Identification of New Purpuroine Analogues from the Arctic Echinodermata Pteraster militaris That Inhibit FLT3-ITD+ AML Cell Lines

Isolation of bioactive products from the marine environment is considered a very promising approach to identify new compounds that can be used for further drug development. In this work we have isolated three new compounds from the purpuroine family by mass-guided preparative HPLC; purpuroine K-M. These compounds where screened for antibacterial- and antifungal activity, antibiofilm formation and anti-cell proliferation activity. Additionally, apoptosis-, cell cycle-, kinase binding- and docking studies were performed to evaluate the mechanism-of-action. None of the compounds showed activity in antibacterial-, antibiofilm- or antifungal assays. However, one of the isolated compounds, purpuroine K, showed activity against two cell lines, MV-4-11 and MOLM-13, two AML cell lines both carrying the FTL3-ITD mutation. In MV-4-11 cells, purpuroine K was found to increase apoptosis and arrest cells cycle in G1/G0, which is a common feature of FLT3 inhibitors. Interactions between purpuroine K and the FLT3 wild type or FLT3 ITD mutant proteins could however not be elucidated in our kinase binding and docking studies. In conclusion, we have isolated three novel molecules, purpuroine K-M, one of which (purpuroine K) shows a potent activity against FLT3-ITD mutated AML cell lines, however, the molecular target(s) of purpuroine K still need to be further investigated.

Acute myeloid leukemia resistant to venetoclax-based therapy: What does the future hold?

Venetoclax is a highly selective B-cell lymphoma-2 (BCL-2) inhibitor, which, combined with a DNA hypomethylating agent or low dose cytarabine, results in high rates of initial responses in patients with acute myeloid leukemia (AML). However, the disease relapses in most patients. Mechanisms of resistance to venetoclax-based therapy include TP53 gene mutations or inactivation of p53 protein, activating kinase mutations such as FLT3 and RAS, and upregulation of other BCL-2 family apoptotic proteins. Current clinical trials are exploring strategies such as doublet or triplet regimens incorporating a p53 activator, an anti-CD47 antibody, or other novel agents that target genes and proteins responsible for resistance to venetoclax. Further studies should focus on identifying predictive biomarkers of response to venetoclax-based therapy and incorporating immunotherapeutic approaches such as checkpoint inhibitors, bispecific antibodies, antibody-drug conjugates, and CAR T-cell therapy to improve outcomes for patients with AML.

Upfront Screening by Quantitative Real-Time PCR Assay Identifies NUP98::NSD1 Fusion Transcript in Indian AML Patients

NUP98::NSD1 fusion, a cryptic translocation of t(5;11)(q35;p15.5), occurs predominantly in pediatric AML, having a poor prognostic outcome. There are limited studies on the diagnosis of NUP98::NSD1 fusion in a clinical setting, and most of the data are from Western countries. No study on the detection of this translocation has been reported from the Indian subcontinent to date. One possible reason could be the lack of availability of a potential tool to detect the fusion transcript. We have developed a real-time quantitative PCR (qRT-PCR)-based assay to detect NUP98::NSD1 fusion transcript with high sensitivity and specificity. Screening 150 AML patients (38 pediatric and 112 adults) using the assay showed the presence of fusion transcript in six patients including 03 pediatric, and 03 adult patients. We observed a prevalence rate of 7.89% (3/38) and 2.67% (3/112) fusion transcript in pediatric and adult patients, respectively. Sanger sequencing further validated the occurrence of NUP98::NSD1 fusion in all six patients. Molecular characterization of these patients revealed a co-occurrence of FLT3-ITD mutation, accompanied by altered expression of the HOX and other genes associated with AML. All six patients responded poorly to induction therapy. Overall, this is the first study to show the presence of the NUP98::NSD1 fusion transcript in Indian AML patients. Further, we demonstrate that our in-house developed qRT-PCR assay can be used to screen NUP98::NSD1 fusion in clinical settings.

Acute myeloid leukemia resistant to venetoclax-based therapy: What does the future hold?

Venetoclax is a highly selective B-cell lymphoma-2 (BCL-2) inhibitor, which, combined with a DNA hypomethylating agent or low dose cytarabine, results in high rates of initial responses in patients with acute myeloid leukemia (AML). However, the disease relapses in most patients. Mechanisms of resistance to venetoclax-based therapy include TP53 gene mutations or inactivation of p53 protein, activating kinase mutations such as FLT3 and RAS, and upregulation of other BCL-2 family apoptotic proteins. Current clinical trials are exploring strategies such as doublet or triplet regimens incorporating a p53 activator, an anti-CD47 antibody, or other novel agents that target genes and proteins responsible for resistance to venetoclax. Further studies should focus on identifying predictive biomarkers of response to venetoclax-based therapy and incorporating immunotherapeutic approaches such as checkpoint inhibitors, bispecific antibodies, antibody-drug conjugates, and CAR T-cell therapy to improve outcomes for patients with AML.

