Fms-like Tyrosine Kinase Research Articles

FMS-like tyrosine kinase 3 inhibitory potentials of some phytochemicals from anti-leukemic plants using computational chemical methodologies

FMS-like tyrosine kinase 3 inhibitory potentials of some phytochemicals from anti-leukemic plants using computational chemical methodologies

Added Value of Mean Blood Pressure and Placental Growth Factor in the Early Detection of Pre-eclampsia among Gabonese Women.

To evaluate the use of the Foetal Medicine Foundation (FMF) algorithm in routine practice for early pre-eclampsia (PE) screening in Libreville. We conducted a cohort study on pregnant women within their 11-13 + 6 weeks of gestation (WG). We had measured mean blood pressure (MBP), placental growth factor (PlGF), soluble Fms-like tyrosine kinase 1, Uterine Artery Pulsatility Index (UtA-PI) and resistance index (UtA-RI). Statistical analyses were considered significant for P < 0.05. There were 30 participants. At the first quarter (T1), 36.7% of them were at high risk of PE according to the FMF algorithm and were consequently prescribed aspirin (100 mg/d). By the end of the observation period, we have found a 13% incidence of PE. MBP was higher in the higher risk PE group than in the lower risk group as early as the T1 (90 ± 6 vs. 81 ± 6 mmHg; P = 0.0007, threshold is >86 mmHg/area under the curve (AUC) = 0.86; P = 0.0012). It was the same for PlGF (58 ± 24 vs. 88 ± 38 pg/ml; P = 0.03; threshold is <71.98 pg/ml/AUC = 0.73; P = 0.03). At the second quarter (20-27 WG), biochemical markers did not change between the two groups. UtA-RI, UtA-PI and notch were unconclusive individually, but they are still very important for FMF algorithm application. Early detection of PE using the FMF algorithm is possible in routine practice in Gabon. MBP and PlGF levels at T1 seem to be very significant. However, the present study must continue to obtain the larger cohorts that would achieve more conclusive statistical analyses.

Value of soluble fms-like tyrosine kinase 1 for predicting acute pancreatitis severity: a systematic review and meta-analysis.

The objective of this study was to explore the relationship between serum soluble fms-like tyrosine kinase 1 and the severity of acute pancreatitis and its diagnostic utility. This study was carried out by searching Chinese and English literature from the establishment of the database to July 9, 2023, systematically, and assessing the quality and heterogeneity of the articles included. Thirteen studies with a total of 986 patients were included. Patients with severe acute pancreatitis showed higher levels of soluble fms-like tyrosine kinase 1 compared with mild acute pancreatitis [weighted mean difference=76.64 pg/mL, 95% confidence interval (95%CI 50.39-102.89, p<0.001)]. Soluble fms-like tyrosine kinase 1 predicted pooled sensitivity, specificity, and area under the curve were 79%, 74%, and 0.85 for severe acute pancreatitis, with some heterogeneity (I2>50% or p<0.05). In the subgroup analysis, cutoff >150 pg/mL was found to be a heterogeneous factor. Soluble fms-like tyrosine kinase 1 is a reliable tool for identifying acute pancreatitis severity, but only as a screening tool.

Clinical profile of FTL3-ITD mutation in West Algerian population with acute myeloid leukemia.

Acute myeloid leukemia(AML) is a cancer of the myeloid line of blood cells, characterized by the abnormal and rapid growth of cells. The mutation of the Fms-like tyrosine kinase 3 ligand gene (FLT3-ITD) represents an important factor in the prognosis of AML. The objective of this study was to determine for the first time the prevalence of FLT3-ITD mutation in west Algerian AML patients. A total of 160 AML patients were genotyped for FLT3-ITD mutation by using polymerase chain reaction. FLT3-ITD mutation was detected in 13% of patients. Mutation rates show no significant difference in the distribution of sex and age. A positive association was found between this mutation and a higher leukocyte and blast cells counts. We also found that the M3 and M5 subtype were the commonest in the FLT3 mutated group. This preliminary study provides first-time prevalence estimates for FLT3-ITD mutation in acute myeloid leukemia patients from the West region of Algeria.

