Design and preparation of N-linked hydroxypyridine-based APJ agonists.

Agonism of the apelin receptor (APJ) has demonstrated beneficial effects in models of heart failure. We have previously disclosed compounds such as 4, which showed good APJ agonist activity but were metabolized to the mono-demethylated, non-interconverting atropisomer metabolites. Herein, we detail the design and optimization of a novel series of N-linked APJ agonists with good potency, metabolic stability, and rat pharmacokinetic profile, which are unable to undergo the same metabolic mono-demethylation cleavage.

Identification of 6-hydroxy-5-phenyl sulfonylpyrimidin-4(1H)-one APJ receptor agonists.

Heart failure (HF) treatment remains a critical unmet medical need. Studies in normal healthy volunteers and HF patients have shown that [Pyr1]apelin-13, the endogenous ligand for the APJ receptor, improves cardiac function. However, the short half-life of [Pyr1]apelin-13 and the need for intravenous administration have limited the therapeutic potential for chronic use. We sought to identify potent, small-molecule APJ agonists with improved pharmaceutical properties to enable oral dosing in clinical studies. In this manuscript, we describe the identification of a series of pyrimidinone sulfones as a structurally differentiated series to the clinical lead (compound 1). Optimization of the sulfone series for potency, metabolic stability and oral bioavailability led to the identification of compound 22, which showed comparable APJ potency to [Pyr1]apelin-13 and exhibited an acceptable pharmacokinetic profile to advance to the acute hemodynamic rat model.

Linking (Pyr)1apelin-13 pharmacokinetics to efficacy: Stabilization and measurement of a high clearance peptide in rodents.

Apelin, the endogenous ligand for the APJ receptor, has generated interest due to its beneficial effects on the cardiovascular system. Synthesized as a 77 amino acid preproprotein, apelin is post-translationally cleaved to a series of shorter peptides. Though (Pyr)1apelin-13 represents the major circulating form in plasma, it is highly susceptible to proteolytic degradation and has an extremely short half-life, making it challenging to quantify. Literature reports of apelin levels in rodents have historically been determined with commercial ELISA kits which suffer from a lack of selectivity, recognizing a range of active and inactive isoforms of apelin peptide. (Pyr)1apelin-13 has demonstrated beneficial hemodynamic effects in humans, and we wished to evaluate if similar effects could be measured in pre-clinical models. Despite development of a highly selective LC/MS/MS method, in rodent studies where (Pyr)1apelin-13 was administered exogenously the peptide was not detectable until a detailed stabilization protocol was implemented during blood collection. Further, the inherent high clearance of (Pyr)1apelin-13 required an extended release delivery system to enable chronic dosing. The ability to deliver sustained doses and stabilize (Pyr)1apelin-13 in plasma allowed us to demonstrate for the first time the link between systemic concentration of apelin and its pharmacological effects in animal models.

Benzothiazole-based compounds as potent endothelial lipase inhibitors.

A series of benzothiazoles with a cyano group was synthesized and evaluated as endothelial lipase (EL) inhibitors for the potential treatment of cardiovascular diseases. Efforts to reduce molecular weight and polarity in the series led to improved physicochemical properties of these compounds, as well as selectivity for EL over hepatic lipase (HL). As a benchmark compound, 8i demonstrated potent EL activity, an acceptable absorption, distribution, metabolism and elimination (ADME) profile and pharmacokinetic (PK) exposure which allowed further evaluation in preclinical animal efficacy studies.

Identification of substituted benzothiazole sulfones as potent and selective inhibitors of endothelial lipase.

A low level of high density lipoprotein (HDL) is an independent risk factor for cardiovascular disease. HDL reduces inflammation and plays a central role in reverse cholesterol transport, where cholesterol is removed from peripheral tissues and atherosclerotic plaque. One approach to increase plasma HDL is through inhibition of endothelial lipase (EL). EL hydrolyzes phospholipids in HDL resulting in reduction of plasma HDL. A series of benzothiazole sulfone amides was optimized for EL inhibition potency, lipase selectivity and improved pharmacokinetic profile leading to the identification of Compound 32. Compound 32 was evaluated in a mouse pharmacodynamic model and found to show no effect on HDL cholesterol level despite achieving targeted plasma exposure (Ctrough > 15 fold over mouse plasma EL IC50 over 4 days).

