Novel imidazo[1,2-a]pyridine derivatives as potent ATX allosteric inhibitors: Design, synthesis and promising in vivo anti-fibrotic efficacy in mice lung model.

Aiming to develop novel allosteric autotaxin (ATX) inhibitors, hybrid strategy was utilized by assembling the benzyl carbamate fragment in PF-8380 onto the imidazo[1,2-a]pyridine skeleton of GLPG-1690. The piperazine moiety in GLPG-1690 was replaced with phenyl ring to enhance the π-π interactions with adjacent residues. In the light of FS-3 based ATX enzymatic assay, further structure-guided optimizations were implemented by exploring the substituents within the carbamate aromatic moiety and examining the effect of the 2-ethyl. Eventually, 13c bearing 1,3-benzodioxole and 2-hydroxyethyl piperazine group was identified as a powerful ATX inhibitor with an IC50 value of 2.7 nM. Subsequently, 13c was forwarded into an in vivo bleomycin-induced mice lung fibrosis model. In histopathological and immunohistochemical assays, 13c could typically alleviate the severity of fibrosis tissues and effectively reduce the deposition of fibrotic biomarker α-SMA. At a dose of 60 mg/kg, 13c was observed equivalent or even better potency than GLPG-1690 with a significant inhibition of the in vivo ATX activity. Except for the fundamental H-bond and π-π interactions, an extra H-bond between the 1,3-benzodioxole (O atom) and Phe306 offered great rationale in constraining the binding conformation of 13c. Finally, binding free energy calculation was conducted to assist in the efficient identification of allosteric ATX inhibitors.

Hybrid imidazo[1,2-a]pyridine analogs as potent ATX inhibitors with concrete in vivo antifibrosis effect.

In recent years, small-molecule inhibitors targeting the autotaxin (ATX)/lysophosphatidic acid axis gradually brought excellent disease management benefits. Herein, a series of imidazo[1,2-a]pyridine compounds (1-11) were designed as ATX inhibitors through a hybrid strategy by combining the imidazo[1,2-a]pyridine skeleton in GLPG1690 and the benzyl carbamate moiety in PF-8380. As indicated by FS-3-based enzymatic assay, the carbamate derivatives revealed moderate to satisfying ATX inhibitory potency (IC50 = 23-343 nM). Subsequently, the carbamate linker was altered to a urea moiety (12-19) with the aim of retaining ATX inhibition and improving the druglikeness profile. The binding mode analysis all over the modification process well rationalized the leading activity of urea derivatives in an enzymatic assay. Following further structural optimization, the diethanolamine derivative 19 exerted an amazing inhibitory activity (IC50 = 3.98 nM) similar to the positive control GLPG1690 (IC50 = 3.72 nM) and PF-8380 (IC50 = 4.23 nM). Accordingly, 19 was tested directly for in vivo antifibrotic effects through a bleomycin model (H&E staining), in which 19 effectively alleviated lung structural damage and fibrosis at an oral dose of 20 and 60 mg/kg. Collectively, 19 qualified as a promising ATX inhibitor for potential application in fibrosis-relevant disease treatment.

An update on allosteric modulators as a promising strategy targeting histone methyltransferase.

Histone methylation is a vital post-translational modification process in epigenetic regulation. The perturbation of histone methylation accounts for many diseases, including malignant cancers. Although achieving significant advances over past decades, orthosteric inhibitors targeting histone methyltransferases still suffer from challenges on subtype selectivity and acquired drug-resistant mutations. As an alternative, new compounds targeting the evolutionarily less conserved allosteric sites, exemplified by HKMTs and PRMTs inhibitors, offer a promising strategy to address this quandary. Herein, we highlight the allosteric sites and mechanisms in histone methyltransferases along with representative allosteric modulators, expecting to facilitate the discovery of allosteric modulators in favor of epigenetic therapy.

Design, synthesis and anti-fibrosis evaluation of imidazo[1,2-a]pyridine derivatives as potent ATX inhibitors.

