Prognosis and outcome of patients with acute myeloid leukemia based on FLT3-ITD mutation with or without additional abnormal cytogenetics

Gilteritinib Reduces FLT3 Expression in Acute Myeloid Leukemia Cells

Acute myeloid leukemia (AML) is a genetically diverse and challenging malignancy, with mutations in the FLT3 gene being particularly common and deleterious. Gilteritinib, a potent FLT3 inhibitor, has been approved by the U.S. Food and Drug Administration (FDA) for the treatment of relapsed/refractory AML with FLT3 mutations. Although gilteritinib was developed based on its inhibitory activity against FLT3 kinase, it is important to understand the precise mechanisms of its antileukemic activity in managing drug resistance and discovering biomarkers. This study was designed to elucidate the effect of gilteritinib on the FLT3 expression level. The results showed that gilteritinib induced a dose-dependent decrease in both FLT3 phosphorylation and expression. This reduction was particularly pronounced after 48 h of treatment. The decrease in FLT3 expression was found to be independent of changes in FLT3 mRNA transcription, suggesting post-transcriptional regulatory mechanisms. Further studies were performed in various AML cell lines and cells with both FLT3 wild-type and FLT3 mutant exhibited FLT3 reduction by gilteritinib treatment. In addition, other FLT3 inhibitors were evaluated for their ability to reduce FLT3 expression. Other FLT3 inhibitors, midostaurin, crenolanib, and quizartinib, also reduced FLT3 expression, consistent with the effect of gilteritinib. These findings hold great promise for optimizing gilteritinib treatment in AML patients. However, it is important to recognize that further research is warranted to gain a full understanding of these mechanisms and their clinical implications in the context of FLT3 reduction.

Current knowledge about FLT3 gene mutations, exploring the isoforms, and protein importance in AML

Acute myeloid leukaemia (AML) is a complex haematological malignancy characterised by diverse genetic alterations leading to abnormal proliferation of myeloid precursor cells. One of the most significant genetic alterations in AML involves mutations in the FLT3 gene, which plays a critical role in haematopoiesis and haematopoietic homeostasis. This review explores the current understanding of FLT3 gene mutations and isoforms and the importance of the FLT3 protein in AML. FLT3 mutations, including internal tandem duplications (FLT3-ITD) and point mutations in the tyrosine kinase domain (FLT3-TKD), occur in 25-30% in AML and are associated with poor prognosis. FLT3-ITD mutations lead to constitutive activation of the FLT3 signalling pathway, promoting cell survival and proliferation. FLT3-TKD mutations affect the tyrosine kinase domain and affect AML prognosis in various ways. Furthermore, FLT3 isoforms, including shorter variants, contribute to the complexity of FLT3 biology. Additionally, nonpathological polymorphisms in FLT3 are being explored for their potential impact on AML prognosis and treatment response. This review also discusses the development of molecular treatments targeting FLT3, including first-generation and next-generation tyrosine kinase inhibitors, highlighting the challenges of resistance that often arise during therapy. The final chapter describes FLT3 protein domain rearrangements and their relevance to AML pathogenesis.

The effect of haploidentical hematopoietic stem cell transplantation on comutations based on next-generation sequencing in adult acute myeloid leukemia patients with the FLT3-ITD mutation

According to the 2022 European LeukemiaNet, all acute myeloid leukemia (AML) cases with FLT3-ITD mutations are now categorized as intermediate risk irrespective of the FLT3-ITD allelic ratio or concurrent presence of NPM1 mutation. However, whether other next-generation sequencing (NGS) comutation genes can add layers to FLT3-ITD and whether the poor outcomes of FLT3-ITD comutations can be overcome by haploidentical hematopoietic stem cell transplantation (haplo-HSCT) are unclear. This study aimed to investigate which comutations based on NGS at diagnosis affect the clinical prognosis of de novo AML patients with FLT3-ITD mutations and the effect of haplo-HSCT on comutations. We analyzed 95 de novo AML patients with FLT3-ITD mutations from January 2018 to August 2021 based on the NGS 99-gene platform. Forty-one other types of molecular mutations were detected. The most common cooccurring mutations were NPM1 (n = 43, 45.3%) and DNMT3A (n = 21, 22.1%). NPM1 mutation did not affect the clinical outcomes. Acute myeloid leukemia patients with FLT3-ITD and DNMT3A comutations had significantly worse 3-year Disease-free survival (DFS) (49.5% vs. 69.3%, P = 0.01) and Overall survival (OS) rates (61.1% vs. 69.8%, P = 0.54) than those without DNMT3A mutations, and survival was significantly more favorable after haplo-HSCT than that after chemotherapy (3-year DFS, 85.7% vs. 30.8%, P = 0.006; 3-year OS, 85.7% vs. 43.1%, p = 0.08). In multivariate analysis, DNMT3A mutation was a risk factor for DFS, while haplo-HSCT was a protective factor. In conclusion, DNMT3A mutation might be a poor prognostic factor in adult AML patients with FLT3-ITD mutations, and haplo-HSCT could overcome the poor prognosis of DNMT3A comutation.

