Search Results (174)

Background/Objectives: Acute myeloid leukemia (AML) with FLT3 internal tandem duplication (FLT3-ITD) mutations carries a poor prognosis. While FLT3 inhibitors like midostaurin show benefits in combination with chemotherapy, the role of allelic ratio (AR), NPM1 mutation status, and hematopoietic stem cell transplantation (HSCT) remains uncertain. Real-world data can help refine prognostic classification and treatment strategies. Methods: We retrospectively analyzed 37 fit patients with FLT3-ITD AML treated with standard “7+3” chemotherapy, with and without midostaurin, between 2013 and 2022. Patients were stratified by FLT3-ITD AR, NPM1 status, and treatment approach. Outcomes assessed included complete remission (CR), disease-free survival (DFS), and overall survival (OS). Results: Overall, 67.6% achieved CR/CRi. Response rates did not differ significantly by AR (low vs. high: 66.7% vs. 69.2%) or midostaurin use (72.6% vs. 60%; p = 0.49). NPM1 mutations were associated with improved DFS (10.3 vs. 3 months, p = 0.036) but not OS. HSCT, performed in 54.1% of patients, mainly in first remission (CR1), significantly prolonged DFS (not reached vs. 5.3 months, p = 0.005) and remained an independent predictor in multivariate analysis (HR: 0.160, p = 0.039). OS (median 15.1 months) did not vary significantly across subgroups. Among patients achieving CR1, OS was significantly longer in those who underwent HSCT after midostaurin-based induction compared to those not transplanted (median OS not reached vs. 12.8 months; 95% CI, 6.9–18.7; p = 0.045), whereas no significant benefit was observed after standard induction. In a landmark analysis restricted to patients transplanted in CR1, those who had received midostaurin-based induction showed a trend toward improved OS compared to those treated with standard induction (median OS not reached vs. 11.5 months; 95% CI, 0.5–25.0; p = 0.086). Conclusions: This real-life study supports the importance of NPM1 mutations and HSCT in CR1, especially in the midostaurin era, for improving DFS in FLT3-ITD AML. These findings support updated guidelines for reducing the prognostic weight of AR and highlight the need for improved post-remission strategies in this setting. Full article

The internal tandem duplication mutation of FMS-like tyrosine kinase 3 (FLT3-ITD) is associated with high recurrence and mortality rates in acute myeloid leukemia (AML), making it a critical target for anti-AML therapies. Plinabulin is a diketopiperazines derivative that exhibits extensive anti-cancer potency by targeting β-tubulin. We designed and synthesized a novel FLT3 inhibitor, namely 5-3, based on the structure of plinabulin and evaluated its effect on FLT3-ITD mutant AML cells. The results indicated that 5-3 potently and selectively inhibits the growth of mutant FLT3-expressingleukemia cells, and had no effect on FLT3 wide-type cancer cells, suggesting the antiproliferative activity of 5-3 depends highly on FLT3-ITD expression. Mechanically, 5-3 significantly suppressed the phosphorylation of FLT3 signaling pathway, including STAT5, Erk and Akt. Moreover, the efficiency of compound 5-3 is not associated with Plinabulin’s typical target, β-tubulin. In conclusion, the study identified diketopiperazine derivative as a novel FLT3-ITD selective inhibitor. These results demonstrated that 5-3 might be a drug candidate for the treatment of FLT3-ITD-positive AML. Full article

