Discovery of hydroxy pyrimidine Factor IXa inhibitors.

The synthesis and structure activity relationship development of a pyrimidine series of heterocyclic Factor IXa inhibitors is described. Increased selectivity over Factor Xa inhibition was achieved through SAR expansion of the P1 element. Select compounds were evaluated in vivo to assess their plasma levels in rat.

Discovery of nor-seco himbacine analogs as thrombin receptor antagonists.

Discovery of a novel nor-seco himbacine analog as potent thrombin receptor (PAR-1) antagonist is described. Despite low plasma level, these new analogs showed excellent ex vivo efficacy in the monkey platelet aggregation assay. A potent hydroxy metabolite generated in vivo was identified as the agent responsible for the ex vivo efficacy. Following this discovery, the metabolite series was optimized to obtain analogs that showed very good ex vivo efficacy along with excellent pharmacokinetic profile in c. monkey.

Discovery of a nortropanol derivative as a potent and orally active GPR119 agonist for type 2 diabetes.

The lead optimization studies of a series of GPR119 agonists incorporating a nortropanol scaffold are described. Extensive structure-activity relationship (SAR) studies of the lead compound 20f led to the identification of compound 36j as a potent, single digit nanomolar GPR119 agonist with high agonist activity. Compound 36j was orally active in lowering blood glucose levels in a mouse oral glucose tolerance test and increased plasma insulin levels in a rat hyperglycemic model. It showed good to excellent pharmacokinetic properties in rats and monkeys and no untoward activities in counter-screen assays. Compound 36j demonstrated an attractive in vitro and in vivo profile for further development.

Azabicyclic sulfonamides as potent 11beta-HSD1 inhibitors.

Inhibition of 11beta-HSD1 has demonstrated potential in the treatment of various components of metabolic syndrome. We wish to report herein the discovery of novel azabicyclic sulfonamide based 11beta-HSD1 inhibitors. Highly potent compounds exhibiting inhibitory activities at both human and mouse 11beta-HSD1 were identified. Several compounds demonstrated significant in vivo activity in the mouse cortisone challenge assay.

Discovery of a vorapaxar analog with increased aqueous solubility.

An analog of the thrombin receptor antagonist vorapaxar (SCH 530348) with increased aqueous solubility, compound 9c (SCH 602539), was discovered through incorporation of polar substituents on the pyridine ring of the himbacine-derived lead series. This analog retained the excellent potency, pharmacokinetic and safety properties of vorapaxar while increasing the aqueous solubility by 20-fold. Also presented are in vivo evaluations of this compound in a cynomolgus monkey platelet aggregation assay and in a Folts model of thrombosis in anesthetized monkeys.

Diaryl piperidines as CB1 receptor antagonists.

The syntheses and SAR investigations of novel CB(1) receptor antagonists based on a 1,2-diaryl piperidine core have been described. Optimization of this core afforded a compound with robust in vivo potency by reducing food intake in a mouse DIO model.

The discovery of azepane sulfonamides as potent 11beta-HSD1 inhibitors.

Discovery of a series of azepine sulfonamides as potent inhibitors of 11beta-hydroxysteroid dehydrogenase type 1 (11beta-HSD1) is described. SAR studies at the 4-position of the azepane ring have resulted in the discovery of a very potent compound 30 which has an 11beta-HSD1 IC(50) of 3.0nM.

Identification of novel cannabinoid CB1 receptor antagonists by using virtual screening with a pharmacophore model.

CB1 receptor antagonists have proven to be clinically effective in treating obesity and related disorders. We report here the identification of a novel class of azetidinone CB1 antagonists by using virtual screening methods. For this purpose, we developed a pharmacophore model based on known representative CB1 antagonists and employed it to screen a database of about a half million Schering-Plough compounds. We applied a stepwise filtering protocol based on molecular weight, compound availability, and a modified rule-of-five to reduce the number of hits. We then combined Bayesian modeling and clustering techniques to select a final set of 420 compounds for in vitro testing. Five compounds were found to have >50% inhibition at 100 nM in a CB1 competitive binding assay and were further characterized by using both CB1 and CB2 assays. The most potent compound has a CB1 K i of 53 nM and >5-fold selectivity against the CB2 receptor.

Discovery of a novel, orally active himbacine-based thrombin receptor antagonist (SCH 530348) with potent antiplatelet activity.

The discovery of an exceptionally potent series of thrombin receptor (PAR-1) antagonists based on the natural product himbacine is described. Optimization of this series has led to the discovery of 4 (SCH 530348), a potent, oral antiplatelet agent that is currently undergoing Phase-III clinical trials for acute coronary syndrome (unstable angina/non-ST segment elevation myocardial infarction) and secondary prevention of cardiovascular events in high-risk patients.

