William R. Ewing

Eleven Amino Acid Glucagon-like Peptide-1 Receptor Agonists with Antidiabetic Activity

Glucagon-like peptide 1 (GLP-1) is a 30 or 31 amino acid peptide hormone that contributes to the physiological regulation of glucose homeostasis and food intake. Herein, we report the discovery of a novel class of 11 amino acid GLP-1 receptor agonists. These peptides consist of a structurally optimized 9-mer, which is closely related to the N-terminal 9 amino acids of GLP-1, linked to a substituted C-terminal biphenylalanine (BIP) dipeptide. SAR studies resulted in 11-mer GLP-1R agonists with similar in vitro potency to the native 30-mer. Peptides 21 and 22 acutely reduced plasma glucose excursions and increased plasma insulin concentrations in a mouse model of diabetes. These peptides also showed sustained exposures over several hours in mouse and dog models. The described 11-mer GLP-1 receptor agonists represent a new tool in further understanding GLP-1 receptor pharmacology that may lead to novel antidiabetic agents.

Sulfonamidopyrrolidinone factor Xa inhibitors : Potency and selectivity enhancements via P-1 and P-4 optimization

Sulfonamidopyrrolidinones were previously disclosed as a selective class of factor Xa (fXa) inhibitors, culminating in the identification of RPR120844 as a potent member with efficacy in vivo. Recognizing the usefulness of the central pyrrolidinone template for the presentation of ligands to the S-1 and S-4 subsites of fXa, studies to optimize the P-1 and P-4 groups were initiated. Sulfonamidopyrrolidinones containing 4-hydroxy- and 4-aminobenzamidines were discovered to be effective inhibitors of fXa. X-ray crystallographic experiments in trypsin and molecular modeling studies suggest that our inhibitors bind by insertion of the 4-hydroxybenzamidine moiety into the S-1 subsite of the fXa active site. Of the P-4 groups examined, the pyridylthienyl sulfonamides were found to confer excellent potency and selectivity especially in combination with 4-hydroxybenzamidine. Compound 20b (RPR130737) was shown to be a potent fXa inhibitor (K(i) = 2 nM) with selectivity against structurally related serine proteinases (>1000 times). Preliminary biological evaluation demonstrates the effectiveness of this inhibitor in common assays of thrombosis in vitro (e.g. activated partial thromboplastin time) and in vivo (e.g. rat FeCl(2)-induced carotid artery thrombosis model).

The Design of Competitive, Small-molecule Inhibitors of Coagulation Factor Xa

The last five years have seen an explosion of research into inhibitors of Factor Xa as potential antithrombotic agents. Aventis Pharma was a participant in this effort and its two founder companies have substantially contributed to the discovery of new inhibitors over the years. This review traces the systematic development of the former Rhone-Poulenc Rorer factor Xa program from conception to the realization of potent, orally bioavailable inhibitors with exquisite selectivity against other serine proteases. The work on beta-aminoesters described in Part 1 culminates in the development of FXV673 (Ki = 0.5 nM), an effective anticoagulant for acute indications. Part 2.2 details the de novo design of the pyrrolidinone series of inhibitors (RPR120844), within which a group of efficacious i.v. agents were identified (e.g. RPR130737, Ki = 2 nM). The first active and bioavailable benzamidine isostere i.e. the 1-aminoisoquinoline (RPR208815, Ki = 22 nM) was discovered on the pyrrolidinone scaffold (Part 2.3). Ultimately a variety of benzamidine mimics were explored and incorporated into the ketopiperazine series; the 6-substituted aminoquinazolines were found to be the most potent (Part 3). The azaindole, as represented by RPR200443 (Ki = 4 nM), stands out as imparting favorable pharmacokinetic properties to the sulfonamido-ketopiperazines.

Potent biphenyl- and 3-phenyl pyridine-based inhibitors of acetyl-CoA carboxylase.

We report the synthesis and enzymatic evaluation of potent inhibitors of acetyl-CoA carboxylases (ACCs) containing biphenyl or 3-phenyl pyridine cores. These compounds inhibit both ACC1 and ACC2, or are moderately selective for either enzyme, depending on side chain substitution. Typical activities of the most potent compounds in this class are in the low double-digit to single-digit nanomolar range in in vitro assays using human ACC1 and ACC2 enzymes.

Decarboxylative alkylation for site-selective bioconjugation of native proteins via oxidation potentials

The advent of antibody–drug conjugates as pharmaceuticals has fuelled a need for reliable methods of site-selective protein modification that furnish homogeneous adducts. Although bioorthogonal methods that use engineered amino acids often provide an elegant solution to the question of selective functionalization, achieving homogeneity using native amino acids remains a challenge. Here, we explore visible-light-mediated single-electron transfer as a mechanism towards enabling site- and chemoselective bioconjugation. Specifically, we demonstrate the use of photoredox catalysis as a platform to selectivity wherein the discrepancy in oxidation potentials between internal versus C-terminal carboxylates can be exploited towards obtaining C-terminal functionalization exclusively. This oxidation potential-gated technology is amenable to endogenous peptides and has been successfully demonstrated on the protein insulin. As a fundamentally new approach to bioconjugation this methodology provides a blueprint toward the development of photoredox catalysis as a generic platform to target other redox-active side chains for native conjugation. Selectively targeting native amino acids for late-stage protein modification is a significant challenge, but now it has been shown that photoredox catalysis can be used to specifically target protein C-termini toward decarboxylative-alkylation with Michael acceptors. This technology harnesses innate differences in side-chain oxidation potentials to select between the various functional groups typical among proteins in order to form a single modified product.

