However, hyperdiploidy patients with MRD ≥ 10% on day 15 had a higher risk of relapse (36.4%) than those with ETV6-RUNX1. TCF3-PBX1 patients had the fastest disease clearance (negative MRD rate on day 33: 92.1%), but the overall prognosis was intermediate (5-year OS: 82.5%). Patients with high-risk characteristics and ALL-T had inferior outcomes: even with undetectable MRD on day 33, cumulative incidence of relapse was 19.9% and 23.4%, respectively. Moreover, those with poor early-treatment response and detectable week-12 MRD had a worse prognosis. After adjusting for other risk factors, re-emergent MRD was the most significant adverse prognostic indicator overall. Sequential MRD measurement is important for MRD-guided therapy, and integration of MRD values at different timepoints based on leukemia subtype could allow for more refined risk stratification.

Outcome and Prognostic Features in Pediatric Acute Megakaryoblastic Leukemia Without Down Syndrome: A Retrospective Study in China

BACKGROUND

Acute megakaryoblastic leukemia (AMKL) is a biologically heterogeneous subtype of acute myeloid leukemia that originates from megakaryocytes. Patients with AMKL with non-Down syndrome (DS) had a poorer prognosis. However, clear prognostic indicators and treatment recommendations for this subgroup remain controversial.

PATIENTS AND METHODS

Herein, we performed a retrospective study on 40 patients (age ≤ 18 years) with non-Down syndrome AMKL at our institution. We assessed the effect of different prognostic factors, such as their cytogenetic abnormalities, early treatment response, and the role of hematopoietic stem cell transplantation (HSCT) as post-remission treatment on the outcomes.

RESULTS

The complete remission (CR) rate of the patients was 57.9% and 81.1%, respectively, at the end of induction therapy 1 and 2. The overall survival (OS) and event-free survival rates at 2 years were 41% ± 13% and 41% ± 10%, respectively. An analysis of the cytogenetic features showed that patients with +21 or hyperdiploid (> 50 chromosomes) had significantly better OS than those in other cytogenetic subgroups (P_log-rank = .048 and P_log-rank = .040, respectively). Besides cytogenetics, an excellent early treatment response (CR and minimal residual disease < 1% after induction therapy 1) also provided a significant survival benefit in univariate analysis in our study. However, multivariate analysis indicated that allogeneic HSCT was the only independent prognostic marker (relative risk, 11.192; 95% confidence interval, 2.045-61.241; P = .005 for OS and relative risk, 5.400; 95% confidence interval, 1.635-17.832; P = .006 for event-free survival, respectively).

CONCLUSION

AMKL in patients with non-Down syndrome has a poor outcome. With poor OS but CR rates comparable with other acute myeloid leukemia subtypes, allogenic HSCT may be a better option for post-remission therapy than conventional chemotherapy, especially for those having a poor response to induction therapy.

High PRDM16 expression predicts poor outcomes in adult acute myeloid leukemia patients with intermediate cytogenetic risk: a comprehensive cohort study from a single Chinese center

Acute myeloid leukemia with intermediate cytogenetic risk (ICR-AML) needs to be stratified and abnormal gene expression might be prognostic. PR/SET domain 16 (PRDM16) transcript levels were assessed in 267 consecutive adult ICR-AML patients at diagnosis by real-time quantitative PCR. 38.2% patients had PRDM16 transcript levels higher than the upper limit of normal bone marrow samples. Through ROC curve analysis and comparison of relapse-free survival (RFS), the optimal cutoff value of PRDM16 transcript levels was identified to group patients into high expression (PRDM16-H, 21.3%) and low expression (PRDM16-L). PRDM16-H was significantly associated with lower 4-year RFS and overall survival (OS) rates in the entire cohort, patients with normal karyotypes, FLT3-ITD (-) and NPM1 mutation (+)/FLT3-ITD (-) patients (all p < .05). Multivariate analysis showed that PRDM16-H was an independent adverse prognostic factor for RFS and OS in the entire cohort. Therefore, high PRDM16 expression at diagnosis predicts poor outcomes in adult ICR-AML patients.

Overexpression of WT1 and PRAME predicts poor outcomes of patients with myelodysplastic syndromes with thrombocytopenia

Thrombocytopenia is associated with life-threatening bleeding and is common in myelodysplastic syndromes (MDS). Robust molecular prognostic biomarkers need to be developed to improve clinical decision making for patients with MDS with thrombocytopenia. Wilms tumor 1 (WT1) and preferentially expressed antigen in melanoma (PRAME) are promising immunogenic antigen candidates for immunotherapy, and their clinical effects on patients with MDS with thrombocytopenia are still not well understood. We performed a multicenter observational study of adult patients with MDS with thrombocytopenia from 7 different tertiary medical centers in China. We examined bone marrow samples collected at diagnosis for WT1 and PRAME transcript levels and then analyzed their prognostic effect for patients with MDS with thrombocytopenia. In total, we enrolled 1110 patients diagnosed with MDS with thrombocytopenia. Overexpression of WT1 and PRAME was associated with elevated blast percentage, worse cytogenetics, and higher Revised International Prognostic Scoring System (IPSS-R) risk. Further, both WT1 and PRAME overexpression were independent poor prognostic factors for acute myeloid leukemia evolution, overall survival, and progression-free survival. Together, the 2 genes overexpression identified a population of patients with MDS with substantially worse survival. On the basis of WT1 and PRAME transcript levels, patients with MDS with IPSS-R low risk were classified into 2 significantly divergent prognostic risk groups: a low-favorable group and a low-adverse group. The low-adverse group had survival similar to that of patients in the intermediate-risk group. Our study demonstrates that the evaluation of WT1/PRAME transcript analysis may improve the prognostication precision and better risk-stratify the patients.

