Role of Biomarkers in FLT3 AML

Multi-omics integration reveals immune hallmarks and biomarkers associated with FLT3 inhibitor sensitivity in FLT3-mutated AML

Acute myeloid leukemia (AML) is an aggressive hematologic malignancy characterized by poor clinical outcomes, frequently exacerbated by mutations in the FMS-like tyrosine kinase 3 (FLT3) gene. Although FLT3 inhibitors (FLT3i) have emerged as promising therapeutic agents, the absence of molecular biomarkers to predict FLT3i response remains a critical limitation in clinical practice. In this study, we performed a comprehensive multi-omics analysis integrating transcriptomic, proteomic, and pharmacogenomic data from the Beat AML cohort, the Cancer Cell Line Encyclopedia (CCLE), and the PXD023201 repository to elucidate the molecular consequences of FLT3 mutations in AML. Our analysis revealed significant differences in RNA and protein expression profiles between FLT3-mutant and wild-type AML cases, with a particularly striking association between FLT3 mutations and immune suppression. We further evaluated the drug sensitivity of FLT3-mutant patients to 3 FDA-approved FLT3i, gilteritinib, midostaurin, and quizartinib, and observed heightened sensitivity in FLT3-mutant cohorts, accompanied by the activation of immune-related pathways in treatment-responsive groups. These findings suggest a potential synergy between FLT3i efficacy and immune activation. Through rigorous bioinformatic analysis, we identified 3 candidate biomarkers: CD36, SASH1, and NIBAN2, associated with FLT3i sensitivity. These biomarkers were consistently upregulated in favorable prognostic subgroups and demonstrated strong correlations with immune activation pathways. The identification of CD36, SASH1, and NIBAN2 as predictive biomarkers offers a novel toolset for stratifying FLT3i response and prognosis.

Recent advances of CAR-T cells in acute myeloid leukemia

Acute myeloid leukemia (AML), the most common type of leukemia in adults, is a highly heterogeneous and aggressive hematologic malignancy. Since the 20th century, the combination of cytosine arabinoside and anthracyclines has been the most common chemotherapy drug used to treat patients with AML. Although, new targeted medicines have emerged, such as midostaurin and gilteritinib targeting FMS-like tyrosine kinase 3 (FLT3), ivosidenib (isocitrate dehydrogenase 1 (IDH1) inhibitor) and enasidenib (IDH2 inhibitor) targeting IDH, and gemtuzumab ozogamicin targeting CD33, which have changed the treatment strategies of AML. But, until now, hematopoietic stem cell transplantation remains the best treatment option in most cases. However, treatment resistance and relapse are still the major consequences of disease progression in AML, highlighting the urgent need for novel therapeutic approaches. As an alternative, chimeric antigen receptor (CAR)-T cells are engineered T-cells developed as a breakthrough in cancer therapy in recent years, and explored and used in various tumor types. In particular, it has achieved remarkable efficacy in the field of relapsed and refractory B lymphocyte tumors. This review mainly summarizes and discusses the research progress and the clinical application of CAR-T cell immunotherapy in AML in recent years.

Concurrent inhibition of FLT3 and sphingosine kinase-1 triggers synergistic cytotoxicity in midostaurin resistant FLT3-ITD positive acute myeloid leukemia cells via blocking FLT3/STAT5A signaling to induce apoptosis

The FMS-like tyrosine kinase 3-internal tandem duplication (FLT3-ITD) is one of the most frequent mutations observed in acute myeloid leukemia (AML) which contributes to disease progression and unfavorable prognosis. Midostaurin, a small FLT3 inhibitor (FLT3I), is clinically approved. However, patients generally possess acquired resistance when midostaurin used alone. Shifting the balance in the sphingolipid rheostat toward anti-apoptotic sphingosine kinase-1 (SK-1) or glucosylceramide synthase (GCS) is related to therapy resistance in cancer, however, their role in midostaurin resistant FLT3-ITD positive AML has not been previously investigated. We generated midostaurin resistant MV4-11 and MOLM-13 cell lines which showed increased IC50 values compared to their sensitive partner cells. SK-1 is overexpressed in resistant cells while GCS remains unchanged. Subsequent pharmacological targeting of SK-1 in resistant cells decreased SK-1 protein level, inhibited cell proliferation and showed additive or synergistic effect on cell growth, as confirmed by the Chou-Talalay combination index, and induced G0/G1 arrest (PI staining by flow cytometry). Cotreatment (SKI-II plus midostaurin) triggered apoptosis via phosphatidylserine exposure (annexin V/PI double staining). Mechanistically, induction of the intrinsic pathway of apoptosis was confirmed as increased activating cleavages of caspase-3 and PARP and increased Bax/Bcl-2 ratios. Activating phosphorylations of FLT3 (at tyrosine residue 591) and STAT5A (at tyrosine residue 694) dramatically inhibited in resistant cells treated with the combination. In conclusion, midostaurin resistance could be reversed by dual SK-1 and FLT3 inhibition in midostaurin resistant AML cell lines, providing the first evidence of a novel treatment approach to re-sensitize FLT3-ITD positive AML.