Outcomes of Patients with FLT3 Positive Acute Myeloid Leukaemia; an Experience from a Tertiary Care Hospital in Karachi, Pakistan

Introduction

Molecular genetic abnormalities in acute myeloid leukaemia (AML) are essential for disease diagnosis and determining prognosis and clinical course. Mutations in FLT3 and nucleophosmin (NPM) genes are the most frequent genetic abnormalities, which are also known to impact disease outcomes. FLT3 mutations have been identified in approximately 30% of de novo AML patients and are associated with poor prognoses. This study aimed to determine the response to induction chemotherapy, overall survival (OS) and relapse rate (RR) in patients with FLT3-positive AML.

Materials and Methods

In this study, a retrospective analysis was performed of 75 newly diagnosed patients with AML registered between January 2015 and July 2022. Patient demographics and clinical-haematological parameters were noted and molecular analysis for FLT3 ITD/TKD and NPM mutations was performed. All the patients received standard induction chemotherapy and their response to treatment, OS and RR were assessed.

Results

A total of 75 cases of AML were analysed. The mean age of the sample was 34.9 years, of which 65.3% were males and 34.7% were females. The patients were stratified into two groups: Those who were positive for FLT3 while negative for NPM (FLT3+/NPM-), representing 17.3% and those who were negative for both FLT3 and NPM (FLT3-/NPM-), representing 82.7% of cases. On day 28 post-induction, the complete remission rate was 69.2% in the FLT3 positive group and 77.4% in the FLT3 negative group. In the FLT3+/NPM- group, 55.6% of cases who were in remission at day 28 subsequently relapsed, compared to 50.0% of FLT3-/NPM- cases. The overall median survival time for the cohort and FLT3+ group was 1467 days, while that of the FLT3-group could not be estimated due to the very high survival rate.

Conclusion

No significant differences in outcomes were observed in patients who were FLT3 positive compared to those who were FLT3 negative.

Prevalence of Gene Rearrangement by Multiplex PCR in De Novo Acute Myeloid Leukemia in Adult Iraqi Patients

Introduction

Gene rearrangements of acute myeloid leukemia (AML) play a significant role in categorizing patients and provide valuable information about prognosis and treatment choices. However, in Iraq, the prevalence and prognostic significance of gene rearrangements in AML have not been previously examined.

Methods

This study utilized a multiplex reverse transcription real-time PCR (RT-qPCR) system to identify gene rearrangements in a group of 115 adult patients from Iraq who had been diagnosed with De Novo AML. The diagnosis of AML was confirmed through blood film and flow cytometry. The ethical committee of the College of Medicine at the University of Baghdad provided approval for this research study.

Results

In this study, 66.1% of the patients diagnosed with acute myeloid leukemia (AML) exhibited distinct genetic abnormalities. Among these abnormalities, the most frequent was the rearrangement involving the KMT2A gene, observed in 19.9% of the patients. The risk stratification analysis revealed that 40% of the patients were classified as having a favorable risk, 4.3% as intermediate risk, and 25.2% as adverse risk. A subtype of AML known as core-binding factor (CBF) AML was identified in 21.7% of the cases, with 84% of these patients achieving complete remission. The NPM-RARA gene rearrangement, found in 43% of acute promyelocytic leukemia (APL) cases, was associated with a 71% complete remission rate. Among patients with KMT2A rearrangement, which accounted for 19.9% of all AML cases, the MLL-AF10 rearrangement was the most common, although only one patient with KMT2A rearrangement achieved complete remission. Furthermore, the analysis of demographic data revealed a significant association between increased risk and advanced age, presence of comorbidities, and FAB classification (M0 subtype).

Conclusion

The prevalence of genetic rearrangements in Iraqi De Novo AML patients is higher than the global trend, highlighting the importance of genetic characterization in risk assessment and treatment decisions.

