Modulating JAK2/STAT3 signaling by quercetin in Qiling Baitouweng Tang: a potential therapeutic approach for diffuse large B-cell lymphoma.

Qiling Baitouweng Tang (QLBTWT) is a traditional clinical formula for treating diffuse large B-cell lymphoma (DLBCL), but its molecular action is not fully understood. This research is utilized in silico analysis and liquid chromatography tandem mass spectrometry (LC‒MS/MS) to identify the active constituents of QLBTWT with anti-DLBCL properties and their targets. The study identified 14 compounds, including quercetin, naringenin, and astilbin, as potentially effective against DLBCL. Molecular modeling highlighted the favorable interaction of quercetin with the JAK2 protein. In vitro studies confirmed the ability of quercetin to inhibit DLBCL cell growth and migration while inducing apoptosis and causing G2/M phase cell cycle arrest. Molecular dynamics simulations revealed that quercetin binds to JAK2 as a type II inhibitor. In vivo studies in U2932 xenograft models demonstrated that QLBTWT inhibited tumor growth in a dose-dependent manner, which was associated with the JAK2/STAT3 signaling pathway. Overall, this study elucidates the therapeutic effect of QLBTWT on DLBCL through quercetin-mediated suppression of the JAK2/STAT3 pathway, offering novel therapeutic insights for DLBCL.

Discovery of SILA-123 as a Highly Potent FLT3 Inhibitor for the Treatment of Acute Myeloid Leukemia with Various FLT3 Mutations.

The FLT3-ITD (internal tandem duplication) mutant has been a promising target for acute myeloid leukemia (AML) drug discovery but is now facing the challenge of resistance due to point mutations. Herein, we have discovered a type II FLT3 inhibitor, SILA-123. This inhibitor has shown highly potent inhibitory effects against FLT3-WT (IC50 = 2.1 nM) and FLT3-ITD (IC50 = 1.0 nM), tumor cells with the FLT3-ITD mutant such as MOLM-13 (IC50 = 0.98 nM) and MV4-11 (IC50 = 0.19 nM), as well as BaF3 cells associated with the FLT3-ITD mutant and point mutations like BaF3-FLT3-ITD-G697R (IC50 = 3.0 nM). Moreover, SILA-123 exhibited promising kinome selectivity against 310 kinases (S score (10) = 0.06). In in vivo studies, SILA-123 significantly suppressed the tumor growth in MV4-11 (50 mg/kg/d, TGI = 87.3%) and BaF3-FLT3-ITD-G697R (50 mg/kg/d, TGI = 60.0%) cell-inoculated allograft models. Our data suggested that SILA-123 might be a promising drug candidate for FLT3-ITD-positive AML.

Non-coding RNAs as therapeutic targets in cancer and its clinical application.

Cancer genomics has led to the discovery of numerous oncogenes and tumor suppressor genes that play critical roles in cancer development and progression. Oncogenes promote cell growth and proliferation, whereas tumor suppressor genes inhibit cell growth and division. The dysregulation of these genes can lead to the development of cancer. Recent studies have focused on non-coding RNAs (ncRNAs), including circular RNA (circRNA), long non-coding RNA (lncRNA), and microRNA (miRNA), as therapeutic targets for cancer. In this article, we discuss the oncogenes and tumor suppressor genes of ncRNAs associated with different types of cancer and their potential as therapeutic targets. Here, we highlight the mechanisms of action of these genes and their clinical applications in cancer treatment. Understanding the molecular mechanisms underlying cancer development and identifying specific therapeutic targets are essential steps towards the development of effective cancer treatments.

Exploring drug repositioning possibilities of kinase inhibitors via molecular simulation.

Kinases, a class of enzymes controlling various substrates phosphorylation, are pivotal in both physiological and pathological processes. Although their conserved ATP binding pockets pose challenges for achieving selectivity, this feature offers opportunities for drug repositioning of kinase inhibitors (KIs). This study presents a cost-effective in silico prediction of KIs drug repositioning via analyzing cross-docking results. We established the KIs database (278 unique KIs, 1834 bioactivity data points) and kinases database (357 kinase structures categorized by the DFG motif) for carrying out cross-docking. Comparative analysis of the docking scores and reported experimental bioactivity revealed that the Atypical, TK, and TKL superfamilies are suitable for drug repositioning. Among these kinase superfamilies, Olverematinib, Lapatinib, and Abemaciclib displayed enzymatic activity in our focused AKT-PI3K-mTOR pathway with IC50 values of 3.3, 3.2 and 5.8 µM. Further cell assays showed IC50 values of 0.2, 1.2 and 0.6 µM in tumor cells. The consistent result between prediction and validation demonstrated that repositioning KIs via in silico method is feasible.

