Aminopyridyl/Pyrazinyl Spiro[indoline-3,4'-piperidine]-2-ones As Highly Selective and Efficacious c-Met/ALK Inhibitors

Targeting MET: Discovery of Small Molecule Inhibitors as Non-Small Cell Lung Cancer Therapy

MET has been considered as a promising drug target for the treatment of MET-dependent diseases, particularly non-small cell lung cancer (NSCLC). Small molecule MET inhibitors with mainly three types of binding modes (Ia/Ib, II, and III) have been developed. In this Review, we provide an overview of the structural features, activation mechanism, and dysregulation pathway of MET and summarize progress on the development and discovery strategies utilized for MET inhibitors as well as mechanisms of acquired resistance to current approved inhibitors. The insights will accelerate discovery of new generation MET inhibitors to overcome clinical acquired resistance.

Construction of Spiro[benzo[a]acridine-12,4'-imidazolidine]-2',5'-dione Derivatives via Ring-Opening and Recyclization of Isatins and C-OH Cleavage of 2-Naphthol

An efficient three-component reaction to access spiro[benzo[a]acridine-12,4'-imidazolidine]-2',5'-dione derivatives has been developed through the ring-opening and recyclization process of isatins and dehydroxylation of 2-naphthol, which is different from their conventional reaction modes. Experimental observations suggest that p-toluenesulfonic acid is the key factor that promotes the success of this synthetic strategy. The research provided a novel approach for the construction of spiro compounds from isatins and 2-naphthol in organic synthesis.

1'-methylspiro[indoline-3,4'-piperidine] Derivatives: Design, Synthesis, Molecular Docking and Anti-tumor Activity Studies

Background:

Spirocyclic indoline compounds widely exist in numerous natural products and synthetic molecules with significant biological activities. In recent years, these kinds of compounds have attracted extensive attention as potent anti-tumor agents in the fields of pharmacology and chemistry.

Objective:

In this study, we focused on designing and synthesizing novel 1'-methylspiro[indoline- 3,4'-piperidine] derivatives, which were evaluated by preliminary bioactivity experiment in vitro and molecular docking.

Methods and Materials:

The key intermediate 1'-methylspiro[indoline-3,4'-piperidine] (B4) reacted with benzenesulfonyl chloride with different substituents under alkaline condition to obtain its derivatives (B5-B10). We evaluated their antiproliferative activities against A549, BEL-7402 and HeLa cell lines by MTT assay. We performed the CDOCKER module in Accelrys Discovery Studio 2.5.5 for molecular docking of compound B5, and investigated the binding modes of compound B5 with three different target proteins.

Results:

The results indicated that compounds B4-B10 exhibited good antiproliferative activities against the above three types of cell lines, in which compound B5 with chloride atom as electronwithdrawing substituent on a phenyl ring showed the highest potency against BEL-7402 cell lines (IC50=30.03±0.43 μg/mL). The results of molecular docking showed that the binding energies of the prominent bioactive compound B5 with CDK, c-Met, and EGFR protein crystals are -44.3583 kcal/mol, -38.3292 kcal/mol, -33.3653 kcal/mol, respectively.

Conclusion:

1'-methylspiro[indoline-3,4'-piperidine] and its six derivatives were synthesized and evaluated against BEL-7402, A 549, and Hela cell lines. Compound B5 showed significant inhibition on BEL-7402 cell lines. Molecular docking assays revealed that B5 as a ligand showed strong affinity and appropriate binding pose on the amino acid residues in active sites of the tested targets, which encourage us to conduct further evaluation such as the kinase experiment.

Stereoselective synthesis and applications of spirocyclic oxindoles

This review summaries recent synthetic developments towards spirocyclic oxindoles and applications as valuable medicinal and synthetic targets.