Crosstalk between genomic variants and DNA methylation in FLT3 mutant acute myeloid leukemia

Acute myeloid leukemia (AML) is a type of blood cancer with diverse genetic variations and DNA methylation alterations. By studying the interaction of gene mutations, expression, and DNA methylation, we aimed to gain valuable insights into the processes that lead to block differentiation in AML. We analyzed TCGA-LAML data (173 samples) with RNA sequencing and DNA methylation arrays, comparing FLT3 mutant (48) and wild-type (125) cases. We conducted differential gene expression analysis using cBioPortal, identified DNA methylation differences with ChAMP tool, and correlated them with gene expression changes. Gene set enrichment analysis (g:Profiler) revealed significant biological processes and pathways. ShinyGo and GeneCards were used to find potential transcription factors and their binding sites among significant genes. We found significant differentially expressed genes (DEGs) negatively correlated with their most significant methylation probes (Pearson correlation coefficient of -0.49, P-value <0.001) between FLT3 mutant and wild-type groups. Moreover, our exploration of 450 k CpG sites uncovered a global hypo-methylated status in 168 DEGs. Notably, these methylation changes were enriched in the promoter regions of Homebox superfamily gene, which are crucial in transcriptional-regulating pathways in blood cancer. Furthermore, in FLT3 mutant AML patient samples, we observed overexpress of WT1, a transcription factor known to bind homeobox gene family. This finding suggests a potential mechanism by which WT1 recruits TET2 to demethylate specific genomic regions. Integrating gene expression and DNA methylation analyses shed light on the impact of FLT3 mutations on cancer cell development and differentiation, supporting a two-hit model in AML. This research advances understanding of AML and fosters targeted therapeutic strategy development.

CAR-T Therapy Beyond B-Cell Hematological Malignancies

Despite the advances of CAR-T cells in certain hematological malignancies, mostly from B-cell derivations such as non-Hodgkin lymphomas, acute lymphoblastic leukemia and multiple myeloma, a significant portion of other hematological and non-hematological pathologies can benefit from this innovative treatment, as the results of clinical studies are demonstrating. The clinical application of CAR-T in the setting of acute T-lymphoid leukemia, acute myeloid leukemia, solid tumors, autoimmune diseases and infections has encountered limitations that are different from those of hematological B-cell diseases. To overcome these restrictions, strategies based on different molecular engineering platforms have been devised and will be illustrated below. The aim of this manuscript is to provide an overview of the CAR-T application in pathologies other than those currently treated, highlighting both the limits and results obtained with these settings.

Clinical Peptidomics in Acute Leukemias: Current Advances and Future Perspectives

The study of circulating peptides in the blood offers significant opportunities for diagnosing, stratifying, and managing various diseases. With recent technological advances and the ongoing need to understand complex diseases such as acute leukemias (AL), peptidomic analysis of peripheral blood, especially serum and plasma, has become increasingly important for studying human biology and pathophysiology. Here, we provide insights and perspectives on technological developments and potential clinical applications using widely used peptidomic analysis methods. We discuss examples where peptidomics using serum or plasma has contributed to the understanding of AL. Specifically, we highlight the scarcity of peptidomic studies applied to AL and emphasize the importance of exploring this area, as the few published studies present promising results that can significantly contribute to precision medicine.

Construction of AML prognostic model with CYP2E1 and GALNT12 biomarkers based on golgi- associated genes

Acute myeloid leukaemia (AML) was originally an aggressive malignancy of the bone marrow and one of the deadliest forms of acute leukaemia. The 5-year mortality benefit for patients with AML was only 28.3%. Moreover, a large proportion of patients experienced frequent relapses even after remission, thus predicting a bleak prognosis. This research employed differential expression analysis of AML and normal samples sourced from the GSE30029 database, as well as weighted gene co-expression network analysis (WGCNA). We discovered differential golgi apparatus-related genes (DGARGs) specifically associated with AML. Via regressivity analysis and machine learning algorithm, the cancer genome atlas-acute myeloid leukemia (TCGA-AML) cohort developed a prognostic model using characteristic prognostic genes. The performance value of risk score was analysed using Kaplan-Meier (KM) curves and Cox regression. A predictive nomogram was developed to assess the outcome. The association between prognostic trait genes and the immune microenvironment was examined. Finally, immunoactivity and drug susceptibilities were evaluated in various risk groups identified by prognostic signature genes. A total of 77 DGARGs were obtained by differential expression analysis with WGCNA analysis. Following univariate Cox regression and LASSO regression, six prognostic signature genes (ARL5B, GALNT12, MANSC1, PDE4DIP, NCALD and CYP2E1) were utilized to develop a prognostic model. This model was calibrated via KM survival and receiver operating characteristic (ROC) curves, which concluded that it had a predictive impact on the prognosis of AML. Further analysis of the tumour microenvironment in AML patients demonstrated notable variances in immune cell APC_co_inhibition, CCR, Parainflammation, Type_I_IFN_Response, and Type_II_IFN_Response between the high-risk and low-risk groups. A prognostic model was devised in this study using six prognostic genes linked to the Golgi apparatus. The exactness of the model in guiding the prognosis of AML was established. As a result of expression validation, CYP2E1 and GALNT12 will be used as biomarkers to offer fresh insights into the prognosis and treatment of AML patients.

TFAP2C/FLT3 axis reduces ferroptosis in breast cancer cells by inhibiting mitochondrial autophagy

BACKGROUND

FMS-like tyrosine kinase 3 (FLT3), a key target protein for treating acute myeloid leukemia, has recently been found to be closely related to ferroptosis in breast cancer (BC). However, the mechanism by which FLT3 regulates ferroptosis in BC remains unknown. Whether this regulatory relationship can be exploited for BC treatment needs further exploration.

