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.

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 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.

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.

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.

Structure-based drug discovery of novel fused-pyrazolone carboxamide derivatives as potent and selective AXL inhibitors.

As a novel and promising antitumor target, AXL plays an important role in tumor growth, metastasis, immunosuppression and drug resistance of various malignancies, which has attracted extensive research interest in recent years. In this study, by employing the structure-based drug design and bioisosterism strategies, we designed and synthesized in total 54 novel AXL inhibitors featuring a fused-pyrazolone carboxamide scaffold, of which up to 20 compounds exhibited excellent AXL kinase and BaF3/TEL-AXL cell viability inhibitions. Notably, compound 59 showed a desirable AXL kinase inhibitory activity (IC50: 3.5 nmol/L) as well as good kinase selectivity, and it effectively blocked the cellular AXL signaling. In turn, compound 59 could potently inhibit BaF3/TEL-AXL cell viability (IC50: 1.5 nmol/L) and significantly suppress GAS6/AXL-mediated cancer cell invasion, migration and wound healing at the nanomolar level. More importantly, compound 59 oral administration showed good pharmacokinetic profile and in vivo antitumor efficiency, in which we observed significant AXL phosphorylation suppression, and its antitumor efficacy at 20 mg/kg (qd) was comparable to that of BGB324 at 50 mg/kg (bid), the most advanced AXL inhibitor. Taken together, this work provided a valuable lead compound as a potential AXL inhibitor for the further antitumor drug development.

Structural Optimization of Fibroblast Growth Factor Receptor Inhibitors for Treating Solid Tumors.

Small-molecule fibroblast growth factor receptor (FGFR) inhibitors have emerged as a promising antitumor therapy. Herein, by further optimizing the lead compound 1 under the guidance of molecular docking, we obtained a series of novel covalent FGFR inhibitors. After careful structure-activity relationship analysis, several compounds were identified to exhibit strong FGFR inhibitory activity and relatively better physicochemical and pharmacokinetic properties compared with those of 1. Among them, 2e potently and selectively inhibited the kinase activity of FGFR1-3 wildtype and high-incidence FGFR2-N549H/K-resistant mutant kinase. Furthermore, it suppressed cellular FGFR signaling, exhibiting considerable antiproliferative activity in FGFR-aberrant cancer cell lines. In addition, the oral administration of 2e in the FGFR1-amplified H1581, FGFR2-amplified NCI-H716, and SNU-16 tumor xenograft models demonstrated potent antitumor efficacy, inducing tumor stasis or even tumor regression.

Discovery of 10H-Benzo[b]pyrido[2,3-e][1,4]oxazine AXL Inhibitors via Structure-Based Drug Design Targeting c-Met Kinase.

Receptor tyrosine kinase AXL exerts pivotal roles in cancer cell survival, metastasis, and drug resistance. Pharmacologic or genetic targeting of the aberrant AXL signaling has proven preferable antitumor efficacies in both preclinical and clinical studies, which highlights AXL as an attractive antitumor drug target. By conformational restriction of the anilinopyrimidine 10e and systematic structure-activity relationship (SAR) exploration, we discovered 10H-benzo[b]pyrido[2,3-e][1,4]oxazine 16j as a potent and orally bioavailable AXL inhibitor. As a type II AXL inhibitor, compound 16j displayed about 15-fold selectivity for AXL over its highly homologous kinase c-Met. And it significantly blocked cellular AXL signaling, inhibited AXL-mediated cell proliferation, and impaired growth arrest-specific protein 6 (Gas6)/AXL-stimulated cell migration and invasion. Moreover, 16j exhibited significant antitumor efficacy in AXL-driven xenograft model at a well-tolerant dosage, causing tumor stasis or regression.

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.

Discovery of 4-cyclopropyl-3-(2-((1-cyclopropyl-1H-pyrazol-4-yl) amino) quinazolin-6-yl)-N-(3-(trifluoromethyl) phenyl) benzamides as potent discoidin domain receptor inhibitors for the treatment of idiopathic pulmonary fibrosis.