The cytochrome P450 metabolic profiling of SMU-B in vitro, a novel small molecule tyrosine kinase inhibitor

A novel small molecule tyrosine kinase inhibitor 6-[6-Amino-5-[(1R)-1-(2,6-dichloro-3-fluorophenyl)ethoxy]-3-pyridyl]-1'-methylspiro[indoline-3,4'-piperidine]-2-one (SMU-B) had good activity against ALK (anaplastic lymphoma kinase) and ROS1 (c-ros oncogene 1) targets in non-small-cell lung cancer. The excellent bioactivity of SMU-B highlights the importance of determining its metabolic traits, which could provide meaningful information for further pharmacokinetic studies of SMU-B. In this work, we studied the metabolism of SMU-B in human liver microsomes. Three metabolites of SMU-B were identified by a quadrupole-time of flight tandem mass spectrometer (Q-TOF-MS), and the metabolic pathways of SMU-B were demethylation, dehydrogenation and oxidation. CYP3A4/5 was the principal isoform involved in SMU-B metabolism, as shown by chemical inhibition and recombination human enzyme studies. Additionally, a predication with a molecular docking model confirmed that SMU-B could interact with the active sites of CYP3A4 and CYP3A5. This study illuminates the metabolic profile of the anti-tumor drug SMU-B, which will accelerate its clinical use.

Three-Component Cascade Reaction of 1,1-Enediamines, N,N-Dimethylformamide Dimethyl Acetal, and 1,3-Dicarbonyl Compounds: Selective Synthesis of Diverse 2-Aminopyridine Derivatives

A novel approach has been developed for the synthesis of three kinds of highly functionalized 2-aminopyridine derivatives (APDs) through a three-component reaction of 1,1-enediamines (EDAMs) 1, N,N-dimethylformamide dimethyl acetal (DMF-DMA) 2, and 1,3-dicarbonyl compounds 3-5 via a base-promoted cascade reaction, producing the desired products in good to excellent yields. This method represents a route to obtain a novel class of APDs in a concise, rapid, and practical manner. This approach is particularly attractive because of the following features: low cost, mild temperature, atom economy, high yields, and potential biological activity of the product.

Design, synthesis, biological evaluation and molecular modeling of novel 2-amino-4-(1-phenylethoxy) pyridine derivatives as potential ROS1 inhibitors

With the aim of discovering potential and selective inhibitors targeting ROS1 kinase, we rationally designed, synthesized and evaluated two series of novel 2-amino-pyridine derivatives with 1-phenylethoxy at C-3 and C-4 position. The enzymic assays results indicated that six of the new compounds 13b-13d and 14a-14c showed remarkably higher inhibitory activities against ROS1 kinase. The most promising compounds, 13d and 14c displayed the most desired ROS1 inhibitory activity with IC₅₀ values of 440 nM and 370 nM respectively. Furthermore, 13d and 14c displayed ROS1 inhibitory selectivity of about 7-fold and 12-fold, relative to that of ALK sharing about 49% amino acid sequence homology in the kinase domains. They also showed good anti-proliferative effects against ROS1-addicted HCC78 cell lines with the IC₅₀ values of 8.1 μM and 65.3 μM, respectively. Moreover, molecular docking and molecular dynamics simulation studies disclosed that compound 14c and 13d shared similar binding poses with Crizotinib except the selective binding site of ROS1. It also gave a probable molecular explanation for their activity and selectivity, which the methoxyl group in benzene ring was the crucial to the selectivity to ROS1 versus ALK.

Data driven polypharmacological drug design for lung cancer: analyses for targeting ALK, MET, and EGFR

Drug design of protein kinase inhibitors is now greatly enabled by thousands of publicly available X-ray structures, extensive ligand binding data, and optimized scaffolds coming off patent. The extensive data begin to enable design against a spectrum of targets (polypharmacology); however, the data also reveal heterogeneities of structure, subtleties of chemical interactions, and apparent inconsistencies between diverse data types. As a result, incorporation of all relevant data requires expert choices to combine computational and informatics methods, along with human insight. Here we consider polypharmacological targeting of protein kinases ALK, MET, and EGFR (and its drug resistant mutant T790M) in non small cell lung cancer as an example. Both EGFR and ALK represent sources of primary oncogenic lesions, while drug resistance arises from MET amplification and EGFR mutation. A drug which inhibits these targets will expand relevant patient populations and forestall drug resistance. Crizotinib co-targets ALK and MET. Analysis of the crystal structures reveals few shared interaction types, highlighting proton-arene and key CH–O hydrogen bonding interactions. These are not typically encoded into molecular mechanics force fields. Cheminformatics analyses of binding data show EGFR to be dissimilar to ALK and MET, but its structure shows how it may be co-targeted with the addition of a covalent trap. This suggests a strategy for the design of a focussed chemical library based on a pan-kinome scaffold. Tests of model compounds show these to be compatible with the goal of ALK, MET, and EGFR polypharmacology.