METHODS

This study combined analysis from The Cancer Genome Atlas database with immunohistochemistry/quantitative reverse transcription-PCR/Western blot experiments to verify the expression of FLT3 in BC. FLT3 knockdown/overexpression plasmids were used in conjunction with mitochondrial autophagy inducers to treat BC cells, analyzing the effects of FLT3 on autophagy and ferroptosis. Key transcription factors for FLT3 were determined through predictions from the KnockTF database and dual luciferase/chromatin immunoprecipitation experiments, further analyzing the impact of this regulatory axis on autophagy and ferroptosis in BC cells.

RESULTS

FLT3 was significantly overexpressed in BC tissues and cells. Overexpression of FLT3 could inhibit autophagy and ferroptosis in BC cells, a regulation that was restored upon the addition of mitochondrial autophagy inducers. Additionally, transcription factor AP-2 gamma (TFAP2C) could mediate the transcriptional activation of FLT3, further inhibiting ferroptosis induced by mitochondrial autophagy.

CONCLUSION

The TFAP2C/FLT3 axis reduced ferroptosis in BC cells by inhibiting mitochondrial autophagy. These research findings elucidated the mechanism by which FLT3 regulated ferroptosis in BC and provided potential targets for BC treatment.

Recent Progress of Exosomes in Hematological Malignancies: Pathogenesis, Diagnosis, and Therapeutic Strategies

Hematological malignancies originate from the hematopoietic system, including lymphoma, multiple myeloma, leukaemia, etc. They are highly malignant with a high incidence, a poor prognosis and a high mortality. Although the novel therapeutic strategies have partly improved the clinical efficacy of hematological malignancies, patients still face up with drug resistance, refractory disease and disease relapse. Many studies have shown that exosomes play an important role in hematological malignancies. Exosomes are nanoscale vesicles secreted by cells with a size ranging from 40 to 160 nm. They contain various intracellular components such as membrane proteins, lipids, and nucleic acids. These nanoscale vesicles transmit information between cells with the cargos. Thus, they participate in a variety of pathological processes such as angiogenesis, proliferation, metastasis, immunomodulation and drug resistance, which results in important role in the pathogenesis and progression of hematological malignancies. Furthermore, exosomes and the components carried in them can be used as potential biomarkers for the diagnosis, therapeutic sensitivity and prognosis in hematological malignancies. In the therapy of hematologic malignancies, certain exosome are potential to be used as therapeutic targets, meanwhile, exosomes are suitable drug carriers with lipid bilayer membrane and the nanostructure. Moreover, the tumor-derived exosomes of patients with hematologic malignancies can be developed into anti-tumor vaccines. The research and application of exosomes in hematological malignancies are summarized and discussed in this review.

Advances in the pathogenesis of FLT3 -mutated acute myeloid leukemia and targeted treatments

PURPOSE OF REVIEW

FLT3 mutations are among the most common myeloid drivers identified in adult acute myeloid leukemia (AML). Their identification is crucial for the precise risk assessment because of the strong prognostic significance of the most recurrent type of FLT3 alterations, namely internal tandem duplications (ITDs). Recent advances in the pathogenesis and biology of FLT3 -mutated AML have opened an opportunity for development and application of selective inhibition of FLT3 pathway.

RECENT FINDINGS

In the last decade, at least three targeted treatments have been approved by regulatory agencies and several others are currently under investigations. Here, we review the latest advance in the role of FLT3 mutations in AML, providing an outline of the available therapeutic strategies, their mechanisms of actions and of resistance, as well as routes for potential improvement.

SUMMARY

The availability of FLT3 inhibitors has improved outcomes in AML harboring such mutations, currently also reflected in disease stratification and recommendations. Newer inhibitors are under investigations, and combinations with chemotherapy or other targeted treatments are being explored to further improve disease outcomes.

CLG promotes mTOR/ULK1 pathway-mediated autophagy to inhibit OS development by inhibiting TRAF6-mediated FLT3 ubiquitination

Corilagin (CLG) has antitumor activities in certain human malignant cancers. Herein, the effects and mechanisms of CLG on osteosarcoma (OS) were investigated. OS cell viability and proliferation were detected by MTT and colony formation assay. Cell cycle and apoptosis were examined using flow cytometry. The interaction between TRAF6 and FLT3 was investigated using a co-immunoprecipitation assay. Results demonstrated that CLG treatment inhibited OS cell viability and proliferation but promoted OS cell autophagy and apoptosis in a concentration-dependent manner. Mechanically, CLG inhibited TRAF6-mediated FLT3 ubiquitination degradation. TRAF6 overexpression abolished the effects of CLG on OS cell proliferation, autophagy, and apoptosis. Finally, CLG administration inhibited OS tumor growth in mice by inducing autophagy-dependent apoptosis. Taken together, CLG inhibited OS progression by facilitating mTOR/ULK1 pathway-mediated autophagy through inhibiting TRAF6-mediated FLT3 ubiquitination, which indicated that CLG was a promising candidate for the treatment of OS.

Enhancing Therapeutic Efficacy of FLT3 Inhibitors with Combination Therapy for Treatment of Acute Myeloid Leukemia

FMS-like tyrosine kinase 3 (FLT3) mutations are genetic changes found in approximately thirty percent of patients with acute myeloid leukemia (AML). FLT3 mutations in AML represent a challenging clinical scenario characterized by a high rate of relapse, even after allogeneic hematopoietic stem cell transplantation (allo-HSCT). The advent of FLT3 tyrosine kinase inhibitors (TKIs), such as midostaurin and gilteritinib, has shown promise in achieving complete remission. However, a substantial proportion of patients still experience relapse following TKI treatment, necessitating innovative therapeutic strategies. This review critically addresses the current landscape of TKI treatments for FLT3+ AML, with a particular focus on gilteritinib. Gilteritinib, a highly selective FLT3 inhibitor, has demonstrated efficacy in targeting the mutant FLT3 receptor, thereby inhibiting aberrant signaling pathways that drive leukemic proliferation. However, monotherapy with TKIs may not be sufficient to eradicate AML blasts. Specifically, we provide evidence for integrating gilteritinib with mammalian targets of rapamycin (mTOR) inhibitors and interleukin-15 (IL-15) complexes. The combination of gilteritinib, mTOR inhibitors, and IL-15 complexes presents a compelling strategy to enhance the eradication of AML blasts and enhance NK cell killing, offering a potential for improved patient outcomes.

