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

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.

The Wilms' tumor gene-1 is a prognostic factor in myelodysplastic syndrome: a meta analysis

Previous studies have suggested that Wilms’ tumor gene-1 (WT1) may be related to a decrease in both relapse-free survival (RFS) and overall survival (OS) for patients with myelodysplastic syndrome (MDS). Therefore, we conducted a meta-analysis on the utility of WT1 as a prognostic indicator of MDS. Published reports were searched in the following databases: Cochrane Library, PubMed, Embase, and Web of Science. The meta-analysis was conducted using the Cochrane Collaboration RevMan 5.2 software. Six publications with 450 total patients met the inclusion criteria and were subjected to further examination. The results showed a reduction in both overall survival (OS) and leukemia-free survival (LFS) with increasing WT1 expression levels: 1-year OS (odds ratio, OR = 0.16; 95% CI = 0.08–0.34, P < 0.001), 3-year OS (OR = 0.21; 95% CI = 0.09–0.47, P < 0.001), 5-year OS (OR = 0.24; 95% CI = 0.06–0.92, P = 0.04), 1-year LFS (OR = 0.06; 95% CI = 0.02–0.18; P < 0.001), 3-year LFS (OR = 0.20; 95% CI = 0.09–0.46; P < 0.001), and 5-year LFS (OR = 0.12; 95% CI = 0.04–0.38; P < 0.001). In terms of patients receiving hematopoietic stem cell transplantation, the cumulative incidence of relapse (CIR) was higher in the WT1 over-expression group than in the low-expression group: 1-year CIR (OR = 13.69; 95% CI = 2.99–62.62; P < 0.001), 3-year CIR (OR = 6.52; 95% CI = 2.31–18.40, P < 0.001). In conclusion, WT1 over-expression is a prognostic factor for MDS.

Targeting of the WT191-138 fragment to human dendritic cells improves leukemia-specific T-cell responses providing an alternative approach to WT1-based vaccination

Due to its immunogenicity and overexpression concomitant with leukemia progression, Wilms tumor protein 1 (WT1) is of particular interest for immunotherapy of AML relapse after allogeneic hematopoietic stem cell transplantation (allo-HSCT). So far, WT1-specific T-cell responses have mainly been induced by vaccination with peptides presented by certain HLA alleles. However, this approach is still not widely applicable in clinical practice due to common limitations of HLA restriction. Dendritic cell (DC) vaccines electroporated with mRNA encoding full-length protein have also been tested for generating WT1-derived peptides for presentation to T-cells. Alternatively, an efficient and broad WT1 peptide presentation could be elicited by triggering receptor-mediated protein endocytosis of DCs. Therefore, we developed antibody fusion proteins consisting of an antibody specific for the DEC205 endocytic receptor on human DCs and various fragments of WT1 as DC-targeting recombinant WT1 vaccines (anti-hDEC205-WT1). Of all anti-hDEC205-WT1 fusion proteins designed for overcoming insufficient expression, anti-hDEC205-WT110-35, anti-hDEC205-WT191-138, anti-hDEC205-WT1223-273, and anti-hDEC205-WT1324-371 were identified in good yields. The anti-hDEC205-WT191-138 was capable of directly inducing ex vivo T-cell responses by co-incubation of the fusion protein-loaded monocyte-derived mature DCs and autologous T-cells of either healthy or HSCT individuals. Furthermore, the DC-targeted WT191-138-induced specific T-cells showed a strong cytotoxic activity by lysing WT1-overexpressing THP-1 leukemia cells in vitro while sparing WT1-negative hematopoietic cells. In conclusion, our approach identifies four WT1 peptide-antibody fusion proteins with sufficient production and introduces an alternative vaccine that could be easily translated into clinical practice to improve WT1-directed antileukemia immune responses after allo-HSCT.

Minimal residual disease prior to allogeneic hematopoietic cell transplantation in acute myeloid leukemia: a meta-analysis