Acute myeloid leukemia (AML) is a heterogeneous hematological malignancy associated with a poor prognosis. Activating mutations in the FLT3 gene occur in approximately 30% of AML cases, with internal tandem duplications in the juxtamembrane domain (FLT3-ITD; 75%) and mutations in the tyrosine kinase domain (FLT3-TKD; 25%). FLT3-ITD mutations are linked to poor prognosis and offer significant clinical predictive value, whereas the implications of FLT3-TKD mutations are less understood. The Hedgehog–Gli pathway is an established therapeutic target in AML, and emerging evidence suggests crosstalk between FLT3-ITD signaling and Gli expression regulation via non-canonical mechanisms. Post-translational modifications involving myristic and palmitic acids regulate various cellular processes, but their role in AML remains poorly defined. In this study, we investigated the role of fatty acid synthase (FASN), which synthesizes myristic and palmitic acids and catalyzes palmitoyl-acyltransferation, in regulating FLT3-ITD-Gli signaling. FASN knockdown using shRNA and the FASN inhibitor TVB-3166 was performed in FLT3-ITD-mutated AML cell lines (MOLM13, MV411) and Baf3-FLT3-ITD cells. The impact of FASN inhibition was assessed through Western blot and kinome profiling, while biological implications were evaluated by measuring cell viability and proliferation. FASN inhibition resulted in reduced levels of phospho-Akt (pAkt) and phospho-S6 kinase (pS6) and decreased expression of Hedgehog–Gli1, confirming non-canonical regulation of Gli by FLT3-ITD signaling. Combining TVB-3166 with the Gli inhibitor GANT61 significantly reduced the survival of MOLM13 and MV411 cells. Full article

Background: FLT3 mutation testing is a key ancillary molecular assay for diagnosing and managing patients with acute myeloid leukemia (AML), including assessing the utility of FLT3 inhibitors during induction chemotherapy. FLT3 PCR utilizing fluorescently labeled primers and capillary electrophoresis readout is the most used technique for the rapid detection of FLT3 internal tandem duplications (ITDs) (including very small ITDs) and tyrosine kinase domain (TKD) mutations. However, capillary electrophoresis (CE) is a relatively lengthy and technically demanding result readout mode that could potentially be replaced by faster alternatives. Methods: Here, we describe the validation of a modified FLT3 PCR assay that uses the Agilent 4200 TapeStation platform for result readouts. This platform generates quantifiable electropherograms and gel images in under two minutes and at a low cost. We validated its ability to detect FLT3-ITD and -TKD mutations using 22 and 18 previously tested patient samples, respectively. Results: The TapeStation 4200 instrument is 100% sensitive, specific, and highly reproducible for post-PCR fragment analysis in detecting FLT3-ITD (greater than 15 bp in size) and TKD mutations in AML patients. Its results are nearly 100% concordant with those obtained from our previously validated NGS and PAGE methods. However, the limitation of this readout mode is its inability to reliably detect FLT3-ITDs smaller than 15 bp in size. Conclusions: Given the widespread use of TapeStation instruments in molecular diagnostics laboratories as part of next-generation sequencing (NGS) workflows, this modified assay is well-suited as a companion test for rapid NGS platforms to detect larger FLT3-ITDs, which are NGS often miscalledor under-called by the NGS bioinformatics algorithms. However, it is not suitable for use as a standalone assay, as it is unable to reliably detect very short FLT3-ITDs. Full article

N-(2-chloro-5-(3-(pyridin-4-yl)-1H-pyrazolo [3,4-b]pyridin-5-yl)pyridin-3-yl)-4-fluorobenzenesulfonamide, namely, FD274, is a promising 7-azaindazole-based PI3K inhibitor candidate with high antitumor efficacy against acute myeloid leukemia and reduced cardiotoxicity in the zebrafish model. To advance its clinical translation, in this work, we conducted comprehensive assessments of the cardiotoxicity of FD274 and preliminarily investigated its synergistic antitumor effects with an FLT3 inhibitor, Gilteritinib. The cardiotoxicity profile of FD274, as well as its bioisostere FD268 (positive control), was evaluated using the C57BL/6 mouse model and the H9C2 cell line. The cardiotoxicity of FD274 after a consecutive 20-day treatment period was further assessed in an HL-60 xenograft mouse model. The synergistic cytotoxicity of FD274 with Gilteritinib was evaluated in the HL-60 cell line and the FLT3-ITD cell line MV-4-11. FD274 demonstrated lower adverse effects associated with cardiac dysfunction, oxidative stress, and myocardial injury in the C57BL/6 mouse model and in the H9C2 cell line as compared with FD268. Its negligible adverse effect was further validated in the HL-60 xenograft mice after the 20-day treatment process. Moreover, FD274 demonstrated a synergistic pro-apoptotic effect with Gilteritinib in both HL-60 and MV-4-11 cells. Our findings confirmed the low cardiotoxicity of FD274 and its great potential for combination therapy with Gilteritinib, warranting further development. Full article