Activating Mutation in the Receptor Tyrosine Kinase FLT3 with Clinicopathological Relevance in Canine Mast Cell Tumors

Recent research has focused on the receptor tyrosine kinase (RTK) KIT which is involved in the pathogenesis of canine mast cell tumors (MCT). However, the role of other RTKs in this neoplasm remains unclear. The present study aimed to determine the frequency of FLT3 mutations and to evaluate the mutational status and clinicopathological relevance of canine MCT patients. There were a total of 20 cases that were cytologically and histopathological diagnosed as canine MCTs; genomic polymerase chain reaction (PCR) and Sanger sequencing were used to identify mutations. For the juxtamembrane (JM) domain, the FLT3 14/15 primer pair was used to investigate exon 14/15 loci. Based on genomic PCR amplification of exon 14/15 and 20 of the FLT3 gene and Sanger sequencing of 20 cases of canine MCTs, the overall frequency of FLT3 mutation in canine MCTs was 75%. The majority of FLT3 mutations (70%) were internal tandem duplications (ITD) of the JM domain, while one case arose from deletion mutations of the tyrosine kinase domain (TKD). However, double mutations were not observed in this study. Furthermore, there is also clinicopathological relevance to MCT dogs carrying FLT3-ITD mutations, showing a tendency toward leukocytosis due to neutrophilia, and resembling human acute myeloid leukemia (AML) with FLT3-ITD mutations. A subset of MCTs with FLT3-ITD mutations, showing an enhanced signal of phosphorylated ERK1/2 identified by immunoblotting, suggests that an activating mutation may be driven by a distinct signal of the ERK pathway. Our results indicate that FLT3-ITD mutation is an oncogenic driver of canine MCTs, and that it shares some clinicopathologic features with human AML. These findings may offer new opportunities for further studies on canine mast cell tumorigenesis and a novel therapeutic target for canine MCT cases harboring FLT3-ITD mutations.

Outcomes of pediatric acute myeloid leukemia patients with FLT3-ITD mutations in the pre-FLT3 inhibitor era

Background

Acute myeloid leukemia (AML) with internal tandem duplication in FMS-like tyrosine kinase 3 (FLT3-ITD) is associated with poor outcomes. This study aimed to analyze the outcomes of pediatric AML patients with FLT3-ITD mutations in the pre-FLT3 inhibitor era.

Methods

We retrospectively reviewed and identified 18 patients diagnosed with non-M3 AML with FLT3-ITD mutations at Seoul National University Children’s Hospital between May 2008 and August 2019.

Results

The median age was 13 years (range, 6‒19 yr). The median follow-up time was 43 months (range, 6‒157 mo). Fourteen patients received BH-AC-based (N4-Behenoy1-1-b-D-arabinofuranosy1cytosine) and 4 received cytarabine-based induction chemotherapy. Complete remission (CR) was achieved in 72.2% of the patients after the first induction chemotherapy and 80% of the patients achieved CR after salvage therapy. The overall CR rate was 94% (17/18 patients). These 17 patients underwent hematopoietic stem cell transplantation (9 matched unrelated donors, 5 matched related donors, and 3 haploidentical donors). Relapse occurred in 22% of the patients. Event free survival and overall survival rates were 53.8±12.1% and 53.6±12.1%, respectively, and they were not significantly different according to the type of induction chemotherapy (P=0.690) or the type of donor (P=0.102).

Conclusion

This study outlines the outcomes of pediatric AML patients with FLT3-ITD-mutations in one institution over a decade. Outcomes were significantly improved in this study compared to our previous report in 2004, where RFS and EFS were 0%. This study can provide baseline data for pediatric patients in the pre-FLT3 inhibitor era.

A novel prognostic scoring model for newly diagnosed FLT3-ITD-positive acute myeloid leukemia

FMS-like tyrosine kinase 3-internal tandem duplication (FLT3-ITD) is one of the most common somatic mutations in acute myeloid leukemia (AML). However, the molecular structure characteristics and widely accepted prognostic factors for FLT3-ITD are still not well described. This study aimed to retrospectively examine 81 patients with FLT3-ITD-positive AML diagnosed and treated at the First Affiliated Hospital of Zhejiang University from December 2013 to March 2018 using the next-generation sequencing 185-gene platform. High variant allele frequency (VAF) [> 0.48, P = 0.0089 for overall survival (OS), P = 0.13 for relapse-free survival (RFS)], multiple ITDs (> 1 ITDs, P = 0.011 for OS, P = 0.033 for RFS) and longer insertion length (> 69 bp, P = 0.14 for OS, P = 0.0078 for RFS) predicted poor survival. The study further proposed an easily applicable scoring model for OS using the Least Absolute Shrinkage and Selector Operation (LASSO) Cox regression model. Also, an independent cohort of 30 patients was used for external model validation. The mode was expressed as follows: 0.659 × FLT3-ITD VAF + 0.375 × FLT3-ITD number + 0.807 × Age + 0.688 × DNMT3A + 1.939 × U2AF1 (FLT3-ITD VAF > 0.48 scored 1; FLT3-ITD number scored 1 if carried 1 ITD, 2 if carried ≥ 2 ITDs; age > 44 years scored 1, the presence of DNMT3A or U2AF1 scored 1; 0 for other conditions). It categorized patients into low-risk (L-R, score < 1, n = 20) and high-risk (H-R, score ≥ 1, n = 61) groups based on the risk score with a significant difference in survival (3-year OS, P < 0.0001; 3-year RFS, P = 0.0005). A prognostic nomogram that integrated these five factors was developed with a concordance index calculation [OS: 0.68, 95% CI (0.64-0.72)].