Deciphering the immuno-pathological role of FLT, and evaluation of a novel dual inhibitor of topoisomerases and mutant-FLT3 for treating leukemia

Acute myeloid leukemia (AML) is a type of leukemia with an aggressive phenotype, that commonly occurs in adults and with disappointing treatment outcomes. Genetic alterations were implicated in the etiology of cancers and form the basis for defining patient prognoses and guiding targeted therapies. In the present study, we leveraged bulk and single-cell RNA sequencing datasets from AML patients to determine the clinical significance of Fms-related receptor tyrosine kinase 3 (FLT3) alterations on the T-cell phenotype and immune response of AML patients. Subsequently, we evaluated the therapeutic potential of Lwk-n019, a novel small-molecule derivative of thiochromeno[2,3-c]quinolin-12-one. Our results suggested that FLT3 plays an important role in the progression, aggressive phenotype, and worse immune response of patients. An FLT3 mutation was associated with dysfunctional T-cell phenotypes, and high risk and shorter survival of AML patients. Our findings further suggested that the aggressiveness of AML and the prognostic role of FLT3 are associated with the co-occurrence of NPM1 and DNMT3A mutations. Lwk-n019 demonstrated dose-dependent anticancer activities against various leukemia cancer cell lines. Lwk-n019 demonstrated highly selective kinase inhibitory activities against the wild-type FLT3 (D835V) and mutant FLT3 (internal tandem duplication (ITD), D835V) with >95% and 99% inhibitory levels, respectively. Moreover, the compound demonstrated the best binding constant (Kd value) of 0.77 µM against FLT3 (ITD, 835V). In addition, Lwk-n019 significantly inhibited the activities of both the topoisomerase I (TOPI) and TOPII enzymes, with higher TOPI inhibitory activity than camptothecin, a clinical inhibitor. While the jejunum, duodenum, cecum, and colon were prime sites of absorption, Lwk-n019 achieved maximum concentration (Cmax), Vd, blood/plasma ratio, time to maximum concentration (Tmax), area under the receiver operating concentration curve (AUC)_(0-24), and AUC_(0-∞) values of 0.665 µg/mL, 5.21 Vc, L/kg, 1.5 h, 6634.7, and 6909.2, respectively. In conclusion, Lwk-n019 demonstrated anticancer activities via multi-target inhibition of TOPs and kinases with high inhibition preference for mutant ITD-FLT3. The present pioneer study provides a basis for advanced optimization of drug potency, selectivity, specificity, and other properties desired of anticancer drug leads. Studies are ongoing to determine the full therapeutic properties of Lwk-n019 and the detailed mechanisms of FLT3 in TOP inhibition.

Ibrutinib Prevents Acute Lung Injury via Multi-Targeting BTK, FLT3 and EGFR in Mice

Ibrutinib has potential therapeutic or protective effects against viral- and bacterial-induced acute lung injury (ALI), likely by modulating the Bruton tyrosine kinase (BTK) signaling pathway. However, ibrutinib has multi-target effects. Moreover, immunity and inflammation targets in ALI treatment are poorly defined. We investigated whether the BTK-, FLT3-, and EGFR-related signaling pathways mediated the protective effects of ibrutinib on ALI. The intratracheal administration of poly I:C or LPS after ibrutinib administration in mice was performed by gavage. The pathological conditions of the lungs were assessed by micro-CT and HE staining. The levels of neutrophils, lymphocytes, and related inflammatory factors in the lungs were evaluated by ELISA, flow cytometry, immunohistochemistry, and immunofluorescence. Finally, the expression of proteins associated with the BTK-, FLT3-, and EGFR-related signaling pathways were evaluated by Western blotting. Ibrutinib (10 mg/kg) protected against poly I:C-induced (5 mg/kg) and LPS-induced (5 mg/kg) lung inflammation. The wet/dry weight ratio (W/D) and total proteins in the bronchoalveolar lavage fluid (BALF) were markedly reduced after ibrutinib (10 mg/kg) treatment, relative to the poly I:C- and LPS-treated groups. The levels of ALI indicators (NFκB, IL-1β, IL-6, TNF-α, IFN-γ, neutrophils, and lymphocytes) were significantly reduced after treatment. Accordingly, ibrutinib inhibited the poly I:C- and LPS-induced BTK-, FLT3-, and EGFR-related pathway activations. Ibrutinib inhibited poly I:C- and LPS-induced acute lung injury, and this may be due to its ability to suppress the BTK-, FLT3-, and EGFR-related signaling pathways. Therefore, ibrutinib is a potential protective agent for regulating immunity and inflammation in poly I:C- and LPS-induced ALI.

