Pharmacological properties of revefenacin (TD-4208), a novel, nebulized long-acting, and lung selective muscarinic antagonist, at human recombinant muscarinic receptors and in rat, guinea pig, and human isolated airway tissues.

Revefenacin (TD-4208) is a novel, long-acting, and lung-selective muscarinic cholinergic receptor (mAChR) antagonist in development as a nebulized inhalation solution for the treatment of chronic obstructive pulmonary disease (COPD) patients. This study evaluated the pharmacology of revefenacin at human recombinant mAChRs and in airway tissues from rats, guinea pigs, and humans. At human recombinant mAChRs, revefenacin displayed high affinity (pKI = 8.2-9.8) and behaved as a competitive antagonist (pKI, apparent = 9.4-10.9) at the five human recombinant mAChRs. Kinetic studies demonstrated that revefenacin dissociated significantly slower from the hM3 (t1/2 = 82 minutes) compared to the hM 2 (t1/2 = 6.9 minutes) mAChR at 37°C, thereby making it kinetically selective for the former subtype. Similarly, in functional studies, revefenacin-mediated antagonism of acetylcholine (ACh)-evoked calcium mobilization responses were reversed less rapidly at hM3 compared to the hM2 mAChR. In isolated tracheal tissues from rat and guinea pig and isolated bronchial tissues from humans, revefenacin potently antagonized mAChR-mediated contractile responses. Furthermore, the antagonistic effects of revefenacin in rat, guinea pig, and human airway tissues were slowly reversible (t1/2 of 13.3, >16, and >10 hours, respectively). These data demonstrate that revefenacin is a potent, high affinity, and selective functional mAChR antagonist with kinetic selectivity for the hM3 receptor and produces potent and long-lasting antagonism of mAChR-mediated contractile responses in rat, guinea pig, and human airway tissue. These data suggest that revefenacin has the potential to be a potent once-daily dosed inhaled bronchodilator in COPD patients.

TLR2 agonism reverses chemotherapy-induced neutropenia in Macaca fascicularis.

Neutropenia is a common consequence of radiation and chemotherapy in cancer patients. The resulting immunocompromised patients become highly susceptible to potentially life-threatening infections. Granulocyte colony-stimulating factor (G-CSF) is known to stimulate neutrophil production and is widely used as a treatment of chemotherapy-induced neutropenia. A small-molecule G-CSF secretagogue without a requirement for refrigerated supply chain would offer a more convenient and cost-effective treatment of chemotherapy-induced neutropenia. Bacterial lipopeptides activate innate immune responses through Toll-like receptor 2 (TLR2) and induce the release of cytokines, including G-CSF, from macrophages, monocytes, and endothelial. Pam2CSK4 is a synthetic lipopeptide that effectively mimics bacterial lipoproteins known to activate TLR2 receptor signaling through the TLR2/6 heterodimer. Substrate-based drug design led to the discovery of GSK3277329, which stimulated the release of G-CSF in activated THP-1 cells, peripheral blood mononuclear cells, and human umbilical vein endothelial cells. When administered subcutaneously to cynomolgus monkeys (Macaca fascicularis), GSK3277329 caused systemic elevation of G-CSF and interleukin-6 (IL-6), but not IL-1ß or tumor necrosis factor α, indicating a selective cytokine-stimulation profile. Repeat daily injections of GSK3277329 in healthy monkeys also raised circulating neutrophils above the normal range over a 1-week treatment period. More importantly, repeated daily injections of GSK3277329 over a 2-week period restored neutrophil loss in monkeys given chemotherapy treatment (cyclophosphamide, Cytoxan). These data demonstrate preclinical in vivo proof of concept that TLR2 agonism can drive both G-CSF induction and subsequent neutrophil elevation in the cynomolgus monkey and could be a therapeutic strategy for the treatment of chemotherapy-induced neutropenia.

Pharmacological characterization of GSK573719 (umeclidinium): a novel, long-acting, inhaled antagonist of the muscarinic cholinergic receptors for treatment of pulmonary diseases.