Both Methylation and Copy Number Variation Participated in the Varied Expression of PRAME in Multiple Myeloma

Purpose

The cancer-testis antigen, which is a preferentially expressed antigen of melanoma (PRAME), is an ideal target for immunotherapy and cancer vaccines. Since the expression of this antigen is relevant to therapy responses, the heterogeneity in its expression and the underlying mechanism need to be investigated.

Patients and Methods

Plasma cell sorting was performed in 48 newly diagnosed multiple myeloma (MM) patients. Real-time quantitative PCR was performed to examine the PRAME transcript levels and gene copy numbers. Bisulfate clone sequencing of the PRAME promoter and exon 1b regions was performed in 4 patients. Quantitative methylation-specific PCR of the +287 CpG site was performed for all patients. The human MM cell lines RPMI8226, LP-1 and MOLP-2 were treated with 5-azacytidine.

Results

The median PRAME transcript level was 3.1% (range: 0–298.3%) in the plasma cells sorted from the 48 MM patients. Eleven (22.9%) and 37 (77.1%) patients were individually categorized into the PRAME low- and high-expression groups according to the cut-off value of 0.05%. The methylation ratios of the promoter and the 3ʹ region of exon 1b region were both negatively related to the transcript levels. The degrees of methylation at the +287 CpG site were significantly negatively related to the transcript levels in all 48 patients (r=−0.44, P=0.0018), and those in the high-expression group (r=−0.69, P<0.0001) but not those in the low-expression group (r=−0.27, P=0.43). All 5 patients with homozygous deletions were categorized into the low-expression group. There were no significant differences in the PRAME transcript levels between the hemizygous deletion (n=8) and no deletion (n=35) groups (P=0.40). Furthermore, the PRAME transcript levels significantly increased in the MM cell lines after treatment with 5-azacytidine.

Conclusion

Both methylation and copy number variation may participate in the regulation of PRAME expression in MM; in patients with no homozygous deletion, PRAME expression is mainly controlled by methylation, and a proportion of fairly low expression is caused by homozygous deletion.

T-Cell Receptor-Based Immunotherapy for Hematologic Malignancies

Adoptive immunotherapy with engineered T cells is at the forefront of cancer treatment. T cells can be engineered to express T-cell receptors (TCRs) specific for tumor-associated antigens (TAAs) derived from intracellular or cell surface proteins. T cells engineered with TCRs (TCR-T) allow for targeting diverse types of TAAs, including proteins overexpressed in malignant cells, those with lineage-restricted expression, cancer-testis antigens, and neoantigens created from abnormal, malignancy-restricted proteins. Minor histocompatibility antigens can also serve as TAAs for TCR-T to treat relapsed hematologic malignancies after allogeneic hematopoietic cell transplantation. Moreover, TCR constructs can be modified to improve safety and enhance function and persistence of TCR-T. Transgenic T-cell receptor therapies targeting 3 different TAAs are in early-phase clinical trials for treatment of hematologic malignancies. Preclinical studies of TCR-T specific for many other TAAs are underway and offer great promise as safe and effective therapies for a wide range of cancers.

WT1 overexpression predicted good outcomes in adult B-cell acute lymphoblastic leukemia patients receiving chemotherapy

Objectives: The prognostic role of WT1 in acute lymphoblastic leukemia (ALL) is still controversial. No study has focused on the prognostic role of WT1 expression in adult B-ALL patients receiving chemotherapy only.Methods: Using TaqMan-based real time quantitative PCR (RQ-PCR), we detected the WT1 transcript levels of 162 de-novo adult B-ALL patients at the time of diagnosis and analysed their clinical features.Results: WT1 overexpression was defined as a transcript level higher than 0.50%, which is the upper limit in normal bone marrow. WT1 overexpression was identified in 66.0% of the patients and was an independent positive prognostic factor for CIR, RFS and OS in patients who received chemotherapy only (CIR: HR = 0.236 [95% confidence interval 0.094-0.592]; P = 0.002; RFS: HR = 0.223 [0.092-0.543]; P = 0.001; OS: HR = 0.409 [0.214-0.783]; P = 0.007) and in patients who did not have BCR-ABL fusion or KMT2A rearrangements (CIR: HR = 0.431 [0.201-0.921]; P = 0.030; RFS: HR = 0.449 [0.224-0.899]; P = 0.024; OS: HR = 0.521 [0.278-0.977]; P = 0.042). However, WT1 overexpression had no prognostic value in patients who received allogenic hematopoietic stem cell transplantation (allo-HSCT). Furthermore, allo-HSCT could improve the prognosis of patients with low WT1 expression.Conclusion: Therefore, testing for WT1 expression at the time of diagnosis may predict outcomes in adult B-ALL patients who receive only chemotherapy and who do not have the BCR-ABL fusion gene or KMT2A rearrangements. Allo-HSCT may improve the prognosis of patients with low WT1 transcript levels.