Antileukemic activity of YPN-005, a CDK7 inhibitor, inducing apoptosis through c-MYC and FLT3 suppression in acute myeloid leukemia

Acute myeloid leukemia (AML) is an aggressive blood cancer with a high rate of relapse associated with adverse survival outcomes, especially in elderly patients. An aberrant expression of cyclin dependent kinase 7 (CDK7) is associated with poor outcomes and CDK7 inhibition has showed antitumor activities in various cancers. We investigated the efficacy of YPN-005, a CDK7 inhibitor in AML cell lines, xenograft mouse model, and primary AML cells. YPN-005 effectively inhibited the proliferation of AML cells by inducing apoptosis and reducing phosphorylation of RNA polymerase II. The c-MYC expression decreased with treatment of YPN-005, and the effect of YPN-005 was negatively correlated with c-MYC expression. YPN-005 also showed antileukemic activities in primary AML cells, especially those harboring FMS-like tyrosine kinase 3-internal tandem duplication (FLT3-ITD) mutation and in in vivo mouse model. Phosphorylated FLT3/Signal transducer and activator of transcription 5 (STAT5) was decreased and FLT3/STAT5 was downregulated with YPN-005 treatment. Our data suggest that YPN-005 has a role in treating AML by suppressing c-MYC and FLT3.

Recent Advances in the Development of Anti-FLT3 CAR T-Cell Therapies for Treatment of AML

Following the success of the anti-CD19 chimeric antigen receptor (CAR) T-cell therapies against B-cell malignancies, the CAR T-cell approach is being developed towards other malignancies like acute myeloid leukemia (AML). Treatment options for relapsed AML patients are limited, and the upregulation of the FMS-like tyrosine kinase 3 (FLT3) in malignant T-cells is currently not only being investigated as a prognostic factor, but also as a target for new treatment options. In this review, we provide an overview and discuss different approaches of current anti-FLT3 CAR T-cells under development. In general, these therapies are effective both in vitro and in vivo, however the safety profile still needs to be further investigated. The first clinical trials have been initiated, and the community now awaits clinical evaluation of the approach of targeting FLT3 with CAR T-cells.

Inhibition of Mcl-1 Synergistically Enhances the Antileukemic Activity of Gilteritinib and MRX-2843 in Preclinical Models of FLT3-Mutated Acute Myeloid Leukemia

FMS-like tyrosine kinase 3 (FLT3)-internal tandem duplication (FLT3-ITD) mutations occur in about 25% of all acute myeloid leukemia (AML) patients and confer a poor prognosis. FLT3 inhibitors have been developed to treat patients with FLT3-mutated AML and have shown promise, though the acquisition of resistance occurs, highlighting the need for combination therapies to prolong the response to FLT3 inhibitors. In this study, we investigated the selective Mcl-1 inhibitor AZD5991 in combination with the FLT3 inhibitors gilteritinib and MRX-2843. The combinations synergistically induce apoptosis in AML cell lines and primary patient samples. The FLT3 inhibitors downregulate c-Myc transcripts through the suppression of the MEK/ERK and JAK2/STAT5 pathways, resulting in the decrease in c-Myc protein. This suppression of c-Myc plays an important role in the antileukemic activity of AZD5991. Interestingly, the suppression of c-Myc enhances AZD5991-inudced cytochrome c release and the subsequent induction of apoptosis. AZD5991 enhances the antileukemic activity of the FLT3 inhibitors gilteritinib and MRX-2843 against FLT3-mutated AML in vitro, warranting further development.

Advances in the pharmacological management of acute myeloid leukemia in adults

INTRODUCTION

With advances in molecular medicine and precision approaches, there has been significant improvement in the treatment of acute myeloid leukemia (AML) in recent years. This reflects better understanding of molecular and metabolic pathways in leukemia cells, including BCL2 upregulation that prevents apoptosis, FLT3 tyrosine kinase activating mutations that allow uncontrolled proliferation, and IDH mutations that result in differentiation block.