A series of imidazo[1,2-a]pyridine compounds bearing urea moiety (8-27) were designed, synthesized and evaluated for their ATX inhibitory activities in vitro by FS-3 based enzymatic assay. Delightfully, benzylamine derivatives (14-27) exhibited higher ATX inhibitory potency with IC50 value ranging from 1.72 to 497 nM superior to benzamide analogues (8-13). Remarkably, benzylamine derivative 20 bearing 4-hydroxypiperidine exerted an amazing inhibitory activity (IC50 = 1.72 nM) which exceeded the positive control GLPG1690 (IC50 = 2.90 nM). Simultaneously, the binding model of 20 with ATX was established which rationalized the well performance of 20 in enzymatic assay. Accordingly, further in vivo studies were carried out to evaluate direct anti-fibrotic effects of 20 through Masson staining. Notably, 20 effectively alleviated lung structural damage with fewer fibrotic lesions at an oral dose of 60 mg/kg, qualifying 20 as a promising ATX inhibitor for IPF treatment.

Structure-based linker exploration: Discovery of 1-ethyl-1H-indole analogs as novel ATX inhibitors.

Aiming to develop novel ATX inhibitors, an indole-3-carboxylic acid lead Indole-1 was identified through high-throughput screening (HTS) efforts. The Indole-1 analogs 1-7 was firstly prepared which exerted mild activity comparable to Indole-1 (740 nM) in ATX enzyme assay. Further structural modification to identify type IV ATX inhibitors was proceeded through derivatization of the indole-3-carboxylic acid group. Resultantly, compounds 8-17 containing acyl hydrazone linker displayed poor activity (over 3.49 µM). Alternatively, replacing the acylhydrazone linker with urea counterpart by the amide bond reversal principle, the acquired compounds 18-22 achieved obvious improvements with submicromolar activities. Furthermore, with the aim to reducing cLogP, the thiazole ring of 18-22 was altered to the benzamide (23-32) with the urea linker unchanged. Remarkably, the benzamide derivative 24 with 4-hydroxy piperidine fragment was identified which exhibited prominent activity with IC50 value of 2.3 nM. Especially, dedicated molecular docking study was throughout the modification process which qualified 24 as optimal entity in accordance with the ATX inhibitory results.

An exploration of solvent-front region high affinity moiety leading to novel potent ALK & ROS1 dual inhibitors with mutant-combating effects.

The pyrimidine-2,4-diamine analogs exerted excellent activities in down-regulation of ALK phosphorylation. However, the prevalent drug-resistant site-mutation has gradually prevented the agents from being widely used. Herein, we conducted an exploration of high affinity moiety that bound to the solvent-front region (G1202R located) within the ATP binding site of ALK leading to the synthesis of thirty-five pyrimidine-2,4-diamine derivatives. Among these compounds, urea group was extensively derivatized which finally resulted in the identification of the 'semi-free urea' compound 39. All compounds were assayed cytotoxicity and enzymatic activities and 39 turned out to be the most potent one with IC50 values of 2.1, 0.91, 4.3 and 0.73 nM towards ALKwt, ALKL1196M, ALKG1202R and ROS1, respectively. The performances of 39 on ALK- & ROS1-dependent cell lines were in good accordance with enzymatic activities with IC50 values below 0.06 µM. Besides, 39 induced cell apoptosis in a dose-dependent manner in H2228 cells. Finally, the binding models of 39 with ALKwt, ROS1, ALKL1196M and ALKG1202R were ideally established which further clearly elucidated their mode of action within the active site.

Discovery and optimization of tetrahydropyrido[4,3-d]pyrimidine derivatives as novel ATX and EGFR dual inhibitors.

In order to discovery autotaxin (ATX) and EGFR dual inhibitors with potential therapeutic effect on IPF-LC, a series of novel tetrahydropyrido[4,3-d]pyrimidine derivatives possessing semicarbazones moiety were designed and synthesized. The preliminary investigation at the cellular level indicated six compounds (7h, 8a, 8c, 8d, 9a and 9d) displayed preferable anti-tumor activities against A549, H1975, MKN-45 and SGC cancer cells. Further enzymatic assay against EGFR kinase identified 8a and 9a as promising hits with IC50 values of 18.0 nM and 24.2 nM. Meanwhile, anti-inflammatory assessment against cardiac fibroblasts (CFs) cell and RAW264.7 macrophages led to the discovery of candidate 9a, which exhibited considerable potency both on inhibition rate of 77% towards CFs and on reducing NO production to 1.05 µM at 10 µg/mL. Simultaneously, 9a indicated preferable potency towards ATX with IC50 value of 29.1 nM. Significantly, a RT-PCR study revealed the function of 9a to down-regulate the mRNA expression of TGF-ß and TNF-α in a dose-dependent manner. The molecular docking analysis together with the pharmacological studies validated 9a as a potential ATX and EGFR dual inhibitor for IPF-LC treatments.