Is Hematopoietic Stem Cell Transplantation Required to Unleash the Full Potential of Immunotherapy in Acute Myeloid Leukemia?

From monoclonal antibodies (mAbs) to Chimeric Antigen Receptor (CAR) T cells, immunotherapies have enhanced the efficacy of treatments against B cell malignancies. The same has not been true for Acute Myeloid Leukemia (AML). Hematologic toxicity has limited the potential of modern immunotherapies for AML at preclinical and clinical levels. Gemtuzumab Ozogamicin has demonstrated hematologic toxicity, but the challenge of preserving normal hematopoiesis has become more apparent with the development of increasingly potent immunotherapies. To date, no single surface molecule has been identified that is able to differentiate AML from Hematopoietic Stem and Progenitor Cells (HSPC). Attempts have been made to spare hematopoiesis by targeting molecules expressed only on later myeloid progenitors as well as AML or using toxins that selectively kill AML over HSPC. Other strategies include targeting aberrantly expressed lymphoid molecules or only targeting monocyte-associated proteins in AML with monocytic differentiation. Recently, some groups have accepted that stem cell transplantation is required to access potent AML immunotherapy and envision it as a rescue to avoid severe hematologic toxicity. Whether it will ever be possible to differentiate AML from HSPC using surface molecules is unclear. Unless true specific AML surface targets are discovered, stem cell transplantation could be required to harness the true potential of immunotherapy in AML.

Overexpressed WT1 exhibits a specific immunophenotype in intermediate and poor cytogenetic risk acute myeloid leukemia

Many studies have confirmed that overexpressed WT1 exists in leukemic cells, especially in AML. However, the immunophenotypic features of this sort of leukemic cells remain to be unclarified. We retrospectively analyzed the immunophenotype of 283 newly diagnosed AML patients with intermediated and poor cytogenetic risk to evaluate the correlation between phenotype and WT1 overexpression. EVI1 transcripts, KMT2A-PTD, FLT3-ITD, and NPM1 mutations were simultaneously assessed. Our results revealed that overexpressed WT1 was significantly associated with the expression of CD117, CD13, and CD123. Besides, leukemic cells with WT1 overexpression also lacked lymphoid and myeloid differentiation-related markers. FAB subtype M2 patients had higher WT1 levels, compared with other FAB subtype. Multivariate analysis was proved that NPM1 mutation, M2 subtype, and the expression of CD123 were independently associated with WT1 overexpression. These indicated that AML with overexpressed WT1 was proliferated and blocked in the early stage of AML development. It presumably provided some clues to detect overexpressed WT1 cells via multiparameter flow cytometry. CD123-targeted drugs might become one of the alternative treatments for patients with WT1 overexpression.

Subgroup Analysis Can Optimize the Relapse-Prediction Cutoff Value for WT1 Expression After Allogeneic Hematologic Stem Cell Transplantation in Acute Myeloid Leukemia

High WT1 expression after allogeneic hematologic stem cell transplantation (allo-HSCT) can strongly predict relapse in acute myeloid leukemia (AML). However, the cutoff values obtained have been inconsistent. Precise cutoff values may be optimized through subtype analysis; the RUNX1-RUNX1T1 fusion transcript provides an ideal reference. RUNX1-RUNX1T1 and WT1 transcript levels were simultaneously measured in 1299 bone marrow samples serially collected from 176 t(8;21) AML patients after allo-HSCT. The upper limit of the normal bone marrow WT1 level was 0.6%, which we previously reported to be the cutoff value for significant relapse prediction in AML as a whole. WT1 cutoff values of 0.6%, 1.2%, and 1.8% significantly differentiated patients in relapse after allo-HSCT. Nonetheless, patients with WT1 levels of 0.6% to 1.2% and those with levels of >1.2% and 1.8% after HSCT had rates of cumulative incidence of relapse similar to those with a continuous WT1 level of ≤0.6%, and both were significantly lower than that in patients with a WT1 level of >1.8%. WT1 expression was significantly related to RUNX1-RUNX1T1 transcript levels at WT1 levels of >1.8% but not at levels of 0.6% to 1.2% or >1.2% to 1.8%. Therefore, subgroup analysis can optimize the relapse-prediction cutoff value of WT1 expression. A cutoff level of 1.8% more accurately differentiates t(8;21) AML patients in relapse after allo-HSCT than does a cutoff level of 0.6%.