Minimal residual disease prior to allogeneic hematopoietic cell transplantation has been associated with increased risk of relapse and death in patients with acute myeloid leukemia, but detection methodologies and results vary widely. We performed a systematic review and meta-analysis evaluating the prognostic role of minimal residual disease detected by polymerase chain reaction or multiparametric flow cytometry before transplant. We identified 19 articles published between January 2005 and June 2016 and extracted hazard ratios for leukemia-free survival, overall survival, and cumulative incidences of relapse and non-relapse mortality. Pre-transplant minimal residual disease was associated with worse leukemia-free survival (hazard ratio=2.76 [1.90-4.00]), overall survival (hazard ratio=2.36 [1.73-3.22]), and cumulative incidence of relapse (hazard ratio=3.65 [2.53-5.27]), but not non-relapse mortality (hazard ratio=1.12 [0.81-1.55]). These associations held regardless of detection method, conditioning intensity, and patient age. Adverse cytogenetics was not an independent risk factor for death or relapse. There was more heterogeneity among studies using flow cytometry-based than WT1 polymerase chain reaction-based detection (I²=75.1% vs. <0.1% for leukemia-free survival, 67.8% vs. <0.1% for overall survival, and 22.1% vs. <0.1% for cumulative incidence of relapse). These results demonstrate a strong relationship between pre-transplant minimal residual disease and post-transplant relapse and survival. Outcome heterogeneity among studies using flow-based methods may underscore site-specific methodological differences or differences in test performance and interpretation.

Clinical Impact of Overexpression of FOXP3 and WT1 on Disease Outcome in Egyptian Acute Myeloid Leukemia Patients

Background:

In the last decade, it has become clear that change of gene expression may alter the hematopoietic cell quiescent state and consequently play a major role in leukemogenesis. WT1 is known to be a player in acute myeloid leukemia (AML) and FOXP3 has a crucial role in regulating the immune response.

Objectives:

To evaluate the impact of overexpression of WT1and FOXP3 genes on clinical course in adult and pediatric AML patients in Egypt.

Patients and methods:

Bone marrow and peripheral blood samples were obtained from 97 de novo non M3 AML patients (63 adult and 34 pediatric). Real-time quantitative PCR was used to detect overexpression WT1 and FOXP3 genes. Patient follow up ranged from 0.2 to 39.0 months with a median of 5 months.

Results:

In the pediatric group; WT1 was significantly expressed with a high total leukocyte count median 50X109/L (p=0.018). In the adult group, WT1 had an adverse impact on complete remission induction, disease-free survival and overall survival (p=0.02, p=0.035, p=0.019 respectively). FOXP3 overexpression was associated with FAB subtypes AML M0 +M1 vs. M2, M4+M5 (p =0.039) and the presence of hepatomegaly (p=0.005).

Conclusions:

WT1 and FOXP3 overexpression has an adverse impact on clinical presentation, treatment response and survival of pediatric and adult Egyptian AML patients.

A Phase I Study of Reduced-Intensity Conditioning and Allogeneic Stem Cell Transplantation Followed by Dose Escalation of Targeted Consolidation Immunotherapy with Gemtuzumab Ozogamicin in Children and Adolescents with CD33+ Acute Myeloid Leukemia

Myeloablative conditioning and allogeneic hematopoietic stem cell transplant (alloHSCT) in children with acute myeloid leukemia (AML) in first complete remission (CR1) may be associated with significant acute toxicity and late effects. Reduced-intensity conditioning (RIC) and alloHSCT in children is safe, feasible, and may be associated with less adverse effects. Gemtuzumab ozogamicin (GO) induces a response in 30% of patients with CD33+ relapsed/refractory AML. The dose of GO is significantly lower when combined with chemotherapy. We examined the feasibility and toxicity of RIC alloHSCT followed by GO targeted immunotherapy in children with CD33+ AML in CR1/CR2. Conditioning consisted of fludarabine 30 mg/m2 × 6 days, busulfan 3.2 to 4 mg/kg × 2 days ± rabbit antithymocyte globulin 2 mg/kg × 4 days followed by alloHSCT from matched related/unrelated donors. GO was administered ≥60 days after alloHSCT in 2 doses (8 weeks apart), following a dose-escalation design (4.5, 6, 7.5, and 9 mg/m2). Fourteen patients with average risk AML received RIC alloHSCT and post-GO consolidation: median age 13.5 years at transplant (range, 1 to 21), male-to-female 8:6, and disease status at alloHSCT 11 CR1 and 3 CR2. Eleven patients received alloHSCT from 5-6/6 HLA-matched family donors: 8 received peripheral blood stem cells, 2 received bone marrow, and 1 received related cord blood transplantation. Three patients received an unrelated allograft (two 4-5/6 and one 9/10) from unrelated cord blood unit and bone marrow, respectively. Neutrophil and platelet engraftment was observed in all assessable patients (100%), achieved at median 15.5 days (range, 7 to 31) and 21 days (range, 10 to 52), respectively. Three patients received GO at dose level 1 (4.5 mg/m2 per dose), 5 at dose level 2 (6 mg/m2 per dose), 3 at dose level 3 (7.5 mg/m2 per dose), and 3 at dose level 4 (9 mg/m2 per dose). Three of 14 patients received only 1 dose of GO after alloHSCT. One patient experienced grade III transaminitis, which resolved; no grade IV transaminitis, no grade III/IV hyperbilirubinemia, or sinusoidal obstructive syndrome were observed. The second dose of GO was given at median of 143 days (range, 120 to 209) after alloHSCT. Probability of grades II to IV acute and chronic graft-versus-host disease were 21% and 33.5%, respectively. Probability of overall survival after RIC alloHSCT and GO consolidation at 1 and 5 years was 78% and 61%, respectively. Probability of 5-year event-free survival after RIC alloHSCT and GO consolidation in patients in CR1 was 78%. No dose-limiting toxicities probably or directly related to GO were observed in this cohort. This preliminary data demonstrate that RIC followed by alloHSCT and consolidation with GO appears to be safe in children and adolescents with CD33+ AML in CR1/CR2. A phase II trial is currently underway investigating this approach with a GO dose of 9 mg/m2 per dose.

