Discovery and optimization of 3-(indolin-5-yloxy)pyridin-2-amine derivatives as potent necroptosis inhibitors.

Necroptosis is a form of regulated necrotic cell death and has been confirmed to play pivotal roles in the pathogenesis of multiple autoimmune diseases such as rheumatoid arthritis (RA) and psoriasis. The development of necroptosis inhibitors may offer a promising therapeutic strategy for the treatment of these autoimmune diseases. Herein, starting from the in-house hit compound 1, we systematically performed structural optimization to discover potent necroptosis inhibitors with good pharmacokinetic profiles. The resulting compound 33 was a potent necroptosis inhibitor for both human I2.1 cells (IC50 < 0.2 nM) and murine Hepa1-6 cells (IC50 < 5 nM). Further target identification revealed that compound 33 was an inhibitor of receptor interacting protein kinase 1 (RIPK1) with favorable selectivity. In addition, compound 33 also exhibited favorable pharmacokinetic profiles (T1/2 = 1.32 h, AUC = 1157 ng·h/mL) in Sprague-Dawley rats. Molecular docking and molecular dynamics simulations confirmed that compound 33 could bind to RIPK1 with high affinity. In silico ADMET analysis demonstrated that compound 33 possesses good drug-likeness profiles. Collectively, compound 33 is a promising candidate for antinecroptotic drug discovery.

Design, synthesis and biological evaluation of 4-aminoquinoline derivatives as receptor-interacting protein kinase 2 (RIPK2) inhibitors.

Receptor-interacting protein kinase 2 (RIPK2) is an essential protein kinase mediating signal transduction by NOD1 and NOD2, which play an important role in regulating immune signalling. In this study, we designed and synthesised a novel series of 4-aminoquinoline-based derivatives as RIPK2 inhibitors. In vitro, compound 14 exhibited high affinity (IC50 = 5.1 ± 1.6 nM) and excellent selectivity to RIPK2 showing in a dendrogram view of the human kinome phylogenetic tree. Bearing favourable lipophilicity and eligible lipophilic ligand efficiency (LipE), compound 14 was selected to investigate cellular anti-inflammatory effect and was identified as a potent inhibitor to reduce the secretion of MDP-induced TNF-α with a dose-dependent manner. Moreover, compound 14 showed moderate stability in human liver microsome. Given these promising results, compound 14 could serve as a favourable inhibitor of RIPK2 for further physiological and biochemical research so as to be used in therapeutic treatment.

DW14383 is an irreversible pan-FGFR inhibitor that suppresses FGFR-dependent tumor growth in vitro and in vivo.

Fibroblast growth factor receptor (FGFR) is a promising anticancer target. Currently, most FGFR inhibitors lack sufficient selectivity and have nonnegligible activity against kinase insert domain receptor (KDR), limiting their feasibility due to the serious side effects. Notably, compensatory activation occurs among FGFR1-4, suggesting the urgent need to develop selective pan-FGFR1-4 inhibitors. Here, we explored the antitumor activity of DW14383, a novel irreversible FGFR1-4 inhibitor. DW14383 exhibited equivalently high potent inhibition against FGFR1, 2, 3 and 4, with IC50 values of less than 0.3, 1.1, less than 0.3, and 0.5 nmol/L, respectively. It is a selective FGFR inhibitor, exhibiting more than 1100-fold selectivity for FGFR1 over recombinant KDR, making it one of the most selective FGFR inhibitors over KDR described to date. Furthermore, DW14383 significantly inhibited cellular FGFR1-4 signaling, inducing G1/S cell cycle arrest, which in turn antagonized FGFR-dependent tumor cell proliferation. In contrast, DW14383 had no obvious antiproliferative effect against cancer cell lines without FGFR aberration, further confirming its selectivity against FGFR. In representative FGFR-dependent xenograft models, DW14383 oral administration substantially suppressed tumor growth by simultaneously inhibiting tumor proliferation and angiogenesis via inhibiting FGFR signaling. In summary, DW14383 is a promising selective irreversible pan-FGFR inhibitor with pan-tumor spectrum potential in FGFR1-4 aberrant cancers, which has the potential to overcome compensatory activation among FGFR1-4.