Возможные перспективы в лечении преэклампсии

Currently, the treatment of preeclampsia is based on the use of symptomatic therapy, and if it is ineffective, the only etiotropic method of treating preeclampsia is delivery. The drugs described in this review as a treatment for preeclampsia are able to affect certain pathogenetic links of the disease. The effect on endothelial dysfunction is achieved by reducing the secretion of soluble fms-like tyrosine kinase 1 and endoglin, enhancing the production of endogenous nitric monoxide, inhibiting the C5 component of the complement system, regulating the hemastasis system, and activating the mother’s immune cells, which is necessary for full trophoblast invasion. The therapeutic effect of the drugs under consideration allows assuming with cautious optimism that these drugs may be used in the treatment of preeclampsia.

Huc-MSC-derived exosomal miR-144 alleviates inflammation in LPS-induced preeclampsia-like pregnant rats via the FosB/Flt-1 pathway

BackgroundPreeclampsia (PE) is a common and severe hypertensive disorder in pregnancy. Mesenchymal stem cell-derived exosomes (Exos-MSC) have been reported to mitigate the progression of inflammatory diseases. The study aimed to explore the effects of human umbilical cord-derived Exos-MSC (huc-Exos-MSC) on PE-like models. MethodsLipopolysaccharide (LPS) was used to construct in vitro and in vivo PE-like models. Exosomes were treated with LPS-induced PE-like cells and rats. ResultsPE-like inflammatory models of pregnant rats and cells were successfully constructed in vivo and in vitro. miR-144 was screened by bioinformatics analysis. Exosomes were successfully extracted. Silencing FosB, overexpressing miR-144 or treating with exosomes extracted from huc-MSC overexpressing miR-144 in (Exos-MSCmiR−144) reversed the LPS-induced decline in HTR-8/SVneo cell viability and migration. In addition, the above groups decreased LPS-induced increases in interleukin 6 (IL-6), tumor necrosis factor-α (TNF-α), phosphorylated nuclear factor-kappaB (p–NF–κB)/NF-κB, soluble FMS-like tyrosine kinase 1 (sFlt-1), and Flt-1 levels. Simultaneously, transfection of miR-144 mimics and overexpressing FosB reversed those changes in the miR-144 mimics group. miR-144 might alleviate LPS-induced HTR-8/SVneo cell inflammation by targeting FosB. Injection of Exos-MSCmiR−144 in PE-like pregnant rats reversed LPS-induced increases in FosB expression, systolic and diastolic blood pressure (SBP and DBP), as well as mean arterial pressure (MAP), heart rate, urine albumin/creatine ratio, inflammatory factors, p–NF–κB/NF-κB, and sFlt-1 levels. Furthermore, compared with the model group, the proportion of live births was significantly higher in the model + Exos-MSCmiR−144 group, while the apoptosis rate of fetal rat brain tissue was significantly lower. ConclusionsWe found that huc-Exos-MSC-derived miR-144 alleviated gestational hypertension and inflammation in PE-like pregnant rats by regulating the FosB/Flt-1 pathway. In addition, huc-Exos-MSC-derived miR-144 could partially reverse the LPS-induced adverse pregnancy outcome and brain injury in fetal rats, laying the foundation for developing new treatments for PE.

Treatment of relapsed or refractory FLT-3 acute myelogenous leukemia with a triplet regimen of hypomethylating agent, venetoclax, and gilteritinib

Relapsed or refractory (R/R) acute myeloid leukemia (AML) with FMS-like tyrosine kinase 3 (FLT3) mutations remains a difficult and hard to treat entity. Gilteritinib is a potent oral FLT-3 inhibitor that improves overall survival in R/R AML, but studies are limited in combining gilteritinib with a hypomethylating agent and venetoclax treatment backbone (HMA-VEN-GILT). Here we report our experience with HMA-VEN-GILT for 22 R/R FLT3 AML patients. HMA-VEN-GILT yielded an ORR of 77.3% (17/22), CR 4.5% (1/22), CRi 13.6% (3/22), MLFS 59.1% (13/22). Median follow-up was 10.4 months with a relapse rate of 29.4% (5/17), median time to relapse of 69 days (range 35–298 days), 6-month overall survival of 84%, and median OS of 10.1 months. Additionally, 36.4% (8/22) of patients proceeded to hematopoietic stem cell transplant. In conclusion, HMA-VEN-GILT for the treatment of R/R FLT3 AML is feasible and can be used as a bridge to allogeneic transplantation.