Research strategies of small molecules as chemotherapeutics to overcome multiple myeloma resistance.

Multiple myeloma (MM), a cancer of plasma cells, is the second most common hematological malignancy which is characterized by aberrant plasma cells infiltration in the bone marrow and complex heterogeneous cytogenetic abnormalities. Over the past two decades, novel treatment strategies such as proteasome inhibitors, immunomodulators, and monoclonal antibodies have significantly improved the relative survival rate of MM patients. However, the development of drug resistance results in the majority of MM patients suffering from relapse, limited treatment options and uncontrolled disease progression after relapse. There are urgent needs to develop and explore novel MM treatment strategies to overcome drug resistance and improve efficacy. Here, we review the recent small molecule therapeutic strategies for MM, and introduce potential new targets and corresponding modulators in detail. In addition, this paper also summarizes the progress of multi-target inhibitor therapy and protein degradation technology in the treatment of MM.

Unraveling the Promise of RET Inhibitors in Precision Cancer Therapy by Targeting RET Mutations.

Over the past decades, the role of rearranged during transfection (RET) alterations in tumorigenesis has been firmly established. RET kinase inhibition is an essential therapeutic target in patients with RET-altered cancers. In clinical practice, initial efficacy can be achieved in patients through the utilization of multikinase inhibitors (MKIs) with RET inhibitory activity. However, the effectiveness of these MKIs is impeded by the adverse events associated with off-target effects. Recently, many RET-selective inhibitors, characterized by heightened specificity and potency, have been developed, representing a substantial breakthrough in the field of RET precision oncology. This Perspective focuses on the contemporary understanding of RET mutations, recent advancements in next-generation RET inhibitors, and the challenges associated with resistance to RET inhibitors. It provides valuable insights for the development of next-generation MKIs and selective RET inhibitors.

Design and synthesis 1H-Pyrrolo[2,3-b]pyridine derivatives as FLT3 inhibitors for the treatment of Acute myeloid Leukemia.

Acute myeloid leukemia (AML) is the most common type of blood cancer and has been strongly correlated with the overexpression of Fms-like tyrosine kinase 3 (FLT3), a member of the class III receptor tyrosine kinase family. With the emergence of FLT3 internal tandem duplication alteration (ITD) and tyrosine kinase domain (TKD) mutations, the development of FLT3 small molecule inhibitors has become an effective medicinal chemistry strategy for AML. Herein, we have designed and synthesized two series of 1H-pyrrolo[2,3-b]pyridine derivatives CM1-CM24, as FLT3 inhibitors based on F14, which we previously reported, that can target the hydrophobic FLT3 back pocket. Among these derivates, CM5 showed significant inhibition of FLT3 and FLT3-ITD, with inhibitory percentages of 57.72 % and 53.77 % respectively at the concentration of 1 µΜ. Furthermore, CM5 demonstrated potent inhibition against FLT3-dependent human AML cell lines MOLM-13 and MV4-11 (both harboring FLT3-ITD mutant), with IC50 values of 0.75 µM and 0.64 µM respectively. In our cellular mechanistic studies, CM5 also effectively induces apoptosis by arresting cell cycle progression in the G0/G1 phase. In addition, the amide and urea linker function were discussed in detail based on computational simulations studies. CM5 will serve as a novel lead compound for further structural modification and development of FLT3 inhibitors specifically targeting AML with FLT3-ITD mutations.

Preclinical characterization of danatinib as a novel FLT3 inhibitor with excellent efficacy against resistant acute myeloid leukemia.