SAF-189s, a potent new-generation ROS1 inhibitor, is active against crizotinib-resistant ROS1 mutant-driven tumors.

The ROS1 fusion kinase is an attractive antitumor target. Though with significant clinical efficacy, the well-known first-generation ROS1 inhibitor (ROS1i) crizotinib inevitably developed acquired resistance due to secondary point mutations in the ROS1 kinase. Novel ROS1is effective against mutations conferring secondary crizotinib resistance, especially G2032R, are urgently needed. In the present study, we evaluated the antitumor efficacy of SAF-189s, the new-generation ROS1/ALK inhibitor, against ROS1 fusion wild-type and crizotinib-resistant mutants. We showed that SAF-189s potently inhibited ROS1 kinase and its known acquired clinically resistant mutants, including the highly resistant G2032R mutant. SAF-189s displayed subnanomolar to nanomolar IC50 values against ROS1 wild-type and mutant kinase activity and a selectivity vs. other 288 protein kinases tested. SAF-189s blocked cellular ROS1 signaling, and in turn potently inhibited the cell proliferation in HCC78 cells and BaF3 cells expressing ROS1 fusion wild-type and resistance mutants. In nude mice bearing BaF3/CD74-ROS1 or BaF3/CD74-ROS1G2032R xenografts, oral administration of SAF-189s dose dependently suppressed the growth of both ROS1 wild-type- and G2032R mutant-driven tumors. In a patient-derived xenograft model of SDC4-ROS1 fusion NSCLC, oral administration of SAF-189s (20 mg/kg every day) induced tumor regression and exhibited notable prolonged and durable efficacy. In addition, SAF-189s was more potent than crizotinib and comparable to lorlatinib, the most advanced ROS1i known against the ROS1G2032R. Collectively, these results suggest the promising potential of SAF-189s for the treatment of patients with the ROS1 fusion G2032R mutation who relapse on crizotinib. It is now recruiting both crizotinib-relapsed and naive ROS1-positive NSCLC patients in a multicenter phase II trial (ClinicalTrials.gov Identifier: NCT04237805).

Synthesis of triazolotriazine derivatives as c-Met inhibitors.

Receptor tyrosine kinase c-Met is an important antitumor drug target. Triazolotriazine analogues 2-10 were prepared efficiently and evaluated the enzymatic and cellular c-Met activities. Brief structure-activity relationships of triazolotriazine core and CF2-quinoline part were investigated, leading to the discovery of compound 8 with nanomolar enzymatic c-Met activity, and subnanomolar MKN45 and EBC-1 cellular potencies. The proposed binding model of 8 and c-Met unraveled that two canonical hydrogen bonds and a π-π stacking interaction formed between the inhibitor and the ATP binding site of c-Met kinase domain, which accounted for its potent c-Met activities.

Discovery of a potent tyrosine kinase AXL inhibitor bearing the 3-((2,3,4,5-tetrahydro-1H-benzo[d]azepin-7-yl)amino)pyrazine core.

Starting from the recently launched FLT3/AXL multi-targeted inhibitor Gilteritinib (5), we conducted a side-chain ring closure medicinal chemistry approach leading to the identification of compound 15c as a highly potent AXL inhibitor in the biochemical and cellular anti-proliferative assays, with IC50 values of 1.2 and 0.3 nM, respectively. Compared with the reference compound 5, our new discovered AXL inhibitor 15c is more potent in both assays.

Synthesis and structure-activity relationship study of pyrazolo[3,4-d]pyrimidines as tyrosine kinase RET inhibitors.

Three series of pyrazolo[3,4-d]pyrimidine derivatives were synthesized and evaluated as RET kinase inhibitors. Compounds 23a and 23c were identified to show significant activity both in the biochemical and the BaF3/CCDC6-RET cell assays. Compound 23c was found to significantly inhibit RET phosphorylation and down-stream signaling in BaF3/CCDC6-RET cells, confirming its potent cellular RET-targeting profile. Different from other RET inhibitors with equal potency against KDR that associated with severe toxicity, 23c did not show significant KDR-inhibition even at the concentration of 1µM. These results demonstrated that 23c is a potent and selective RET inhibitor.