Synthesis of bis-spiropiperidines using nano-CuFe2O4@chitosan as a robust and retrievable heterogeneous catalyst

An efficient pseudo six-component synthesis of bis-spiropiperidines is described by one-pot condensation of formaldehyde, aromatic amine and dimedone or N,N-dimethyl-barbituric acid using nano-CuFe2O4@chitosan at room temperature. This method provides several advantages including mild reaction conditions, applicability to wide range of substrates, reusability of the catalyst and little catalyst loading.

Spirooxindole-derived morpholine-fused-1,2,3-triazoles: Design, synthesis, cytotoxicity and apoptosis inducing studies

A series of new spirooxindole-derived morpholine-fused-1,2,3-triazole derivatives has been synthesized from isatin spiro-epoxides. The protocol involves regiospecific isatin-epoxide ring opening with azide nucleophile followed by sequential O-propargylation, and intramolecular 1,3-dipolar cycloaddition reaction. These compounds have been evaluated for their antiproliferative activity against selected human tumor cell lines of lung (A549), breast (MCF-7), cervical (HeLa), and prostate (DU-145). Among the tested compounds, 6i, 6n and 6p showed potent growth inhibition against A549 cell line with IC50 values in the range of 1.87-4.36 μM, which are comparable to reference standards doxorubicin and 5-flourouracil. The compounds 6i and 6p treated A549 cells displayed typical apoptotic morphological features such as cell shrinkage, nuclear condensation, fragmentation, and decreased migration potential. Flow-cytometry analysis revealed that the compounds arrested the cells in G2/M phase of cell cycle. Hoechst and acridine orange/ethidium bromide staining studies also showed that the cell proliferation was inhibited through induction of apoptosis. Moreover, the compounds treatment led to collapse of the mitochondrial membrane potential (DΨm) and increased levels of reactive oxygen species (ROS) were noted in A549 cells.

Discovery and Biological Evaluation of Novel Dual EGFR/c-Met Inhibitors

Activating mutations in the epidermal growth factor receptor (EGFR) have been identified in a subset of non-small cell lung cancer (NSCLC), which is one of the leading cancer types worldwide. Application of EGFR tyrosine kinase inhibitors leads to acquired resistance by secondary EGFR mutations or by amplification of the hepatocyte growth factor receptor (c-Met) gene. Although several EGFR and c-Met inhibitors have been reported, potent dual EGFR/c-Met inhibitors, which can overcome this latter resistance mechanism, have hitherto not been published and have not reached clinical trials. In the present study we have identified dual EGFR/c-Met inhibitors and designed novel N-[4-(quinolin-4-yloxy)-phenyl]-biarylsulfonamide derivatives, which inhibit the c-Met receptor and both the wild-type and the activating mutant EGFR kinases in nanomolar range. We have demonstrated by Western blot analysis that compound 10 inhibits EGFR and c-Met phosphorylation at cellular level and effectively inhibits viability of the NSCLC cell lines.

Targeting receptor tyrosine kinase MET in cancer: small molecule inhibitors and clinical progress

The HGF/MET signaling pathway is critical in mediating a wide range of normal physiological functions including embryological development, wound healing, and tissue regeneration. Aberrant activation of the pathway has frequently been found in human cancers via protein overexpression, mutation, gene amplification, and also paracrine or autocrine up-regulation. In addition, the activation of HGF/MET signaling confers resistance to the effects of cancer treatments. Therefore, inhibition of the HGF/MET signaling pathway has great potential for therapeutic intervention in cancer. Currently, there are three approaches toward modulating HGF/MET signaling in human clinical studies of cancer: anti-HGF monoclonal antibodies, MET monoclonal antibodies, and small molecule MET inhibitors. Preliminary clinical benefit from inhibition of HGF or MET has been reported. This Perspective will provide an overview of the HGF/MET signaling pathway in cancer and then will review the development of small molecule MET inhibitors and their progress in clinical applications.