A programmable releasing versatile hydrogel platform boosts systemic immune responses via sculpting tumor immunogenicity and reversing tolerogenic dendritic cells

Immunogenicity improvement is a valuable strategy for tumor immunotherapy. However, immunosuppressive factors bestow tolerogenic phenotype on tumor-infiltrating DCs, which exhibit weak antigen presentation and strong anti-inflammatory cytokines secretion abilities, limiting the effectiveness of tumor immunotherapy even if the tumor has adequate immunogenicity. Herein, we designed a programmable releasing versatile hydrogel platform (PIVOT) to sculpt tumor immunogenicity, increase intratumoral DCs and cDC1s abundance, and reverse the tolerogenic phenotype of DCs, thus promoting their maturation for boosting innate and adaptive immune responses. Responsive to tumoral reactive oxygen species (ROS), the hydrogel splits and promotes the activation of DCs and macrophages. Then, oxaliplatin is first released from PIVOT to sculpt tumor immunogenicity by inducing immunogenic cell death (ICD) and causing tumoral DNA fragments exposure simultaneously. Subsequently, the impaired DNA fragments bind to high mobility group protein 1 (HMGB1) forming the DNA-HMGB1 complex. Moreover, exogenous FMS-like tyrosine kinase 3 ligand (Flt-3L) recruits masses of DCs, especially cDC1s, which will endocytose the complex benefiting from TIM-3 blockade (αTIM3) that can reverse tolerogenic DCs. Finally, the endocytosis activates the cGAS-STING pathway of cDC1s, which promotes the secretion of type I IFN that triggers innate immune responses, and CXCL9 which recruits CD8+ effector T cells to initiate the following adaptive immune response against tumor progress. PIVOT achieves nearly 90 % tumor growth inhibition and induces systemic antitumor immune responses. In conclusion, this study focuses on ICD-mediated tumor immunogenicity sculpture and nucleic acid endocytosis-involved tolerogenic DCs reversal, providing a novel paradigm for enhancing DCs-based antitumor immune responses.

Bayesian Optimization in the Latent Space of a Variational Autoencoder for the Generation of Selective FLT3 Inhibitors.

The process of drug design requires the initial identification of compounds that bind their targets with high affinity and selectivity. Advances in generative modeling of small molecules based on deep learning are offering novel opportunities for making this process faster and cheaper. Here, we propose an approach to achieve this goal, where predictions of binding affinity are used in conjunction with the Junction Tree Variational Autoencoder (JTVAE) whose latent space is used to facilitate the efficient exploration of the chemical space using a Bayesian optimization strategy. The exploration identifies small molecules predicted to have both high affinity and high selectivity by using an objective function that optimizes the binding to the target while penalizing the binding to off-targets. The framework is demonstrated for FMS-like tyrosine kinase 3 (FLT3) and shown to predict small molecules with predicted affinity and selectivity comparable to those of clinically approved drugs for this target.

FLT3 signaling augments macrophage production from human pluripotent stem cells.

Recent advances in cell engineering technologies enable immune cells to be utilized for adoptive cell transfer (ACT) immunotherapy against cancers. Macrophages have the potential to directly and indirectly exterminate cancers and are therefore an attractive option for therapies. To develop new ACT therapies using macrophages, a great number of macrophages are required. Human induced pluripotent stem cells (iPSCs) are expected to be a source of macrophages; therefore, a system to efficiently produce macrophages from human iPSCs is needed. Here, we demonstrated that human iPSCs were robustly differentiated into macrophages by enforced FMS-like tyrosine kinase-3 (FLT3) signaling via the introduction of exogenous FLT3 into iPSCs and the addition of its ligand FLT3L to the macrophage induction culture. These iPSC-derived macrophages were identical to those obtained by standard differentiation induction methods. Thus, our novel system enables the preparation of scalable macrophages from human iPSCs. We believe that this system will be useful to develop a novel ACT therapy using macrophages.

The Clinical Utility of FLT3 Mutation Testing in Acute Leukemia: A Canadian Consensus.