AREAS COVERED

We performed a compressive review of important pre-clinical studies in AML that involve major molecular and metabolic pathways in AML, and we discussed standard therapeutic modalities and ongoing clinical trials for patients with AML, as well as an overall update of recent efforts in this area.

EXPERT OPINION

Targeting these pathways has resulted in improvement in the overall survival of some groups of AML patients. Secondary AML and TP53 mutated AML remain challenging subtypes of AML with limited treatment options and represent areas of unmet research need. Ongoing work with menin inhibitors in MLL rearranged leukemia, which comprise a large portion of secondary AML cases, the development of CAR T cell products and targeting the CD47 receptor on macrophages in myeloid neoplasms including in TP53 mutated AML have provided hope for these challenging subtypes of AML.

BCL-2 inhibitor synergizes with PI3Kδ inhibitor and overcomes FLT3 inhibitor resistance in acute myeloid leukaemia

Inhibitors targeting the antiapoptotic molecule BCL-2 have therapeutic potential for the treatment of acute myeloid leukaemia (AML); however, BCL-2 inhibitors such as venetoclax exhibit limited monotherapy efficacy in relapsed or refractory human AML. PI3Kδ/AKT signalling has been shown to be constitutively active in AML patients. Here, we demonstrate that the combination of BCL-2 and PI3Kδ inhibitors exerts synergistic antitumour effects both in vitro and in vivo in AML. Cotreatment with venetoclax and the specific PI3Kδ inhibitor idelalisib significantly enhanced antiproliferative effects and induced caspase-dependent apoptosis in a panel of AML cell lines. The synergistic effects were mechanistically based on the inactivation of AKT/4E-BP-1 signalling and the reduction of MCL-1 expression, which diminished the binding of Bim to MCL-1. Notably, compared with the parental FLT3-ITD-positive MV-4-11, the acquired FLT3 inhibitor quizartinib-resistant xenograft model carrying the F691L mutation, exhibited a markedly higher sensitivity to venetoclax. Furthermore, venetoclax combined with idelalisib led to tumour regression in all animals in this quizartinib-resistant AML model. Thus, these data indicate that combined inhibition of BCL-2 and PI3Kδ may be a promising strategy in AML, especially for patients with FLT3-ITD and/or FLT3-TKD mutations.

Design, synthesis, in silico studies, and antiproliferative evaluations of novel indolin-2-one derivatives containing 3-hydroxy-4-pyridinone fragment

Keeping in view the pharmacological properties of indolinones as promising scaffold as kinase inhibitors, herein, a novel series of 3-hydrazonoindolin-2-one derivatives bearing 3-hydroxy-4-pyridinone moiety were synthesized, studied by molecular docking, and fully characterized by spectroscopic techniques. All the prepared compounds were evaluated for their cytotoxicity attributes against a panel of tumor cell lines, including non-small cell lung cancer (A549), breast carcinoma (MCF-7), acute myeloid leukemia (AML), and chronic myeloid leukemia (CML). They displayed moderate to promising antiproliferative effects toward A549 and MCF-7 cells but remarkable results against AML and CML. Especially, compound 10k was found to be more potent against AML (EC₅₀ = 0.69 μM) compare to the other halogen-substituted derivatives. FMS-like tyrosine kinase 3 (FLT3) is known to be expressed in AML cancer cells. The molecular docking studies demonstrated that our prepared compounds were potentially bound to AML active site through essential H-bond and other vital interactions with critical binding residues.

Understanding gilteritinib resistance to FLT3-F691L mutation through an integrated computational strategy

FMS-like tyrosine kinase 3 (FLT3) serves as an important drug target for acute myeloid leukemia (AML), and gene mutations of FLT3 have been closely associated with AML patients with an incidence rate of ~ 30%. However, the mechanism of the clinically relevant F691L gatekeeper mutation conferred resistance to the drug gilteritinib remained poorly understood. In this study, multiple microsecond molecular dynamics (MD) simulations, end-point free energy calculations, and dynamic correlated and network analyses were performed to investigate the molecular basis of gilteritinib resistance to the FLT3-F691L mutation. The simulations revealed that the resistant mutation largely induced the conformational changes of the activation loop (A-loop), the phosphate-binding loop, and the helix αC of the FLT3 protein. The binding abilities of the gilteritinib to the wild-type and the F691L mutant were different through the binding free energy prediction. The simulation results further indicated that the driving force to determine the binding affinity of gilteritinib was derived from the differences in the energy terms of electrostatic and van der Waals interactions. Moreover, the per-residue free energy decomposition suggested that the four residues (Phe803, Gly831, Leu832, and Ala833) located at the A-loop of FLT3 had a significant impact on the binding affinity of gilteritinib to the F691L mutant. This study may provide useful information for the design of novel FLT3 inhibitors specially targeting the F691L gatekeeper mutant.