Background: Chemoresistance and tumor recurrence remain major obstacles in colorectal cancer (CRC) therapy. Elucidating the molecular mechanisms underlying treatment resistance is critical for improving therapeutic outcomes. Methods: We analyzed transcriptomic profiles from public datasets (TCGA and GSE39582) to identify differentially expressed genes associated with a poor response to neoadjuvant chemotherapy in CRC patients. Among 298 candidate genes, ANXA9 emerged as significantly overexpressed in chemoresistant tumors and associated with a poor prognosis. These findings were further validated in an independent cohort of 146 Stage III CRC patients using immunohistochemistry and survival analysis. The expression of ANXA9 was evaluated in oxaliplatin acquired-resistant CRC cell lines via qPCR and Western blot. Functional studies, including RNA interference, colony formation, apoptosis assays, and drug sensitivity testing, were performed in vitro and in vivo to assess the role of ANXA9. A high-throughput drug screen identified G749, a FLT3 inhibitor, as a potential therapeutic agent. Results: ANXA9 expression was significantly elevated in non-responders to chemotherapy and oxaliplatin-resistant CRC cell lines. The knockdown of ANXA9 reduced proliferation and enhanced oxaliplatin sensitivity. G749 was found to suppress ANXA9 expression in a dose-dependent manner and inhibit CRC cell growth in vitro and in patient-derived organoids. In a CRC xenograft mouse model, G749 reduced the tumor burden without observable toxicity. Mechanistically, we identified ZMYM2 as a transcriptional regulator of ANXA9. ChIP-qPCR confirmed ZMYM2 binding to the ANXA9 promoter, especially in resistant cells. Silencing ZMYM2 suppressed tumor cell growth and restored chemosensitivity. Conclusions: The ZMYM2-ANXA9 signaling axis drives chemoresistance and tumor progression in CRC. FLT3 inhibition by G749 effectively downregulates ANXA9 and sensitizes tumors to chemotherapy, highlighting a novel therapeutic approach for chemoresistant CRC. Full article

Acute myeloid leukemia (AML) presents a significant global health challenge due to its aggressive behavior and mortality rates. Traditionally, AML treatment has relied on intensive chemotherapy—anthracyclines and cytarabine. However, recent breakthroughs in targeted therapies are transforming clinical practices. This review examines current treatment strategies, including breakthrough therapies. Also, a global perspective on AML management includes the disparity in treatment availability, particularly the difficulties faced by low- and middle-income countries due to the high cost and restricted access to novel therapies. Full article

Acute myeloid leukemia (AML) has traditionally been linked to a poor prognosis, particularly in older patients who are ineligible for intensive chemotherapy. The advent of Venetoclax, a powerful oral BH3 mimetic targeting anti-apoptotic protein BCL2, has significantly advanced AML treatment. Its combination with the hypomethylating agent azacitidine (AZA/VEN) has become a standard treatment for this group of AML patients, demonstrating a 65% overall response rate and a median overall survival of 14.7 months, compared to 22% and 8 months with azacitidine monotherapy, respectively. However, resistance and relapses remain common, representing a significant clinical challenge. Recent studies have identified molecular alterations, such as mutations in FLT3-ITD, NRAS/KRAS, TP53, and BAX, as major drivers of resistance. Additionally, other factors, including metabolic changes, anti-apoptotic protein expression, and monocytic or erythroid/megakaryocytic differentiation status, contribute to treatment failure. Clinical trials are exploring strategies to overcome venetoclax resistance, including doublet or triplet therapies targeting IDH and FLT3 mutations; novel epigenetic approaches; menin, XPO1, and MDM2 inhibitors; along with immunotherapies like monoclonal antibodies and antibody–drug conjugates. A deeper understanding of the molecular mechanisms of resistance through single-cell analysis will be crucial for developing future therapeutic strategies. Full article