Activation of muscarinic subtype 3 (M3) muscarinic cholinergic receptors (mAChRs) increases airway tone, whereas its blockade improves lung function and quality of life in patients with pulmonary diseases. The present study evaluated the pharmacological properties of a novel mAChR antagonist, GSK573719 (4-[hydroxy(diphenyl)methyl]-1-{2-[(phenylmethyl)oxy]ethyl}-1-azoniabicyclo[2.2.2]octane; umeclidinium). The affinity (Ki) of GSK573719 for the cloned human M1-M5 mAChRs ranged from 0.05 to 0.16 nM. Dissociation of [(3)H]GSK573719 from the M3 mAChR was slower than that for the M2 mAChR [half-life (t1/2) values: 82 and 9 minutes, respectively]. In Chinese hamster ovary cells transfected with recombinant human M3 mAChRs, GSK573719 demonstrated picomolar potency (-log pA2 = 23.9 pM) in an acetylcholine (Ach)-mediated Ca(2+) mobilization assay. Concentration-response curves indicate competitive antagonism with partial reversibility after drug washout. Using isolated human bronchial strips, GSK573719 was also potent and showed competitive antagonism (-log pA2 = 316 pM) versus carbachol, and was slowly reversible in a concentration-dependent manner (1-100 nM). The time to 50% restoration of contraction at 10 nM was about 381 minutes (versus 413 minutes for tiotropium bromide). In mice, the ED50 value was 0.02 µg/mouse intranasally. In conscious guinea pigs, intratracheal administration of GSK573719 dose dependently blocked Ach-induced bronchoconstriction with long duration of action, and was comparable to tiotropium; 2.5 µg elicited 50% bronchoprotection for >24 hours. Thus, GSK573719 is a potent anticholinergic agent that demonstrates slow functional reversibility at the human M3 mAChR and long duration of action in animal models. This pharmacological profile translated into a 24-hour duration of bronchodilation in vivo, which suggested umeclidinium will be a once-daily inhaled treatment of pulmonary diseases.

Tyrosine urea muscarinic acetylcholine receptor antagonists: achiral quaternary ammonium groups.

Tyrosine ureas had been identified as potent muscarinic receptor antagonists with promising in vivo activity. Controlling the stereochemistry of the chiral quaternary ammonium center had proved to be a serious issue for this series, however. Herein we describe the preparation and SAR of tyrosine urea antagonists containing achiral quaternary ammonium centers. The most successful such moiety was the 2-methylimidazo[2,1-b][1,3]thiazol-7-ium group which yielded highly potent antagonists with long duration of action in an inhaled animal model of bronchoconstriction.

Design, synthesis and structure-activity relationship of N-substituted tropane muscarinic acetylcholine receptor antagonists.

A novel series of N-substituted tropane derivatives was characterized as potent muscarinic acetylcholine receptor antagonists (mAChRs). Kinetic washout studies showed that the N-endosubstituted analog 24 displayed much slower reversibility at mAChRs than the methyl-substituted parent molecule darotropium. In addition, it was shown that this characteristic appeared to translate into enhanced which duration of action in a mouse model of bronchonstriction.

2' biaryl amides as novel and subtype selective M1 agonists. Part I: Identification, synthesis, and initial SAR.

Biaryl amides were discovered as novel and subtype selective M(1) muscarinic acetylcholine receptor agonists. The identification, synthesis, and initial structure-activity relationships that led to compounds 3j and 4c, possessing good M(1) agonist potency and intrinsic activity, and subtype selectivity for M(1) over M(2-5), are described.

Discovery of (3-endo)-3-(2-cyano-2,2-diphenylethyl)-8,8-dimethyl-8-azoniabicyclo[3.2.1]octane bromide as an efficacious inhaled muscarinic acetylcholine receptor antagonist for the treatment of COPD.

Design and syntheses of a novel series of muscarinic antagonists are reported. These efforts have culminated in the discovery of (3-endo)-3-(2-cyano-2,2-diphenylethyl)-8,8-dimethyl-8-azoniabicyclo[3.2.1]octane bromide (4a) as a potent and pan-active muscarinic antagonist as well as a functionally active compound in a murine model of bronchoconstriction. The compound has also displayed pharmacokinetic characteristics suitable for inhaled delivery.

Optimized procedures for producing biologically active chemokines.

We describe here two strategies to produce biologically active chemokines with authentic N-terminal amino acid residues. The first involves producing the target chemokine with an N-terminal 6xHis-SUMO tag in Escherichia coli as inclusion bodies. The fusion protein is solubilized and purified with Ni-NTA-agarose in denaturing reagents. This is further followed by tag removal and refolding in a redox refolding buffer. The second approach involves expressing the target chemokine with an N-terminal 6xHis-Trx-SUMO tag in an engineered E. coli strain that facilitates formation of disulfide bonds in the cytoplasm. Following purification of the fusion protein via Ni-NTA and tag removal, the target chemokine is refolded without redox buffer and purified by reverse phase chromatography. Using the procedures, we have produced more than 15 biologically active chemokines, with a yield of up to 15 mg/L.

Discovery of novel 1-azoniabicyclo[2.2.2]octane muscarinic acetylcholine receptor antagonists.

A novel 4-hydroxyl(diphenyl)methyl substituted quinuclidine series was discovered as a very promising class of muscarinic antagonists. The structure-activity relationships of the connectivity of the diphenyl moiety to the quinuclidine core and around the ring nitrogen side chain are described. Computational docking studies using an homology model of the M(3) receptor readily explained the observed structure-activity relationship of the various compounds. Compound 14o was identified as a very potent, slowly reversible M(3) antagonist with a very long in vivo duration of bronchoprotection.

