quizartinib and Leukemia--Myeloid--Acute

Despite progressive advances in understanding the molecular biology of acute myeloid leukemia (AML), the conventional therapeutic approach has not changed substantially, and the outcome for most patients is poor. Thus, continuous efforts on the discovery of new compounds with improved features are required. Following a multistep sequence, we have identified a new tetracyclic ring system with strong antiproliferative activity towards several haematological cell lines. The new compounds possess structural properties typical of inactive-state-binding kinase inhibitors and are structurally related to quizartinib which is known as type-II tyrosine kinase inhibitor. In particular, the high activity found in two cell lines MOLM-13 and MV4-11, expressing the constitutively activated mutant FLT3/ITD, indicates inhibition of FLT3 kinase and on the basis of structure-activity relationship (SAR) the presence of an ureido moiety demonstrates to play a key role in driving the antiproliferative activity towards these cell lines. Molecular modelling studies supported the mechanism of recognition of the most active compounds within the FLT3 pocket where quizartinib binds. Moreover, Molecular Dynamics simulation (MDs) revealed the formation of a recurrent H-bond with Asp829, which more stabilizes the complex of 9c and the FLT3 inactive state. In MV4-11 cell line compound 9c reduces the phosphorylation of FLT3 (Y591) and some of its downstream targets leading to cell cycle arrest at G1 phase and induction of apoptosis. In an MV4-11 xenograft mouse model, 9c significantly reduces the tumor growth at the dose of 1-3 mg/kg without apparent toxicity.

Topics: Animals; Apoptosis; Cell Line, Tumor; fms-Like Tyrosine Kinase 3; Humans; Leukemia, Myeloid, Acute; Mice; Mutation; Protein Kinase Inhibitors

The 3

Topics: Antineoplastic Agents; Cell Proliferation; Dose-Response Relationship, Drug; Drug Screening Assays, Antitumor; fms-Like Tyrosine Kinase 3; Humans; Leukemia, Myeloid, Acute; Molecular Structure; Protein Kinase Inhibitors; Structure-Activity Relationship; Tumor Cells, Cultured

FMS-like tyrosine kinase 3 (FLT3) with an internal tandem duplication (ITD) mutation has been validated as a driver lesion and a therapeutic target for acute myeloid leukemia (AML). Currently, several potent small-molecule FLT3 kinase inhibitors are being evaluated or have completed evaluation in clinical trials. However, many of these inhibitors are challenged by the secondary mutations on kinase domain, especially the point mutations at the activation loop (D835) and gatekeeper residue (F691). To overcome the resistance challenge, we identified a novel series of imidazo[1,2-a]pyridine-thiophene derivatives from a NIMA-related kinase 2 (NEK2) kinase inhibitor CMP3a, which retained inhibitory activities on FTL3-ITD

Topics: Antineoplastic Agents; Cell Line, Tumor; Cell Proliferation; Dose-Response Relationship, Drug; Drug Discovery; Drug Screening Assays, Antitumor; fms-Like Tyrosine Kinase 3; Humans; Leukemia, Myeloid, Acute; Molecular Structure; Mutation; NIMA-Related Kinases; Protein Kinase Inhibitors; Pyridines; Structure-Activity Relationship; Thiophenes

Mutants of the FLT3 receptor tyrosine kinase (RTK) with duplications in the juxtamembrane domain (FLT3-ITD) act as drivers of acute myeloid leukemia (AML). Potent tyrosine kinase inhibitors (TKi) of FLT3-ITD entered clinical trials and showed a promising, but transient success due to the occurrence of secondary drug-resistant AML clones. A further caveat of drugs targeting FLT3-ITD is the co-targeting of other RTKs which are required for normal hematopoiesis. This is observed quite frequently. Therefore, novel drugs are necessary to treat AML effectively and safely. Recently bis(1H-indol-2-yl)methanones were found to inhibit FLT3 and PDGFR kinases. In order to optimize these agents we synthesized novel derivatives of these methanones with various substituents. Methanone 16 and its carbamate derivative 17b inhibit FLT3-ITD at least as potently as the TKi AC220 (quizartinib). Models indicate corresponding interactions of 16 and quizartinib with FLT3. The activity of 16 is accompanied by a high selectivity for FLT3-ITD.