Design, synthesis and biological evaluation of c-Met kinase inhibitors bearing 2-oxo-1,2-dihydroquinoline scaffold.

A series of 2-oxo-1,2-dihydroquinoline-containing c-Met inhibitors were designed, synthesized and evaluated for their in vitro activities targeting c-Met. Most compounds showed high potency against c-Met with IC50 values in the single-digit nM range. Among these compounds, two target compounds, namely 1h and 1n, stood out as the most potent c-Met inhibitors with IC50s of 0.6 and 0.7nM, respectively. And 1a exhibited higher potency than BMS-777607 did with respect to the inhibition of cell proliferation. The introduction of electron-donating substituent was favorable for the activities of the compounds to some extent. Furthermore, molecular docking studies also gave encouraging results that supported this work.

Metabolism-based structure optimization: Discovery of a potent and orally available tyrosine kinase ALK inhibitor bearing the tetracyclic benzo[b]carbazolone core.

A metabolism-based fine-tuning structure-optimization was conducted to address the oxidative metabolism and hERG blockade of our early ALK inhibitor. Compound 8 was identified showing high potency against both ALK wild type and gatekeeper mutant. In addition to the optimal PK properties and significant cell antiproliferative effects, 8 showed complete tumor growth inhibition at doses of 50 or 10mg/kg once daily in the Karpas299 xenograft model. All these results encouraged the further development of 8 as a potent and orally bioavailable ALK inhibitor.

Discovery of a new series of imidazo[1,2-a]pyridine compounds as selective c-Met inhibitors.

AIM: Aberrant c-Met activation plays a critical role in cancer formation, progression and dissemination, as well as in development of resistance to anticancer drugs. Therefore, c-Met has emerged as an attractive target for cancer therapy. The aim of this study was to develop new c-Met inhibitors and elaborate the structure-activity relationships of identified inhibitors. METHODS: Based on the predicted binding modes of Compounds 5 and 14 in docking studies, a new series of c-Met inhibitor-harboring 3-((1H-pyrrolo[3,2-c]pyridin-1-yl)sulfonyl)imidazo[1,2-a]pyridine scaffolds was discovered. Potent inhibitors were identified through extensive optimizations combined with enzymatic and cellular assays. A promising compound was further investigated in regard to its selectivity, its effects on c-Met signaling, cell proliferation and cell scattering in vitro. RESULTS: The most potent Compound 31 inhibited c-Met kinase activity with an IC50 value of 12.8 nmol/L, which was >78-fold higher than those of a panel of 16 different tyrosine kinases. Compound 31 (8, 40, 200 nmol/L) dose-dependently inhibited the phosphorylation of c-Met and its key downstream Akt and ERK signaling cascades in c-Met aberrant human EBC-1 cancer cells. In 12 human cancer cell lines harboring different background levels of c-Met expression/activation, Compound 31 potently inhibited c-Met-driven cell proliferation. Furthermore, Compound 31 dose-dependently impaired c-Met-mediated cell scattering of MDCK cells. CONCLUSION: This series of c-Met inhibitors is a promising lead for development of novel anticancer drugs.

Discovery and SAR study of c-Met kinase inhibitors bearing an 3-amino-benzo[d]isoxazole or 3-aminoindazole scaffold.

A series of 3-amino-benzo[d]isoxazole-/3-aminoindazole-based compounds were designed, synthesized and pharmacologically evaluated as tyrosine kinase c-Met inhibitors. The SAR study was conducted leading to identification of nine compounds (8d, 8e, 12, 28a-d, 28h and 28i) with IC50s less than 10nM against c-Met. Compound 28a stood out as the most potent c-Met inhibitor displaying potent inhibitory effects both at enzymatic (IC50=1.8 nM) and cellular (IC50=0.18 µM on EBC-1 cells) levels. In addition, 28a had a relatively good selectivity compared to a panel of our in-house 14 RTKs.

SOMG-833, a novel selective c-MET inhibitor, blocks c-MET-dependent neoplastic effects and exerts antitumor activity.