The therapeutic benefits of available FLT3 inhibitors for AML are limited by drug resistance, which is related to mutations, as well toxicity caused by off-target effects. In this study, we introduce a new small molecule FLT3 inhibitor called danatinib, which was designed to overcome the limitations of currently approved agents. Danatinib demonstrated greater potency and selectivity, resulting in cytotoxic activity specific to FLT3-ITD and/or FLT3-TKD mutated models. It also showed a superior kinome inhibition profile compared to several currently approved FLT3 inhibitors. In diverse FLT3-TKD models, danatinib exhibited substantially improved activity at clinically relevant doses, outperforming approved FLT3 inhibitors. In vivo safety evaluations performed on the granulopoiesis of transgenic myeloperoxidase (MPO) zebrafish and mice models proved danatinib to have an acceptable safety profile. Danatinib holds promise as a new and improved FLT3 inhibitor for the treatment of AML, offering long-lasting remissions and improved overall survival rates.

GART Functions as a Novel Methyltransferase in the RUVBL1/ß-Catenin Signaling Pathway to Promote Tumor Stemness in Colorectal Cancer.

Tumor stemness is associated with the recurrence and incurability of colorectal cancer (CRC), which lacks effective therapeutic targets and drugs. Glycinamide ribonucleotide transformylase (GART) fulfills an important role in numerous types of malignancies. The present study aims to identify the underlying mechanism through which GART may promote CRC stemness, as to developing novel therapeutic methods. An elevated level of GART is associated with poor outcomes in CRC patients and promotes the proliferation and migration of CRC cells. CD133+ cells with increased GART expression possess higher tumorigenic and proliferative capabilities both in vitro and in vivo. GART is identified to have a novel methyltransferase function, whose enzymatic activity center is located at the E948 site. GART also enhances the stability of RuvB-like AAA ATPase 1 (RUVBL1) through methylating its K7 site, which consequently aberrantly activates the Wnt/ß-catenin signaling pathway to induce tumor stemness. Pemetrexed (PEM), a compound targeting GART, combined with other chemotherapy drugs greatly suppresses tumor growth both in a PDX model and in CRC patients. The present study demonstrates a novel methyltransferase function of GART and the role of the GART/RUVBL1/ß-catenin signaling axis in promoting CRC stemness. PEM may be a promising therapeutic agent for the treatment of CRC.

Challenges for the development of mutant isocitrate dehydrogenases 1 inhibitors to treat glioma.

Glioma is one of the most common types of brain tumors, and its high recurrence and mortality rates threaten human health. In 2008, the frequent isocitrate dehydrogenase 1 (IDH1) mutations in glioma were reported, which brought a new strategy in the treatment of this challenging disease. In this perspective, we first discuss the possible gliomagenesis after IDH1 mutations (mIDH1). Subsequently, we systematically investigate the reported mIDH1 inhibitors and present a comparative analysis of the ligand-binding pocket in mIDH1. Additionally, we also discuss the binding features and physicochemical properties of different mIDH1 inhibitors to facilitate the future development of mIDH1 inhibitors. Finally, we discuss the possible selectivity features of mIDH1 inhibitors against WT-IDH1 and IDH2 by combining protein-based and ligand-based information. We hope that this perspective can inspire the development of mIDH1 inhibitors and bring potent mIDH1 inhibitors for the treatment of glioma.

Tomentosin suppressed M1 polarization via increasing MERTK activation mediated by regulation of GAS6.

ETHNOPHARMACOLOGICAL RELEVANCE: Xanthium sibiricum Patrin ex Widder (X. sibiricum) are widely used traditional herbal medicines for arthritis treatment in China. Rheumatoid arthritis (RA) is characterized by progressive destructions of joints, which is accompanied by chronic, progressive inflammatory disorder. According to our previous research, tomentosin was isolated from X. sibiricum and revealed anti-inflammatory activity. However, the potential therapeutic effect of tomentosin on RA and the anti-inflammatory mechanism of tomentosin remain to be clarified. The present study lays theoretical support for X. sibiricum in RA treatment, also provides reference for further development of X. sibiricum in clinic. AIM OF THE STUDY: To investigate the effect of tomentosin in collagen-induced arthritis (CIA) mice and reveal its underlying mechanism. MATERIALS AND METHODS: In vivo, tomentosin (10, 20 and 40 mg/kg) was given to CIA mice for seven consecutive days, to evaluate its therapeutic effect and anti-inflammatory activity. In vitro, THP-1-derived macrophages were used to verify the effect of tomentosin on inflammation. Then, molecular docking and experiments in vitro was conducted to predict and explore the mechanism of tomentosin inhibiting inflammation. RESULTS: Tomentosin attenuated the severity of arthritis in CIA mice, which was evidenced by the swelling of the hind paws, arthritis scores, and pathological changes. Particularly, tomentosin effectively reduced the ratio of M1 macrophage and TNF-α levels in vitro and vivo. Then, molecular docking and experiments in vitro was carried out, indicating that tomentosin inhibited M1 polarization and TNF-α levels accompanied by the increase of MERTK and up-regulated GAS6 levels. Moreover, it has been proved that GAS6 was necessary for MERTK activation and tomentosin could up-regulate GAS6 levels effectively in transwell system. Further mechanistic studies revealed that tomentosin suppressed M1 polarization via increasing MERTK activation mediated by regulation of GAS6 in transwell system. CONCLUSION: Tomentosin relieved the severity of CIA mice by inhibiting M1 polarization. Furthermore, tomentosin suppressed M1 polarization via increasing MERTK activation mediated by regulation of GAS6.

