Discovery of Potent and Selective Quinoxaline-Based Protease-Activated Receptor 4 (PAR4) Antagonists for the Prevention of Arterial Thrombosis.

PAR4 is a promising antithrombotic target with potential for separation of efficacy from bleeding risk relative to current antiplatelet therapies. In an effort to discover a novel PAR4 antagonist chemotype, a quinoxaline-based HTS hit 3 with low µM potency was identified. Optimization of the HTS hit through the use of positional SAR scanning and the design of conformationally constrained cores led to the discovery of a quinoxaline-benzothiazole series as potent and selective PAR4 antagonists. The lead compound 48, possessing a 2 nM IC50 against PAR4 activation by γ-thrombin in platelet-rich plasma (PRP) and greater than 2500-fold selectivity versus PAR1, demonstrated robust antithrombotic efficacy and minimal bleeding in the cynomolgus monkey models.

Discovery of Two Novel Antiplatelet Clinical Candidates (BMS-986120 and BMS-986141) That Antagonize Protease-Activated Receptor 4.

Protease-activated receptor 4 (PAR4) is a G-protein coupled receptor that is expressed on human platelets and activated by the coagulation enzyme thrombin. PAR4 plays a key role in blood coagulation, and its importance in pathological thrombosis has been increasingly recognized in recent years. Herein, we describe the optimization of a series of imidazothiadiazole PAR4 antagonists to a first-in-class clinical candidate, BMS-986120 (43), and a backup clinical candidate, BMS-986141 (49). Both compounds demonstrated excellent antithrombotic efficacy and minimal bleeding time prolongation in monkey models relative to the clinically important antiplatelet agent clopidogrel and provide a potential opportunity to improve the standard of care in the treatment of arterial thrombosis.

Discovery of an Oxycyclohexyl Acid Lysophosphatidic Acid Receptor 1 (LPA1) Antagonist BMS-986278 for the Treatment of Pulmonary Fibrotic Diseases.

The oxycyclohexyl acid BMS-986278 (33) is a potent lysophosphatidic acid receptor 1 (LPA1) antagonist, with a human LPA1 Kb of 6.9 nM. The structure-activity relationship (SAR) studies starting from the LPA1 antagonist clinical compound BMS-986020 (1), which culminated in the discovery of 33, are discussed. The detailed in vitro and in vivo preclinical pharmacology profiles of 33, as well as its pharmacokinetics/metabolism profile, are described. On the basis of its in vivo efficacy in rodent chronic lung fibrosis models and excellent overall ADME (absorption, distribution, metabolism, excretion) properties in multiple preclinical species, 33 was advanced into clinical trials, including an ongoing Phase 2 clinical trial in patients with lung fibrosis (NCT04308681).

Biologic-like In Vivo Efficacy with Small Molecule Inhibitors of TNFα Identified Using Scaffold Hopping and Structure-Based Drug Design Approaches.

Scaffold hopping and structure-based drug design were employed to identify substituted 4-aminoquinolines and 4-aminonaphthyridines as potent, small molecule inhibitors of tumor necrosis factor alpha (TNFα). Structure-activity relationships in both the quinoline and naphthyridine series leading to the identification of compound 42 with excellent potency and pharmacokinetic profile are discussed. X-ray co-crystal structure analysis and ultracentrifugation experiments clearly demonstrate that these inhibitors distort the TNFα trimer upon binding, leading to aberrant signaling when the trimer binds to TNF receptor 1 (TNFR1). Pharmacokinetic-pharmacodynamic activity of compound 42 in a TNF-induced IL-6 mouse model and in vivo activity in a collagen antibody-induced arthritis model, where it showed biologic-like in vivo efficacy, will be discussed.

Discovery of a phenylpyrazole amide ROCK inhibitor as a tool molecule for in vivo studies.

Structure-activity relationship optimization on a series of phenylpyrazole amides led to the identification of a dual ROCK1 and ROCK2 inhibitor (25) which demonstrated good potency, kinome selectivity and favorable pharmacokinetic profiles. Compound 25 was selected as a tool molecule for in vivo studies including evaluating hemodynamic effects in telemeterized mice, from which moderate decreases in blood pressure were observed.

An amide-based sulfenamide prodrug of gamma secretase inhibitor BMS-708163 delivers parent drug from an oral conventional solid dosage form in male beagle dog.

