Discovery and evaluation of a novel monocyclic series of CXCR2 antagonists

Expanding role of CXCR2 and therapeutic potential of CXCR2 antagonists in inflammatory diseases and cancers

C-X-C motif chemokine receptor 2 (CXCR2) is G protein-coupled receptor (GPCR) and plays important roles in various inflammatory diseases and cancers, including chronic obstructive pulmonary disease (COPD), atherosclerosis, asthma, and pancreatic cancer. Upregulation of CXCR2 is closely associated with the migration of neutrophils and monocytes. To date, many small-molecule CXCR2 antagonists have entered clinical trials, showing favorable safety and therapeutic effects. Hence, we provide an overview containing the discovery history, protein structure, signaling pathways, biological functions, structure-activity relationships and clinical significance of CXCR2 antagonists in inflammatory diseases and cancers. According to the latest development and recent clinical progress of CXCR2 small molecule antagonists, we speculated that CXCR2 can be used as a biomarker and a new target for diabetes and that CXCR2 antagonists may also attenuate lung injury in coronavirus disease 2019 (COVID-19).

Exploration of Pyrido[3,4-d]pyrimidines as Antagonists of the Human Chemokine Receptor CXCR2

Upregulated CXCR2 signalling is found in numerous inflammatory, autoimmune and neurodegenerative diseases, as well as in cancer. Consequently, CXCR2 antagonism is a promising therapeutic strategy for treatment of these disorders. We previously identified, via scaffold hopping, a pyrido[3,4-d]pyrimidine analogue as a promising CXCR2 antagonist with an IC₅₀ value of 0.11 µM in a kinetic fluorescence-based calcium mobilization assay. This study aims at exploring the structure-activity relationship (SAR) and improving the CXCR2 antagonistic potency of this pyrido[3,4-d]pyrimidine via systematic structural modifications of the substitution pattern. Almost all new analogues completely lacked the CXCR2 antagonism, the exception being a 6-furanyl-pyrido[3,4-d]pyrimidine analogue (compound 17b) that is endowed with similar antagonistic potency as the original hit.

Novel benzimidazole-based pseudo-irreversible butyrylcholinesterase inhibitors with neuroprotective activity in an Alzheimer's disease mouse model

As levels of acetylcholinesterase (AChE) decrease while levels of butyrylcholinesterase (BChE) increase in later stages of Alzheimer's disease (AD), BChE stands out as a promising target for treatment of AD. Therefore, several benzimidazole-carbamates were designed based on docking studies to inhibit BChE selectively over AChE, while retaining a reasonable solubility. Synthesized molecules exhibit IC50 values from 2.4 μM down to 3.7 nM with an overall highly hBChE-selective profile of the designed compound class. After evaluation of potential neurotoxicity, the most promising compound was further investigated in vivo. Compound 11d attenuates Aβ25-35-induced learning impairments in both spontaneous alternation and passive avoidance responses at a very low dosage of 0.03 mg kg-1, proving selective BChE inhibition to lead to effective neuroprotectivity in AD.

Targeting chemokine receptors from the inside-out: discovery and development of small-molecule intracellular antagonists

Ever since the first biologically active chemokines were discovered in the late 1980s, these messenger proteins and their receptors have been the target for a plethora of drug discovery efforts in the pharmaceutical industry, as well as in academia. Owing to the publication of several chemokine receptor X-ray crystal structures, a highly druggable, intracellular, allosteric binding site which partially overlaps with the G protein binding site was discovered. This intriguing, new approach for chemokine receptor antagonism has captured researchers around the world, pushing the exploration of this intracellular binding site and new antagonists thereof. In this review, we have highlighted the past two decades of research on small-molecule chemokine receptor antagonists that modulate receptor function at the intracellular binding site.