The hepatocyte growth factor/c-MET signaling axis plays an important role in tumor cell proliferation, metastasis, and tumor angiogenesis, and therefore presents as an attractive target for cancer therapy. Notably, most small-molecule c-MET inhibitors currently undergoing clinical trials are multitarget inhibitors with the unwanted inhibition of additional kinases, often accounting for undesirable toxicity. Here, we discovered SOMG-833 [3-(4-methylpiperazin-1-yl)-5-(3-nitrobenzylamino)-7-(trifluoromethyl) quinoline] as a potent and selective small-molecule c-MET inhibitor, with an average IC50 of 0.93 nM against c-MET, over 10,000-fold more potent compared with 19 tyrosine kinases, including c-MET family members and highly homologous kinases. SOMG-833 strongly suppressed c-MET-mediated signaling transduction regardless of mechanistic complexity implicated in c-MET activation, including MET gene amplification, MET gene fusion, and HGF-stimulated c-MET activation. In a panel of 24 human cancer or genetically engineered model cell lines, SOMG-833 potently inhibited c-MET-driven cell proliferation, whereas cancer cells lacking c-MET activation were markedly less sensitive (at least 15-fold) to the treatment. SOMG-833 also suppressed c-MET-mediated migration, invasion, urokinase activity, and invasive growth phenotype. In addition, inhibition of primary human umbilical vascular endothelial cell (HUVEC) proliferation and downregulation of plasma proangiogenic factor interleukin-8 secretion resulted from SOMG-833 treatment, suggesting its significant antiangiogenic properties. Together, these results led to the remarkable antitumor efficacy of SOMG-833 in vivo, as demonstrated in c-MET-dependent NIH-3T3/TPR-MET, U-87MG, and EBC-1 xenograft models. Collectively, our results suggested SOMG-833 as a promising candidate for highly selective c-MET inhibition and a powerful tool to investigate the sole role of MET kinase in cancer.

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.

Design, synthesis, and structure-activity relationship studies of 6,7-dihydro-5H-pyrrolo[1,2-b][1,2,4]triazole derivatives as necroptosis inhibitors.

The development of necroptosis inhibitors has emerged as a promising strategy to effectively mitigate necroptosis-related inflammatory diseases, neurodegenerative diseases, and cancers. In this paper, we reported a series of 6,7-dihydro-5H-pyrrolo[1,2-b][1,2,4]triazole derivatives as potent necroptosis inhibitors. The representative compound 26 displayed potent anti-necroptotic activity in both human and mouse cellular assays and exhibited potent inhibitory activity against receptor-interacting protein kinase 1 (RIPK1). In vivo pharmacokinetic studies were performed to determine the oral exposure of compound 26. Finally, molecular docking elucidated that compound 26 could effectively bind to the allosteric pocket of RIPK1 and serve as a type III inhibitor. Taken together, our findings highlighted that compound 26 represented a promising lead compound for future necroptosis inhibitor development.

Discovery of a 1,6-naphthyridin-4-one-based AXL inhibitor with improved pharmacokinetics and enhanced in vivo antitumor efficacy.

The receptor tyrosine kinase AXL has emerged as an attractive target in anticancer drug discovery. Herein, we described the discovery of a new series of 1,6-naphthyridin-4-one derivatives as potent AXL inhibitors. Starting from a low in vivo potency compound 9 which was previously reported by our group, we utilized structure-based drug design and scaffold hopping strategies to discover potent AXL inhibitors. The privileged compound 13c was a highly potent and orally bioavailable AXL inhibitor with an IC50 value of 3.2 ± 0.3 nM. Compound 13c exhibited significantly improved in vivo antitumor efficacy in AXL-driven tumor xenograft mice, causing tumor regression at well-tolerated dose, and demonstrated favorable pharmacokinetic properties (MRT = 16.5 h, AUC0-∞ = 59,815 ng h/mL) in Sprague-Dawley rats. These results suggest that 13c is a promising therapeutic candidate for AXL-targeting cancer treatment.

Remodeling tumor-associated macrophage for anti-cancer effects by rational design of irreversible inhibition of mitogen-activated protein kinase-activated protein kinase 2.