Design, Synthesis, and Biological Evaluation of 4-Phenoxyquinoline Derivatives Containing Benzo[d]thiazole-2-yl Urea as c-Met Kinase Inhibitors.

A series of novel 4-phenoxyquinoline derivatives containing the benzo[d]thiazole-2-yl urea moiety were synthesized and evaluated for their cytotoxicity against the HT-29, MKN-45, and H460 cell lines. The structures of the target compounds were confirmed by (1) H NMR and MS spectra. Most of them showed moderate to excellent potency against the three tested cell lines. Especially, compound 23 was identified a promising agent (c-Met IC50 = 17.6 nM), showing the most potent anticancer activities with IC50 values of 0.18, 0.06, and 0.01 µM against the HT-29, MKN-45, and H460 cell lines, respectively. The docking results of 23 with the c-Met kinase model 3LQ8 showed a specific binding mode between the ligand and the target protein.

Recent advances and challenges of revolutionizing drug-resistant tuberculosis treatment.

Tuberculosis (TB), an infectious disease induced by Mycobacterium tuberculosis, is one of the primary public health threats all over the world. Since the prevalence of first-line anti-TB agents, the morbidity and mortality issues of TB descended obviously. Nevertheless, the emergences of multidrug-resistant (MDR) and extensively drug-resistant (XDR) strains, the double prevalence of HIV-TB co-infection, and the insufficiency of plentiful health care have led to an increased incidence of TB. It is noted that current drugs for treating TB have proved unsustainable in the face of highly resistant strains. Fortunately, five categories of new drugs and candidates with new mechanisms of action have emerged in the field of anti-TB research after decades of stagnation in the progression of anti-TB drugs. In this paper, the research status of these promising anti-TB drugs and candidates are reviewed, emphasizing the challenges to be addressed for efficient development of future TB therapies.

Precise engineering of disulfide bond-bridged prodrug nanoassemblies to balance antitumor efficacy and safety.

Prodrug-based nanoassemblies, which combine the merits of prodrug technology and nanocarriers, are regarded as promising platforms for cancer treatment. Notably, the chemical structure of prodrugs is closely associated with antitumor efficacy and safety, and the intrinsic relationships among them need further exploration. Herein, paclitaxel was conjugated with 2-octyldodecan-1-ol through different positions of disulfide bond to construct the prodrug nanoassemblies. Interestingly, the minor differences in chemical structure not only dominated the assembly performance and drug release of nanoassemblies, but also significantly impacted the pharmacokinetics, antitumor efficacy, and safety. It was worth noting that prodrug nanoassemblies with one carbon atom between disulfide bond and ester bond had faster drug release and better antitumor effect, while prodrug nanoassemblies with three carbon atoms between disulfide bond and ester bond possessed moderate antitumor effect and better safety. Our findings illustrated the structure-function relationships of self-assembled prodrugs and provided a promising paradigm for the precise engineering of advanced prodrug nanoplatforms. STATEMENT OF SIGNIFICANCE: 1. The major effects of minor differences in prodrug chemical structure on pharmacodynamics and safety were explored, which had important clinical reference significance and value. 2. The in-depth exploration of structure-function relationships to balance efficacy and safety had important guiding significance for the design of prodrug nanoassemblies.

Structural and PK-guided identification of indole-based non-acidic autotaxin (ATX) inhibitors exhibiting high in vivo anti-fibrosis efficacy in rodent model.

In recent decades, pharmacological targeting of the autotaxin (ATX)/lysophosphatidic acid (LPA) axis accounted for excellent disease management benefits. Herein, to extend the scope of structure-activity relationships (SARs), fifteen indole-based carbamate derivatives (1-15) were prepared to evaluate the ATX inhibitory potency. Among them, compound 4 bearing morpholine moiety was identified as the optimal ATX inhibitor (0.41 nM), superior to the positive control GLPG1690 (2.90 nM). To resolve the intractable issue of poor pharmacokinetic (PK) property, urea moiety was introduced as a surrogate of carbamate which furnished compounds 16-30. The dedicated modification identified the diethanolamine entity 30 with satisfactory water solubility and PK profiles with a minimum sacrifice of ATX inhibition (2.17 nM). The most promising candidate 30 was evaluated for anti-fibrosis effect in a bleomycin challenged mice lung fibrosis model. Upon treatment with 30, the in vivo ATX activity in both lung homogenate and broncheoalveolar fluid (BALF) sample was significantly down-regulated. Furthermore, the gene expression of pro-fibrotic cytokines transforming growth factor-ß (TGF-ß), interleukin- 6 (IL-6) and tumor necrosis factor-α (TNF-α) in lung tissue was reduced to normal level. Collectively, the promising biological effects may advocate potential application of 30 in fibrosis relevant diseases.