Discovery of 1,5-Dihydro-4H-imidazol-4-one Derivatives as Potent, Selective Antagonists of CXC Chemokine Receptor 2

CXC chemokine receptors 1 (CXCR1) and 2 (CXCR2) have been demonstrated to have critical roles in cancer metastasis. Because they share high homology sequences, it is still unclear how to design selective CXCR1 or CXCR2 antagonists. Based on a pharmacophore model we built, compound 2 bearing a 1,5-dihydro-4H-imidazol-4-one scaffold was identified as a selective CXCR2 antagonist with a low CXCR1 antagonism preference. Further optimization and structure-activity relationship studies led to compound C5 that overcame the disadvantages of compound 2 and performed with higher selectivity. It showed excellent oral bioavailability and in vitro anticancer metastasis activity. Further dynamic simulation of the molecular protein complex showed that the amino acid residue K320 of CXCR2 contributed most to the selectivity of C5. This study provides important clues for the design of new CXCR2 selective antagonists, and C5 can be a molecular tool for investigating the difference in the biological function of CXCR1 and CXCR2.

Discovery and characterization of a neutralizing pan-ELR+CXC chemokine monoclonal antibody

CXCR1 and CXCR2 signaling play a critical role in neutrophil migration, angiogenesis, and tumorigenesis and are therefore an attractive signaling axis to target in a variety of indications. In human, a total of seven chemokines signal through these receptors and comprise the ELR⁺CXC chemokine family, so named because of the conserved ELRCXC N-terminal motif. To fully antagonize CXCR1 and CXCR2 signaling, an effective therapeutic should block either both receptors or all seven ligands, yet neither approach has been fully realized clinically. In this work, we describe the generation and characterization of LY3041658, a humanized monoclonal antibody that binds and neutralizes all seven human and cynomolgus monkey ELR⁺CXC chemokines and three of five mouse and rat ELR⁺CXC chemokines with high affinity. LY3041658 is able to block ELR⁺CXC chemokine-induced Ca²⁺ mobilization, CXCR2 internalization, and chemotaxis in vitro as well as neutrophil mobilization in vivo without affecting other neutrophil functions. In addition to the in vitro and in vivo activity, we characterized the epitope and structural basis for binding in detail through alanine scanning, crystallography, and mutagenesis. Together, these data provide a robust preclinical characterization of LY3041658 for which the efficacy and safety is being evaluated in human clinical trials for neutrophilic skin diseases.

Targeting CXCR1/2: The medicinal potential as cancer immunotherapy agents, antagonists research highlights and challenges ahead

Immune suppression in the tumor microenvironment (TME) is an intractable issue in anti-cancer immunotherapy. The chemokine receptors CXCR1 and CXCR2 recruit immune suppressive cells such as the myeloid derived suppressor cells (MDSCs) to the TME. Therefore, CXCR1/2 antagonists have aroused pharmaceutical interest in recent years. In this review, the medicinal chemistry of CXCR1/2 antagonists and their relevance in cancer immunotherapy have been summarized. The development of the drug candidates, along with their design rationale, clinical status and current challenges have also been discussed.

The synthesis of [(14) C]AZD5122. Incorporation of an IV (14) C-microtracer dose into a first in human study to determine the absolute oral bioavailability of AZD5122

AZD5122, N-(2-(2,3-difluorobenzylthio)-6-((2R,3R)-3,4-dihydroxybutan-2-ylamino)pyrimidin-4-yl)azetidine-1-sulfonamide was under investigation as a potential chemokine receptor CXCR2 antagonist for the treatment for inflammatory diseases. To gain a better understanding of the human pharmacokinetic profile, an exploratory phase I IV microtracer study was conducted using carbon-14 radiolabelled AZD5122. [(14) C]AZD5122 was carbon-14 labelled in the pyrimidine ring in five steps in an overall radiochemical yield of 19% from [(14) C]thiourea. The absolute oral bioavailability of AZD5122 was assessed in healthy subjects by an oral administration of AZD5122, followed by a concomitant intravenous [(14) C]AZD5122 microdose.

Discovery of CNS Penetrant CXCR2 Antagonists for the Potential Treatment of CNS Demyelinating Disorders

Structure-activity relationship exploration of the historical biarylurea series led to the identification of novel CNS penetrant CXCR2 antagonists with nanomolar potency, favorable PK profile, and good developability potentials. More importantly, the key compound 22 showed efficacy in a cuprizone-induced demyelination model with twice daily oral administration, thereby supporting CXCR2 to be a potential therapeutic target for the treatment of demyelinating diseases such as multiple sclerosis.