Background/Objectives: Acute myeloid leukemia (AML) is a rare hematological malignancy with a poor prognosis. Activating c-Kit (CD117) mutations occur in 5% of de novo AML and 30% of core-binding factor (CBF) AML, leading to worse clinical outcomes. Posttranslational modifications, particularly with myristic and palmitic acid, are crucial for various cellular processes, including membrane organization, signal transduction, and apoptosis regulation. However, most research has focused on solid tumors, with limited understanding of these mechanisms in AML. Fatty acid synthase (FASN), a key palmitoyl-acyltransferase, regulates the subcellular localization, trafficking, and degradation of target proteins, such as H-Ras, N-Ras, and FLT3-ITDmut receptors in AML. Methods: In this study, we investigated the role of FASN in two c-Kit-N822K-mutated AML cell lines using FASN knockdown via shRNA and the FASN inhibitor TVB-3166. Functional implications, including cell proliferation, were assessed through Western blotting, mass spectrometry, and PamGene. Results: FASN inhibition led to an increased phosphorylation of c-Kit (p-c-Kit), Lyn kinase (pLyn), MAP kinase (pMAPK), and S6 kinase (pS6). Furthermore, we observed sustained high expression of Gli1 in Kasumi1 cells following FASN inhibition, which is well known to be mediated by the upregulation of pS6. Conclusions: The combination of TVB-3166 and the Gli inhibitor GANT61 resulted in a significant reduction in the survival of Kasumi1 cells. Full article

Background/Objectives: Acute myeloid leukemia (AML) presents significant therapeutic challenges, particularly in cases driven by mutations in the FLT3 tyrosine kinase. This study aimed to develop a robust and user-friendly machine learning-based quantitative structure–activity relationship (QSAR) model to predict the inhibitory potency (pIC₅₀ values) of FLT3 inhibitors, addressing the limitations of previous models in dataset size, diversity, and predictive accuracy. Methods: Using a dataset which was 14 times larger than those employed in prior studies (1350 compounds with 1269 molecular descriptors), we trained a random forest regressor, chosen due to its superior predictive performance and resistance to overfitting. Rigorous internal validation via leave-one-out and 10-fold cross-validation yielded ${\mathrm{Q}}^2$ values of 0.926 and 0.922, respectively, while external validation on 270 independent compounds resulted in an R² value of 0.941 with a standard deviation of 0.237. Results: Key molecular descriptors influencing the inhibitor potency were identified, thereby improving the interpretability of structural requirements. Additionally, a user-friendly computational tool was developed to enable rapid prediction of pIC₅₀ values and facilitate ligand-based virtual screening, leading to the identification of promising FLT3 inhibitors. Conclusions: These results represent a significant advancement in the field of FLT3 inhibitor discovery, offering a reliable, practical, and efficient approach for early-stage drug development, potentially accelerating the creation of targeted therapies for AML. Full article