Topics: Antineoplastic Agents; Cell Proliferation; Dose-Response Relationship, Drug; Drug Screening Assays, Antitumor; fms-Like Tyrosine Kinase 3; Humans; Indoles; Leukemia, Myeloid, Acute; Models, Molecular; Molecular Structure; Protein Kinase Inhibitors; Structure-Activity Relationship; Tumor Cells, Cultured

Aberrant activation of FMS-like tyrosine receptor kinase 3 (FLT3) is implicated in the pathogenesis of acute myeloid leukemia (AML) in 20-30% of patients. In this study we identified a highly selective (phenylethenyl)quinazoline compound family as novel potent inhibitors of the FLT3-ITD and FLT3-D835Y kinases. Their prominent effects were confirmed by biochemical and cellular proliferation assays followed by mice xenograft studies. Our modelling experiments and the chemical structures of the compounds predict the possibility of covalent inhibition. The most effective compounds triggered apoptosis in FLT3-ITD AML cells but had either weak or no effect in FLT3-independent leukemic and non-leukemic cell lines. Our results strongly suggest that our compounds may become therapeutics in relapsing and refractory AML disease harboring various ITD and tyrosine kinase domain mutations, by their ability to overcome drug resistance.

Topics: Antineoplastic Agents; Cell Line, Tumor; Cell Proliferation; Dose-Response Relationship, Drug; Drug Discovery; Drug Screening Assays, Antitumor; fms-Like Tyrosine Kinase 3; Humans; Leukemia, Myeloid, Acute; Molecular Structure; Mutation; Protein Kinase Inhibitors; Pyrimidines; Structure-Activity Relationship

FLT3 tyrosine kinase is a potential drug target in acute myeloid leukemia (AML) because patients with FLT3-ITD mutations respond poorly to standard cytotoxic agents and there is a clear link between the disease and the oncogenic properties of FLT3. We present novel 2,6,9-trisubstituted purine derivatives with potent FLT3 inhibitory activity. The lead compound 7d displays nanomolar activity in biochemical assays and selectively blocks proliferation of AML cell lines harboring FLT3-ITD mutations, whereas other transformed and normal human cells are several orders of magnitude less sensitive. The MV4-11 cells treated with 7d suppressed the phosphorylation of FLT3 and its downstream signaling pathways, with subsequent G1 cell cycle arrest and apoptosis. Additionally, a single dose of 7d in mice with subcutaneous MV4-11 xenografts caused sustained inhibition of FLT3 and STAT5 phosphorylation over 48 h, in contrast to the shorter effect observed after administration of the reference FLT3 inhibitor quizartinib.

Topics: Animals; Antineoplastic Agents; Cell Line, Tumor; Diamines; Drug Discovery; fms-Like Tyrosine Kinase 3; Leukemia, Myeloid, Acute; Mice; Molecular Docking Simulation; Protein Conformation; Protein Kinase Inhibitors; Structure-Activity Relationship; Xenograft Model Antitumor Assays

Kinase inhibitors are important cancer therapeutics. Polypharmacology is commonly observed, requiring thorough target deconvolution to understand drug mechanism of action. Using chemical proteomics, we analyzed the target spectrum of 243 clinically evaluated kinase drugs. The data revealed previously unknown targets for established drugs, offered a perspective on the "druggable" kinome, highlighted (non)kinase off-targets, and suggested potential therapeutic applications. Integration of phosphoproteomic data refined drug-affected pathways, identified response markers, and strengthened rationale for combination treatments. We exemplify translational value by discovering SIK2 (salt-inducible kinase 2) inhibitors that modulate cytokine production in primary cells, by identifying drugs against the lung cancer survival marker MELK (maternal embryonic leucine zipper kinase), and by repurposing cabozantinib to treat FLT3-ITD-positive acute myeloid leukemia. This resource, available via the ProteomicsDB database, should facilitate basic, clinical, and drug discovery research and aid clinical decision-making.