Mechanistic Study of Icaritin-Induced Inactivation of Cytochrome P450 2C9.

Icaritin (ICT) is a prenylflavonoid derivative that has been approved by National Medical Products Administration for the treatment of hepatocellular carcinoma. This study aims to evaluate the potential inhibitory effect of ICT against cytochrome P450 (CYP) enzymes and to elucidate the inactivation mechanisms. Results showed that ICT inactivated CYP2C9 in a time-, concentration-, and NADPH-dependent manner with Ki = 1.896 µM, Kinact = 0.02298 minutes-1, and Kinact/Ki = 12 minutes-1 mM-1, whereas the activities of other CYP isozymes was minimally affected. Additionally, the presence of CYP2C9 competitive inhibitor, sulfaphenazole, superoxide dismutase/catalase system, and GSH all protected CYP2C9 from ICT-induced activity loss. Moreover, the activity loss was neither recovered by washing the ICT-CYP2C9 preincubation mixture nor the addition of potassium ferricyanide. These results, collectively, implied the underlying inactivation mechanism involved the covalent binding of ICT to the apoprotein and/or the prosthetic heme of CYP2C9. Furthermore, an ICT-quinone methide (QM)-derived GSH adduct was identified, and human glutathione S-transferases (GST) isozymes GSTA1-1, GSTM1-1, and GSTP1-1 were shown to be substantially involved in the detoxification of ICT-QM. Interestingly, our systematic molecular modeling work predicted that ICT-QM was covalently bound to C216, a cysteine residue located in the F-G loop downstream of substrate recognition site (SRS) 2 in CYP2C9. The sequential molecular dynamics simulation confirmed the binding to C216 induced a conformational change in the active catalytic center of CYP2C9. Lastly, the potential risks of clinical drug-drug interactions triggered by ICT as a perpetrator were extrapolated. In summary, this work confirmed that ICT was an inactivator of CYP2C9. SIGNIFICANCE STATEMENT: This study is the first to report the time-dependent inhibition of CYP2C9 by icaritin (ICT) and the intrinsic molecular mechanism behind it. Experimental data indicated that the inactivation was via irreversible covalent binding of ICT-quinone methide to CYP2C9, while molecular modeling analysis provided additional evidence by predicting C216 as the key binding site which influenced the structural confirmation of CYP2C9's catalytic center. These findings suggest the potential of drug-drug interactions when ICT is co-administered with CYP2C9 substrates clinically.

Discovery of 4-(4-aminophenyl)-6-phenylisoxazolo[3,4-b]pyridine-3-amine derivatives as novel FLT3 covalent inhibitors for the intervention of acute myeloid leukemia.

Small molecule covalent drugs have proved to be desirable therapies especially on drug resistance related to point mutations. Secondary mutations of FLT3 have become the main mechanism of FLT3 inhibitors resistance which further causes the failure of treatment. Herein, a series of 4-(4-aminophenyl)-6-phenylisoxazolo[3,4-b]pyridine-3-amine covalent derivatives were synthesized and optimized to overcome the common secondary resistance mutations of FLT3. Among these derivatives, compound F15 displayed potent inhibition activities against FLT3 (IC50 = 123 nM) and FLT3-internal tandem duplication (ITD) by 80% and 26.06%, respectively, at the concentration of 1 µM. Besides, F15 exhibited potent activity against FLT3-dependent human acute myeloid leukemia (AML) cell lines MOLM-13 (IC50 = 253 nM) and MV4-11 (IC50 = 91 nM), as well as BaF3 cells with variety of secondary mutations. Furthermore, cellular mechanism assays indicated that F15 inhibited phosphorylation of FLT3 and its downstream signaling factors. Notably, F15 could be considered for further development as potential drug candidate to treat AML.