FMS-like tyrosine kinase 3 (FLT3) mutations are detected in approximately 20-30% of patients with acute myeloid leukemia (AML), with the presence of a FLT3 internal tandem duplication (FLT3-ITD) mutation being associated with an inferior outcome. Assessment of FLT3 mutational status is now essential to define optimal upfront treatment in both newly diagnosed and relapsed AML, to support post-induction allogeneic hematopoietic stem cell transplantation (alloSCT) decision-making, and to evaluate treatment response via measurable (minimal) residual disease (MRD) evaluation. In view of its importance in AML diagnosis and management, the Canadian Leukemia Study Group/Groupe canadien d'étude sur la leucémie (CLSG/GCEL) undertook the development of a consensus statement on the clinical utility of FLT3 mutation testing, as members reported considerable inter-center variability across Canada with respect to testing availability and timing of use, methodology, and interpretation. The CLSG/GCEL panel identified key clinical and hematopathological questions, including: (1) which patients should be tested for FLT3 mutations, and when?; (2) which is the preferred method for FLT3 mutation testing?; (3) what is the clinical relevance of FLT3-ITD size, insertion site, and number of distinct FLT3-ITDs?; (4) is there a role for FLT3 analysis in MRD assessment?; (5) what is the clinical relevance of the FLT3-ITD allelic burden?; and (6) how should results of FLT3 mutation testing be reported? The panel followed an evidence-based approach, taken together with Canadian clinical and laboratory experience and expertise, to create a consensus document to facilitate a more uniform approach to AML diagnosis and treatment across Canada.

Durable responses in acute lymphoblastic leukaemia with the use of FLT3 and IDH inhibitors.

Data regarding the use of FMS-like tyrosine kinase 3 (FLT3) and isocitrate dehydrogenase 1/2 (IDH1/2) inhibitors in acute lymphoblastic leukaemia (ALL) are lacking. We identified 14 patients with FLT3- or IDH1/2-mutated ALL. Three early T-cell precursor-ALL patients received FLT3 or IDH2 inhibitors. Patient 1 maintains a complete remission (CR) with enasidenib after intolerance to chemotherapy. Patient 2 maintained a CR for 27 months after treatment with enasidenib for relapsed disease. Patient 3 was treated with venetoclax and gilteritinib at the time of relapse and maintained a CR with gilteritinib for 8 months. These cases suggest that FLT3 and IDH inhibitors could represent a viable therapeutic option for ALL patients with these mutations.

Luteolin prevents TNF-α-induced NF-κB activation and ROS production in cultured human placental explants and endothelial cells

IntroductionPreeclampsia (PE) is a serious hypertensive pregnancy disorder and a leading cause of maternal and perinatal morbidity and mortality. Despite the prevalence and complications, there are no approved therapeutics to relieve PE symptoms. Inflammation, oxidative stress, and angiogenic imbalance have been shown to contribute to the PE pathophysiology, though there is a lack of understanding in how best to target these pathways in PE. We recently demonstrated that the bioflavonoid luteolin is a potent inhibitor of the anti-angiogenic and pro-hypertensive soluble fms-like tyrosine kinase 1 (sFlt-1), and here we aimed to determine if luteolin was also capable of reducing inflammation and oxidative stress pathways. MethodsTumor necrosis factor (TNF)-α, which is upregulated in PE, was utilized to stimulate these pathways in human placental explants and endothelial cells. Endothelin-1 (ET-1) and interleukin (IL)-6 in the media from explants and cells were measured via ELISA, and NF-κB localization and reactive oxygen species were detected via fluorescence microscopy. ResultsPretreatment with luteolin demonstrated significant reductions in NF-κB activation, reactive oxygen species, superoxide, and IL-6 and ET-1 expression in endothelial cells. We also saw a significant reduction in phosphorylation of NF-κB in human placental explants. DiscussionThese data demonstrate that luteolin inhibits pathways implicated in the development of PE and should be explored further for its potential as a PE therapeutic.

A study of the synthetic route and resistance of gilteritinib

Gilteritinib is used to treat acute myeloid leukemia (AML) carrying FMS-like tyrosine kinase 3 (FLT3) mutations. As it is a new drug, there are still many aspects that need improvement. This article will be written according to the following three points: Analysis of its mechanism of action with the receptor; Analysis of the three main synthetic routes of gilteritinib and reasonable suggestions are given; Causes and solutions to the emergence of drug resistance. The following 4 points have been found that:(1) FLT3-internal tandem duplication (ITD) mutation and FLT3-tyrosine kinase domain (TKD) mutation, leukemic cells' ability to proliferate, differentiate, and survive aberrant changes due to both kinds of mutations. (2) Gilteritinib combines with FLT3's ATP pocket, and the compound shaped from FLT3 to gilteritinib was synthesized by the juxtamembrane (JM) domain. (3) Synthesis route 3 in this paper is most suitable for industrial mass production. (4) Resistance to gilteritinib is divided into primary resistance and secondary resistance, research in the future should focus on finding new therapeutic targets.

