Discovery and optimization of novel 4-phenoxy-6,7-disubstituted quinolines possessing semicarbazones as c-Met kinase inhibitors

Discovery of LAH-1 as potent c-Met inhibitor for the treatment of non-small cell lung cancer

ABSTRCTDysregulated HGF/c-Met pathway has been implicated in multiple human cancers and has become an attractive target for cancer intervention. Herein, we report the discovery of N-(3-fluoro-4-((2-(3-hydroxyazetidine-1-carboxamido)pyridin-4-yl)oxy)phenyl)-1-(4-fluorophenyl)-4-methyl-6-oxo-1,6-dihydropyridazine-3-carboxamide (LAH-1), which demonstrated nanomolar MET kinase activity as well as desirable antiproliferative activity, especially against EBC-1 cells. Mechanism studies confirmed the effects of LAH-1 on modulation of HGF/c-Met pathway, induction of cell apoptosis, inhibition on colony formation as well as cell migration and invasion. In addition, LAH-1 also showed desirable in vitro ADME properties as well as acceptable in vivo PK parameters. The design, synthesis, and characterisation of LAH-1 are described herein.

Design, synthesis, and biological evaluation of thiazole/thiadiazole carboxamide scaffold-based derivatives as potential c-Met kinase inhibitors for cancer treatment

As part of our continuous efforts to discover novel c-Met inhibitors as antitumor agents, four series of thiazole/thiadiazole carboxamide-derived analogues were designed, synthesised, and evaluated for the in vitro activity against c-Met and four human cancer cell lines. After five cycles of optimisation on structure-activity relationship, compound 51am was found to be the most promising inhibitor in both biochemical and cellular assays. Moreover, 51am exhibited potency against several c-Met mutants. Mechanistically, 51am not only induced cell cycle arrest and apoptosis in MKN-45 cells but also inhibited c-Met phosphorylation in the cell and cell-free systems. It also exhibited a good pharmacokinetic profile in BALB/c mice. Furthermore, the binding mode of 51am with both c-Met and VEGFR-2 provided novel insights for the discovery of selective c-Met inhibitors. Taken together, these results indicate that 51am could be an antitumor candidate meriting further development.

Transforming Type II to Type I c-Met kinase inhibitors via combined scaffold hopping and structure-guided synthesis of new series of 1,3,4-thiadiazolo[2,3-c]-1,2,4-triazin-4-one derivatives

Novel 1,3,4-thiadiazolo[2,3-c]-1,2,4-triazin-4-one derivatives 3a-e, 4a-f and 5a-f were designed as Type I c-Met kinase inhibitors based on scaffold hopping of our previous Type II c-Met kinase lead. Target compounds were then synthesized under the guidance of molecular docking analysis to identify the potential inhibitors that fit the binding pocket of c-Met kinase in the characteristic manner as the reported Type I c-Met kinase inhibitors. All synthesized derivatives were evaluated for their c-Met kinase inhibitory activity at 10 µM concentration, where 3d, 5d and 5f displayed >80% inhibition. Further IC₅₀ investigation of these compounds identified 5d as the most potent c-Met kinase inhibitor with IC₅₀ value of 1.95 µM. Moreover, 5d showed selective antitumor activity against c-Met over-expressing colon HCT-116 and lung A549 adenocarcinoma cells with IC₅₀ values of 6.18 and 10.6 µg/ml, respectively. More significantly, 5d effectively inhibited c-Met phosphorylation in the Western blot experiment. Also, 5d induced cellular apoptosis in HCT-116 cancer cells as well as cell cycle arrest with accumulation of cells in G2/M phase. Finally, kinase selectivity profiling of 5d against nine oncogenic kinases revealed its selectivity to only Tyro3 kinase (% inhibition = 80%, IC₅₀ = 3 µM). All these experimental findings clearly demonstrate that 5d is a potential dual acting inhibitor against c-Met and Tyro3 kinases, standing out as a viable lead that deserves further investigation and development to new generation of antitumor agents.

Structure-guided design and development of novel N-phenylpyrimidin-2-amine derivatives as potential c-Met inhibitors

The HGF/Met signaling pathway is over-expressed in many types of cancers and closely related to oncogenesis and metastasis. Thus, we developed novel N-phenylpyrimidin-2-amine derivatives to test their inhibitory activities towards c-Met kinase, and most of the compounds (15a-i, 15o-r, 20 and 34a-c) could inhibit the target with IC₅₀ values from 550.8 nM to 15.0 nM. Subsequently, compound 15b, 15d, 15f, 15i, 15o, 15r, 20, 34a and 34b also showed high antiproliferative activities in c-Met sensitive tumor cell lines (PC-3, Panc-1, HepG2, HCT116 and Caki-1) with IC₅₀ values from 0.53 to 1.37 μM. The lead compound 34a displayed outstanding c-Met inhibitory activity (IC₅₀: 15.0 nM) and antiproliferative activities. Furthermore, 34a also performed favorable pharmacokinetic properties in mice (F%: 59.3) and an acceptable safety profile in preclinical studies. Further docking studies showed a common interaction of 34a with c-Met at the ATP-binding site, which indicated that 34a could be a potential candidate for c-Met inhibitors.