[An interlaboratory comparison study on the detection of RUNX1-RUNX1T1 fusion transcript levels and WT1 transcript levels]

Objective: To investigate the current status and real performance of the detection of RUNX1-RUNX1T1 fusion transcript levels and WT1 transcript levels in China through interlaboratory comparison. Methods: Peking University People's Hospital (PKUPH) prepared the samples for comparison. That is, the fresh RUNX1-RUNX1T1 positive (+) bone morrow nucleated cells were serially diluted with RUNX1-RUNX1T1 negative (-) nucleated cells from different patients. Totally 23 sets with 14 different samples per set were prepared. TRIzol reagent was added in each tube and thoroughly mixed with cells for homogenization. Each laboratory simultaneously tested RUNX1-RUNX1T1 and WT1 transcript levels of one set of samples by real-time quantitative PCR method. All transcript levels were reported as the percentage of RUNX1-RUNX1T1 or WT1 transcript copies/ABL copies. Spearman correlation coefficient between the reported transcript levels of each participated laboratory and those of PKUPH was calculated. Results: ①RUNX1-RUNX1T1 comparison: 9 samples were (+) and 5 were (-) , the false negative and positive rates of the 20 participated laboratories were 0 (0/180) and 5% (5/100) , respectively. The reported transcript levels of all 9 positive samples were different among laboratories. The median reported transcript levels of 9 positive samples were from 0.060% to 176.7%, which covered 3.5-log. The ratios of each sample's highest to the lowest reported transcript levels were from 5.5 to 12.3 (one result which obviously deviated from other laboratories' results was not included) , 85% (17/20) of the laboratories had correlation coefficient ≥0.98. ②WT1 comparison: The median reported transcript levels of all 14 samples were from 0.17% to 67.6%, which covered 2.6-log. The ratios of each sample's highest to the lowest reported transcript levels were from 5.3-13.7, 62% (13/21) of the laboratories had correlation coefficient ≥0.98. ③ The relative relationship of the reported RUNX1-RUNX1T1 transcript levels between the participants and PKUPH was not always consistent with that of WT1 transcript levels. Both RUNX1-RUNX1T1 and WT1 transcript levels from 2 and 7 laboratories were individually lower than and higher than those of PKUPH, whereas for the rest 11 laboratories, one transcript level was higher than and the other was lower than that of PKUPH. Conclusion: The reported RUNX1-RUNX1T1 and WT1 transcript levels were different among laboratories for the same sample. Most of the participated laboratories reported highly consistent result with that of PKUPH. The relationship between laboratories of the different transcript levels may not be the same.

Wilms' tumor 1 mRNA expression: a good tool for differentiating between myelodysplastic syndrome and aplastic anemia in children?

Objectives: To evaluate the value of Wilms' tumor 1 mRNA (WT1) expression in the differential diagnosis of childhood myelodysplastic syndrome (MDS) and aplastic anemia (AA). Methods: This study compared WT1 expression levels in children of MDS and AA to evaluate its value in differential diagnosis. Results: WT1 overexpression rate and mean WT1 expression level were significantly higher in MDS compared to AA (P = 0.000 and P = 0.013, respectively). Patients with RCC and normal cytogenetics exhibited significantly greater portion of patients exposing WT1 overexpression, compared to all AA subtypes (P = 0.001, P = 0.000 and P = 0.001, respectively). ROC curve analysis revealed that WT1 expression could differentiate between RCC with normal cytogenetics and non-severe AA. Based on a cut-off value of 1.45%, WT1 expression provided a sensitivity of 23.2% and a specificity of 100%. Discussion: In the present study, WT1 overexpression rate was gradually decreased in RAEB group, RCC group and AA subtypes, and the mean WT1 expression level of the MDS patients was significantly higher than that of the AA group. It is very difficult to differentiate between RCC with normal cytogenetics and NSAA in children. Our results showed significant differences in WT1 overexpression rate between these two groups. When we set the cut-off value as 1.45%, WT1 expression levels could be used to differentiate between cases of RCC with normal cytogenetics and NSAA in children. Conclusion: WT1 expression might be useful for distinguishing between myelodysplastic syndrome and aplastic anemia in children.

PRAME peptide-specific CD8+ T cells represent the predominant response against leukemia-associated antigens in healthy individuals

Antigen-specific T cells isolated from healthy individuals (HIs) have shown great therapeutic potential upon adoptive transfer for the treatment of viremia in immunosuppressed patients. The lack of comprehensive data on the prevalence and characteristics of leukemia-associated antigen (LAA)-specific T cells in HIs still limits such an approach for tumor therapy. Therefore, we have investigated T-cell responses against prominent candidates comprising Wilms' tumor protein 1 (WT1), preferentially expressed antigen in melanoma (PRAME), Survivin, NY-ESO, and p53 by screening PBMCs from HIs using intracellular IFN-γ staining following provocation with LAA peptide mixes. Here, we found predominantly poly-functional effector/effector memory CCR7^- /CD45RA^+/- /CD8⁺ LAA peptide-specific T cells with varying CD95 expression in 34 of 100 tested HIs, whereas CD4⁺ T cells responses were restricted to 5. Most frequent LAA peptide-specific T cell responses were directed against WT1 and PRAME peptides with a prevalence of 20 and 17%, respectively, showing the highest magnitude (0.16% ± 0.22% (mean ± SD)) for PRAME peptides. Cytotoxicity of PRAME peptide-specific T cells was demonstrated by specific killing of PRAME peptide-pulsed T2 cells. Furthermore, the proliferative capacity of PRAME peptide-specific T cells was confined to HIs responsive toward PRAME peptide challenge corroborating the accuracy of the screening results. In conclusion, we identified PRAME as a promising target antigen for adoptive leukemia therapy.