The objective of this Letter is to report the first (to our knowledge) in vivo proof of concept for a sulfenamide prodrug to orally deliver a poorly soluble drug containing a weakly-acidic NH-acid from a conventional solid dosage formulation. This proof of concept was established using BMS-708163 (1), a gamma secretase inhibitor containing a weakly acidic primary amide NH-acid as the chemical handle for attaching a series of thiol-based promoieties via a sulfenamide linkage. Aqueous stabilities and solubilities are reported for a series of six sulfenamide prodrugs (2-7) of 1. The sulfenamide prodrug containing the cysteine methyl ester promoiety (5) was chosen for a orally-dosed PK study in male beagle dog comparing a solubilized formulation of 1 against a solid dosage form of 5 in a cross-over fashion at an equivalent molar dose of 3 mg/kg. Prodrug 5 delivered essentially a superimposable PK profile of 1 compared to the solubilized formulation of 1, without any detectable exposure of 5 in systemic circulation.

Discovery of Potent Protease-Activated Receptor 4 Antagonists with in Vivo Antithrombotic Efficacy.

In an effort to identify novel antithrombotics, we have investigated protease-activated receptor 4 (PAR4) antagonism by developing and evaluating a tool compound, UDM-001651, in a monkey thrombosis model. Beginning with a high-throughput screening hit, we identified an imidazothiadiazole-based PAR4 antagonist chemotype. Detailed structure-activity relationship studies enabled optimization to a potent, selective, and orally bioavailable PAR4 antagonist, UDM-001651. UDM-001651 was evaluated in a monkey thrombosis model and shown to have robust antithrombotic efficacy and no prolongation of kidney bleeding time. This combination of excellent efficacy and safety margin strongly validates PAR4 antagonism as a promising antithrombotic mechanism.

Discovery of Clinical Candidate BMS-906024: A Potent Pan-Notch Inhibitor for the Treatment of Leukemia and Solid Tumors.

Structure-activity relationships in a series of (2-oxo-1,4-benzodiazepin-3-yl)-succinamides identified highly potent inhibitors of γ-secretase mediated signaling of Notch1/2/3/4 receptors. On the basis of its robust in vivo efficacy at tolerated doses in Notch driven leukemia and solid tumor xenograft models, 12 (BMS-906024) was selected as a candidate for clinical evaluation.

BMS-871: a novel orally active pan-Notch inhibitor as an anticancer agent.

This Letter describes synthesis, SAR, and biological activity of (2-oxo-1,4-benzodiazepin-3-yl)-succinamides as inhibitors of γ-secretase mediated signaling of Notch receptors. Optimization of this series led to the identification of BMS-871 (compound 30) which displayed robust in vivo efficacy in Notch-dependent leukemia and solid tumor xenograft models.

Determination of the permeability characteristics of two sulfenamide prodrugs of linezolid across Caco-2 cells.

The purpose of this work was to study the permeability of two relatively lipophilic sulfenamide prodrugs of linezolid (clogP 0.85), N-(phenylthio)linezolid (1, clogP 2.77) and N-[(2-ethoxycarbonyl)ethylthio]linezolid (2, clogP 1.43), across Caco-2 cell monolayers. Both prodrugs were found to convert to linezolid in the donor compartment presumably from the reaction with free thiol groups on proteins on the surface of the Caco-2 cells, as no conversion was seen in the donor compartment media per se. Neither of the prodrugs could be detected in the receptor phase from either apical (AP) to basolateral (BL) or BL to AP studies. However, the appearance of linezolid in the receptor phase was biphasic with an initial rapid phase suggesting that the prodrugs were indeed more permeable, and for a short period, some prodrug was able to permeate in competition with conversion to linezolid on the donor phase surface. It appears that the prodrug was able to permeate was rapidly converted to linezolid prior to acceptor phase appearance. The second slower phase was due to the permeability of the donor-phase-formed linezolid, with the slopes similar to those from control experiments with linezolid. The limitations and possible utility of oral sulfenamide prodrugs are discussed.