Optimization and biological evaluation of nicotinamide derivatives as Aurora kinase inhibitors

Aurora kinases are known to be overexpressed in various solid tumors and implicated in oncogenesis and tumor progression. A series of nicotinamide derivatives were synthesized and their biological activities were evaluated, including kinase inhibitory activity against Aur A and Aur B and in vitro antitumor activity against SW620, HT-29, NCI-H1975 and Hela cancer cell lines. In addition, the study of antiproliferation, cytotoxicity and apoptosis was performed meanwhile. As the most potent inhibitor of Aur A, 4-((3-bromo-4-fluorophenyl)amino)-6-chloro-N-(4-((6,7-dimethoxyquinolin-4-yl)oxy)-3-fluorophenyl)nicotinamide (10l) showed excellent antitumor activity against SW620 and NCI-H1975 with IC₅₀ values were 0.61 and 1.06 μM, while the IC₅₀ values of reference compound were 3.37 and 6.67 μM, respectively. Furthermore, binding mode studies indicated that compound 10l forms better interaction with Aur A.

Revealing quinquennial anticancer journey of morpholine: A SAR based review

Morpholine, a six-membered heterocycle containing one nitrogen and one oxygen atom, is a moiety of great significance. It forms an important intermediate in many industrial and organic syntheses. Morpholine containing drugs are of high therapeutic value. Its wide array of pharmacological activity includes anti-diabetic, anti-emetic, growth stimulant, anti-depressant, bronchodilator and anticancer. Multi-drug resistance in cancer cases have emerged in the last few years and have led to the failure of many chemotherapeutic drugs. Newer treatment methods and drugs are being developed to overcome this problem. Target based drug discovery is an effective method to develop novel anticancer drugs. To develop newer drugs, previously reported work needs to be studied. Keeping this in mind, last five year's literature on morpholine used as anticancer agents has been reviewed and summarized in the paper herein.

Identification of novel N1-(2-aryl-1, 3-thiazolidin-4-one)-N3-aryl ureas showing potent multi-tyrosine kinase inhibitory activities

A total of 29 novel compounds bearing N¹-(2-aryl-1, 3-thiazolidin-4-one)-N³-aryl ureas were designed, synthesized and evaluated for their biological activities. The structure-activity relationships (SARs) and binding modes of this series of compounds were clarified together. Compound 29b was identified possessing high potency against multi-tyrosine kinases including Ron, c-Met, c-Kit, KDR, Src and IGF-1R, etc. In vitro antiproliferation and cytotoxicity of compound 29b against A549 cancer cell line were confirmed by IncuCyte live-cell imaging.

Synthesis and bioevaluation and doking study of 1H-pyrrolo[2,3-b]pyridine derivatives bearing aromatic hydrazone moiety as c-Met inhibitors

Two series of aromatic hydrazone derivatives bearing 1H-pyrrolo[2,3-b]pyridine moiety (7a-r, 8a-i, 12a-b, 13a-c, 16a-d and 17a-e) were designed, synthesized and evaluated for the IC₅₀ values against four cancer cell lines (A549, HepG2, MCF-7and PC-3). Two selected compounds (7c and 17e) were further evaluated for the activity against c-Met, Flt-3, VEGFR-2 and EGFR kinases. The data indicated that targets compounds were selective for c-Met kinase. And the most promising compound 7c was further studied in terms of dose-dependent, time-dependent and cell apoptosis. Most of the compounds showed excellent cytotoxicity activity, especially the most promising compound 7c with the IC₅₀ values of 0.82 ± 0.08 μM, 1.00 ± 0.11 μM, 0.93 ± 0.28 μM and 0.92 ± 0.17 μM against A549, HepG2, MCF-7 and PC-3 cell lines and 0.506 μM against c-Met kinase. Structure-activity relationships (SARs) and docking studies indicated that the activities of the phenyl hydrazone derivatives (7a-r and 8a-i) were superior to that of the heterocyclic hydrazone series (12a-b, 13a-c, 16a-d and 17a-e). What's more, the further studies indicated that the target compounds can induce apoptosis of A549 cells and arrest efficiently the cell cycle progression in G2/M phase of A549 cells.