Application of sunitinib in cancer treatment and analysis of its synthetic route

Sunitinib, also known as the free base of sunitinib malate, is an innovative oral agent used in the treatment of tumors. It functions by inhibiting various members of the receptor tyrosine kinase (RTK) family, which possess a split kinase structural domain. These members include vascular endothelial growth factor receptors (VEGFR) 1, 2, and 3, platelet-derived growth factor receptors (PDGFR) and , stem cell factor receptors, FMS-like tyrosine kinase 3, colony-stimulating factor 1 receptor, and BCR/ABL fusion genes. This paper briefly introduces the research background, pharmacological activity and toxicity of sunitinib, sorting out the incidence and pathogenesis of the diseases it is targeted to treat, and its regulatory mechanism in treating the diseases, etc., summarising several synthetic routes of sunitinib researched by the previous researchers, and at the same time analysing and evaluating the synthetic routes and suggesting the synthetic routes, summing up and proposing the outlook of its subsequent research contents and directions, providing references and help to the research on sunitinib afterward.

Phenotypic and functional differences of dendritic cells in tumor.

Dendritic cells (DCs) are a unique class of immune cells vital to the immune system, functioning as antigen-presenting cells that play a key role in launching both cellular and humoral immune responses. They are crucial in preventing infectious diseases and regulating tumor growth. DCs can be categorized based on various criteria such as phenotype, function, and tissue location, resulting in several subgroups. Generally, DCs are divided into two primary groups: plasmacytoid DCs (pDCs) and conventional DCs (cDCs), which are further classified into Type I classical DCs (cDC1) and Type II classical DCs (cDC2). cDC1 cells are distinguishable by specific gene programs and associated markers, while cDC2 cells display more diversity. Moreover, there is an ongoing debate surrounding a recently identified subgroup called DC3, and whether it can be considered a distinct cell type in the maturation process of DCs remains uncertain. Most of these DC subgroups rely on the growth factor Fms-like tyrosine kinase 3 ligand (FLT3L) for differentiation from a common DC precursor (CDP), guided by various cytokines. Although the general classification of DC subgroups is similar in both humans and mice, numerous phenotypic and functional variations exist within each subgroup. Therefore, comprehending these differences between DC subgroups in humans and mice holds the potential to significantly advance relevant research.

Longitudinal assessment of angiogenic markers in prediction of adverse outcome in women with confirmed pre-eclampsia.