Discovery and synthesis of tetrahydropyrimidinedione-4-carboxamides as endothelial lipase inhibitors.

Endothelial lipase (EL) inhibitors have been shown to elevate HDL-C levels in pre-clinical murine models and have potential benefit in prevention and treatment of cardiovascular diseases. Modification of the 1-ethyl-3-hydroxy-1,5-dihydro-2H-pyrrol-2-one (DHP) lead, 1, led to the discovery of a series of potent tetrahydropyrimidinedione (THP) EL inhibitors. Synthesis and SAR studies including modification of the amide group, together with changes on the pyrimidinone core led to a series of arylcycloalkyl, indanyl, and tetralinyl substituted 5-amino or 5-hydroxypyrimidinedione-4-carboxamides. Several compounds were advanced to PK evaluation. Among them, compound 4a was one of the most potent with measurable ELHDL hSerum potency and compound 3g demonstrated the best overall pharmacokinetic parameters.

Discovery of hydroxyl 1,2-diphenylethanamine analogs as potent cholesterol ester transfer protein inhibitors.

Hydroxyl 1,2-diphenylethanamine analogs were identified as potent inhibitors of cholesterol ester transfer protein (CETP), a therapeutic target to raise HDL cholesterol. In an effort to improve the pharmaceutical properties in the previously disclosed DiPhenylPyridineEthanamine (DPPE) series, polar groups were introduced to the N-linked quaternary center. Optimization of analogues for potency, in vitro liability profile and efficacy led to identification of lead compound 16 which demonstrated robust pharmacodynamic effects in human CETP/apo-B100 dual transgenic mice.

Pseudosaccharin amines as potent and selective KV1.5 blockers.

Phenethyl aminoheterocycles like compound 1 were known to be potent I(Kur) blockers although they lacked potency in vivo. Modification of the heterocycle led to the design and synthesis of pseudosaccharin amines. Compounds such as 14, 17d and 21c were found to be potent K(V)1.5 blockers and selective over other cardiac ion channels. These compounds had potent pharmacodynamic activity, however, they also showed off-target activities such as hemodynamic effects.

Design, synthesis and evaluation of phenethylaminoheterocycles as K(v)1.5 inhibitors.

Phenethylaminoheterocycles have been prepared and assayed for inhibition of the Kv1.5 potassium ion channel as a potential approach to the treatment of atrial fibrillation. A diverse set of heterocycles were identified as potent Kv1.5 inhibitors and were advanced to pharmacodynamic evaluation based on selectivity and pharmacokinetic profile. Heterocycle optimization and template modification lead to the identification of compound 24 which demonstrated increased atrial effective refractory period in the rabbit pharmacodynamic model with mild effects on blood pressure and heart rate.

Diphenylpyridylethanamine (DPPE)-based aminoheterocycles as cholesteryl ester transfer protein inhibitors.

A series of diphenylpyridylethanamine-based inhibitors of cholesteryl ester transfer protein with aminoheterocycles appended onto the N-terminus of the chemotype were explored as urea mimetics. Potent compounds were discovered and were further optimized to improve metabolic stability and PXR transactivation profile.

Triazolo and imidazo dihydropyrazolopyrimidine potassium channel antagonists.

Previously disclosed C6 amido and benzimidazole dihydropyrazolopyrimidines were potent and selective blockers of IKur current. Syntheses and SAR for C6 triazolo and imidazo dihydropyrazolopyrimidines series are described. Trifluoromethylcyclohexyl N(1) triazole, compound 51, was identified as a potent and selective Kv1.5 inhibitor with an acceptable PK and liability profile.

In Vitro and In Vivo Evaluation of a Small-Molecule APJ (Apelin Receptor) Agonist, BMS-986224, as a Potential Treatment for Heart Failure.