Topics: Animals; Antineoplastic Agents; Cell Line, Tumor; Cytokines; Drug Discovery; fms-Like Tyrosine Kinase 3; Humans; Leukemia, Myeloid, Acute; Lung Neoplasms; Mice; Molecular Targeted Therapy; Protein Kinase Inhibitors; Protein Serine-Threonine Kinases; Proteomics; Xenograft Model Antitumor Assays

Fms-like tyrosine kinase 3 (FLT3) is a well-known and important target for the treatment of acute myeloid leukemia (AML). A series of thieno[2,3-d]pyrimidine derivatives from a modification at the 6-position were synthesized to identify effective FLT3 inhibitors. Although compounds 1 and 2 emerged as promising FLT3 inhibitors among the synthesized compounds, both compounds exhibited poor metabolic stability in human and rat liver microsomes. Hence, further optimization was required for the discovery of FLT3 inhibitors, with a focus on improving metabolic stability. Compound 16d, which had structural modifications of the methyl group at the 5-position and the 4-(2-methylaminoethoxy) phenyl group at the 6-position, exhibited good inhibitory activity against FLT3 and showed effective antiproliferative activity against four leukemia cell lines, including MV4-11. Moreover, compound 16d displayed enhanced metabolic stability. The results of this study indicated that 16d could be a promising compound for further optimization and development as a potent FLT3 inhibitor.

Topics: Animals; Antineoplastic Agents; Cell Line, Tumor; Cell Proliferation; Drug Stability; fms-Like Tyrosine Kinase 3; Humans; Leukemia, Myeloid, Acute; Pyrimidines; Rats; Structure-Activity Relationship

FLT3 has been validated as a therapeutic target for the treatment of acute myeloid leukemia (AML). In this paper, we describe for the first time, pteridin-7(8H)-one as a scaffold for potent FLT3 inhibitors derived from structural optimizations on irreversible EGFR inhibitors. The representative inhibitor (31) demonstrates single-digit nanomolar inhibition against FLT3 and subnanomolar KD for drug-resistance FLT3 mutants. In profiling of the in vitro tumor cell lines, it shows good selectivity against AML cells harboring FLT3-ITD mutations over other leukemia and solid tumor cell lines. The mechanism of action study illustrates that pteridin-7(8H)-one derivatives suppress the phosphorylation of FLT3 and its downstream pathways, thereby inducing G0/G1 cell cycle arrest and apoptosis in AML cells. In in vivo studies, 31 significantly suppresses the tumor growth in MV4-11 xenograft model. Overall, we provide a structurally distinct chemical scaffold with which to develop FLT3 mutants-selective inhibitors for AML treatment.

Topics: Antineoplastic Agents; Apoptosis; Cell Cycle Checkpoints; Cell Line, Tumor; Cell Proliferation; fms-Like Tyrosine Kinase 3; Humans; Leukemia, Myeloid, Acute; Molecular Docking Simulation; Mutation; Phosphorylation; Protein Kinase Inhibitors; Pteridines