Idiopathic pulmonary fibrosis (IPF) is a chronic fatal lung disease with a median survival time of 3-5 years. Inaccurate diagnosis, limited clinical therapy and high mortality together indicate that the development of effective therapeutics for IPF is an urgent need. In recent years, it was reported that DDRs are potential targets in anti-fibrosis treatment. Based on previous work we carried out further structure modifications and led to a more selective inhibitor 47 by averting some fibrosis-unrelated kinases, such as RET, AXL and ALK. Extensive profiling of compound 47 has demonstrated that it has potent DDR1/2 inhibitory activities, low toxicity, good pharmacokinetic properties and reliable in vivo anti-fibrosis efficacy. Therefore, we confirmed that discoidin domain receptors are promising drug targets for IPF, and compound 47 would be a promising candidate for further drug development.

The Novel RET Inhibitor SYHA1815 Inhibits RET-Driven Cancers and Overcomes Gatekeeper Mutations by Inducing G1 Cell-Cycle Arrest through c-Myc Downregulation.

Rearranged during transfection (RET), an oncogenic driver, has been found in multiple tumor types and is thus a promising anticancer therapeutic target. Novel selective RET inhibitors (RETi) that can overcome V804 gatekeeper mutations, endowing resistance to multikinase inhibitors (MKI) and, in particular, achieving KDR selectivity, are needed. In addition, the mechanisms underlying RET-inhibition-induced antiproliferative effects in the context of RET addiction are incompletely understood. This study describes a novel selective RETi, SYHA1815, which inhibited the kinase activity of RET wild type and V804 mutant with an IC50 in the subnanomolar to nanomolar range. Notably, SYHA1815 exhibited approximately 20-fold selectivity for RET over KDR, almost equivalent to that of the launched selective inhibitor pralsetinib. SYHA1815 had only a marginal inhibitory effect on cellular KDR signaling at a high (200 nmol/L) concentration, confirming the selectivity over KDR. In addition, SYHA1815 exhibited a favorable selectivity profile, with greater than 100-fold selectivity for RET over 347 other kinases. It exhibited potent antitumor efficacy and overcame V804 mutations in vitro and in vivo by targeting RET. Then, using SYHA1815 as a probe, we found that RET inhibition suppressed RET-driven cell proliferation via G1 cell-cycle arrest through downregulating c-Myc. Furthermore, disruption of c-Myc upon Brd4 inhibitor treatment led to G1 cell-cycle arrest and overrode RET-driven cell proliferation. Moreover, consistent with the marked in vivo efficacy of RET inhibition, the intratumoral c-Myc level was significantly decreased. In summary, SYHA1815 is a promising RETi for RET-aberrant cancer treatment that is currently in a phase I trial.

Discovery of pyrrolo[2,3-d]pyrimidine derivatives as potent Axl inhibitors: Design, synthesis and biological evaluation.

Axl has emerged as an attractive target for cancer therapy due to its strong correlation with tumor growth, metastasis, poor survival, and drug resistance. Herein, we report the design, synthesis and structure-activity relationship (SAR) investigation of a series of pyrrolo[2,3-d]pyrimidine derivatives as new Axl inhibitors. Among them, the most promising compound 13b showed high enzymatic and cellular Axl potencies. Furthermore, 13b possessed preferable pharmacokinetic properties and displayed promising therapeutic effect in BaF3/TEL-Axl xenograft tumor model. Compound 13b may serve as a lead compound for new antitumor drug discovery.

Discovery of a Pyrimidinedione Derivative as a Potent and Orally Bioavailable Axl Inhibitor.