BACKGROUND: New heart failure therapies that safely augment cardiac contractility and output are needed. Previous apelin peptide studies have highlighted the potential for APJ (apelin receptor) agonism to enhance cardiac function in heart failure. However, apelin's short half-life limits its therapeutic utility. Here, we describe the preclinical characterization of a novel, orally bioavailable APJ agonist, BMS-986224. METHODS: BMS-986224 pharmacology was compared with (Pyr1) apelin-13 using radio ligand binding and signaling pathway assays downstream of APJ (cAMP, phosphorylated ERK [extracellular signal-regulated kinase], bioluminescence resonance energy transfer-based G-protein assays, ß-arrestin recruitment, and receptor internalization). Acute effects on cardiac function were studied in anesthetized instrumented rats. Chronic effects of BMS-986224 were assessed echocardiographically in the RHR (renal hypertensive rat) model of cardiac hypertrophy and decreased cardiac output. RESULTS: BMS-986224 was a potent (Kd=0.3 nmol/L) and selective APJ agonist, exhibiting similar receptor binding and signaling profile to (Pyr1) apelin-13. G-protein signaling assays in human embryonic kidney 293 cells and human cardiomyocytes confirmed this and demonstrated a lack of signaling bias relative to (Pyr1) apelin-13. In anesthetized instrumented rats, short-term BMS-986224 infusion increased cardiac output (10%-15%) without affecting heart rate, which was similar to (Pyr1) apelin-13 but differentiated from dobutamine. Subcutaneous and oral BMS-986224 administration in the RHR model increased stroke volume and cardiac output to levels seen in healthy animals but without preventing cardiac hypertrophy and fibrosis, effects differentiated from enalapril. CONCLUSIONS: We identify a novel, potent, and orally bioavailable nonpeptidic APJ agonist that closely recapitulates the signaling properties of (Pyr1) apelin-13. We show that oral APJ agonist administration induces a sustained increase in cardiac output in the cardiac disease setting and exhibits a differentiated profile from the renin-angiotensin system inhibitor enalapril, supporting further clinical evaluation of BMS-986224 in heart failure.

Identification of a Hydroxypyrimidinone Compound (21) as a Potent APJ Receptor Agonist for the Potential Treatment of Heart Failure.

This paper describes our continued efforts in the area of small-molecule apelin receptor agonists. Recently disclosed compound 2 showed an acceptable metabolic stability but demonstrated monodemethylation of the dimethoxyphenyl group to generate atropisomer metabolites in vitro. In this article, we extended the structure-activity relationship at the C2 position that led to the identification of potent pyrazole analogues with excellent metabolic stability. Due to the increased polarity at C2, the permeability for these compounds decreased. Further adjustment of the polarity by replacing the N1 2,6-dimethoxyphenyl group with a 2,6-diethylphenyl group and reoptimization for the potency of the C5 pyrroloamides resulted in potent compounds with improved permeability. Compound 21 displayed excellent pharmacokinetic profiles in rat, monkey, and dog models and robust pharmacodynamic efficacy in the rodent heart failure model. Compound 21 also showed an acceptable safety profile in preclinical toxicology studies and was selected as a backup development candidate for the program.

Identification of 6-Hydroxypyrimidin-4(1H)-one-3-carboxamides as Potent and Orally Active APJ Receptor Agonists.

The apelin receptor (APJ) is a significant regulator of cardiovascular function and is involved in heart failure and other cardiovascular diseases. (Pyr1)apelin-13 is one of the endogenous agonists of the APJ receptor. Administration of (Pyr1)apelin-13 increases cardiac output in preclinical models and humans. Recently we disclosed clinical lead BMS-986224 (1), a C3 oxadiazole pyridinone APJ receptor agonist with robust pharmacodynamic effects similar to (Pyr1)apelin-13 in an acute rat pressure-volume loop model. Herein we describe the structure-activity relationship of the carboxamides as oxadiazole bioisosteres at C3 of the pyridinone core and C5 of the respective pyrimidinone core. This study led to the identification of structurally differentiated 6-hydroxypyrimidin-4(1H)-one-3-carboxamide 14a with pharmacodynamic effects comparable to those of compound 1.