Clinical Significance and Potential Function of Complement Factor D in Acute Myeloid Leukemia

BACKGROUND

Acute myeloid leukemia (AML) is a hematologic malignancy characterized by aggressive proliferation and a poor prognosis. The objective of this study is to elucidate the specific role of complement factor D (CFD) in AML, with the aim of identifying robust prognostic markers for the disease.

METHODS

We performed a systematic investigation on clinical significance and potential function of CFD in AML by using the R Programming Language with The Cancer Genome Atlas (TCGA), Gene Expression Omnibus (GEO), The Human Protein Atlas (HPA), The University of ALabama at Birmingham CANcer data analysis Portal (UALCAN), Gene Expression Profiling Interactive Analysis (GEPIA), Kaplan-Meier plotter, Cancer Cell Line Encyclopedia (CCLE) database, and Comprehensive Analysis on Multi-Omics of Immunotherapy in Pan-cancer (CAMOIP) database. The expression of CFD in AML patients was verified by reverse transcription-quantitative polymerase chain reaction (RT-qPCR).

RESULTS

The expression of CFD was the highest in AML cells than in other tumor cell lines. The expression of CFD was also higher in AML patients than in the matched normal group. Compared with the low expression of the CFD group, high expression of CFD predicted better overall survival (OS) and lower tumor mutational burden (TMB) in AML patients. Moreover, a nomogram model based on CFD was successfully constructed to predict the OS of AML patients. Notably, the expression of CFD was associated with drug sensitivity and monocyte cell infiltration.

CONCLUSION

CFD could serve as a potential OS prognostic biomarker and guide clinical treatment for AML.

Cell-Based Treatment in Acute Myeloid Leukemia Relapsed after Allogeneic Stem Cell Transplantation

Allogeneic stem cell transplant (ASCT) remains the only treatment option for patients with high-risk acute myeloid leukemia (AML). Recurrence of leukemic cells after ASCT represents a dramatic event associated with a dismal outcome, with a 2-year survival rate of around 20%. Adoptive cell therapy (ACT) is a form of cell-based strategy that has emerged as an effective therapy to treat and prevent post-ASCT recurrence. Lymphocytes are the principal cells used in this therapy and can be derived from a hematopoietic stem cell donor, the patient themselves, or healthy donors, after being engineered to express the chimeric antigen receptor (CAR-T and UniCAR-T). In this review, we discuss recent advances in the established strategy of donor lymphocyte infusion (DLI) and the progress and challenges of CAR-T cells.

Recent advances in CAR-T cell therapy for acute myeloid leukaemia

Acute myeloid leukaemia (AML) is a fatal and refractory haematologic cancer that primarily affects adults. It interferes with bone marrow cell proliferation. Patients have a 5 years survival rate of less than 30% despite the availability of several treatments, including chemotherapy, allogeneic haematopoietic stem cell transplantation (Allo-HSCT), and receptor antagonist drugs. Allo-HSCT is the mainstay of acute myeloid leukaemia treatment. Although it does work, there are severe side effects, such as graft-versus-host disease (GVHD). In recent years, chimeric antigen receptor (CAR)-T cell therapies have made significant progress in the treatment of cancer. These engineered T cells can locate and recognize tumour cells in vivo and release a large number of effectors through immune action to effectively kill tumour cells. CAR-T cells are among the most effective cancer treatments because of this property. CAR-T cells have demonstrated positive therapeutic results in the treatment of acute myeloid leukaemia, according to numerous clinical investigations. This review highlights recent progress in new targets for AML immunotherapy, and the limitations, and difficulties of CAR-T therapy for AML.

Treatment Patterns and FLT3 Mutation Testing Among Patients with Acute Myeloid Leukemia in China: A Retrospective Observational Study

Introduction

For acute myeloid leukemia (AML), prognosis is particularly poor in patients harboring FMS-like tyrosine kinase 3 (FLT3) gene mutations, though routine screening for these mutations at diagnosis has been shown to be insufficient. The understanding of the impact of FLT3 mutations on treatment decisions is limited.

Methods

In this retrospective, observational study, we investigated the key epidemiological characteristics, treatment patterns and responses among adult patients with newly diagnosed (ND) AML in China, who initiated treatment from January 1, 2015, to December 31, 2019, or progressed to relapsed/refractory (R/R) AML by December 31, 2020.

Results

Of the 853 ND AML patients included, 63.4% were screened for FLT3 status, and 20.1% tested positive (FLT3MUT) at initial diagnosis. Of 289 patients who progressed to R/R AML during the study period, 24.9% were screened at the diagnosis of R/R AML, and 19.4% tested positive; 20.5% of screened patients changed FLT3 status at first diagnosis of R/R AML. Initial treatment regimens or treatment responses did not seem to differ in patients with ND AML by FLT3 mutation status. In patients with R/R AML, there was an apparent difference in second-line treatment choices by FLT3 mutation status; however, the number of FLT3-mutated patients were limited to demonstrate any meaningful distinction. FLT3-mutated R/R AML was associated with shorter relapse time.