A truncated derivative of FGFR1 kinase cooperates with FLT3 and KIT to transform hematopoietic stem cells in syndromic and de novo AML

Background

Myeloid and lymphoid malignancies associated with chimeric FGFR1 kinases are the hallmark of stem cell leukemia and lymphoma syndrome (SCLL). In all cases, FGFR1 kinase is constitutively phosphoactivated as a result of chromosome translocations, which lead to acquisition of dimerization motifs in the chimeric proteins. Recently, we demonstrated that these chimeric kinases could be cleaved by granzyme B to generate a truncated derivative, tnFGFR1, which localized exclusively into the nucleus and was not phosphorylated.

Methods

Stem cell transduction and transplantation in syngeneic mice was used to assess the transforming ability of tnFGFR1 in bone marrow stem cells, and RPPA and RNA-Seq was used to examine the related signaling pathways and regulated target genes.

Results

For the first time, we show that this non-classical truncated form of FGFR1 can independently lead to oncogenic transformation of hematopoietic stem cells in an animal model in vivo. These leukemia cells show a mixed immunophenotype with a B-cell B220 + Igm- profile in the majority of cells and Kit+ in virtually all cells, suggesting a stem cell disease. tnFGFR1, however, does not activate classic FGFR1 downstream signaling pathways but induces a distinct profile of altered gene expression with significant upregulation of transmembrane signaling receptors including FLT3 and KIT. We further show that de novo human AML also express tnFGFR1 which correlates with upregulation of FLT3 and KIT as in mouse leukemia cells. ChIP analysis demonstrates tnFGFR1 occupancy at the Flt3 and Kit promoters, suggesting a direct transcriptional regulation. Cells transformed with tnFGFR1 are insensitive to FGFR1 inhibitors but treatment of these cells with the Quizartinib (AC220) FLT3 inhibitor, suppresses in vitro growth and development of leukemia in vivo. Combined treatment with FGFR1 and FLT3 inhibitors provides increased survival compared to FGFR1 inhibition alone.

Conclusions

This study demonstrates a novel model for transformation of hematopoietic stem cells by chimeric FGFR1 kinases with the combined effects of direct protein activation by the full-length kinases and transcriptional regulation by the truncated nuclear tnFGFR1 derivative, which is associated with GZMB expression levels. Genes significantly upregulated by tnFGFR1 include Flt3 and Kit which promote a leukemia stem cell phenotype. In human AML, tnFGFR1 activation leads to increased FLT3 and KIT expression, and higher FLT3 and GZMB expression levels are associated with an inferior prognosis. These observations provide insights into the relative therapeutic value of targeting FGFR1 and FLT3 in treating AML with this characteristic gene expression profile.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12943-022-01628-3.

Gilteritinib monotherapy for relapsed/refractory FLT3 mutated acute myeloid leukemia: a real-world, multi-center, matched analysis

Patients with FLT3-mutated relapsed or refractory (R/R) acute myeloid leukemia (AML) have a dismal prognosis. Gilteritinib is a FLT3 tyrosine kinase inhibitor (TKI) recently approved for patients with R/R AML. We aimed to characterize real-world data regarding gilteritinib treatment in FLT3-mutated R/R AML and to compare outcomes with matched FLT3-mutated R/R AML patients treated with chemotherapy-based salvage regimens. Twenty-five patients from six academic centers were treated with gilteritinib for FLT3-mutated R/R AML. Eighty percent were treated with a prior intensive induction regimen and 40% of them received prior TKI therapy. Twelve patients (48%) achieved complete response (CR) with gilteritinib. The estimated median overall survival (OS) of the entire cohort was eight (CI 95% 0-16.2) months and was significantly higher in patients who achieved CR compared to those who did not (16.3 months, CI 95% 0-36.2 vs. 2.6 months, CI 95% 1.47-3.7; p value = 0.046). In a multivariate cox regression analysis, achievement of CR was the only predictor for longer OS (HR 0.33 95% CI 0.11-0.97, p = 0.044). Prior TKI exposure did not affect OS but was associated with better event-free survival (HR 0.15 95% CI 0.03-0.71, p = 0.016). An age and ELN-risk matched comparison between patients treated with gilteritinib and intensive salvage revealed similar response rates (50% in both groups); median OS was 9.6 months (CI 95% 2.3-16.8) vs. 7 months (CI 95% 5.1-8.9) in gilteritinib and matched controls, respectively (p = 0.869). In conclusion, in the real-world setting, gilteritinib is effective, including in heavily pre-treated, TKI exposed patients.