High EVI1 Expression Predicts Poor Outcomes in Adult Acute Myeloid Leukemia Patients with Intermediate Cytogenetic Risk Receiving Chemotherapy

BACKGROUND Acute myeloid leukemia with intermediate cytogenetic risk (ICR-AML) needs to be stratified. The abnormal gene expression might be prognostic, and its cutoff value for patient grouping is pivotal. MATERIAL AND METHODS Ecotropic viral integration site 1 (EVI1) transcripts were assessed in 191 adult ICR-AML patients at diagnosis who received chemotherapy only. MLL-PTD, WT1 transcript levels, FLT3-ITD, and NPM1 mutations were simultaneously evaluated, and 27 normal bone marrow samples were tested to define normal threshold. RESULTS The normal upper limit of EVI1 transcript levels was 8.0%. Receiver operating characteristic curve analysis showed that 1.0% (a 0.9-log reduction from the normal limit) was the EVI1 optimal cutoff value for significantly differentiating relapse (P=0.049). A total of 23 patients (12%) had EVI1 levels ≥1.0%. EVI1 ≥1.0% had no effect on CR achievement, whereas it was significantly associated with lower 2-year relapse-free survival (RFS), disease-free survival (DFS), and overall survival (OS) rates in the entire cohort (P=0.0003, 0.0017, and 0.0009, respectively), patients with normal karyotypes (P=0.0032, 0.0047, and 0.0007, respectively), and FLT3-ITD (-) patients (all P<0.0001). Multivariate analysis showed that EVI1 ≥1.0% was an independent adverse prognostic factor for RFS, DFS, and OS in the entire cohort. In addition, patients with EVI1 transcript levels between 1.0% and 8.0% had 2-year RFS rates similar to those with EVI1 ≥8.0%, and they both had significantly lower RFS rates than those with EVI1 <1.0% (P=0.0005 and 0.027). CONCLUSIONS High EVI1 expression predicts poor outcome in ICR-AML patients receiving chemotherapy. The optimal cutoff value for patient stratification is different from the normal limit.

PRAME Gene Copy Number Variation Is Related to Its Expression in Multiple Myeloma

Multiple myeloma (MM) patients commonly present abnormal expression of cancer-testis antigens, which may serve as immunotherapeutic targets and prognostic factors. We previously reported that preferentially expressed antigen of melanoma (PRAME) overexpression in bone marrow mononuclear cells is related to progression in MM patients treated with non-bortezomib-containing regimens. The mechanism underlying variations in PRAME expression remains unknown. To investigate the impact of gene copy number variation (CNV) on PRAME expression, plasma cells were sorted from 50 newly diagnosed patients and 8 healthy volunteers to measure PRAME transcript levels and gene copy numbers by real-time quantitative polymerase chain reaction. A total of 14 (28.0%), 7 (14.0%), and 29 (58.0%) patients exhibited overexpression, expression within the normal range, and low expression, respectively. PRAME overexpression was significantly related to a lower 1-year progression-free survival rate compared with PRAME low expression (20.0% vs. 88.9%, p = 0.043). The mean PRAME gene copy number relative to albumin (ALB) in normal samples was ∼1.0, whereas 4.0%, 24.0%, 70.0%, and 2.0% of patients had PRAME gene relative copy numbers of approximately 0, 0.5, 1.0, and 2.0, respectively. Patients with PRAME gene deletion (relative copy number of 0 or 0.5) had significantly higher frequency of PRAME nonoverexpression and lambda light chain expression than those with no deletion (p = 0.011 and 0.003). Thus, PRAME gene CNV occurs in MM. Gene deletion may be one mechanism leading to PRAME nonoverexpression and related to immunoglobulin lambda light chain locus rearrangement. PRAME overexpression in plasma cells might be an adverse prognostic factor for progression in MM.

The diverse expression of the WT1 gene in patients with acquired bone marrow failure syndromes

Acquired bone marrow failure syndromes (aBMFS) encompass a wide range of diseases. A study to investigate WT1 expression in BM was conducted in 387 patients with aBMFS in China. The WT1 level in patients with aplastic anemia (AA) was significantly lower than that in patients with paroxysmal nocturnal hemoglobinuria (PNH, p = .023) and myelodysplastic syndrome (MDS, p < .001). In addition, the WT1 level in patients with MDS significantly increased as the disease progressed to an advanced stage. Patients with hypoplastic MDS had a differentiated expression level of WT1 compared with that of NSAA (p < .001). Furthermore, post-treatment patients of AA with partial response (PR) or complete response (CR) status had relatively higher WT1 levels than those with naive AA (p = .017, p = .003, respectively). Thus, the WT1 expression level could be a useful genetic marker for routine clinical work in aBMFS.