Conclusion

Study findings showed that there was a lack of routine testing for FLT3 mutations at first diagnosis of R/R AML, and initial treatment decisions did not differ by FLT3 mutation status. Given the clinical burden of FLT3MUT, likelihood of FLT3 status changes, and emerging FLT3 inhibitors, further routine FLT3 screening is needed to optimize treatment of R/R AML.

ALOX5AP is a new prognostic indicator in acute myeloid leukemia

BACKGROUND

The overexpression of ALOX5AP has been observed in many types of cancer and has been identified as an oncogene. However, its role in acute myeloid leukemia (AML) has not been extensively studied. This study aimed to identify the expression and methylation patterns of ALOX5AP in bone marrow (BM) samples of AML patients, and further explore its clinical significance.

METHODS

Eighty-two de novo AML patients and 20 healthy donors were included in the study. Meanwhile, seven public datasets from Gene Expression Omnibus (GEO) and The Cancer Genome Atlas (TCGA) were included to confirm the alteration of ALOX5AP. Receiver operating characteristic (ROC) curve analysis was applied to determine the discriminative capacity of ALOX5AP expression to discriminate AML. The prognostic value of ALOX5AP was identified by the Kaplan-Meier method and log-rank test. It was further validated in four independent cohorts (n = 1186). Significantly different genes associated with ALOX5AP expression were subsequently compared by LinkedOmics, and Metascape database.

RESULTS

The level of ALOX5AP expression was significantly increased in bone marrow cells of AML patients compared with healthy donors (P < 0.05). ROC curve analysis suggested that ALOX5AP expression might be a potential biomarker to discriminate AML from controls. ALOX5AP overexpression was associated with decreased overall survival (OS) in AML according to the TCGA data (P = 0.006), which was validated by other four independent cohorts. DNA methylation levels of ALOX5AP were significantly lower in AML patients compared to normal samples (P < 0.05), as confirmed in the Diseasemeth database and the independent cohort GSE63409. ALOX5AP level was positively associated with genes with proleukemic effects such as PAX2, HOX family, SOX11, H19, and microRNAs that act as oncogenes in leukemia, such as miR125b, miR-93, miR-494, miR-193b, while anti-leukemia-related genes and tumor suppressor microRNAs such as miR-582, miR-9 family and miR-205 were negatively correlated.

CONCLUSION

ALOX5AP overexpression, associated with its hypomethylation, predicts poorer prognosis in AML.

Blockade of de novo pyrimidine biosynthesis triggers autophagic degradation of oncoprotein FLT3-ITD in acute myeloid leukemia

The internal tandem duplication of the FMS-like tyrosine kinase 3 (FLT3-ITD) is one of the most frequent genetic alterations in acute myeloid leukemia (AML). Limited and transient clinical benefit of FLT3 kinase inhibitors (FLT3i) emphasizes the need for alternative therapeutic options for this subset of myeloid malignancies. Herein, we showed that FLT3-ITD mutant (FLT3-ITD+) AML cells were susceptible toward inhibitors of DHODH, a rate-limiting enzyme of de novo pyrimidine biosynthesis. Genetic and pharmacological blockade of DHODH triggered downregulation of FLT3-ITD protein, subsequently suppressed activation of downstream ERK and STAT5, and promoted cell death of FLT3-ITD+ AML cells. Mechanistically, DHODH blockade triggered autophagy-mediated FLT3-ITD degradation via inactivating mTOR, a potent autophagy repressor. Notably, blockade of DHODH synergized with an FDA-approved FLT3i quizartinib in significantly impairing the growth of FLT3-ITD+ AML cells and improving tumor-bearing mice survival. We further demonstrated that DHODH blockade exhibited profound anti-proliferation effect on quizartinib-resistant cells in vitro and in vivo. In summary, this study demonstrates that the induction of degradation of FLT3-ITD protein by DHODH blockade may offer a promising therapeutic strategy for AML patients harboring FLT3-ITD mutation.

A Review of FLT3 Kinase Inhibitors in AML

Acute myeloid leukemia (AML) is a highly aggressive illness distinguished by the accumulation of abnormal hematopoietic precursors in both the bone marrow and peripheral blood. The prevalence of FLT3 gene mutations is high and escalates the probability of relapse and mortality. The survival rates for AML patients, particularly those over 65, are low. FLT3 mutation screening at diagnosis is mandatory, and FLT3 inhibitors are crucial in treating AML patients with mutations. There are two categories of FLT3 mutations: FLT3-ITD located in the juxtamembrane domain and FLT3-TKD in the tyrosine kinase domain. FLT3-ITD is the most common type, affecting nearly a quarter of patients, whereas FLT3-TKD only affects 6-8% of patients. FLT3 inhibitors are now crucial in treating AML patients with FLT3 mutations. When dealing with FLT3-mutated AML, the recommended course of treatment typically involves chemotherapy and midostaurin, followed by allogeneic hematopoietic cell transplantation (HCT) to maximize the likelihood of success. Maintenance therapy can lower the risk of relapse, and gilteritinib is a better option than salvage chemotherapy for relapsed or refractory cases. Clinical trials for new or combined therapies are the most effective approach. This review discusses treatment options for patients with FLT3-mutated AML, including induction chemotherapy and options for relapsed or refractory disease. Additional treatment options may become available as more studies are conducted based on the patient's condition and susceptibility.