Reductions in log P improved protein binding and clearance predictions enabling the prospective design of cannabinoid receptor (CB1) antagonists with desired pharmacokinetic properties.

Several strategies have been employed to reduce the long in vivo half-life of our lead CB1 antagonist, triazolopyridazinone 3, to differentiate the pharmacokinetic profile versus the lead clinical compounds. An in vitro and in vivo clearance data set revealed a lack of correlation; however, when compounds with <5% free fraction were excluded, a more predictable correlation was observed. Compounds with log P between 3 and 4 were likely to have significant free fraction, so we designed compounds in this range to give more predictable clearance values. This strategy produced compounds with desirable in vivo half-lives, ultimately leading to the discovery of compound 46. The progression of compound 46 was halted due to the contemporaneous marketing and clinical withdrawal of other centrally acting CB1 antagonists; however, the design strategy successfully delivered a potent CB1 antagonist with the desired pharmacokinetic properties and a clean off-target profile.

To Market, To Market—2011

Abstract This years To-Market-To-Market chapter provides summaries for 26 new molecular entities (NMEs) that received first time approval world-wide in 2011. •Anticancer agents topped the list with seven first-time NMEs, of which five are small molecules and two are biologic agents. In the infectious disease area, three antiviral agents and one antibacterial agent were approved. There were three first-time NME drug approvals each for central nervous system, cardiovascular, and endocrine diseases. There were also three approvals in the immunology therapeutic area, with one small molecule two biologic agents. The remaining NMEs include a biologic agent for macular degeneration, a small molecule for the rare disease transthyretin familial amyloidosis, and a small molecule for urinary incontinence. The summaries include indication, information about the disease treated, mechanism of action, selected preclinical data, key steps in the synthesis, pharmacokinetic metabolism profile, clinical efficacy and safety data, and other key information about the approval.

Identification of potent 11mer Glucagon-Like Peptide-1 Receptor agonist peptides with novel C-terminal amino acids: Homohomophenylalanine analogs

We report the identification of potent agonists of the Glucagon-Like Peptide-1 Receptor (GLP-1R). These compounds are short, 11 amino acid peptides containing several unnatural amino acids, including (in particular) analogs of homohomophenylalanine (hhPhe) at the C-terminal position. Typically the functional activity of the more potent peptides in this class is in the low picomolar range in an in vitro cAMP assay, with one example demonstrating excellent in vivo activity in an ob/ob mouse model of diabetes.

To Market, To Market—2010

Publisher Summary This chapter provides summaries of 24 new molecular entities (NMEs) that have been approved for the first time worldwide, of which 19 are small molecules. Twelve of the summaries presented in the chapter were first approved in the United States and seven were first approved in the European Union. The remaining NMEs are from Canada, Japan, and Russia. Treatments for cancer dominate the list of the NMEs, with five drug approvals for small molecules and approval of the first vaccine for hormone-refractory prostate cancer. The infectious and cardiovascular disease areas are next in the number of new drug approvals, with three each. Two new drugs were approved for the treatment of multiple sclerosis and associated symptoms. In the anticancer area, five new small molecules were approved along with a novel therapeutic vaccine for the treatment of hormone-refractory prostate cancer. Four of the small molecules are related to natural products and one is a cyclic peptide.

REDUCTION OF SITE-SPECIFIC CYP3A-MEDIATED METABOLISM FOR DUAL ANGIOTENSIN AND ENDOTHELIN RECEPTOR ANTAGONISTS IN VARIOUS IN VITRO SYSTEMS AND IN CYNOMOLGUS MONKEYS

2-{Butyryl-[2′-(4,5-dimethyl-isoxazol-3-ylsulfamoyl)-biphenyl-4-ylmethyl]-amino}-N-isopropyl-3-methyl-butyramide (BMS-1) is a potent dual acting angiotensin-1 and endothelin-A receptor antagonist. The compound was subject to rapid metabolic clearance in monkey and human liver microsomes and exhibited low systemic exposure and marked interanimal variability in cynomolgus monkeys after p.o. administration. The variability pattern was identical to that of midazolam given p.o. in the same monkeys, as measured by area under the curve and Cmax values, suggesting that CYP3A-mediated metabolism might play a role in the rapid clearance and observed interanimal variability. Subsequent in vitro metabolism studies using human liver microsomes and cDNA-expressed human cytochrome P450 (P450) enzymes revealed that BMS-1 was a CYP3A4 substrate and was not metabolized by other human P450 enzymes. Mass spectral and NMR analyses of key metabolites led to the identification of the dimethyl isoxazole group as a major metabolic soft spot for BMS-1. Replacement of the 4-methyl group on the isoxazole ring with halogens not only improved overall metabolic stability but also decreased CYP3A-mediated hydroxylation of the isoxazole 5-methyl group. As exemplified by 2-{butyryl-[2′-(4-fluoro-5-methyl-isoxazol-3-ylsulfamoyl)-biphenyl-4-ylmethyl]-amino}-N-isopropyl-3-methyl-butyramide (BMS-3), a fluorinated analog of BMS-1, the structural modification resulted in an increase in the systemic exposure relative to previous analogs and a dramatic reduction in interanimal variability in the monkeys after p.o. administration. In addition, BMS-3 could be metabolized by both CYP2C9 and CYP3A4, thus avoiding the reliance on a single P450 enzyme for metabolic clearance. Integration of results obtained from in vitro metabolism studies and in vivo pharmacokinetic evaluations enabled the modulation of site-specific CYP3A-mediated metabolism, yielding analogs with improved overall metabolic profiles.