Design, synthesis, and structure-activity-relationship of a novel series of CXCR4 antagonists

Discovery of novel CXCR4 inhibitors for the treatment of inflammation by virtual screening and biological evaluation

C-X-C chemokine receptor type 4 (CXCR4) exerts considerable influence on the pathogenesis of inflammatory disorders and offers a potent avenue for drug intervention. This research utilizes a hybrid virtual screening methodology constructed using computer-aided drug design to discover novel CXCR4 inhibitors for the treatment of inflammation. First, a compound library was screened by Lipinski's five rules and adsorption, distribution, metabolism, excretion and toxicity properties. Second, the HypoGen algorithm was used in constructing a 3D-QSAR pharmacophore model and verify it layer by layer, and the obtained optimal pharmacophore 1 (Hypo 1) was used as a 3D query for compound screening. Then, hit compounds were obtained through molecular docking (Libdock and CDOCKER). The toxicity of the compounds to MDA-MB-231 cells was evaluated in vitro, and their binding affinity to the target was evaluated according to how they compete with 12G5 antibody for CXCR4 on the surfaces of the MDA-MB-231 cells. Compound Hit14 showed the strongest binding affinity among the hit compounds and inhibited cell migration and invasion in Matrigel invasion and wound healing assay at a concentration of 100 nM, demonstrating a better effect than AMD3100. Western Blot experiments further showed that Hit14 blocked the CXCR4/CXCL12-mediated phosphorylation of Akt. Meanwhile, cellular thermal displacement assay analysis showed that CXCR4 protein bound to Hit14 had high thermal stability. Finally, through in vivo experiments, we found that Hit14 inhibited mouse ear inflammation and reduced ear swelling and damage. Therefore, Hit14 is a promising drug for the further development of CXCR4 inhibitors for inflammation treatment.

Development and therapeutic perspectives of CXCR4 antagonists for disease therapy

Chemokine receptor 4 (CXCR4) is a subtype receptor protein of the GPCR family with a seven-transmembrane structure widely distributed in human tissues. CXCR4 is involved in diseases (e.g., HIV-1 infection), cancer proliferation and metastasis, inflammation signaling pathways, and leukemia, making it a promising drug target. Clinical trials on CXCR4 antagonists mainly focused on peptides and antibodies, with a few small molecule compounds, such as AMD11070 (2) and MSX-122 (3), showing promise in cancer treatment. This perspective discusses the structure-activity relationship (SAR) of CXCR4 and its role in diseases, mainly focusing on the SAR of CXCR4 antagonists. It also explores the standard structural features and target interactions of CXCR4 binding in different disease categories. Furthermore, it investigates various modification strategies to propose potential improvements in the effectiveness of CXCR4 drugs.

Polar Heterobenzylic C(sp3)-H Chlorination Pathway Enabling Efficient Diversification of Aromatic Nitrogen Heterocycles

Site-selective radical reactions of benzylic C-H bonds are now highly effective methods for C(sp3-H) functionalization and cross-coupling. The existing methods, however, are often ineffective with heterobenzylic C-H bonds in alkyl-substituted pyridines and related aromatic heterocycles that are prominently featured in pharmaceuticals and agrochemicals. Here, we report new synthetic methods that leverage polar, rather than radical, reaction pathways to enable the selective heterobenzylic C-H chlorination of 2- and 4-alkyl-substituted pyridines and other heterocycles. Catalytic activation of the substrate with trifluoromethanesulfonyl chloride promotes the formation of enamine tautomers that react readily with electrophilic chlorination reagents. The resulting heterobenzyl chlorides can be used without isolation or purification in nucleophilic coupling reactions. This chlorination-diversification sequence provides an efficient strategy to achieve heterobenzylic C-H cross-coupling with aliphatic amines and a diverse collection of azoles, among other coupling partners.

Synthesis and Anti-HIV Activity of a Novel Series of Isoquinoline-Based CXCR4 Antagonists

An expansion of the structure–activity relationship study of CXCR4 antagonists led to the synthesis of a series of isoquinolines, bearing a tetrahydroquinoline or a 3-methylpyridinyl moiety as head group. All compounds were investigated for CXCR4 affinity and antagonism in competition binding and calcium mobilization assays, respectively. In addition, the anti-HIV activity of all analogues was determined. All compounds showed excellent activity, with compound 24c being the most promising one, since it displayed consistently low nanomolar activity in the various assays.