Genome sequencing reveals molecular subgroups in oral epithelial dysplasia

This study aimed to analyze the molecular characteristics of oral epithelial dysplasia (OED), highlighting the pathways and variants of genes that are frequently mutated in oral squamous cell carcinoma (OSCC) and other cancers. Ten archival OED cases were retrieved for retrospective clinicopathological analysis and exome sequencing. Comparative genomic analysis was performed between high-grade dysplasia (HGD) and low-grade dysplasia (LGD), focusing on 57 well-known cancer genes, of which 10 were previously described as the most mutated in OSCC. HGD cases had significantly more variants; however, a similar mutational landscape to OSCC was observed in both groups. CASP8+FAT1/HRAS, TP53, and miscellaneous molecular signatures were also present. FAT1 is the gene that is most affected by pathogenic variants. Hierarchical divisive clustering showed division between the two groups: "HGD-like cluster" with 4HGD and 2LGD and "LGD-like cluster" with 4 LGD. MLL4 pathogenic variants were exclusively in the "LGD-like cluster". TP53 was affected in one case of HGD; however, its pathway was usually altered. We describe new insights into the genetic basis of epithelial malignant transformation by genomic analysis, highlighting those associated with FAT1 and TP53. Some LGDs presented a similar mutational landscape to HGD after cluster analysis. Perhaps molecular alterations have not yet been reflected in histomorphology. The relative risk of malignant transformation in this molecular subgroup should be addressed in future studies.

How ITD Insertion Sites Orchestrate the Biology and Disease of FLT3-ITD-Mutated Acute Myeloid Leukemia

Mutations of the FLT3 gene are among the most common genetic aberrations detected in AML and occur mainly as internal tandem duplications (FLT3-ITD). However, the specific sites of FLT3-ITD insertion within FLT3 show marked heterogeneity regarding both biological and clinical features. In contrast to the common assumption that ITD insertion sites (IS) are restricted to the juxtamembrane domain (JMD) of FLT3, 30% of FLT3-ITD mutations insert at the non-JMD level, thereby integrating into various segments of the tyrosine kinase subdomain 1 (TKD1). ITDs inserted within TKD1 have been shown to be associated with inferior complete remission rates as well as shorter relapse-free and overall survival. Furthermore, resistance to chemotherapy and tyrosine kinase inhibition (TKI) is linked to non-JMD IS. Although FLT3-ITD mutations in general are already recognized as a negative prognostic marker in currently used risk stratification guidelines, the even worse prognostic impact of non-JMD-inserting FLT3-ITD has not yet been particularly considered. Recently, the molecular and biological assessment of TKI resistance highlighted the pivotal role of activated WEE1 kinase in non-JMD-inserting ITDs. Overcoming therapy resistance in non-JMD FLT3-ITD-mutated AML may lead to more effective genotype- and patient-specific treatment approaches.

CAR-T Cells Immunotherapies for the Treatment of Acute Myeloid Leukemia-Recent Advances

In order to increase the effectiveness of cancer therapies and extend the long-term survival of patients, more and more often, in addition to standard treatment, oncological patients receive also targeted therapy, i.e., CAR-T cells. These cells express a chimeric receptor (CAR) that specifically binds an antigen present on tumor cells, resulting in tumor cell lysis. The use of CAR-T cells in the therapy of relapsed and refractory B-type acute lymphoblastic leukemia (ALL) resulted in complete remission in many patients, which prompted researchers to conduct tests on the use of CAR-T cells in the treatment of other hematological malignancies, including acute myeloid leukemia (AML). AML is associated with a poorer prognosis compared to ALL due to a higher risk of relapse caused by the development of resistance to standard treatment. The 5-year relative survival rate in AML patients was estimated at 31.7%. The objective of the following review is to present the mechanism of action of CAR-T cells, and discuss the latest findings on the results of anti-CD33, -CD123, -FLT3 and -CLL-1 CAR-T cell therapy, the emerging challenges as well as the prospects for the future.

A Multicenter, Open-Label, Phase I/II Study of FN-1501 in Patients with Advanced Solid Tumors

BACKGROUND

FN-1501, a potent inhibitor of receptor FMS-like tyrosine kinase 3 (FLT3) and CDK4/6, KIT, PDGFR, VEGFR2, ALK, and RET tyrosine kinase proteins, has demonstrated significant in vivo activity in various solid tumor and leukemia human xenograft models. Anomalies in FLT3 have an established role as a therapeutic target where the gene has been shown to play a critical role in the growth, differentiation, and survival of various cell types in hematopoietic cancer and have shown promise in various solid tumors. An open-label, Phase I/II study (NCT03690154) was designed to evaluate the safety and PK profile of FN-1501 as monotherapy in patients (pts) with advanced solid tumors and relapsed, refractory (R/R) AML.

METHODS

Pts received FN-1501 IV three times a week for 2 weeks, followed by 1 week off treatment in continuous 21-day cycles. Dose escalation followed a standard 3 + 3 design. Primary objectives include the determination of the maximum tolerated dose (MTD), safety, and recommended Phase 2 dose (RP2D). Secondary objectives include pharmacokinetics (PK) and preliminary anti-tumor activity. Exploratory objectives include the relationship between pharmacogenetic mutations (e.g., FLT3, TP53, KRAS, NRAS, etc.), safety, and efficacy; as well as an evaluation of the pharmacodynamic effects of treatment with FN-1501. Dose expansion at RP2D further explored the safety and efficacy of FN-1501 in this treatment setting.