Background/Objectives: Patients with relapsed/refractory (R/R) AML with FLT3 mutation (FLT3^mut) have a dismal prognosis. FLT3^mut offers a target for therapy in these patients. Gilteritinib (gilter) and quizartinib (quizar) have demonstrated efficacy as single agents in two phase 3 clinical trials. Methods: We retrospectively analyzed the characteristics, treatments, and outcomes of 50 patients with R/R FLT3^mut AML who received gilter or quizar as monotherapy in 27 Spanish centers before their commercial availability. Forty-four patients were treated with gilter and six with quizar. Results: The median age was 62.5 years, and 52% were women. Most patients presented with FLT3-ITD mutations (80%); 46% had refractory disease and 54% had relapsed disease at treatment initiation. First-line treatment was chemotherapy in 80% of patients, with 40% of these also receiving midostaurin. Twenty-five patients (50%) had previously received FLT3 inhibitor, and twenty-eight (56%) had received more than one line treatment before starting gilter/quizar. The rates of complete remission (CR), CR without hematological recovery (CRi), and partial remission were 22%, 18%, and 16%, respectively. The median overall survival (OS) and disease-free survival were 4.74 months and 2.99 months, respectively. We observed a significant improvement in OS in patients who had received only one prior line of therapy compared to those who had received two or more therapies (10.77 months vs. 4.24 months, p = 0.016). Multivariate analysis identified failure to achieve CR/CRi, receiving more than one prior line of therapy, age, and white blood cells count as independent prognostic factors for OS. The most common toxicities were febrile neutropenia, liver function abnormalities, and QT interval prolongation. Conclusions: Gilter/quizar monotherapy are effective and tolerable options for patients with R/R FLT3^mut AML in a real-world setting. Response and toxicity rates are similar to those reported in the phase 3 trials, despite the more heterogeneous nature of the study population. Full article

Background: FMS-like tyrosine kinase 3 (FLT3) mutations or internal tandem duplication occur in 30% of acute myeloid leukemia (AML) cases. In these cases, FLT3 inhibitors (FLT3i) are approved for induction treatment and relapse. Allogeneic hematopoietic stem cell transplantation (alloHSCT) remains the recommended post-induction therapy for suitable patients. However, the role of FLT3i therapy after alloHSCT remains unclear. Therefore, we investigated the three currently available FLT3i, gilteritinib, midostaurin, and quizartinib, in terms of their immunosuppressive effect on dendritic cells (DCs). DCs are professional antigen-presenting cells inducing T-cell responses to infectious stimuli. Highly activated DCs can also cause complications after alloHSCT, such as triggering Graft versus Host disease, a serious and potentially life-threatening complication after alloHSCT. Methods: To study the immunomodulatory effects on DCs, we differentiated murine and human DCs in the presence of FLT3i and performed immunophenotyping by flow cytometry and cytokine measurements and investigated gene and protein expression. Results: We detected a dose-dependent immunosuppressive effect of midostaurin, which decreased the expression of costimulatory markers like CD86, and found a reduced secretion of pro-inflammatory cytokines such as IL-12, TNFα, and IL-6. Mechanistically, we show that midostaurin inhibits TLR and TNF signaling and NFκB, PI3K, and MAPK pathways. The immunosuppressive effect of gilteritinib was less pronounced, while quizartinib did not show truncation of relevant signaling pathways. Conclusions: Our results suggest different immunosuppressive effects of these three FLT3i and may, therefore, provide an additional rationale for optimal maintenance therapy after alloHSCT of FLT3-positive AML patients to prevent infectious complications and GvHD mediated by DCs. Full article

Acute myeloid leukemia (AML) is an aggressive hematologic neoplasia with a complex polyclonal architecture. Among driver lesions, those involving the FLT3 gene represent the most frequent mutations identified at diagnosis. The development of tyrosine kinase inhibitors (TKIs) has improved the clinical outcomes of FLT3-mutated patients (Pt). However, overcoming resistance to these drugs remains a challenge. To unravel the molecular mechanisms underlying therapy resistance and clonal selection, we conducted a longitudinal analysis using a single-cell DNA sequencing approach (MissionBioTapestri® platform, San Francisco, CA, USA) in two patients with FLT3-mutated AML. To this end, samples were collected at the time of diagnosis, during TKI therapy, and at relapse or complete remission. For Pt #1, disease resistance was associated with clonal expansion of minor clones, and 2nd line TKI therapy with gilteritinib provided a proliferative advantage to the clones carrying NRAS and KIT mutations, thereby responsible for relapse. In Pt #2, clonal architecture was less complex, and 1st line TKI therapy with midostaurin was able to eradicate the leukemic clones. Our results corroborate previous findings about clonal selection driven by TKIs, highlighting the importance of a deeper characterization of individual clonal architectures for choosing the best treatment plan for personalized approaches aimed at optimizing outcomes. Full article