Molecular landscape in acute myeloid leukemia: where do we stand in 2016

Acute myeloid leukemia (AML) is a clonal disorder characterized by the accumulation of complex genomic alterations that define the disease pathophysiology and overall outcome. Recent advances in sequencing technologies have described the molecular landscape of AML and identified several somatic alterations that impact overall survival. Despite all these advancement, several challenges remain in translating this information into effective therapy. Herein we will review the molecular landscape of AML and discuss the impact of the most common somatic mutations on disease biology and outcome.

[The relationship between WT1 expression level and prognosis in patients of acute T lymphoblastic leukemia following allogeneic hematopoietic stem cell transplantation]

OBJECTIVE

To probe monitoring Wilms tumor-1（WT1）gene expression level in acute T lymphoblastic leukemia（T- ALL）following allogeneic hematopoietic stem cell transplantation（allo-HSCT）with prognostic significance.

METHODS

This retrospective study analyzed 68 T-ALL cases from January 2009 to March 2012, that monitoring WT1 gene expression level after allo-HSCT. WT1 expression level was measured with real-time quantitative reverse transcription polymerase chain reaction（RQ-PCR） method at + 30, + 60, + 90, + 180, + 270, + 360 days after allo-HSCT, simultaneously monitoring residual leukemia using flow cytometry（FCM）.

RESULTS

Low WT1 gene expression level associated with a low risk of recurrence after allo-HSCT in T-ALL. Increased WT1 gene expression levels at +60 and + 90 days after allo- HSCT associated with higher cumulative incidences of relapse（P<0.001, P=0.003）, and low disease- free survival rates（P=0.004, P=0.006）, and low overall survival rates（P=0.004, P=0.007）. The presence of MRD after allo-HSCT was an independent prognostic factor for relapse in T-ALL. Combining WT1 gene and FCM could be used to monitor recurrence after allo-HSCT.

CONCLUSION

Increased WT1 gene expression level at +60 and + 90 days after allo-HSCT significantly associated with worse prognosis, that should be intervened as early as possible to reduce the risk of recurrence or death. WT1 gene expression level that was less than 0.6% associated with lower risk of recurrence. WT1 gene expression more than 0.6% that needed close follow- up, combined with FCM monitoring MRD, which required intervention to reduce the relapse.

Molecular Genetic Markers in Acute Myeloid Leukemia

Genetics play an increasingly important role in the risk stratification and management of acute myeloid leukemia (AML) patients. Traditionally, AML classification and risk stratification relied on cytogenetic studies; however, molecular detection of gene mutations is playing an increasingly important role in classification, risk stratification, and management of AML. Molecular testing does not take the place of cytogenetic testing results, but plays a complementary role to help refine prognosis, especially within specific AML subgroups. With the exception of acute promyelocytic leukemia, AML therapy is not targeted but the intensity of therapy is driven by the prognostic subgroup. Many prognostic scoring systems classify patients into favorable, poor, or intermediate prognostic subgroups based on clinical and genetic features. Current standard of care combines cytogenetic results with targeted testing for mutations in FLT3, NPM1, CEBPA, and KIT to determine the prognostic subgroup. Other gene mutations have also been demonstrated to predict prognosis and may play a role in future risk stratification, although some of these have not been confirmed in multiple studies or established as standard of care. This paper will review the contribution of cytogenetic results to prognosis in AML and then will focus on molecular mutations that have a prognostic or possible therapeutic impact.