Next generation sequencing guided treatment modulation and prognosis in Acute myeloid leukemia: Case vignettes

OBJECTIVE

The genomic mutational landscape of Acute Myeloid Leukemia has contributed to better treatment options, risk stratification and prognostication of this genetically heterogeneous disease. With several approved new drugs targeting specific mutations with better outcomes, we describe here two cases of AML in which, NPM1 was detected at diagnosis. The impact of age, type of treatment, stability of NPM1 mutation, and co-occurring mutations on survival are the essential parameters for investigation.

METHOD

Both the cases of AML were females, >60 years of age with normal 46XX karyotype. Allele specific RT-PCR and fragment analysis was performed for the detection of NPM1-A mutation at diagnosis. Both the patients were unfit for intensive chemotherapy therefore reduced intensity induction chemotherapy regimen was initially administered. Next-generation sequencing was performed for comprehensive mutational profiling, which guided targeted treatment, prognostic stratification, and response assessment.

RESULT

We report that the older AML patients with NPM1 mutation may not have a good outcome with intensive chemotherapy, especially patients with concurrent DNMT3A/IDH-1/2 mutations. In the second case with mutated NPM1, concurrent FLT3-ITD mutation served as a therapeutic target. The FLT3 inhibitor used in combination with standard therapy showed promising results in this case.

CONCLUSION

Here, we emphasize on the utility of next generation sequencing in guiding the treatment initiation or modulation during the disease course and risk stratification in AML. In conclusion, conventional chemotherapy in AML gives very poor overall survival rates and targeted chemotherapy against specific mutations may drastically improve patient survival and treatment outcomes.

Identification of the key genes and microRNAs in adult acute myeloid leukemia with FLT3 mutation by bioinformatics analysis

Background: Associated with poor prognosis, FMS-like tyrosine kinase 3 (FLT3) mutation appeared frequently in acute myeloid leukemia (AML). Herein, we aimed to identify the key genes and miRNAs involved in adult AML with FLT3 mutation and find possible therapeutic targets for improving treatment. Materials: Gene and miRNA expression data and survival profiles were obtained from The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) database. EdgeR of R platform was applied to identify the differentially expressed genes and miRNAs (DEGs, DE-miRNAs). Gene ontology (GO) and the Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses were performed by Metascape and DAVID. And protein-protein interaction network, miRNA-mRNA regulatory network and clustering modules analyses were performed by STRING database and Cytoscape software. Results: Survival analysis showed FLT3 mutation led to adverse outcome in AML. 24 DE-miRNAs (6 upregulated, 18 downregulated) and 250 DEGs (54 upregulated, 196 downregulated) were identified. Five miRNAs had prognostic value and the results matched their expression levels (miR-1-3p, miR-10a-3p, miR-10a-5p, miR-133a-3p and miR-99b-5p). GO analysis showed DEGs were enriched in skeletal system development, blood vessel development, cartilage development, tissue morphogenesis, cartilage morphogenesis, cell morphogenesis involved in differentiation, response to growth factor, cell-substrate adhesion and so on. The KEGG analysis showed DEGs were enriched in PI3K-Akt signaling pathway, ECM-receptor interaction and focal adhesion. Seven genes (LAMC1, COL3A1, APOB, COL1A2, APP, SPP1 and FSTL1) were simultaneously identified by hub gene analysis and module analysis. SLC14A1, ARHGAP5 and PIK3CA, the target genes of miR-10a-3p, resulted in poor prognosis. Conclusion: Our study successfully identified molecular markers, processes and pathways affected by FLT3 mutation in AML. Furthermore, miR-10a-3p, a novel oncogene, might involve in the development of FLT3 mutation adult AML by targeting SLC14A1, ARHGAP5 and PIK3CA.