The receptor tyrosine kinase Axl plays important roles in promoting cancer progression, metastasis, and drug resistance and has been identified as a promising target for anticancer therapeutics. We used molecular modeling-assisted structural optimization starting with the low micromolar potency compound 9 to discover compound 13c, a highly potent and orally bioavailable Axl inhibitor. Selectivity profiling showed that 13c could inhibit the well-known oncogenic kinase Met with equal potency to its inhibition of Axl superfamily kinases. Compound 13c significantly inhibited cellular Axl and Met signaling, suppressed Axl- and Met-driven cell proliferation, and restrained Gas6/Axl-mediated cancer cell migration or invasion. Furthermore, 13c exhibited significant antitumor efficacy in Axl-driven and Met-driven tumor xenograft models, causing tumor stasis or regression at well-tolerated doses. All these favorable data make 13c a promising therapeutic candidate for cancer treatment.

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.

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.

Preclinical evaluation of 3D185, a novel potent inhibitor of FGFR1/2/3 and CSF-1R, in FGFR-dependent and macrophage-dominant cancer models.

BACKGROUND: The interaction between tumor cells and their immunosuppressive microenvironment promotes tumor progression and drug resistance. Thus, simultaneously targeting tumor cells and stromal cells is expected to have synergistic antitumor effects. Herein, we present for the first time a preclinical antitumor investigation of 3D185, a novel dual inhibitor targeting FGFRs, which are oncogenic drivers, and CSF-1R, which is the major survival factor for protumor macrophages. METHODS: The antitumor characteristics of 3D185 were assessed by a range of assays, including kinase profiling, cell viability, cell migration, immunoblotting, CD8+ T cell suppression, and in vivo antitumor efficacy, followed by flow cytometric and immunohistochemical analyses of tumor-infiltrating immune cells and endothelial cells in nude mice and immune-competent mice. RESULTS: 3D185 significantly inhibited the kinase activity of FGFR1/2/3 and CSF-1R, with equal potency and high selectivity over other kinases. 3D185 suppressed FGFR signaling and tumor cell growth in FGFR-driven models both in vitro and in vivo. In addition, 3D185 could inhibit the survival and M2-like polarization of macrophages, reversing the immunosuppressive effect of macrophages on CD8+ T cells as well as CSF1-differentiated macrophage induced-FGFR3-aberrant cancer cell migration. Furthermore, 3D185 inhibited tumor growth via remodeling the tumor microenvironment in TAM-dominated tumor models. CONCLUSIONS: 3D185 is a promising antitumor candidate drug that simultaneously targets tumor cells and their immunosuppressive microenvironment and has therapeutic potential due to synergistic effects. Our study provides a solid foundation for the investigation of 3D185 in cancer patients, particularly in patients with aberrant FGFR and abundant macrophages, who respond poorly to classic pan-FGFRi treatment.

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.

Discovery and optimization of a series of 3-substituted indazole derivatives as multi-target kinase inhibitors for the treatment of lung squamous cell carcinoma.

Although lung adenocarcinoma patients have benefited from the development of targeted therapy, patients with lung squamous cell carcinoma (SqCC) have no effective treatment due to the complexity and heterogeneity of the disease. Therefore, basing on the genetic analysis of mutations in lung squamous cell carcinoma to design multi-target inhibitors represents a potential strategy for the medical treatment. In this study, through screening an in-house focused library, we identified an interesting indazole scaffold. And following with binding analysis, we elaborated the structure-activity relationship of this hit compound by optimizing four parts guided by the DDR2 enzymatic assay, which resulted in a potent lead compound 10a. We conducted further optimization of dual enzymatic inhibitions towards FGFR1 and DDR2, two important kinases in lung squamous cell carcinoma. Finally, from the cellular antiproliferative activity tests and in vivo pharmacokinetic test, 3-substituted indazole derivative 11k was found to be a promising candidate and subjected to in vivo pharmacology study with the mouse xenograft models, demonstrating profound anti-tumor efficacy. Additional in vitro druglike assessment reinforced that compound 11k could be valuable for SqCC drug development.