A highly selective and potent CXCR4 antagonist for hepatocellular carcinoma treatment

The CXC chemokine receptor type 4 (CXCR4) receptor and its ligand, CXCL12, are overexpressed in various cancers and mediate tumor progression and hypoxia-mediated resistance to cancer therapy. While CXCR4 antagonists have potential anticancer effects when combined with conventional anticancer drugs, their poor potency against CXCL12/CXCR4 downstream signaling pathways and systemic toxicity had precluded clinical application. Herein, BPRCX807, known as a safe, selective, and potent CXCR4 antagonist, has been designed and experimentally realized. In in vitro and in vivo hepatocellular carcinoma mouse models it can significantly suppress primary tumor growth, prevent distant metastasis/cell migration, reduce angiogenesis, and normalize the immunosuppressive tumor microenvironment by reducing tumor-associated macrophages (TAMs) infiltration, reprogramming TAMs toward an immunostimulatory phenotype and promoting cytotoxic T cell infiltration into tumor. Although BPRCX807 treatment alone prolongs overall survival as effectively as both marketed sorafenib and anti-PD-1, it could synergize with either of them in combination therapy to further extend life expectancy and suppress distant metastasis more significantly.

Microtiter plate-based antibody-competition assay to determine binding affinities and plasma/blood stability of CXCR4 ligands

C-X-C chemokine receptor type 4 (CXCR4) is involved in several intractable disease processes, including HIV infection, cancer cell metastasis, leukemia cell progression, rheumatoid arthritis, asthma and pulmonary fibrosis. Thus, CXCR4 represents a promising drug target and several CXCR4 antagonizing agents are in preclinical or clinical development. Important parameters in drug lead evaluation are determination of binding affinities to the receptor and assessment of their stability and activity in plasma or blood of animals and humans. Here, we designed a microtiter plate-based CXCR4 antibody competition assay that enables to measure inhibitory concentrations (IC₅₀ values) and affinity constants (K_i values) of CXCR4 targeting drugs. The assay is based on the observation that most if not all CXCR4 antagonists compete with binding of the fluorescence-tagged CXCR4 antibody 12G5 to the receptor. We demonstrate that this antibody-competition assay allows a convenient and cheap determination of binding affinities of various CXCR4 antagonists in living cells within just 3 h. Moreover, the assay can be performed in the presence of high concentrations of physiologically relevant body fluids, and thus is a useful readout to evaluate stability (i.e. half-life) of CXCR4 ligands in serum/plasma, and even whole human and mouse blood ex vivo. Thus, this optimized 12G5 antibody-competition assay allows a robust and convenient determination and calculation of various important pharmacological parameters of CXCR4 receptor-drug interaction and may not only foster future drug development but also animal welfare by reducing the number of experimental animals.

Design, synthesis, and evaluation of pyrrolidine based CXCR4 antagonists with in vivo anti-tumor metastatic activity

The chemokine receptor CXCR4 has been proposed as a drug target based on its important functions in HIV infection, inflammation/autoimmune diseases and cancer metastasis. Herein we report the design, synthesis and evaluation of novel CXCR4 antagonists based on a pyrrolidine scaffold. The structural exploration/optimization identified numerous potent CXCR4 antagonists, represented by compound 46, which displayed potent binding affinity to CXCR4 receptor (IC₅₀ = 79 nM competitively displacing fluorescent 12G5 antibody) and inhibited CXCL12 induced cytosolic calcium flux (IC₅₀ = 0.25 nM). Moreover, in a transwell invasion assay, compound 46 significantly mitigated CXCL12/CXCR4 mediated cell migration. Compound 46 exhibited good physicochemical properties (MW 367, logD_7.4 1.12, pKa 8.2) and excellent in vitro safety profiles (e.g., hERG patch clamp IC₅₀ > 30 μM and minimal CYP isozyme inhibition). Importantly, 46 displayed much improved metabolic stability in human and rat liver microsomes. Lastly, 46 demonstrated marked efficacy in a cancer metastasis model in mice. These results strongly support 46 as a prototypical lead for the development of promising CXCR4 antagonists as clinical candidates.

Design, Synthesis, and Characterization of Novel CXCR4 Antagonists Featuring Cyclic Amines

Chemokine receptor CXCR4 and its natural ligand CXCL12 (also known as stromal cell-derived factor-1, or SDF-1) regulate a broad range of physiological functions. Dysregulation of the CXCL12/CXCR4 axis is involved in numerous pathological conditions such as HIV infection, inflammation and cancer. Herein, we report the design, synthesis, and characterization of novel CXCR4 antagonists based on cyclic amine scaffolds. Compound 24 was identified as a potent CXCR4 receptor antagonist (competitive inhibition of 12G5 binding, IC₅₀ =24 nM; functional inhibition of CXCL12-induced cytosolic calcium increase, IC₅₀ =0.1 nM). In addition, compound 24 potently inhibited cell migration in CXCR4/CXCL12-mediated chemotaxis in a matrigel invasion assay. The absolute configuration of compound 24 was elucidated by X-ray crystallography.