M3 muscarinic acetylcholine receptor antagonists: SAR and optimization of bi-aryl amines.

Exploration of multiple regions of a bi-aryl amine template led to the identification of highly potent M(3) muscarinic acetylcholine receptor antagonists such as 14 (pA(2)=11.0) possessing good sub-type selectivity for M(3) over M(2). The structure-activity relationships (SAR) and optimization of the bi-aryl amine series are described.

Camphor sulfonamide derivatives as novel, potent and selective CXCR3 antagonists.

A series of N-arylpiperazine camphor sulfonamides was discovered as novel CXCR3 antagonists. The synthesis, structure-activity relationships, and optimization of the initial hit that resulted in the identification of potent and selective CXCR3 antagonists are described.

Discovery of biphenyl piperazines as novel and long acting muscarinic acetylcholine receptor antagonists.

A series of novel biphenyl piperazines was discovered as highly potent muscarinic acetylcholine receptor antagonists via high throughput screening and subsequent optimization. Compound 5c with respective 500- and 20-fold subtype selectivity for M3 over M2 and M1 exhibited excellent inhibitory activity and long duration of action in a bronchoconstriction in vivo model in mice via intranasal administration. The novel inhaled mAChR antagonists are potentially useful therapeutic agents for the treatment of chronic obstructive pulmonary disease.

Muscarinic acetylcholine receptor antagonists: SAR and optimization of tyrosine ureas.

SAR exploration of multiple regions of a tyrosine urea template led to the identification of very potent muscarinic acetylcholine receptor antagonists such as 10b with good subtype selectivity for M(3) over M(1). The structure-activity relationships (SAR) and optimization of the tyrosine urea series are described.

Discovery of novel and long acting muscarinic acetylcholine receptor antagonists.

High throughput screening and subsequent optimization led to the discovery of novel quaternary ammonium salts as highly potent muscarinic acetylcholine receptor antagonists with excellent selectivity. Compounds 8a, 13a, and 13b showed excellent inhibitory activity and long duration of action in bronchoconstriction in vivo models in two species via intranasal or intratracheal administration. The novel inhaled muscarinic receptor antagonists are potentially useful therapeutic agents for the treatment of chronic obstructive pulmonary disease and other bronchoconstriction disorders.

Urotensin-II receptor antagonists: synthesis and SAR of N-cyclic azaalkyl benzamides.

SAR exploration of the central diamine, benzyl, and terminal aminoalkoxy regions of the N-cyclic azaalkyl benzamide series led to the identification of very potent human urotensin-II receptor antagonists such as 1a with a K(i) of 4 nM. The synthesis and structure-activity relationships (SAR) of N-cyclic azaalkyl benzamides are described.

Discovery of novel 8-azoniabicyclo[3.2.1]octane carbamates as muscarinic acetylcholine receptor antagonists.

In the course of our research program to develop novel muscarinic receptor antagonists for the treatment of COPD, new tropane carbamate derivatives were identified as potent anti-muscarinic agents. The synthesis, structure-activity relationships and pharmacological evaluation that led to the identification of compound 5o, are described.

3-Arylamino-2H-1,2,4-benzothiadiazin-5-ol 1,1-dioxides as novel and selective CXCR2 antagonists.

A series of 3-arylamino-2H-1,2,4-benzothiadiazin-5-ol 1,1-dioxides were prepared and shown to be novel and selective antagonists of the CXCR2 receptor. Synthesis, structure and activity relationships, selectivity, and some developability properties are described.

Oxazolidinones as novel human CCR8 antagonists.

High-throughput screening of the corporate compound collection led to the discovery of a novel series of N-substituted-5-aryl-oxazolidinones as potent human CCR8 antagonists. The synthesis, structure-activity relationships, and optimization of the series that led to the identification of SB-649701 (1a), are described.

Comparison of N,N'-diarylsquaramides and N,N'-diarylureas as antagonists of the CXCR2 chemokine receptor.

N,N'-diarylsquaramides were prepared and evaluated as antagonists of CXCR2. The compounds were found to be potent and selective antagonists of CXCR2. Significant differences in SAR was observed relative to the previously described N,N'-diarylurea series. As was the case in the N,N'-diarylurea series, placing sulfonamide substituent adjacent to the acidic phenol significantly reduced the clearance in rat pharmacokinetic studies.

N,N'-Diarylcyanoguanidines as antagonists of the CXCR2 and CXCR1 chemokine receptors.

A series of N-(2-hydroxy-3-sulfonamidobenzene)-N'-arylcyanoguanidines was prepared. In general, these compounds proved to be potent antagonists of CXCR2 while the selectivity versus CXCR1 ranged from non-selective to >200-fold.