Design, synthesis and molecular modeling studies of new series of antitumor 1,2,4-triazines with potential c-Met kinase inhibitory activity

The receptor tyrosine kinase c-Met is an attractive target for therapeutic treatment of cancers nowadays. Herein we describe the design and synthesis of a novel series of 1,2,4-triazine derivatives based on our lead NCI 748494/1, possessing different N-linkers to aromatic and heterocyclic rings. In addition, a molecular hybrid series combining the 1,2,4-triazine scaffold to the well-known anticancer drug 6-mercaptopurine (6-MP) was synthesized in order to explore its "double-drug" antitumor effect. The synthesized compounds were evaluated for their in vitro antitumor activity against three c-Met addicted cancer cell lines (A549, HT-29 and MKN-45). Most compounds showed moderate to excellent antitumor activity. Compound 3d showed potent inhibitory activity more than reference Foretinib, BMS-777607 and NCI 748494/1 with IC₅₀ values in the range 0.01-0.31 µM against the cancer cell lines. The calculated IC₅₀ of 3d against c-Met kinase was found to be 2.71 µM, which is more potent than NCI 748494/1 (IC₅₀ = 31.70 µM). Docking studies were performed to identify the binding mode of 3d with c-Met kinase domain in comparison to moderate and weak derivatives. The present study clearly demonstrates that 1,2,4-triazine ring exhibits promising antitumor activity and the double-drug optimization strategy led to identifying 3d as a potent c-Met kinase inhibitor suitable for further development.

Development of efficient docking strategies and structure-activity relationship study of the c-Met type II inhibitors

c-Met is a transmembrane receptor tyrosine kinase and an important therapeutic target for anticancer drugs. In the present study, we systematically investigated the influence of a range of parameters on the correlation between experimental and calculated binding free energies of type II c-Met inhibitors. We especially focused on evaluating the impact of different force fields, binding energy calculation methods, docking protocols, conformation sampling strategies, and conformations of the binding site captured in several crystallographic structures. Our results suggest that the force fields, the protein flexibility, and the selected conformation of the binding site substantially influence the correlation coefficient, while the sampling strategies and ensemble docking only mildly affect the prediction accuracy. Structure-activity relationship study suggests that the structural determinants to the high binding affinity of the type II inhibitors originate from its overall linear shape, hydrophobicity, and two conserved hydrogen bonds. Results from this study will form the basis for establishing an efficient computational docking approach for c-Met type II inhibitors design.

Discovery of a novel 6,7-disubstituted-4-(2-fluorophenoxy)quinolines bearing 1,2,3-triazole-4-carboxamide moiety as potent c-Met kinase inhibitors

A series of 6,7-disubstituted-4-(2-fluorophenoxy)quinoline derivatives possessing 1,2,3-triazole-4-carboxamide moiety were designed, synthesized and evaluated for their in vitro cytotoxic activities against four typical cancer cell lines (A549, H460, HT-29, and MKN-45). Most compounds showed moderate-to-excellent antiproliferative activity. Compounds 32, 36, 37, 45, 51, and 52 were further examined for their inhibitory activity against c-Met kinase. The promising compound 37, with a c-Met IC50 value of 2.27 nM, was identified as a multitargeted receptor tyrosine kinase inhibitor. The analysis of their structure-activity relationships indicated that compounds with EWGs, especially chloro group, at 2-position on the phenyl ring (moiety B) have potent antitumor activity.

A rapid and sensitive LC-MS/MS method for evaluation of the absolute oral bioavailability of a novel c-Met tyrosine kinase inhibitor QBH-196 in rats

A sensitive, selective and high-throughput UPLC-MS/MS method was developed and validated for the determination of a novel c-Met tyrosine kinase inhibitor, QBH-196, in rat plasma. QBH-196 and its analog BH357 (IS) were extracted from rat plasma using a mixture of dichloromethane and N-hexane (2:3, v/v). The chromatographic separation was carried out on Phenomenex C18 column (50 × 2.1 mm, 2.6 µm particle size) with a gradient mobile phase of methanol (A) and water containing 0.05% formic acid (B) at a flow rate of 0.2 mL/min. The assay was performed by positive electrospray ionization in multiple reaction monitoring mode using transitions of m/z 622.68 → 140.41 for QBH-196 and m/z 591.19 →126.21 for the IS, respectively. Good linearity was obtained over the concentration range of 8.0-4000 ng/mL (r(2) > 0.99) for QBH-196 and the lower limit of quantification was 8.0 ng/mL in rat plasma. Validations of the method, including its sensitivity, extraction recovery, matrix effect, intra- and inter-day precision, accuracy and stability, were all within acceptable limits. The established method was successfully applied to determine absolute oral bioavailability of QBH-196 in rats for the first time. The mean oral absolute bioavailability of QBH-196 was found to be about 40.8% and the elimination half-life was 40.0 ± 13.1 h. This result suggested that QBH-196 exhibits good oral absorption in vivo, which is very important for the further development of QBH-196 as a new oral anticancer drug.

Discovery of novel c-Met inhibitors bearing a 3-carboxyl piperidin-2-one scaffold

A series of compounds containing a novel 3-carboxypiperidin-2-one scaffold based on the lead structure BMS-777607 were designed, synthesized and evaluated for their c-Met kinase inhibition and cytotoxicity against MKN45 cancer cell lines. The results indicated that five compounds exhibited significant inhibitory effect on c-Met with IC₅₀ values of 8.6−81 nM and four compounds showed potent inhibitory activity against MKN45 cell proliferation, with IC₅₀s ranging from 0.57−16 μM.