There are no effective therapies to prevent preeclampsia (PE). Pravastatin shows promise by attenuating processes associated with PE such as decreased cytotrophoblast (CTB) migration, aberrant angiogenesis, and increased oxidative stress. This study assesses the effects of pravastatin on hyperglycemia-induced CTB dysfunction. Methods: Human CTB cells were treated with 100, 150, 200, 300, or 400 mg/dL glucose for 48 h. Some cells were pretreated with pravastatin (1 µg/mL), while others were cotreated with pravastatin and glucose. The expression of urokinase plasminogen activator (uPA), plasminogen activator inhibitor 1 (PAI-1) mRNA, vascular endothelial growth factor (VEGF), placenta growth factor (PlGF), soluble fms-like tyrosine kinase-1 (sFlt-1), and soluble endoglin (sEng) were measured. CTB migration was assayed using a CytoSelect migration assay kit. Statistical comparisons were performed using an analysis of variance with Duncan’s post hoc test. Results: The hyperglycemia-induced downregulation of uPA was attenuated in CTB cells pretreated with pravastatin at glucose levels > 200 mg/dL and cotreated at glucose levels > 300 mg/dL (p < 0.05). Hyperglycemia-induced decreases in VEGF and PlGF and increases in sEng and sFlt-1 were attenuated in both the pretreatment and cotreatment samples regardless of glucose dose (p < 0.05). Pravastatin attenuated hyperglycemia-induced dysfunction of CTB migration. Conclusions: Pravastatin mitigates stress signaling responses in hyperglycemic conditions, weakening processes leading to abnormal CTB migration and invasion associated with PE in pregnancy. Full article

Activating FLT3 mutations plays a crucial role in leukemogenesis, but identifying the optimal candidates for FLT3 inhibitor therapy remains controversial. This study aims to explore the impacts of FLT3 mutations in pediatric acute lymphoblastic leukemia (ALL) and acute myeloid leukemia (AML) and to compare the mutation profiles between the two types to inspire the targeted application of FLT3 inhibitors. We retrospectively analyzed 243 ALL and 62 AML cases, grouping them into FLT3-mutant and wild-type categories, respectively. We then assessed the associations between FLT3 mutations and the clinical manifestations, genetic characteristics, and prognosis in ALL and AML. Additionally, we compared the distinct features of FLT3 mutations between ALL and AML. In ALL patients, those with FLT3 mutations predominantly exhibited hyperdiploidy (48.6% vs. 14.9%, p < 0.001) and higher FLT3 expression (108.02 [85.11, 142.06] FPKM vs. 23.11 [9.16, 59.14] FPKM, p < 0.001), but lower expression of signaling pathway-related genes such as HRAS, PIK3R3, BAD, MAP2K2, MAPK3, and STAT5A compared to FLT3 wild-type patients. There was no significant difference in prognosis between the two groups. In contrast, AML patients with FLT3 mutations were primarily associated with leucocytosis (82.90 [47.05, 189.76] G/L vs. 20.36 [8.90, 55.39] G/L, p = 0.001), NUP98 rearrangements (30% vs. 4.8%, p = 0.018), elevated FLT3 expression (74.77 [54.31, 109.46] FPKM vs. 34.56 [20.98, 48.28] FPKM, p < 0.001), and upregulated signaling pathway genes including PIK3CB, AKT1, MTOR, BRAF, and MAPK1 relative to FLT3 wild-type, correlating with poor prognosis. Notably, internal tandem duplications were the predominant type of FLT3 mutation in AML (66.7%) with higher inserted base counts, whereas they were almost absent in ALL (6.3%, p < 0.001). In summary, our study demonstrated that the forms and impacts of FLT3 mutations in ALL differed significantly from those in AML. The gene expression profiles of FLT3-related pathways may provide a rationale for using FLT3 inhibitors in AML rather than ALL when FLT3 mutations are present. Full article