Azaxanthene based selective glucocorticoid receptor modulators: design, synthesis, and pharmacological evaluation of (S)-4-(5-(1-((1,3,4-thiadiazol-2-yl)amino)-2-methyl-1-oxopropan-2-yl)-5H-chromeno[2,3-b]pyridin-2-yl)-2-fluoro-N,N-dimethylbenzamide (BMS-776532) and its methylene homologue (BMS-791826).

Structurally novel 5H-chromeno[2,3-b]pyridine (azaxanthene) selective glucocorticoid receptor (GR) modulators have been identified. A screening paradigm utilizing cellular assays of GR-mediated transrepression of proinflammatory transcription factors and transactivation of GR-dependent genes combined with three physiologically relevant assays of cytokine induction in human whole blood has allowed for the identification of high affinity, selective GR ligands that display a broad range of pharmacological profiles. Agonist efficacy in reporter assays can be tuned by halogenation of a pendent phenyl ring and correlates well with efficacy for cytokine inhibition in human whole blood. A hypothetical binding mode is proposed, invoking an expanded ligand binding pocket resembling that of arylpyrazole-bound GR structures. Two compounds of close structural similarity (35 and 37; BMS-776532 and BMS-791826, respectively) have been found to maintain distinct and consistent levels of partial agonist efficacy across several assays, displaying anti-inflammatory activity comparable to that of prednisolone 2 in suppressing cytokine production in whole blood and in rodent models of acute and chronic inflammation.

Reprint of "MDCK cell permeability characteristics of a sulfenamide produg: strategic implications in considering sulfenamide prodrugs for oral delivery of NH acids" [Bioorg. Med. Chem. Lett. 21 (2011) 172-175].

The objective of this Letter is both to report the permeability results of a linezolid-based sulfenamide prodrug in an MDCK cell model (enterocyte surrogate system) and to discuss the strategic implications of these results for considering sulfenamide prodrugs to enhance the oral delivery of weakly acidic NH-acids (e.g., amides, ureas, etc.). The two main findings from this study are that the sulfenamide prodrug does not appear to survive intracellular transport due to conversion to linezolid and that there appears to be an apically-oriented surface conversion pathway that can additionally serve to convert the sulfenamide prodrug to linezolid upon approach of the apical membrane. It is hoped that these findings, along with the discussion of the strategic implications, will facilitate a greater awareness of the potential strengths and weaknesses inherent in the sulfenamide prodrug approach for enhancing the oral delivery of weakly acidic NH-acid drugs.

MDCK cell permeability characteristics of a sulfenamide prodrug: strategic implications in considering sulfenamide prodrugs for oral delivery of NH-acids.

The objective of this Letter is both to report the permeability results of a linezolid-based sulfenamide prodrug in an MDCK cell model (enterocyte surrogate system) and to discuss the strategic implications of these results for considering sulfenamide prodrugs to enhance the oral delivery of weakly acidic NH-acids (e.g., amides, ureas, etc.). The two main findings from this study are that the sulfenamide prodrug does not appear to survive intracellular transport due to conversion to linezolid and that there appears to be an apically-oriented surface conversion pathway that can additionally serve to convert the sulfenamide prodrug to linezolid upon approach of the apical membrane. It is hoped that these findings, along with the discussion of the strategic implications, will facilitate a greater awareness of the potential strengths and weaknesses inherent in the sulfenamide prodrug approach for enhancing the oral delivery of weakly acidic NH-acid drugs.

Preparation, characterization and in vivo conversion of new water-soluble sulfenamide prodrugs of carbamazepine.

Improved synthetic methods are reported for the preparation of sulfenamide derivatives of carbamazepine (CBZ) for evaluation as prodrugs. These sulfenamide prodrugs were designed to rapidly release CBZ in vivo by cleavage of the sulfenamide bond by chemical reaction with glutathione and other sulfhydryl compounds. Physicochemical characterization and in vivo conversion of a new prodrug of CBZ was evaluated to further establish the proof of concept of the sulfenamide prodrug approach.

Sulfenamides as prodrugs of NH-acidic compounds: a new prodrug option for the amide bond.

The objective of this report is to introduce the novel concept of utilizing sulfenamides as prodrugs for compounds containing an NH-acidic functionality, particularly weakly acidic amide-type functionalities (amides, ureas, carbamates, etc.). Included are the syntheses and physicochemical characterizations of some model sulfenamides to illustrate the promise of this new prodrug technology.