Methylation pattern of preferentially expressed antigen of melanoma in acute myeloid leukemia and myelodysplastic syndromes

Preferentially expressed antigen of melanoma (PRAME), a tumor-associated antigen, is overexpressed in a variety of hematologic malignancies with a great variation in expression. The majority of patients with acute myeloid leukemia (AML) 1-eight-twenty one (ETO)⁺ AML and a certain number of myelodysplastic syndromes (MDS) have an abnormally high increase in PRAME expression level. The landscape of PRAME methylation requires evaluation in order to determine the most relevant sites and the exact association of its methylation with expression level and type of disease. In the present study, bone marrow samples collected from 8 AML1-ETO⁺ AML, 4 MDS, 3 AML1-ETO^- AML and 2 normal volunteers underwent bisulfate sequencing to analyze the methylation status of all four 5'-C-phosphate-G-3' (CpG) regions within the entire PRAME gene. The median PRAME transcript level of 15 patients was 204.5% (range, 0.02-710.3%). PRAME transcript levels were inversely associated with the degree of methylation of the -389 to -146 CpG sites (r=-0.69; P=0.002) in the 3' part of the promoter region and the +132 to +363 CpG sites (r=-0.69; P=0.006) in the exon 1b region. However, not every sample strictly followed this correlation: Certain samples with high degrees of methylation demonstrated abnormally high expression levels, and vice versa. The methylation ratios of CpG sites in exon 1a were low for all samples (range, 0.0-13.8%), and those in exon 2 were similar in 16 samples (range, 72.4-93.4%), with the exception of one patient with high expression (425.2%) and significantly low degree of methylation in the PRAME gene (22.2%). MDS patients revealed similar methylation ratios in the 3' section of the promoter region, but tended to have lower methylation ratios in the exon 1b region (P=0.62 and P=0.09, respectively) compared with those observed in AML1-ETO⁺ patients with AML and similar degree of PRAME overexpression. Therefore, the hypomethylation of CpG sites in the 3' part of the promoter region and in exon 1b was typically found with PRAME overexpression in AML and MDS. Methylation of other CpG islands, epigenetic and genetic mechanisms, and type of disease may also be involved.

PRAME overexpression predicted good outcome in pediatric B-cell acute lymphoblastic leukemia patients receiving chemotherapy

To investigate the prognostic value of PRAME expression in pediatric acute lymphoblastic leukemia(ALL), we measured PRAME transcript levels at diagnosis in 191 patients(146 B-ALL; 45T-ALL)receiving chemotherapy only. PRAME overexpression was defined as transcript levels higher than 0.30%, which is the upper limit of normal bone marrow and the optimal cutoff value derived from ROC curve analysis. PRAME overexpression was identified in 45.5% of patients. In B-ALL, PRAME overexpression was significantly associated with lower CIR(cumulative incidence of relapse), higher DFS (disease-freesurvival), and OS(overall survival) rates at 3 years, respectively (5.8% vs. 14.9%, P=0.014; 94.2% vs. 85.1%, P=0.014; 96.0% vs. 87.4%, P=0.039). PRAME overexpression had no impact on outcome in T-ALL patients. Among B-ALL patients with non-poor cytogenetic risk, those with PRAME overexpression showed significantly lower CIR, higher DFS and OS rates at 3 years, respectively (8.47% vs. 14.5%, P=0.009; 96.5% vs. 85.5%, P=0.009; 98.4% vs. 88.0%, P=0.023). Furthermore, PRAME overexpression was an independent good prognostic factor for relapse in all B-ALL patients and B-ALL patients with non-poor cytogenetic risk. Therefore, the prognostic significance of PRAME overexpression differed by ALL subtype; It predicted good outcome in pediatric B-ALL receiving chemotherapy.

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.

Low WT1 transcript levels at diagnosis predicted poor outcomes of acute myeloid leukemia patients with t(8;21) who received chemotherapy or allogeneic hematopoietic stem cell transplantation

Background

Acute myeloid leukemia (AML) with t(8;21) is a heterogeneous disease. Identifying AML patients with t(8;21) who have a poor prognosis despite achieving remission is important for determining the best subsequent therapy. This study aimed to evaluate the impact of Wilm tumor gene-1 (WT1) transcript levels and cellular homolog of the viral oncogene v-KIT receptor tyrosine kinase (C-KIT) mutations at diagnosis, and RUNX1-RUNX1T1 transcript levels after the second consolidation chemotherapy cycle on outcomes.