FLT3 inhibitors have been explored as a viable therapy for acute myeloid leukemia (AML). However, the clinical outcomes of these FLT3 inhibitors were underwhelming except AC220. Therefore, the development of novel FLT3 inhibitors with high potency against both FLT3-WT and FLT3-ITD mutants are strongly demanded at the present time. In this study, we designed and synthesized a series of novel N-(5-(tert-butyl)isoxazol-3-yl)-N'-phenylurea derivatives as FLT3 inhibitors. SAR studies focused on the fused rings led to the discovery of a series of compounds with high potency against FLT3-ITD-bearing MV4-11 cells and significantly inhibitory activity toward FLT3. Among these compounds, N-(5-(tert-butyl)isoxazol-3-yl)-N'-(4-(7-methoxyimidazo[1,2-a]pyridin-2-yl)phenyl)urea (16i), displayed acceptable aqueous solubility, desirable pharmacokinetic profile and high cytotoxicity selectivity against MV4-11 cells. This compound can inhibit phosphorylation of FLT3 and induce apoptosis in a concentration-dependent manner. Further in vivo antitumor studies showed that 16i led to complete tumor regression in the MV4-11 xenograft model at a dose of 60 mg/kg/d while without observable body weight loss. This study had provided us a new chemotype of FLT3 inhibitors as novel therapic candidates for AML.

Topics: Animals; Apoptosis; Cell Line, Tumor; Female; fms-Like Tyrosine Kinase 3; Half-Life; Humans; Immunohistochemistry; Leukemia, Myeloid, Acute; Mice; Mice, Inbred NOD; Mice, SCID; Phenylurea Compounds; Phosphorylation; Protein Kinase Inhibitors; Rats; Rats, Sprague-Dawley; Structure-Activity Relationship; Transplantation, Heterologous; Xenograft Model Antitumor Assays

The most common mutations in acute myeloid leukemia (AML) are those that cause the activation of FMS-like tyrosine kinase 3 (FLT3). Therefore, FLT3 is regarded as a potential target for the treatment of AML. A novel series of thieno[2,3-d]pyrimidine-based analogs was designed and synthesized as FLT3 inhibitors. All synthesized compounds were assayed for the tyrosine kinase activity of FLT3 and growth inhibitory activity in four human leukemia cell lines (THP1, MV4-11, K562, and HL-60). Among these compounds, compound 17a, which possesses relatively short and simple substituents at the C6 position of thieno[2,3-d]pyrimidine, emerged as the most promising anti-leukemic agent. Compound 17a exhibited potent inhibition of FLT3-positive leukemic cell growth and of the FLT3 D835Y kinase; such inhibition is required for the successful treatment of AML. The data supports the further investigation of this class of compounds as potential anti-leukemic agents.

Topics: Antineoplastic Agents; Apoptosis; Cell Line, Tumor; Cell Proliferation; Chemistry Techniques, Synthetic; Drug Design; Feasibility Studies; fms-Like Tyrosine Kinase 3; Humans; Leukemia, Myeloid, Acute; Protein Kinase Inhibitors; Pyrimidines; Structure-Activity Relationship

Activating mutations in the receptor tyrosine kinase FLT3 are present in up to approximately 30% of acute myeloid leukemia (AML) patients, implicating FLT3 as a driver of the disease and therefore as a target for therapy. We report the characterization of AC220, a second-generation FLT3 inhibitor, and a comparison of AC220 with the first-generation FLT3 inhibitors CEP-701, MLN-518, PKC-412, sorafenib, and sunitinib. AC220 exhibits low nanomolar potency in biochemical and cellular assays and exceptional kinase selectivity, and in animal models is efficacious at doses as low as 1 mg/kg given orally once daily. The data reveal that the combination of excellent potency, selectivity, and pharmacokinetic properties is unique to AC220, which therefore is the first drug candidate with a profile that matches the characteristics desirable for a clinical FLT3 inhibitor.

Topics: Animals; Benzenesulfonates; Benzothiazoles; Bone Marrow; Carbazoles; Cell Line, Tumor; Cell Proliferation; Female; fms-Like Tyrosine Kinase 3; Furans; Humans; Leukemia, Myeloid, Acute; Mice; Mice, Nude; Mice, SCID; Niacinamide; Phenylurea Compounds; Phosphorylation; Piperazines; Prognosis; Protein Interaction Mapping; Protein Kinase C; Protein Kinase Inhibitors; Pyridines; Quinazolines; Sorafenib; Staurosporine; Xenograft Model Antitumor Assays