'FLT3-ITD Mutation Does Not Influence Survival Outcome in Adult Acute Promyelocytic Leukemia Patients Treated With ATO and ATRA-Based Therapeutic Regimen: Experience From a North Indian Tertiary Care Centre'

INTRODUCTION

NPM1 and FLT3-ITD are frequently mutated genes in acute myeloid leukemia. We studied clinico-hematological profile and survival outcome of adult acute promyelocytic leukemia (APL) patients harboring these mutations.

MATERIALS AND METHODS

De novo APL cases (> 12 years), enrolled between January 2019 and June 2020, were evaluated for FLT3-ITD and NPM1 mutations (A, B, D mutations) by conventional and real-time qualitative PCR respectively.

RESULTS

FLT3-ITD mutation was detected in 12 of 36 (33.3%) de novo APLs cases while NPM1 mutation was not detected. FLT3-ITD was more frequently associated with Sanz high-risk category as compared to the intermediate-risk category (75% vs. 29%, P = .02), with BCR3 transcript type (P = .08) and higher median WBC count [22.7 × 10⁹/L)(range 1.3-184), P = .018]. One and half-years overall survival (OS) and event-free survival (EFS) were not significantly altered by the presence/absence of FLT3-ITD mutation (OS 86% vs. 70%, P = .32; EFS 86% vs. 70%, P = .33), between genders (OS, EFS both 89% in males vs. 69% in females, P = .15) and between adolescent and younger adults (AYA) (≤ 30 years) and older adult APL cases (> 30 years) (OS 86% vs. 78%, P = .55; EFS 85% vs. 77%, P = .55), however were significantly lower with BCR3 transcript as compared to BCR1 transcript (OS 56% vs. 91%, P = .019; EFS 56% vs. 91%, P = .016) in univariate analysis, although not in multivariate analysis. One and half-year OS and EFS was 57% (6/14, P = .009 for each) in high-risk APL.

CONCLUSION

FLT3-ITD mutation did not influence survival outcome in adult APL treated with ATO and ATRA-based therapeutic regimen.

ABCB1 as a potential beneficial target of midostaurin in acute myeloid leukemia

Low curability of patients diagnosed with acute myeloid leukemia (AML) must be seen as a call for better understanding the disease's mechanisms and improving the treatment strategy. Therapeutic outcome of the crucial anthracycline-based induction therapy often can be compromised by a resistant phenotype associated with overexpression of ABCB1 transporters. Here, we evaluated clinical relevance of ABCB1 in a context of the FMS-like tyrosine kinase 3 (FLT3) inhibitor midostaurin in a set of 28 primary AML samples. ABCB1 gene expression was absolutely quantified, confirming its association with CD34 positivity, adverse cytogenetic risk, and unachieved complete remission (CR). Midostaurin, identified as an ABCB1 inhibitor, increased anthracycline accumulation in peripheral blood mononuclear cells (PBMC) of CD34⁺ AML patients and those not achieving CR. This effect was independent of FLT3 mutation, indicating even FLT3^- AML patients might benefit from midostaurin therapy. In line with these data, midostaurin potentiated proapoptotic processes in ABCB1-overexpressing leukemic cells when combined with anthracyclines. Furthermore, we report a direct linkage of miR-9 to ABCB1 efflux activity in the PBMC and propose miR-9 as a useful prognostic marker in AML. Overall, we highlight the therapeutic value of midostaurin as more than just a FLT3 inhibitor, suggesting its maximal therapeutic outcomes might be very sensitive to proper timing and well-optimized dosage schemes based upon patient's characteristics, such as CD34 positivity and ABCB1 activity. Moreover, we suggest miR-9 as a predictive ABCB1-related biomarker that could be immensely helpful in identifying ABCB1-resistant AML phenotype to enable optimized therapeutic regimen and improved treatment outcome.