Methods

Eighty-eight AML patients with t(8;21) who received chemotherapy only or allogeneic hematopoietic stem cell transplantation (allo-HSCT) were included. Patients who achieved remission, received two or more cycles of consolidation chemotherapy, and had a positive measureable residual disease (MRD) test result (defined as <3-log reduction in RUNX1-RUNX1T1 transcript levels compared to baseline) after 2–8 cycles of consolidation chemotherapy were recommended to receive allo-HSCT. Patients who had a negative MRD test result were recommended to receive further chemotherapy up to only 8 cycles. WT1 transcript levels and C-KIT mutations at diagnosis, and RUNX1-RUNX1T1 transcript levels after the second consolidation chemotherapy cycle were tested.

Results

Patients who had a C-KIT mutation had significantly lower WT1 transcript levels than patients who did not have a C-KIT mutation (6.7% ± 10.6% vs. 19.5% ± 19.9%, P < 0.001). Low WT1 transcript levels (≤5.0%) but not C-KIT mutation at diagnosis, a positive MRD test result after the second cycle of consolidation chemotherapy, and receiving only chemotherapy were independently associated with high cumulative incidence of relapse in all patients (hazard ratio [HR] = 3.53, 2.30, and 11.49; 95% confidence interval [CI] 1.64–7.62, 1.82–7.56, and 4.43–29.82; P = 0.002, 0.034, and <0.001, respectively); these conditions were also independently associated with low leukemia-free survival (HR = 3.71, 2.33, and 5.85; 95% CI 1.82–7.56, 1.17–4.64, and 2.75–12.44; P < 0.001, 0.016, and <0.001, respectively) and overall survival (HR = 3.50, 2.32, and 4.34; 95% CI 1.56–7.82, 1.09–4.97, and 1.98–9.53; P = 0.002, 0.030, and <0.001, respectively) in all patients.

Conclusions

Testing for WT1 transcript levels at diagnosis in patients with AML and t(8;21) may predict outcomes in those who achieve remission. A randomized study is warranted to determine whether allo-HSCT can improve prognosis in these patients.

Postremission sequential monitoring of minimal residual disease by WT1 Q-PCR and multiparametric flow cytometry assessment predicts relapse and may help to address risk-adapted therapy in acute myeloid leukemia patients

Risk stratification in acute myeloid leukemia (AML) patients using prognostic parameters at diagnosis is effective, but may be significantly improved by the use of on treatment parameters which better define the actual sensitivity to therapy in the single patient. Minimal residual disease (MRD) monitoring has been demonstrated crucial for the identification of AML patients at high risk of relapse, but the best method and timing of MRD detection are still discussed. Thus, we retrospectively analyzed 104 newly diagnosed AML patients, consecutively treated and monitored by quantitative polymerase chain reactions (Q‐PCR) on WT1 and by multiparametric flow cytometry (MFC) on leukemia‐associated immunophenotypes (LAIPs) at baseline, after induction, after 1st consolidation and after 1st intensification. By multivariate analysis, the factors independently associated with adverse relapse‐free survival (RFS) were: bone marrow (BM)‐WT1 ≥ 121/10⁴ABL copies (P = 0.02) and LAIP ≥ 0.2% (P = 0.0001) (after 1st consolidation) (RFS at the median follow up of 12.5 months: 51% vs. 82% [P < 0.0001] and 57% vs. 81%, respectively [P = 0.0003]) and PB‐WT1 ≥ 16/10⁴ABL copies (P = 0.0001) (after 1st intensification) (RFS 43% vs. 95% [P < 0.0001]) Our data confirm the benefits of sequential MRD monitoring with both Q‐PCR and MFC. If confirmed by further prospective trials, they may significantly improve the possibility of a risk‐adapted, postinduction therapy of AML.

Allogeneic stem cell transplant may improve the outcome of adult patients with inv(16) acute myeloid leukemia in first complete remission with poor molecular responses to chemotherapy

Eighty-six adult patients with inv(16) acute myeloid leukemia (AML) in first complete remission (CR1) were serially monitored for CBFB-MYH11 transcript levels during the early courses of chemotherapy. Fifty-seven and 29 of them received chemotherapy/autologous stem cell transplant (SCT) and allogeneic (allo-)SCT after second consolidation, respectively. For patients receiving chemotherapy/autologous SCT, the sole independent adverse prognostic factor for the cumulative incidence of relapse (CIR), disease-free survival (DFS) and overall survival (OS) was a CBFB-MYH11 level > 0.2% after course 2 consolidation (p = 0.003, 0.003 and 0.031), which was used to define a poor molecular response (MR). Allo-SCT significantly decreased the 3-year CIR and increased the DFS and OS of patients with a poor MR (p < 0.0001, 0.0001 and 0.045) but did not improve the outcome of patients with good MR (all p > 0.05) compared with chemotherapy/autologous SCT. Therefore, allo-SCT could improve the outcome of adult patients with inv(16) AML in CR1 with a poor MR during the early courses of chemotherapy.