Design and synthesis of selective FLT3 inhibitors via exploration of back pocket II.

Aim: The clinical benefits of FLT3 inhibitors against acute myeloid leukemia (AML) have been limited by selectivity and resistance mutations. Thus, to identify FLT3 inhibitors possessing high selectivity and potency is of necessity. Methods & results: The authors used computational methods to systematically compare pocket similarity with 269 kinases. Subsequently, based on these investigations and beginning with in-house compound 10, they synthesized a series of 6-methyl-isoxazol[3,4-b]pyridine-3-amino derivatives and identified that compound 45 (IC50: 103 nM) displayed gratifying potency in human AML cell lines with FLT3-internal tandem duplications mutation as well as FLT3-internal tandem duplications-tyrosine kinase domain-transformed BaF3 cells. Conclusion: The integrated biological activity results indicated that compound 45 deserves further development for therapeutic remedies for AML.

NAT10 acetylates BCL-XL mRNA to promote the proliferation of multiple myeloma cells through PI3K-AKT pathway.

Multiple myeloma (MM) is a clinically distinctive plasma cell malignancy in the bone marrow (BM), in which epigenetic abnormalities are featured prominently. Epigenetic modifications including acetylation have been deemed to contribute to tumorigenesis. N-acetyltransferase 10 (NAT10) is an important regulator of mRNA acetylation in many cancers, however its function in MM is poorly studied. We first analyzed MM clinical databases and found that elevated NAT10 expression conferred a poor prognosis in MM patients. Furthermore, overexpression of NAT10 promoted MM cell proliferation. The correlation analysis of acRIP-seq screened BCL-XL (BCL2L1) as a significant downstream target of NAT10. Further RNA decay assay showed that increased NAT10 improved the stability of BCL-XL mRNA and promoted protein translation to suppress cell apoptosis. NAT10 activated PI3K-AKT pathway and upregulated CDK4/CDK6 to accelerate cellular proliferation. Importantly, inhibition of NAT10 by Remodelin suppressed MM cell growth and induced cell apoptosis. Our findings show the important role of NAT10/BCL-XL axis in promoting MM cell proliferation. Further explorations are needed to fully define the potential of targeting NAT10 therapy in MM treatment.

Synthesis and biological evaluation of 4-(4-aminophenyl)-6-methylisoxazolo[3,4-b] pyridin-3-amine covalent inhibitors as potential agents for the treatment of acute myeloid leukemia.

Fms-like tyrosine kinase 3 (FLT3) mutation has been strongly associated with increased risk of relapse, and the irreversible covalent FLT3 inhibitors had the potential to overcome the drug-resistance. In this study, a series of simplified 4-(4-aminophenyl)-6-methylisoxazolo[3,4-b] pyridin-3-amine derivatives containing two types of Michael acceptors (vinyl sulfonamide, acrylamide) were conveniently synthesized to target FLT3 and its internal tandem duplications (ITD) mutants irreversibly. The kinase inhibitory activities showed that compound C14 displayed potent inhibition activities against FLT3 (IC50 = 256 nM) and FLT3-ITD by 73 % and 25.34 % respectively, at the concentration of 1 µM. The antitumor activities indicated that C14 had strong inhibitory activity against the human acute myeloid leukemia (AML) cell lines MOLM-13 (IC50 = 507 nM) harboring FLT3-ITD mutant, as well as MV4-11 (IC50 = 325 nM) bearing FLT3-ITD mutation. The biochemical analyses showed that these effects were related to the ability of C14 to inhibit FLT3 signal pathways, and C14 could induce apoptosis in MV4-11 cell as demonstrated by flow cytometry. Fortunately, C14 showed very weak potency against FLT3-independent human cervical cancer cell line HL-60 (IC50 > 10 µM), indicating that it might have no off-target toxic effects. In light of these data, compound C14 represents a novel covalent FLT3 kinase inhibitor for targeted therapy of AML.

AHSA1 is a promising therapeutic target for cellular proliferation and proteasome inhibitor resistance in multiple myeloma.