Fast Maturation of Splenic Dendritic Cells Upon TBI Is Associated With FLT3/FLT3L Signaling

The consequences of systemic inflammation are a significant burden after traumatic brain injury (TBI), with almost all organs affected. This response consists of inflammation and concurrent immunosuppression after injury. One of the main immune regulatory organs, the spleen, is highly interactive with the brain. Along this brain–spleen axis, both nerve fibers as well as brain-derived circulating mediators have been shown to interact directly with splenic immune cells. One of the most significant comorbidities in TBI is acute ethanol intoxication (EI), with almost 40% of patients showing a positive blood alcohol level (BAL) upon injury. EI by itself has been shown to reduce proinflammatory mediators dose-dependently and enhance anti-inflammatory mediators in the spleen. However, how the splenic immune modulatory effect reacts to EI in TBI remains unclear. Therefore, we investigated early splenic immune responses after TBI with and without EI, using gene expression screening of cytokines and chemokines and fluorescence staining of thin spleen sections to investigate cellular mechanisms in immune cells. We found a strong FLT3/FLT3L induction 3 h after TBI, which was enhanced by EI. The FLT3L induction resulted in phosphorylation of FLT3 in CD11c+ dendritic cells, which enhanced protein synthesis, maturation process, and the immunity of dendritic cells, shown by pS6, peIF2A, MHC-II, LAMP1, and CD68 by immunostaining and TNF-α expression by in-situ hybridization. In conclusion, these data indicate that TBI induces a fast maturation and immunity of dendritic cells which is associated with FLT3/FLT3L signaling and which is enhanced by EI prior to TBI.

Target Therapy for Extramedullary Relapse of FLT3-ITD Acute Myeloid Leukemia: Emerging Data from the Field

FMS-like tyrosine kinase 3 (FLT3) is a receptor tyrosine kinase family member. Mutations in FLT3, as well known, represent the most common genomic alteration in acute myeloid leukemia (AML), identified in approximately one-third of newly diagnosed adult patients. In recent years, this has represented an important therapeutic target. Drugs such as midostaurin, gilteritinib, and sorafenib, either alone in association with conventional chemotherapy, play a pivotal role in AML therapy with the mutated FLT3 gene. A current challenge lies in treating forms of AML with extramedullary localization. Here, we describe the general features of myeloid sarcoma and the ability of a targeted drug, i.e., gilteritinib, approved for relapsed or refractory disease, to induce remission of these extramedullary leukemic localizations in AML patients with FLT3 mutation, analyzing how in the literature, there is an important development of cases describing this promising potential for care.

Atractylenolide-1 Targets FLT3 to Regulate PI3K/AKT/HIF1-α Pathway to Inhibit Osteogenic Differentiation of Human Valve Interstitial Cells

Atractylenolide-1 (AT-1), a natural active ingredient extracted from Atractylodes macrocephala, was reported to have good anti-fibrotic and anti-inflammatory effects. Osteogenic changes induced by the inflammation of valve interstitial cells (VICs) play a role in the development of calcified aortic valve disease (CAVD). This study aimed to investigate the anti-osteogenic effects of AT-1 in human VICs. Human VICs were exposed to osteogenic induction medium (OM) containing AT-1 to analyze cell viability, as well as protein and osteogenic gene expression. Anti-calcification tests were also performed. mRNA transcriptome sequencing was performed to identify differential genes and pathways regulated by AT-1. Western blotting was used to verify the enrichment pathway, protein-protein interaction (PPI) analysis was conducted to identify drug targets. Finally, molecular docking and inhibitors are used to verify the drug targets. Treatment of VICs with 20 μM AT-1 resulted in no significant cytotoxicity. The addition of AT-1 to OM prevented the accumulation of calcified nodules, and decreases in the level of (Alkaline Phosphatase) ALP and RUNX2 gene and protein expression were observed. Atractylenolide-1 can target FLT3 protein and inhibit the phosphorylation of FLT3, thereby blocking PI3K/AKT pathway activation, reducing the production of Hypoxia inducible factor(HIF)1-α, and inhibiting the osteogenic differentiation of VICs. These results suggest AT-1 as a potential drug for treating calcified aortic valve disease.

Technological Advances: CEBPA and FLT3 Internal Tandem Duplication Mutations Can be Reliably Detected by Next Generation Sequencing

BACKGROUND

The detection of CEBPA and FLT3 mutations by next generation sequencing (NGS) is challenging due to high GC content and Internal Tandem Duplications (ITDs). Recent advances have been made to surmount these challenges. In this study, we compare three commercial kits and evaluate the performance of these more advanced hybrid-capture and AMP-chemistry based methods.