Design, synthesis and promising anti-tumor efficacy of novel imidazo[1,2-a]pyridine derivatives as potent autotaxin allosteric inhibitors.

Aiming to track the potential antitumor effect of novel allosteric autotaxin (ATX) inhibitors, a hybrid strategy was utilized by merging ATX inhibitors PF-8380 and GLPG1690, while the piperazinyl group in GLPG1690 was replaced with benzene ring to furnish imidazo[1,2-a]pyridine derivatives 10ã10k. Based on ATX enzymatic assay, we further changed the substituents within benzyl carbamate moiety and tuned the carbamate linker to urea group. Delightfully, compound 10c bearing a N-hydroxyethyl piperazinyl group was identified as the optimal ATX inhibitor with an IC50 value of 3.4 nM 10c exerted the most impressive antitumor effects, especially on Hep3B (0.58 µM) and RAW264.7 (0.63 µM) cell lines highly expressing ATX mRNA. Moreover, 10c could dose-dependently suppress the RAW264.7 cell migration rate in wound healing assay and significantly inhibit RAW264.7 cell colony formation. Meanwhile, 10c was capable of inducing weak to moderate apoptosis and achieved notable G2 phase arrest on RAW264.7 cells. Taken together, 10c may serve as a novel lead to probe possible role of ATX allosteric inhibitors in tumor diseases.

An updated patent review of autotaxin inhibitors (2017-present).

INTRODUCTION: The ATX-LPA axis is an attractive target for therapeutic intervention in a variety of diseases, such as tumor metastasis, fibrosis, pruritus, multiple sclerosis, inflammation, autoimmune conditions, metabolic syndrome, and so on. Accordingly, considerable efforts have been devoted to the development of new chemical entities capable of modulating the ATX-LPA axis. AREAS COVERED: This review aims to provide an overview of novel ATX inhibitors reported in patents from September 2016 to August 2020, discussing their structural characteristics and inhibitory potency in vitro and in vivo. EXPERT OPINION: In the past four years, the classification of ATX inhibitors based on binding modes has brought great benefits to the discovery of more efficacious inhibitors. In addition to GLPG1690 currently in phase III clinical studies for IPF, BBT-877, and BLD-0409 as potent ATX inhibitors have been enrolled in phase I clinical evaluation; meanwhile, many effective molecules were also reported successively. However, most emerging ATX inhibitors in the last four years are closely analogs of previous entities, such as GLPG1690 and PF-8380, which translate into the urgently identification of ATX inhibitors with diverse structural features and promising properties in the near future.

Structure guided design of potent indole-based ATX inhibitors bearing hydrazone moiety with tumor suppression effects.

ATX was capable of catalyzing the hydrolysis of LPC to the lipid mediator LPA which attracted considerable attention on the development of potent ATX inhibitors. Herein, driven by the HTS product indole-based lead 1, a hybridization strategy was utilized to construct the trifluoroacetyl hydrazone moiety through assembling the phenyl thiazole fragment to the indole skeleton of lead 1. After a systematic structure guided optimization, by cycling the phenyl thiazole to the compacted benzothiazole or decreasing the lipophilicity, two promising ATX inhibitors (9j and 25a) were identified with IC50 values of 2.1 nM and 19.0 nM, respectively. All compounds were tested a panel of cancer cell lines and a preliminary affinity on breast cancer cell lines (SI > 16.5) were observed which shed a light on their potential application of breast cancer relevant cases. Through a dedicated docking study, the intramolecular pseudo-ring within the trifluoroacetylhydrazone moiety played a significant role in constraining the binding poses of 9j and 25a. Finally, a binding free energy calculation was conducted to examine the contribution of different interactions in binding affinity.

Optimization and evaluation of novel tetrahydropyrido[4,3-d]pyrimidine derivatives as ATX inhibitors for cardiac and hepatic fibrosis.