Mitogen-activated protein kinase-activated protein kinase 2 (MK2) emerges as a pivotal target in developing anti-cancer therapies. The limitations of ATP-competitive inhibitors, due to insufficient potency and selectivity, underscore the urgent need for a covalent irreversible MK2 inhibitor. Our initial analyses of The Cancer Genome Atlas database revealed MK2's overexpression across various cancer types, especially those characterized by inflammation, linking it to poor prognosis and highlighting its significance. Investigating MK2's kinase domain led to the identification of a unique cysteine residue, enabling the creation of targeted covalent inhibitors. Compound 11 was developed, demonstrating robust MK2 inhibition (IC50 = 2.3 nM) and high selectivity. It binds irreversibly to MK2, achieving prolonged signal suppression and reducing pathological inflammatory cytokines in macrophages. Furthermore, compound 11 or MK2 knockdown can inhibit the tumor-promoting macrophage M2 phenotype in vitro and in vivo. In macrophage-rich tumor model, compound 11 notably slowed growth in a dose-dependent manner. These findings support MK2 as a promising anticancer target, especially relevant in cancers fueled by inflammation or dominated by macrophages, and provide compound 11 serving as an invaluable chemical tool for exploring MK2's functions.

Discovery, Optimization, and Evaluation of Novel Pyridin-2(1H)-one Analogues as Potent TRK Inhibitors for Cancer Treatment.

Tropomyosin receptor kinase (TRK) fusion, an oncogenic form of kinase with pan-tumor occurrence, is a clinically validated important antitumor target. In this study, we screened our in-house kinase inhibitor library against TRK and identified a promising hit compound 4 with a novel pyridin-2(1H)-one scaffold. Through a combination of structure-based drug design and structure-activity relationship (SAR) study, compound 14q was identified as a potent TRK inhibitor with good kinase selectivity. It also blocked cellular TRK signaling, thereby inhibiting TRK-dependent cell viability. Additionally, 14q displayed acceptable pharmacokinetic properties with 37.8% oral bioavailability in mice. Strong in vivo tumor growth inhibition of 14q was observed in subcutaneous M091 and KM12 tumor xenograft models with TRK fusion, causing significant tumor inhibition or even complete tumor regression.

Novel 5-(benzyloxy)pyridin-2(1H)-one derivatives as potent c-Met inhibitors.

A series of novel 5-(benzyloxy)pyridin-2(1H)-ones were designed, synthesized and biologically evaluated for c-Met inhibition. Various amides and benzoimidazoles at C-3 position were investigated. A potent compound 12b with a c-Met IC50 of 12nM was identified. This compound exhibited potent inhibition of EBC-1 cell associated with c-Met constitutive activation and showed high selectivity for c-Met than other tested 11 kinases. The binding model 12b with c-Met was disclosed by docking analysis.

Investigation on the 1,6-naphthyridine motif: discovery and SAR study of 1H-imidazo[4,5-h][1,6]naphthyridin-2(3H)-one-based c-Met kinase inhibitors.

The 1,6-naphthyridine motif is a multivalent scaffold in medicinal chemistry presenting various bioactivities when properly substituted. By incorporating a cyclic urea pharmacophore into the 1,6-naphthyridine framework through conformationally constraining the 7,8-positions, the resulting 1H-imidazo[4,5-h][1,6]naphthyridin-2(3H)-one was identified as a new class of c-Met kinase inhibitor. A comprehensive SAR study indicated that an N-1 alkyl substituent bearing a terminal free amino group, a hydrophobic substituted benzyl group at the N-3 position and the tricyclic core were essential for retaining effective Met inhibition of the 1H-imidazo[4,5-h][1,6]naphthyridin-2(3H)-one chemotype. Further introduction of a 4'-carboxamide phenoxy group at the C-5 position significantly improved the potency. The best c-Met kinase inhibitory activity was exemplified by 2t with an IC(50) = 2.6 µM, which also displayed effective inhibition against TPR-Met phosphorylation and the proliferation of the BaF3-TPR-Met cells at low micromolar concentrations.