Design, synthesis, and evaluation of novel CXCR4 antagonists based on an aminoquinoline template

The chemokine receptor CXCR4 has been explored as a drug target due to its involvement in pathological conditions such as HIV infection and cancer metastasis. Here we report the structure-activity relationship study of novel CXCR4 antagonists based on an aminoquinoline template. This template is devoid of the chiral center in the classical tetrahydroquinoline (THQ) ring moiety and therefore can be easily synthesized. A number of potent CXCR4 antagonists were identified, exemplified by compound 3, which demonstrated excellent binding affinity with CXCR4 receptor (IC₅₀ = 57 nM) and inhibited CXCL12 induced cytosolic calcium increase (IC₅₀ = 0.24 nM). Furthermore, compound 3 potently inhibited CXLC12/CXCR4 mediated cell migration in a transwell invasion assay. The simplified synthetic approach combined with good physicochemical properties (e.g. MW 362, clogP 2.1, PSA 48, pKa 7.0 for compound 3) demonstrate the potential of this aminoquinoline template as a novel scaffold to develop CXCR4 antagonists.

Identification of Synthetic Activators of Cancer Cell Migration by Hybrid Deep Learning

Deep convolutional neural networks (CNNs) are a method of choice for image recognition. Herein a hybrid CNN approach is presented for molecular pattern recognition in drug discovery. Using self-organizing map images of molecular pharmacophores as input, CNN models were trained to identify chemokine receptor CXCR4 modulators with high accuracy. This machine learning classifier identified first-in-class synthetic CXCR4 full agonists. The receptor-activating effects were confirmed by intracellular cAMP response and in a phenotypic spheroid invasion assay of medulloblastoma cell invasion. Additional macromolecular targets of the small molecules were predicted in silico and tested in vitro, revealing modulatory effects on dopamine receptors and CCR1. These results positively advocate the applicability of molecular image recognition by CNNs to ligand-based virtual compound screening, and demonstrate the complementarity of machine intelligence and human expert knowledge.

Amide-sulfamide modulators as effective anti-tumor metastatic agents targeting CXCR4/CXCL12 axis

Breast cancer is the most frequently diagnosed malignancy and the second common cause of death in women worldwide. High mortality in breast cancer is frequently associated with metastatic progression rather than the primary tumor itself. It has been recently identified that the CXCR4/CXCL12 axis plays a pivotal role in breast cancer metastasis, especially in directing metastatic cancer cells to CXCL12-riched organs and tissues. Herein, taking the amide-sulfamide as the lead structure, the second-round structural modifications to the sulfamide structure were performed to obtain more active CXCR4 modulators against tumor metastasis. Both in vivo and in vitro experiments illustrated that compound IIIe possessed potent CXCR4 binding affinity, excellent anti-metastatic and anti-angiogenetic activity against breast cancer. More importantly, in a mouse breast cancer lung metastasis model, compound IIIe exerted a significant inhibitory effect on breast cancer metastasis. Taken together, all these positive results demonstrated that developing of CXCR4 modulators is a promising strategy to mediate breast cancer metastasis.

Design, synthesis and biological study of hybrid drug candidates of nitric oxide releasing cucurbitacin-inspired estrone analogs for treatment of hepatocellular carcinoma

Development of hybrid drug candidates is well known strategy for designing antitumor agents. Herein, a novel class of nitric oxide donating cucurbitacin inspired estrone analogs (NO-CIEAs) were designed and synthesized as multitarget agents. Synthesized analogs were initially evaluated for their anti-hepatocellular carcinoma activities. Among the tested analogs, NO-CIEAs 17 and 20a exhibited more potent activity against HepG2 cells (IC₅₀ = 4.69 and 12.5 µM, respectively) than the reference drug Erlotinib (IC₅₀ = 25 µM). Interestingly, NO-CIEA 17 exerted also a high potent activity against Erlotinib-resistant HepG2 cell line (HepG2-R) (IC₅₀ = 8.21 µM) giving insight about its importance in drug resistance therapy. Intracellular measurements of NO revealed that NO-CIEAs 17 and 20a showed a significant increase in NO production in tumor cells after 1 h of incubation comparable to the reference prodrug JS-K. Flow cytometric analysis showed that both NO-CIEAs 17 and 20a mainly arrested the HepG2 cells in the G0/G1 phase. Also, In-Cell Based ELISA screening showed that NO-CIEA 17 resulted in a potential inhibitory activity towards the EGFR and MAPK (25% and 29% inhibition compared to untreated control cells, respectively). This data suggests the binding ability of NO-CIEA 17 to the EGFR and ERK to be well correlated along with the docking and cellular studies. Also, treatment of HepG2-R cells with NO-CIEA 17 showed a potential reduction of MRP2 expression in a dose dependent manner providing a significant impact on the chemotherapeutic resistance. Overall, the current study provides a potential new approach for the discovery of a novel antitumor agent against HCC.