Aiming to develop potent autotaxin (ATX) inhibitors for fibrosis diseases, a novel series of tetrahydropyrido[4,3-d]pyrimidine derivatives was designed and synthesized based on our previous study. The enzymatic assay combined with anti-proliferative activities against cardiac fibroblasts (CFs) and hepatic stellate cell (HSC) in vitro were applied for preliminary evaluation of anti-fibrosis potency of target compounds, resulting in two outstanding ATX inhibitors 8b and 10g with the IC50 values in a nanomolar range (24.6 and 15.3 nM). Differently, 8b was the most prominent compound against CFs with inhibition ratio of 81.5%, while 10g exhibited the maximum inhibition ratio of 83.7% against t-HSC/Cl-6 cells. In the further pharmacological evaluations in vivo, collagen deposition assay demonstrated the conspicuous capacity of 8b to suppress TGF-ß-mediated cardiac fibrosis. Simultaneously, H&E and Masson stains assays of mice liver validated 10g as an excellent anti-hepatofibrosis candidate, which reduced CCl4-induced hepatic fibrosis level prominently. Besides, the molecular binding models identified the essential interactions between 8b and ATX which was coincided with the SARs.

Discovery of Novel Indole-Based Allosteric Highly Potent ATX Inhibitors with Great In Vivo Efficacy in a Mouse Lung Fibrosis Model.

Autotaxin (ATX) is the dominant catalytic enzyme accounting for the lipid mediator lysophosphatidic acid (LPA) through hydrolysis of lysophosphatidylcholine (LPC). There is great interest in developing nonacidic ATX inhibitors with a specific binding mode to serve as potential in vivo effective therapeutic tools. Herein, dating from a high-throughput screening (HTS) product Indole-1 (740 nM), a dedicated optimization campaign was implemented through derivatizing the -COOH group to versatile linkers that well-bridged the indole skeleton and the hydrophobic pocket binding groups. Ultimately, it was established that the coexistence of a carbamate linker and -OH-group-containing amines could generally furnish excellent indole-based ATX inhibitors with even below 1 nM in vitro activities. Two optimal entities were advanced to a bleomycin-induced mice pulmonary fibrosis model, which exerted promising efficacy in alleviating the damaged lung texture caused by bleomycin exposure. The novel carbamate-containing indole-based ATX inhibitors with a concrete binding mode may contribute to the identification of potential therapeutic agents to intervene in fibrotic diseases.

Discovery of novel mutant-combating ALK and ROS1 dual inhibitors bearing imidazolidin-2-one moiety with reasonable PK properties.

Aiming to identify novel potent ALK and ROS1 dual inhibitors, the relatively bulky piperidine fragment in ceritinib was replaced with substituted imidazolidin-2-one moiety which gave rise to a series of 2,4-diaryl-aminopyrimidine (DAAP) analogs (6-33). SAR studies were conducted based on cellular assays on five cell lines and most compounds exerted moderated to excellent activities. Among them, 15 showed excellent inhibitory activities against ROS1 and ALK positive cell lines, especially Ba/F3G1202R, with IC50 values ranging from 14 to 37 nM. As a continuation, several compounds were tested in enzymatic assays and 15 displayed encouraging activities against wild-type ALK (1.2 nM), ROS1(0.43 nM) as well as extremely resistant ALKL1196M and ALKG1202R mutants with IC50 values of 0.73 nM and 6.7 nM, respectively. To our delight, both cellular and enzymatic results of 15 were in good accordance with western blot assays on H2228 and HCC78 cell lines. Importantly, pharmacokinetic (PK) profiles of 15 were obtained with quite satisfying AUC and Cmax values. Besides, the binding models of 15 with ALKWT, ALKG1202R and ROS1 clearly present the essential interactions within the active site.

Design, synthesis and biological evaluation of novel 4-arylaminopyrimidine derivatives possessing a hydrazone moiety as dual inhibitors of L1196M ALK and ROS1.

A series of 4-arylaminopyrimidine derivatives possessing a hydrazone moiety were designed, synthesized and evaluated for their biological activity. Most compounds exhibited moderate to excellent cytotoxic activity against ALK-addicted KARPAS299 and ROS1-addicted HCC78, while also showing much less potent activity against A549, H460 and HT-29, whose growth were not dependent on ALK and/or ROS1, as compared with crizotinib and ceritinib. The most promising compound, 7b, showed high antiproliferative effects on ALK-addicted KARPAS299 and ROS1-addicted HCC78 cell lines with IC50 of 20 nM and 28 nM, respectively, but showed no inhibitory activity against A549, H460 and HT-29. The enzymatic assay identified 7b as a potent and selective ALK and ROS1 dual inhibitor with IC50 of 2.5 nM and 2.7 nM, respectively. It also exhibited good inhibitory activity against the L1196M ALK with an IC50 value of 67 nM.