Angiogenic marker assessment, such as the ratio of soluble fms-like tyrosine kinase-1 (sFlt-1) to placental growth factor (PlGF), is known to be a useful tool in the prediction of pre-eclampsia (PE). However, evidence from surveillance strategies in pregnancies with a PE diagnosis is lacking. Therefore, we aimed to assess the predictive performance of longitudinal maternal serum angiogenic marker assessment for both maternal and perinatal adverse outcomes when compared to standard laboratory parameters in pregnancies with confirmed PE. This was a retrospective analysis of prospectively collected data from January 2013 to December 2020 at the Medical University of Vienna. The inclusion criteria were singleton pregnancy with confirmed PE and post-diagnosis maternal serum angiogenic marker assessment at a minimum of two timepoints. The primary outcome was the predictive performance of longitudinal sFlt-1 and PlGF assessment for adverse maternal and perinatal outcomes compared to conventional laboratory monitoring at the same time in pregnancies with confirmed PE. Composite adverse maternal outcome included intensive care unit admission, pulmonary edema, eclampsia and/or death. Composite adverse perinatal outcome included stillbirth, neonatal death, placental abruption, neonatal intensive care unit admission, intraventricular hemorrhage, necrotizing enterocolitis, respiratory distress syndrome and/or mechanical ventilator support. In total, 885 post-diagnosis sFlt-1/PlGF ratio measurements were obtained from 323 pregnant women with confirmed PE. For composite adverse maternal outcome, the highest standalone predictive accuracy was obtained using maternal serum sFlt-1/PlGF ratio (area under the receiver-operating-characteristics curve (AUC), 0.72 (95% CI, 0.62-0.81)), creatinine (AUC, 0.71 (95% CI, 0.62-0.81)) and lactate dehydrogenase (LDH) levels (AUC, 0.73 (95% CI, 0.65-0.81)). Maternal platelet levels (AUC, 0.65 (95% CI, 0.55-0.74)), serum alanine aminotransferase (ALT) (AUC, 0.59 (95% CI, 0.49-0.69)) and aspartate aminotransferase (AST) (AUC, 0.61 (95% CI, 0.51-0.71) levels had poor standalone predictive accuracy. The best prediction model consisted of a combination of maternal serum LDH, creatinine levels and sFlt-1/PlGF ratio, which had an AUC of 0.77 (95% CI, 0.68-0.85), significantly higher than sFlt-1/PlGF ratio alone (P = 0.037). For composite adverse perinatal outcome, the highest standalone predictive accuracy was obtained using maternal serum sFlt-1/PlGF ratio (AUC, 0.82 (95% CI, 0.75-0.89)) and creatinine (AUC, 0.74 (95% CI, 0.67-0.80)) levels, sFlt-1/PlGF ratio being superior to creatinine alone (P < 0.001). Maternal serum LDH levels (AUC, 0.65 (95% CI, 0.53-0.74)), platelet count (AUC, 0.57 (95% CI, 0.44-0.67)), ALT (AUC, 0.58 (95% CI, 0.48-0.67)) and AST (AUC, 0.58 (95% CI, 0.48-0.67)) levels had poor standalone predictive accuracy. No combination of biomarkers was superior to maternal serum sFlt-1/PlGF ratio alone for prediction of composite adverse perinatal outcome (P > 0.05 for all). In pregnancies with confirmed PE, longitudinal maternal serum angiogenic marker assessment is a good predictor of adverse maternal and perinatal outcomes and superior to some conventional laboratory parameters. Further studies should focus on optimal surveillance following diagnosis of PE. © 2023 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

Abstract B020: Hypoxia as tumor-intrinsic regulator of Flt3L production by NK cells

Abstract Natural killer (NK) cell abundance in the tumor correlates with increased immunotherapy responses and better survival in cancer patients. As their name suggests, NK cells can control tumors through their direct cytotoxicity, but also play an important part in regulating immune responses through their immunomodulatory production of cytokines and chemokines. We recently discovered that NK cells control immunotherapy responses through their production of a cytokine called FMS-like tyrosine kinase 3 ligand (Flt3L) in the tumor, which regulates type 1 conventional dendritic cell (cDC1) abundance. However, the mechanisms regulating NK cell phenotype and function, including Flt3L production, in the tumor remain unknown. Here, we define tumor cell-intrinsic mechanisms that control these protective NK cell functions in the tumor. Across eight mouse melanoma tumor models, we found two genetically distinct murine ectopic tumors (referred to as Mel1 and Mel2) that are similarly infiltrated with total NK cells, but have distinct skewing of NK cell phenotypes and differential production of Flt3L, correlating with differences in cDC1 abundance. Pathway analysis of differentially expressed genes in tumor cells from these two models found a significant increase in hypoxia signaling in Mel1 tumors. Using an in vivo hypoxia tracer and in vitro hypoxia chamber studies, we found that NK cells in Mel1 tumors experience more severe hypoxia and that NK cells produce significantly less Flt3L under hypoxic conditions (1% O2) compared to NK cells in normoxic conditions (21% O2). Our findings suggest that hypoxia is a tumor-intrinsic regulator of Flt3L production by NK cells and highlight a previously unknown inhibitory pathway within the tumor that can shape the protective immunomodulatory effects of NK cells. Citation Format: Renske J.E. van den Bijgaart, Shayan C. Avanessian, Nayvin W. Chew, Thao T. Tang, Kevin C. Barry. Hypoxia as tumor-intrinsic regulator of Flt3L production by NK cells [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Tumor Immunology and Immunotherapy; 2023 Oct 1-4; Toronto, Ontario, Canada. Philadelphia (PA): AACR; Cancer Immunol Res 2023;11(12 Suppl):Abstract nr B020.