BACKGROUND: Currently, multiple myeloma (MM) is still an incurable plasma cell malignancy in urgent need of novel therapeutic targets and drugs. METHODS: Bufalin was known as a highly toxic but effective anti-cancer compound. We used Bufalin as a probe to screen its potential targets by proteome microarray, in which AHSA1 was the unique target of Bufalin. The effects of AHSA1 on cellular proliferation and drug resistance were determined by MTT, western blot, flow cytometry, immunohistochemistry staining and xenograft model in vivo. The potential mechanisms of Bufalin and KU-177 in AHSA1/HSP90 were verified by co-immunoprecipitation, mass spectrometry, site mutation and microscale thermophoresis assay. RESULTS: AHSA1 expression was increased in MM samples compared to normal controls, which was significantly associated with MM relapse and poor outcomes. Furthermore, AHSA1 promoted MM cell proliferation and proteasome inhibitor (PI) resistance in vitro and in vivo. Mechanism exploration indicated that AHSA1 acted as a co-chaperone of HSP90A to activate CDK6 and PSMD2, which were key regulators of MM proliferation and PI resistance respectively. Additionally, we identified AHSA1-K137 as the specific binding site of Bufalin on AHSA1, mutation of which decreased the interaction of AHSA1 with HSP90A and suppressed the function of AHSA1 on mediating CDK6 and PSMD2. Intriguingly, we discovered KU-177, an AHSA1 selective inhibitor, and found KU-177 targeting the same site as Bufalin. Bufalin and KU-177 treatments hampered the proliferation of flow MRD-positive cells in both primary MM and recurrent MM patient samples. Moreover, KU-177 abrogated the cellular proliferation and PI resistance induced by elevated AHSA1, and decreased the expression of CDK6 and PSMD2. CONCLUSIONS: We demonstrate that AHSA1 may serve as a promising therapeutic target for cellular proliferation and proteasome inhibitor resistance in multiple myeloma.

An efficient strategy for digging protein-protein interactions for rational drug design - A case study with HIF-1α/VHL.

The ubiquitination of the hypoxia-inducible factor-1α (HIF-1α) is mediated by interacting with the von Hippel-Lindau protein (VHL), and is associated with cancer, chronic anemia, and ischemia. VHL, an E3 ligase, has been reported to degrade HIF-1 for decades, however, there are few successful inhibitors currently. Poor understanding of the binding pocket and a lack of in-depth exploration of the interactions between two proteins are the main reasons. Hence, we developed an effective strategy to identify and design new inhibitors for protein-protein interaction targets. The hydroxyproline (Hyp564) of HIF-1α contributed the key interaction between HIF-1α and VHL. In this study, detailed information of the binding pocket were explored by alanine scanning, site-directed mutagenesis and molecular dynamics simulations. Interestingly, we found the interaction(s) between Y565 and H110 played a key role in the binding of VHL/HIF-1α. Based on the interactions, 8 derivates of VH032, 16a-h, were synthesized by introducing various groups bounded to H110. Further assay on protein and cellular level exhibited that 16a-h accessed higher binding affinity to VHL and markable or modest improvement in stabilization of HIF-1α or HIF-1α-OH in HeLa cells. Our work provides a new orientation for the modification or design of VHL/HIF-1α protein-protein interaction inhibitors.

Small-Molecule Fms-like Tyrosine Kinase 3 Inhibitors: An Attractive and Efficient Method for the Treatment of Acute Myeloid Leukemia.

Fms-like tyrosine kinase 3 (FLT3) is an important member of the class III receptor tyrosine kinase (RTK) family, which is involved in the proliferation of hematopoietic cells and lymphocytes. In recent years, increasing evidence have demonstrated that the activation and mutation of FLT3 is closely implicated in the occurrence and development of acute myeloid leukemia (AML). The exploration of small-molecule inhibitors targeting FLT3 has aroused wide interest of pharmaceutical chemists and is expected to bring new hope for AML therapy. In this review, we specifically highlighted FLT3 mediated JAK/STAT, RAS/MAPK, and PI3K/AKT/mTOR signaling. The structural properties and biological activities of representative FLT3 inhibitors reported from 2014 to the present were also summarized. In addition, the major challenges in the current advance of novel FLT3 inhibitors were further analyzed, with the aim to guide future drug discovery.