Preferentially Expressed Antigen of Melanoma (PRAME) and Wilms' Tumor 1 (WT 1) Genes Expression in Childhood Acute Lymphoblastic Leukemia, Prognostic Role and Correlation with Survival

BACKGROUND:

Acute lymphocytic leukemia (ALL) is the most common hematologic malignancy in children. In young children it is also largely curable, with more than 90% of afflicted children achieving long-term remission. PRAME (Preferentially expressed antigen of melanoma) gene belongs to Group 3 class I HLA-restricted widely expressed antigens in which genes encoding widely expressed tumor antigens have been detected in many normal tissues as well as in histologically different types of tumors with no preferential expression on a certain type of cancer. It has been found to be expressed in a variety of cancer cells as leukemia & lymphoma. PRAME monitoring can be useful for detection of minimal residual disease and subsequent relapses particularly those leukemias in which specific tumor markers are unavailable. Wilms’ tumor1 (WT1) gene was identified as a gene that plays an important role in normal kidney development and inactivation of its function was shown to result in the development of Wilms’ tumors in paediatric patients. Disruption of WT1 function has been implicated in the formation of many different tumor types.

AIM:

to study how PRAME & WT 1 genes expression patterns influence cancer susceptibility & prognosis.

PATIENTS & METHODS:

50 patients with denovo childhood acute lymphoblastic leukemia, as well as 50 age and sex matched apparently healthy volunteers were genotyped for PRAME and WT1 genes expression by reverse transcription polymerase chain reaction (RT-PCR).

RESULTS:

PRAME gene was expressed in 34 of the patients (68%) and WT1 gene was expressed in 26 of the patients (52%). Expression of both genes was significantly higher compared to controls (P < 0.0001). Analysis of relapse free survival among our patients revealed that patients expressing PRAME gene or WT1 gene had better relapse free survival (p value=0.02 and 0.01 respectively). Relapse free survival increased significantly among patients coexpressing PRAME and WT 1(p value =0.001).

CONCLUSION:

It is concluded that the expression of PRAME and WT1 genes are indicators of favorable prognosis and can be useful tools for monitoring minimal residual disease (MRD) in acute leukemia especially in patients without known genetic markers. Differential expression between acute leukemia patients and healthy volunteers suggests that the immunogenic antigens (PRAME and WT1) are potential candidates for immunotherapy in childhood acute leukemia.

Prevalence and prognostic significance of c-KIT mutations in core binding factor acute myeloid leukemia: a comprehensive large-scale study from a single Chinese center

To clarify the prevalence and prognostic significance of c-KIT mutations in patients with core binding factor acute myeloid leukemia (CBF-AML), a total of 351 patients who were categorized as pediatric t(8;21), adult t(8;21), pediatric inv(16), or adult inv(16) were screened at diagnosis for c-KIT mutations in exons 17 and 8 using direct sequencing. A total of 250 patients underwent follow-up. Overall, 36.5% of the patients had a c-KIT mutation. Adult t(8;21) and inv(16) patients had mutations predominantly in exons 17 and 8, respectively. Higher White blood cell (WBC) count, WBC index, and AML1-ETO transcript levels in adult t(8;21) patients were significantly associated with c-KIT mutations and mutations in exon 17 (P≤0.030). c-KIT mutations in adult t(8;21) patients were significantly correlated with a high cumulative incidence of relapse (CIR, P=0.0070) at 2 years and a low 2-year disease-free survival (DFS, P=0.013) and overall survival (OS, P=0.0055). However, no significant difference was revealed in the effect of c-KIT mutations on outcome of adult inv(16) and pediatric t(8;21) patients (all P>0.05). Multivariate analysis revealed that c-KIT mutation is an independent prognostic factor for relapse, DFS, and OS (P≤0.016) in adult t(8;21) AML patients. Therefore, with regard to c-KIT mutation, CBF-AML is a heterogeneous disease. c-KIT mutations have a strong adverse effect on the relapse and survival of adult t(8;21) AML patients.

PRAME Gene Expression in Acute Leukemia and Its Clinical Significance

OBJECTIVE

To investigate the expression of the preferentially expressed antigen of melanoma (PRAME) gene in acute leukemia and its clinical significance.

METHODS

The level of expressed PRAME mRNA in bone marrow mononuclear cells from 34 patients with acute leukemia (AL) and in 12 bone marrow samples from healthy volunteers was measured via RT-PCR. Correlation analyses between PRAME gene expression and the clinical characteristics (gender, age, white blood count, immunophenotype of leukemia, percentage of blast cells, and karyotype) of the patients were performed.

RESULTS

The PRAME gene was expressed in 38.2% of all 34 patients, in 40.7% of the patients with acute myelogenous leukemia (AML, n=27), and in 28.6% of the patients with acute lymphoblastic leukemia (ALL, n=7), but was not expressed in the healthy volunteers. The difference in the expression levels between AML and ALL patients was statistically significant. The rate of gene expression was 80% in M3, 33.3% in M2, and 28.6% in M5. Gene expression was also found to be correlated with CD15 and CD33 expression and abnormal karyotype, but not with age, gender, white blood count or percentage of blast cells.

CONCLUSIONS

The PRAME gene is highly expressed in acute leukemia and could be a useful marker to monitor minimal residual disease. This gene is also a candidate target for the immunotherapy of acute leukemia.