GNF-7, a novel FLT3 inhibitor, overcomes drug resistance for the treatment of FLT3‑ITD acute myeloid leukemia

BackgroundAcute myeloid leukemia (AML) with FMS-like tyrosine kinase 3 internal tandem duplication (FLT3-ITD) mutation accounts for a large proportion of AML patients and diagnosed with poor prognosis. Although the prognosis of FLT3-ITD AML has been greatly improved, the drug resistance frequently occurred in the treatment of FLT3 targeting drugs. GNF-7, a multitargeted kinase inhibitor, which provided a novel therapeutic strategy for overriding leukemia. In this study, we explored the antitumor activity of GNF-7 against FLT3-ITD and clinically-relevant drug resistance in FLT3 mutant AML.MethodsGrowth inhibitory assays were performed in AML cell lines and Ba/F3 cells expressing various FLT3 mutants to evaluate the antitumor activity of GNF-7 in vitro. Western blotting was used to examine the inhibitory effect of GNF-7 on FLT3 and its downstream pathways. Molecular docking and cellular thermal shift assay (CETSA) were performed to demonstrate the binding of FLT3 to GNF-7. The survival benefit of GNF-7 in vivo was assessed in mouse models of transformed Ba/F3 cells harboring FLT3-ITD and FLT3-ITD/F691L mutation. Primary patient samples and a patient-derived xenograft (PDX) model were also used to determine the efficacy of GNF-7.ResultsGNF-7 inhibited the cell proliferation of Ba/F3 cells expressing FLT3-ITD and exhibited potently anti-leukemia activity on primary FLT3-ITD AML samples. Moreover, GNF-7 could bind to FLT3 protein and inhibit the downstream signaling pathway activated by FLT3 including STAT5, PI3K/AKT and MAPK/ERK. In vitro and in vivo studies showed that GNF-7 exhibited potent inhibitory activity against FLT3-ITD/F691L that confers resistant to quizartinib (AC220) or gilteritinib. Importantly, GNF-7 showed potent cytotoxic effect on leukemic stem cells, significantly extend the survival of PDX model and exhibited similar therapy effect compared with gilteritinib.ConclusionsOur results show that GNF-7 is a potent FLT3-ITD inhibitor and may become a promising lead compound applied for treating some of the clinically drug resistant patients.

Identification of dendritic cell precursor from the CD11c+ cells expressing high levels of MHC class II molecules in the culture of bone marrow with FLT3 ligand.

Dendritic cells (DCs) are readily generated from the culture of mouse bone marrow (BM) treated with either granulocyte macrophage-colony stimulating factor (GM-CSF) or FMS-like tyrosine kinase 3 ligand (FLT3L). CD11c+MHCII+ or CD11c+MHCIIhi cells are routinely isolated from those BM cultures and generally used as in vitro-generated DCs for a variety of experiments and therapies. Here, we examined CD11c+ cells in the BM culture with GM-CSF or FLT3L by staining with a monoclonal antibody 2A1 that is known to recognize mature or activated DCs. Most of the cells within the CD11c+MHCIIhi DC gate were 2A1+ in the BM culture with GM-CSF (GM-BM culture). In the BM culture with FLT3L (FL-BM culture), almost of all the CD11c+MHCIIhi cells were within the classical DC2 (cDC2) gate. The analysis of FL-BM culture revealed that a majority of cDC2-gated CD11c+MHCIIhi cells exhibited a 2A1-CD83-CD115+CX3CR1+ phenotype, and the others consisted of 2A1+CD83+CD115-CX3CR1- and 2A1-CD83-CD115-CX3CR1- cells. According to the antigen uptake and presentation, morphologies, and gene expression profiles, 2A1-CD83-CD115-CX3CR1- cells were immature cDC2s and 2A1+CD83+CD115-CX3CR1- cells were mature cDC2s. Unexpectedly, however, 2A1-CD83-CD115+CX3CR1+ cells, the most abundant cDC2-gated MHCIIhi cell subset in FL-BM culture, were non-DCs. Adoptive cell transfer experiments in the FL-BM culture confirmed that the cDC2-gated MHCIIhi non-DCs were precursors to cDC2s, i.e., MHCIIhi pre-cDC2s. MHCIIhi pre-cDC2s also expressed the higher level of DC-specific transcription factor Zbtb46 as similarly as immature cDC2s. Besides, MHCIIhi pre-cDC2s were generated only from pre-cDCs and common DC progenitor (CDP) cells but not from monocytes and common monocyte progenitor (cMoP) cells, verifying that MHCIIhi pre-cDC2s are close lineage to cDCs. All in all, our study identified and characterized a new cDC precursor, exhibiting a CD11c+MHCIIhiCD115+CX3CR1+ phenotype, in FL-BM culture.