METHODS

Amplicon-based TSM 54-Gene Panel (Illumina) was evaluated against hybridization-capture SOPHiA Genetics MSP, OGT SureSeq, and AMP chemistry-based VariantPlex (Archer) for wet-lab workflow and data-analysis pipelines. Standard kit directions and commercial analysis pipelines were followed. Seven CEBPA and 10 FLT3-positive cases were identified that previously were missed on an amplicon NGS assay. The average reads, coverage uniformity, and the detection of CEBPA or FLT3 mutations were compared.

RESULTS

All three panels detected all 10 CEBPA mutations and all 10 FLT3 ITDs with 100% sensitivity. In addition, there was high concordance (100%) between all three panels detecting 47/47 confirmed variants in a set of core myeloid genes.

CONCLUSIONS

The results show that the NGS assays are now able to reliably detect CEBPA mutations and FLT3 ITDs. These assays may allow foregoing additional orthogonal testing for CEBPA and FLT3.

Whole exome sequencing of pediatric leukemia reveals a novel InDel within FLT-3 gene in AML patient from Mizo tribal population, Northeast India

Background

Leukemia is the most common type of cancer in pediatrics. Genomic mutations contribute towards the molecular mechanism of disease progression and also helps in diagnosis and prognosis. This is the first scientific mutational exploration in whole exome of pediatric leukemia patients from a cancer prone endogamous Mizo tribal population, Northeast India.

Result

Three non-synonymous exonic variants in NOTCH1 (p.V1699E), MUTYH (p.G143E) and PTPN11 (p.S502P) were found to be pathogenic. A novel in-frame insertion-deletion within the juxtamembrane domain of FLT3 (p.Tyr589_Tyr591delinsTrpAlaGlyAsp) was also observed.

Conclusion

These unique variants could have a potential mutational significance and these could be candidate genes in elucidating the possibility of predisposition to cancers within the population. This study merits further investigation for its role in diagnosis and prognosis and also suggests the need for population wide screening to identify unique mutations that might play a key role towards precision medicine.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12863-022-01037-x.

Companion gene mutations and their clinical significance in AML with double or single mutant CEBPA

INTRODUCTION

We report the co-mutations in AML with CEBPA^sm or CEBPA^dm and their clinical features in a large cohort (n = 302) of CEBPA^mut AML patients.

MATERIALS AND METHODS

We retrospectively sequenced 112 genes in 302 patients with CEBPA^mut using NGS, and studied the spectrum and clinical impact of co-mutations in CEBPA^dm and CEBPA^sm.

RESULTS

① The average number of mutations in CEBPA^sm and CEBPA^dm AML was comparable, but not significant (P = 0.17). ② CEBPA^dm patients exhibited more mutations in CSF3R (P = 0.037), GATA2 (P = 0.022), and WT1 (P = 0.046). In contrast, CEBPA^sm patients more frequently harbored mutations in NPM1 (P = 0.000), FLT3-ITD (P = 0.025) and NOTCH2 (P = 0.043), as well as mutations in signaling pathways and spliceosomes (P = 0.064, P = 0.027, respectively). ③ Patients with CEBPA^sm/TET2^mut or CEBPA^sm /GATA2^mut had higher platelet counts (both P = 0.011), while patients with CEBPA^dm /TET2^mut had significantly higher hemoglobin levels (P = 0.009). The CR rate of patients with FLT3-ITD mutations was significantly lower in the CEBPA^sm group than the CEBPA^dm group (P = 0.028).

CONCLUSIONS

CEBPA^sm and CEBPA^dm AML are each associated with their own complex co-mutation cluster. Some co-mutations influence the clinical features and CR rate differently in patients with different CEBPA mutational status.

A review of FLT3 inhibitors in acute myeloid leukemia

FLT3 mutations are the most common genetic aberrations found in acute myeloid leukemia (AML) and associated with poor prognosis. Since the discovery of FLT3 mutations and their prognostic implications, multiple FLT3-targeted molecules have been evaluated. Midostaurin is approved in the U.S. and Europe for newly diagnosed FLT3 mutated AML in combination with standard induction and consolidation chemotherapy based on data from the RATIFY study. Gilteritinib is approved for relapsed or refractory FLT3 mutated AML as monotherapy based on the ADMIRAL study. Although significant progress has been made in the treatment of AML with FLT3-targeting, many challenges remain. Several drug resistance mechanisms have been identified, including clonal selection, stromal protection, FLT3-associated mutations, and off-target mutations. The benefit of FLT3 inhibitor maintenance therapy, either post-chemotherapy or post-transplant, remains controversial, although several studies are ongoing.