RESULTS

A total of 48 adult pts with advanced solid tumors (N = 47) and AML (N = 1) were enrolled at doses ranging from 2.5 to 226 mg IV three times a week for two weeks in 21-day cycles (2 weeks on and 1 week off treatment). The median age was 65 years (range 30-92); 57% were female and 43% were male. The median number of prior lines of treatment was 5 (range 1-12). Forty patients evaluable for dose-limiting toxicity (DLT) assessment had a median exposure of 9.5 cycles (range 1-18 cycles). Treatment-related adverse events (TRAEs) were reported for 64% of the pts. The most common treatment-emergent adverse events (TEAEs), defined as those occurring in ≥20% of pts, primarily consisted of reversible Grade 1-2 fatigue (34%), nausea (32%), and diarrhea (26%). The most common Grade ≥3 events occurring in ≥5% of pts consisted of diarrhea and hyponatremia. Dose escalation was discontinued due to DLTs of Grade 3 thrombocytopenia (N = 1) and Grade 3 infusion-related reaction (N = 1) occurring in 2 pts. The maximum tolerated dose (MTD) was determined to be 170 mg.

CONCLUSIONS

FN-1501 demonstrated reasonable safety, tolerability, and preliminary activity against solid tumors in doses up to 170 mg. Dose escalation was terminated based on 2 DLTs occurring at the 226 mg dose level.

A Rare B-Myeloid Conversion of Follicular Lymphoma into Clonally Related Acute Myeloid Leukemia: A Case Report

Follicular lymphoma (FL) is a highly prevalent indolent lymphoma, and the risk of histological transformation is approximately 2–3% per year. Transformation of FL generally occurs in the same lineage (B cell lineage). Another rare form of disease progression is the transformation of neoplastic B-cells to another cell lineage such as acute myeloid leukemia (AML). The low incidence of B-myeloid transformation associated with poor prognosis hinders the establishment of model systems to identify molecular mechanisms. A 64-year-old woman was diagnosed with FL and achieved a satisfactory response after six cycles of R-CHOP (rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone). Approximately one month after treatment terminated, the disease progressed to AML with an increased white blood cell count and abnormal coagulation. Interestingly, nucleotide sequence analysis of the genomic region encoding the immunoglobulin heavy-chain variable domain showed the possibility of homologous transformation from lymphoma to leukemia cells. Although the patient experienced transient improvement after undergoing treatment with one cycle of idarubicin and cytarabine combined with etoposide, she relapsed and died 8 days after venetoclax salvage therapy. Patient with B-myeloid transformation was associated with an aggressive clinical course and poor prognosis. Conventional strategies for treating histologically transformed AML were ineffective. However, treatment with a Bcl-2 inhibitor could serve as an option. Here we review the literature relevant to this rare histological transformation of FL.

Research progress on molecular biomarkers of acute myeloid leukemia

Acute myeloid leukemia (AML) is the most common type of adult acute leukemia. The pathophysiology of the disease has been studied intensively at the cellular and molecular levels. At present, cytogenetic markers are an important basis for the early diagnosis, prognostic stratification and treatment of AML. However, with the emergence of new technologies, the detection of other molecular markers, such as gene mutations and epigenetic changes, began to play important roles in evaluating the occurrence and development of diseases. Recent evidence shows that identifying new AML biomarkers contributes to a better understanding of the molecular mechanism of the disease and is essential for AML screening, diagnosis, prognosis monitoring, and individualized treatment response. In this review, we summarized the promising AML biomarkers from four aspects, which contributing to a better understanding of the disease. Of course, it must be soberly aware that we have not listed all biomarkers of AML. Anyway, the biomarkers we mentioned are representative. For example, mutations in TP53, FLT3, and ASXL1 suggest poor prognosis, low remission rate, short survival period, and often require allogeneic hematopoietic stem cell transplantation. The CEBPA double mutation, NPM1 and CBF mutation suggest that the prognosis is good, the remission rate is high, the survival period is long, and the effect of chemotherapy or autotherapy is good. As for other mutations mentioned in the article, they usually predict a moderate prognosis. All in all, we hope it could provide a reference for the precise diagnosis and treatment of AML.

CD86 Is Associated with Immune Infiltration and Immunotherapy Signatures in AML and Promotes Its Progression

Background

Cluster of differentiation 86 (CD86), also known as B7-2, is a molecule expressed on antigen-presenting cells that provides the costimulatory signals required for T cell activation and survival. CD86 binds to two ligands on the surface of T cells: the antigen CD28 and cytotoxic T lymphocyte-associated protein 4 (CTLA-4). By binding to CD28, CD86-together with CD80-promotes the participation of T cells in the antigen presentation process. However, the interrelationships among CD86, immunotherapy, and immune infiltration in acute myeloid leukemia (AML) are unclear.

Methods

The immunological effects of CD86 in various cancers (including on chemokines, immunostimulators, MHC, and receptors) were evaluated through a pan-cancer analysis using TCGA and GEO databases. The relationship between CD86 expression and mononucleotide variation, gene copy number variation, methylation, immune checkpoint blockers (ICBs), and T-cell inflammation score in AML was subsequently examined. ESTIMATE and limma packages were used to identify genes at the intersection of CD86 with StromalScore and ImmuneScore. Subsequently, GO/KEGG and PPI network analyses were performed. The immune risk score (IRS) model was constructed, and the validation set was used for verification. The predictive value was compared with the TIDE score.