Biaryl and heteroaryl derivatives of SCH 58261 as potent and selective adenosine A2A receptor antagonists.

SCH 58261 is a reported adenosine A(2A) receptor antagonist, which is active in rat in vivo models of Parkinson's Disease upon ip administration. However, it has poor selectivity versus the A(1) receptor and does not demonstrate oral activity. We report the design and synthesis of biaryl and heteroaryl analogs of SCH 58261 which improve the A(2A) receptor binding selectivity as well as the pharmacokinetic properties of SCH 58261. In particular, the quinoline 25 has excellent A(2A) receptor in vitro binding affinity and selectivity, sustained rat plasma levels upon oral dosing, and is active orally in a rat behavioral assay.

Design, synthesis, and evaluation of fused heterocyclic analogs of SCH 58261 as adenosine A2A receptor antagonists.

SCH 58261 is a reported adenosine A(2A) receptor antagonist which is active in rat in vivo models of Parkinson's Disease upon ip administration. However, it has poor selectivity versus the A(1) receptor and does not demonstrate oral activity. Quinoline analogs have improved upon the selectivity and pharmacokinetics of SCH 58261, but were difficult to handle due to poor aqueous solubility. We report the design and synthesis of fused heterocyclic analogs of SCH 58261 with aqueous solubility as well as improved A(2A) receptor binding selectivity and pharmacokinetic properties. In particular, the tetrahydronaphthyridine 4s has excellent A(2A) receptor in vitro binding affinity and selectivity, is active orally in a rat in vivo model of Parkinson's Disease, and has aqueous solubility of 100 microM at physiological pH.

Discovery of MK-8282 as a Potent G-Protein-Coupled Receptor 119 Agonist for the Treatment of Type 2 Diabetes.

The ever-growing prevalence of type 2 diabetes in the world has necessitated an urgent need for multiple orally effective agents that can regulate glucose homeostasis with a concurrent reduction in body weight. G-Protein coupled receptor 119 (GPR119) is a GPCR target at which agonists have demonstrated glucose-dependent insulin secretion and shows beneficial effects on glycemic control. Herein, we describe our efforts leading to the identification of a potent, oral GPR-119 agonist, MK-8282, which shows improved glucose tolerance in multiple animal models and has excellent off-target profile. The key design elements in the compounds involved a combination of a fluoro-pyrimidine and a conformationally constrained bridged piperidine to impart good potency and efficacy.

Heterotricyclic himbacine analogs as potent, orally active thrombin receptor (protease activated receptor-1) antagonists.

Pursuing our earlier efforts in the himbacine-based thrombin receptor antagonist area, we have synthesized a series of compounds that incorporate heteroatoms in the C-ring of the tricyclic motif. This effort has resulted in the identification of several potent heterocyclic analogs with excellent affinity for the thrombin receptor. Several of these compounds demonstrated robust inhibition of platelet aggregation in an ex vivo model in cynomolgus monkeys following oral administration. A detailed profile of 28b, a benchmark compound in this series, with a Ki of 4.3 nM, is presented.

Metabolism-based identification of a potent thrombin receptor antagonist.

The metabolism of our prototypical thrombin receptor antagonist 1, Ki = 2.7 nM, was studied and three major metabolites (2, 4, and 5) were found. The structures of the metabolites were verified independently by synthesis. Compound 4 was shown to be a potent antagonist of the thrombin receptor with a Ki = 11 nM. Additionally, compound 4 showed a 3-fold improvement in potency with respect to 1 in an agonist-induced ex-vivo platelet aggregation assay in cynomolgus monkeys after oral administration; this activity was sustained with 60% inhibition observed at 24 h post-dose. Compound 4 was highly active in functional assays and showed excellent oral bioavailability in rats and monkeys. Compound 4 showed a superior rat enzyme induction profile relative to compound 1, allowing it to replace compound 1 as a development candidate.

Design and Synthesis of P2-P4 Macrocycles Containing a Unique Spirocyclic Proline: A New Class of HCV NS3/4A Inhibitors.

A new class of hepatitis C NS3/4A inhibitors was identified by introducing a novel spirocyclic proline-P2 surrogate onto the P2-P4 macrocyclic core of MK-5172 (grazoprevir). The potency profile of new analogues showed excellent pan-genotypic activity for most compounds. The potency evaluation included the most difficult genotype 3a (EC50 values ≤10 nM) and other key genotype 1b mutants. Molecular modeling was used to design new target compounds and rationalize our results. A synthetic approach based on the Julia-Kocienski olefination and macrolactamization to assemble the P2-P4 macrocyclic core containing the novel spirocyclic proline-P2 moiety is presented as well.