Discovery of a Hydroxypyridinone APJ Receptor Agonist as a Clinical Candidate.

Apelin-13 is an endogenous peptidic agonist of the apelin receptor (APJ) receptor with the potential for improving cardiac function in heart failure patients. However, the low plasma stability of apelin-13 necessitates continuous intravenous infusion for therapeutic use. There are several approaches to increase the stability of apelin-13 including attachment of pharmacokinetic enhancing groups, stabilized peptides, and Fc-fusion approaches. We sought a small-molecule APJ receptor agonist approach to target a compound with a pharmacokinetic profile amenable for chronic oral administration. This manuscript describes sequential optimization of the pyrimidinone series, leading to pyridinone 14, with in vitro potency equivalent to the endogenous ligand apelin-13 and with an excellent oral bioavailability and PK profile in multiple preclinical species. Compound 14 exhibited robust pharmacodynamic effects similar to apelin-13 in an acute rat pressure-volume loop model and was advanced as a clinical candidate.

Pyrrolidine amides of pyrazolodihydropyrimidines as potent and selective KV1.5 blockers.

Design and synthesis of pyrazolodihydropyrimidines as KV1.5 blockers led to the discovery of 7d as a potent and selective antagonist. This compound showed atrial selective prolongation of effective refractory period in rabbits and was selected for clinical development.

Identification of Reversible Small Molecule Inhibitors of Endothelial Lipase (EL) That Demonstrate HDL-C Increase In Vivo.

Endothelial lipase (EL) hydrolyzes phospholipids in high-density lipoprotein (HDL) resulting in reduction in plasma HDL levels. Studies with murine transgenic, KO, or loss-of-function variants strongly suggest that inhibition of EL will lead to sustained plasma high-density lipoprotein cholesterol (HDL-C) increase and, potentially, a reduced cardiovascular disease (CVD) risk. Herein, we describe the discovery of a series of oxadiazole ketones, which upon optimization, led to the identification of compound 12. Compound 12 was evaluated in a mouse pharmacodynamics (PD) model and demonstrated a 56% increase in plasma HDL-C. In a mouse reverse cholesterol transport study, compound 12 stimulated cholesterol efflux by 53% demonstrating HDL-C functionality.

Dihydropyrazolopyrimidines containing benzimidazoles as K(V)1.5 potassium channel antagonists.

Dihydropyrazolopyrimidines with a C6 heterocycle substituent were found to have high potency for block of K(V)1.5. Investigation of the substitution in the benzimidazole ring and the substituent in the 5-position of the dihydropyrazolopyrimidine ring produced 31a with an IC50 for K(V)1.5 block of 0.030muM without significant block of other cardiac ion channels. This compound also showed good bioavailability in rats and robust pharmacodynamic effects in a rabbit model.

Discovery of a Lead Triphenylethanamine Cholesterol Ester Transfer Protein (CETP) Inhibitor.

Lead optimization of the diphenylpyridylethanamine (DPPE) and triphenylethanamine (TPE) series of CETP inhibitors to improve their pharmaceutical profile is described. Polar groups at the N-terminus position in the DPPE series resulted in further improvement in potency and pharmaceutical properties concomitant with retaining the safety, efficacy, and pharmacokinetic (PK) profile. A structure-activity relationship observed in the DPPE series was extended to the corresponding analogs in the more potent TPE series, and further optimization resulted in the identification of 2-amino-N-((R)-1-(3-cyclopropoxy-4-fluorophenyl)-1-(3-fluoro-5-(1,1,2,2-tetrafluoroethoxy)phenyl)-2-phenylethyl)-4,4,4-trifluoro-3-hydroxy-3-(trifluoromethyl)butanamide (13). Compound 13 demonstrated no significant changes in either mean arterial blood pressure or heart rate in telemetry rats, had an excellent PK profile, and demonstrated robust efficacy in human CETP/apo-B-100 dual transgenic mice and in hamsters.