Results

CD86 was overexpressed in many cancers, and its overexpression was associated with a poor prognosis. CD86 expression was positively correlated with the expression of CTLA4, PDCD1LG2, IDO1, HAVCR2, and other genes and negatively correlated with CD86 methylation. The expression of CD86 in AML cell lines was detected by QRT-PCR and Western blot, and the results showed that CD86 was overexpressed in AML cell lines. Immune infiltration assays showed that CD86 expression was positively correlated with CD8 T cell, Dendritic cell, macrophage, NK cell, and Th1_cell and also with immune examination site, immune regulation, immunotherapy response, and TIICs. ssGSEA showed that CD86 was enriched in immune-related pathways, and CD86 expression was correlated with mutations in the genes RB1, ERBB2, and FANCC, which are associated with responses to radiotherapy and chemotherapy. The IRS score performed better than the TIDE website score.

Conclusion

CD86 appears to participate in immune invasion in AML and is an important player in the tumor microenvironment in this malignancy. At the same time, the IRS score developed by us has a good effect and may provide some support for the diagnosis of AML. Thus, CD86 may serve as a potential target for AML immunotherapy.

Therapeutic Targeting of FLT3 in Acute Myeloid Leukemia: Current Status and Novel Approaches

FMS-like tyrosine kinase 3 (FLT3) is mutated in approximately 30% of acute myeloid leukemia (AML) patients. The presence of FLT3-ITD (internal tandem duplication, 20-25%) mutation and, to a lesser extent, FLT3-TKD (tyrosine kinase domain, 5-10%) mutation is associated with poorer diagnosis and therapy response since the leukemic cells become hyperproliferative and resistant to apoptosis after continuous activation of FLT3 signaling. Targeting FLT3 has been the focus of many pre-clinical and clinical studies. Hence, many small-molecule FLT3 inhibitors (FLT3is) have been developed, some of which are approved such as midostaurin and gilteritinib to be used in different clinical settings, either in combination with chemotherapy or alone. However, many questions regarding the best treatment strategy remain to be answered. On the other hand, various FLT3-dependent and -independent resistance mechanisms could be evolved during FLT3i therapy which limit their clinical impact. Therefore, identifying molecular mechanisms of resistance and developing novel strategies to overcome this obstacle is a current interest in the field. In this review, recent studies of approved FLT3i and knowledge about major resistance mechanisms of clinically approved FLT3i's will be discussed together with novel treatment approaches such as designing novel FLT3i and dual FLT3i and combination strategies including approved FLT3i plus small-molecule agents targeting altered molecules in the resistant cells to abrogate resistance. Moreover, how to choose an appropriate FLT3i for the patients will be summarized based on what is currently known from available clinical data. In addition, strategies beyond FLT3i's including immunotherapeutics, small-molecule FLT3 degraders, and flavonoids will be summarized to highlight potential alternatives in FLT3-mutated AML therapy.

"FLipping" the Story: FLT3-Mutated Acute Myeloid Leukemia and the Evolving Role of FLT3 Inhibitors

The treatment of many types of cancers, including acute myeloid leukemia (AML), has been revolutionized by the development of therapeutics targeted at crucial molecular drivers of oncogenesis. In contrast to broad, relatively indiscriminate conventional chemotherapy, these targeted agents precisely disrupt key pathways within cancer cells. FMS-like tyrosine kinase 3 (FLT3)-encoding a critical regulator of hematopoiesis-is the most frequently mutated gene in patients with AML, and these mutations herald reduced survival and increased relapse in these patients. Approximately 30% of newly diagnosed AML carries an FLT3 mutation; of these, approximately three-quarters are internal tandem duplication (ITD) mutations, and the remainder are tyrosine kinase domain (TKD) mutations. In contrast to its usual, tightly controlled expression, FLT3-ITD mutants allow constitutive, "run-away" activation of a large number of key downstream pathways which promote cellular proliferation and survival. Targeted inhibition of FLT3 is, therefore, a promising therapeutic avenue. In April 2017, midostaurin became both the first FLT3 inhibitor and the first targeted therapy of any kind in AML to be approved by the US FDA. The use of FLT3 inhibitors has continued to grow as clinical trials continue to demonstrate the efficacy of this class of agents, with an expanding number available for use as both experimental standard-of-care usage. This review examines the biology of FLT3 and its downstream pathways, the mechanism of FLT3 inhibition, the development of the FLT3 inhibitors as a class and uses of the agents currently available clinically, and the mechanisms by which resistance to FLT3 inhibition may both develop and be overcome.

Binding Studies and Lead Generation of Pteridin-7(8H)-one Derivatives Targeting FLT3

Ligand modification by substituting chemical groups within the binding pocket is a popular strategy for kinase drug development. In this study, a series of pteridin-7(8H)-one derivatives targeting wild-type FMS-like tyrosine kinase-3 (FLT3) and its D835Y mutant (FL3D835Y) were studied using a combination of molecular modeling techniques, such as docking, molecular dynamics (MD), binding energy calculation, and three-dimensional quantitative structure-activity relationship (3D-QSAR) studies. We determined the protein–ligand binding affinity by employing molecular mechanics Poisson–Boltzmann/generalized Born surface area (MM-PB/GBSA), fast pulling ligand (FPL) simulation, linear interaction energy (LIE), umbrella sampling (US), and free energy perturbation (FEP) scoring functions. The structure–activity relationship (SAR) study was conducted using comparative molecular field analysis (CoMFA) and comparative molecular similarity indices analysis (CoMSIA), and the results were emphasized as a SAR scheme. In both the CoMFA and CoMSIA models, satisfactory correlation statistics were obtained between the observed and predicted inhibitory activity. The MD and SAR models were co-utilized to design several new compounds, and their inhibitory activities were anticipated using the CoMSIA model. The designed compounds with higher predicted pIC50 values than the most active compound were carried out for binding free energy evaluation to wild-type and mutant receptors using MM-PB/GBSA, LIE, and FEP methods.