Discovery of MK-8831, A Novel Spiro-Proline Macrocycle as a Pan-Genotypic HCV-NS3/4a Protease Inhibitor.

We have been focused on identifying a structurally different next generation inhibitor to MK-5172 (our Ns3/4a protease inhibitor currently under regulatory review), which would achieve superior pangenotypic activity with acceptable safety and pharmacokinetic profile. These efforts have led to the discovery of a novel class of HCV NS3/4a protease inhibitors containing a unique spirocyclic-proline structural motif. The design strategy involved a molecular-modeling based approach, and the optimization efforts on the series to obtain pan-genotypic coverage with good exposures on oral dosing. One of the key elements in this effort was the spirocyclization of the P2 quinoline group, which rigidified and constrained the binding conformation to provide a novel core. A second focus of the team was also to improve the activity against genotype 3a and the key mutant variants of genotype 1b. The rational application of structural chemistry with molecular modeling guided the design and optimization of the structure-activity relationships have resulted in the identification of the clinical candidate MK-8831 with excellent pan-genotypic activity and safety profile.

Discovery of potent orally active thrombin receptor (protease activated receptor 1) antagonists as novel antithrombotic agents.

Structurally novel thrombin receptor (protease activated receptor 1, PAR-1) antagonists based on the natural product himbacine are described. The prototypical PAR-1 antagonist 55 showed a Ki of 2.7 nM in the binding assay, making it the most potent PAR-1 antagonist reported. 55 was highly active in several functional assays, showed excellent oral bioavailability in rat and monkey models, and showed complete inhibition of agonist-induced ex vivo platelet aggregation in cynomolgus monkeys after oral administration.

Development of proteinase-activated receptor 1 antagonists as therapeutic agents for thrombosis, restenosis and inflammatory diseases.

Thrombin, a plasma serine protease, plays a key role not only in coagulation and hemostasis but in thrombosis, restenosis and atherosclerosis. Thrombin activates platelets, endothelium, inflammatory cells and smooth muscle cells. The cellular action of thrombin is mediated by specific G-protein coupled thrombin receptors called proteinase-activated receptors (protease-activated receptor or PARs). Among the three thrombin receptors, PAR1 is the primary thrombin receptor in human and animal cells with an exception of non-primate platelets. An increased thrombin generation and PAR1 expression are observed on cells within atherosclerotic plaque and thrombus and following vascular injury. Animal studies with PAR1 deficient mice and small molecule antagonists indicate an important role of PAR1 in thrombosis and restenosis and thus the therapeutic potential of a PAR1 antagonist in treating these diseases. Development of a thrombin receptor tethered ligand analog binding assay led to the discovery of several different series of potent, nonpeptide small molecular antagonists of PAR1. These antagonists are PAR1 selective and inhibit most of the cellular effects of thrombin. A PAR1 antagonist has an advantage over a direct thrombin inhibitor since it does not inhibit enzymatic action of thrombin in the coagulation cascade with the consequent minimal bleeding side-effects, unlike a direct thrombin inhibitor. In addition, the emerging evidence for the role of PAR1 in various inflammatory diseases suggests as yet unexplored therapeutic potentials of PAR1 antagonists in various inflammatory diseases.

G-protein coupled receptor antagonists-1: protease activated receptor-1 (PAR-1) antagonists as novel cardiovascular therapeutic agents.

Inhibition of thrombin receptor (PAR-1) is a promising therapeutic approach for the treatment of various cardiovascular disorders such as unstable angina, acute myocardial infarction, stroke, and restenosis. Since a PAR-1 antagonist is specific for the cellulalr actions of thrombin, and does not interfere with fibrin generation, it is expected to have less bleeding liability than the currently available treatments. Several peptide and non-peptide PAR-1 antagonists with potent inhibition of platelet aggregation have been reported. Antithrombotic effect of a PAR-1 antibody has been demonstrated in a baboon thrombosis model and the antirestenosis property of a PAR-1 antagonist has been demonstrated in a rat model.

Improving the oral efficacy of CNS drug candidates: discovery of highly orally efficacious piperidinyl piperidine M2 muscarinic receptor antagonists.

In search of a backup M(2) muscarinic receptor antagonist to the previously reported compound 1, we discovered compound (+)-14, which showed superior oral efficacy in animal models. The improvement of oral efficacy was achieved by modulating both the molecular weight and lipophilicity of the lead compounds.