Identification and biological activity of 6-alkyl-substituted 3-methyl-pyridine-2-carbonyl amino dimethyl-benzoic acid EP4 antagonists

Docking for EP4R antagonists active against inflammatory pain

The lipid prostaglandin E2 (PGE2) mediates inflammatory pain by activating G protein-coupled receptors, including the prostaglandin E2 receptor 4 (EP4R). Nonsteroidal anti-inflammatory drugs (NSAIDs) reduce nociception by inhibiting prostaglandin synthesis, however, the disruption of upstream prostanoid biosynthesis can lead to pleiotropic effects including gastrointestinal bleeding and cardiac complications. In contrast, by acting downstream, EP4R antagonists may act specifically as anti-inflammatory agents and, to date, no selective EP4R antagonists have been approved for human use. In this work, seeking to diversify EP4R antagonist scaffolds, we computationally dock over 400 million compounds against an EP4R crystal structure and experimentally validate 71 highly ranked, de novo synthesized molecules. Further, we show how structure-based optimization of initial docking hits identifies a potent and selective antagonist with 16 nanomolar potency. Finally, we demonstrate favorable pharmacokinetics for the discovered compound as well as anti-allodynic and anti-inflammatory activity in several preclinical pain models in mice.

Discovery of Novel, Selective Prostaglandin EP4 Receptor Antagonists with Efficacy in Cancer Models

Prostaglandin E2 (PGE2) receptor 4 (EP4) is one of four EP receptors commonly upregulated in the tumor microenvironment and plays vital roles in stimulating cell proliferation, invasion, and metastasis. Biochemical blockade of the PGE2-EP4 signaling pathway is a promising strategy for controlling inflammatory and immune related disorders. Recently combination therapies of EP4 antagonists with anti-PD-1 or chemotherapy agents have emerged in clinical studies for lung, breast, colon, and pancreatic cancers. Herein, a novel series of indole-2-carboxamide derivatives were identified as selective EP4 antagonists, and SAR studies led to the discovery of the potent compound 36. Due to favorable pharmacokinetics properties and good oral bioavailability (F = 76%), compound 36 was chosen for in vivo efficacy studies. Compound 36 inhibited tumor growth in a CT-26 colon cancer xenograft better than E7046 and a combination of 36 with capecitabine significantly suppressed tumor growth (TGI up to 94.26%) in mouse models.

A randomized clinical efficacy study targeting mPGES1 or EP4 in dogs with spontaneous osteoarthritis

Canine studies of spontaneous osteoarthritis (OA) pain add valuable data supporting drug treatment mechanisms that may translate to humans. A multicenter, randomized, double-blind, placebo- and active-controlled study was conducted in client-owned dogs with moderate OA pain to evaluate efficacy of LYA, an inhibitor of microsomal prostaglandin E synthase-1 (mPGES1), an EP4 antagonist (LYB), and carprofen, versus placebo. Of 255 dogs screened, 163 were randomized (placebo/LYA/LYB/carprofen: n = 43/39/42/39) and 158 completed treatment. Efficacy versus placebo was assessed using Bayesian mixed-effect model for repeated measure analyses of the Canine Brief Pain Inventory (CBPI) pain interference score (PIS; primary endpoint), pain severity score, and overall impression, as well as the Liverpool Osteoarthritis in Dogs (LOAD) mobility score. The posterior probability that the difference to placebo was <0 at week 2 was 80% for LYA and 54% for LYB for CBPI PIS (both <95% predefined threshold). For secondary endpoints, the posterior probability that the difference to placebo was <0 at week 2 ranged from 89 to 96% for LYA and from 56 to 89% for LYB. The posterior probabilities comparing carprofen to placebo groups were ≥90% for all efficacy endpoints. The proportion of dogs with one or more adverse event was not significantly different from placebo (32.6%) for LYA (35.9%) or carprofen (25.6%), but the rate for LYB (59.5%) was higher versus placebo (P = 0.017). LYA treatment demonstrated consistent improvement in all efficacy measures, suggesting that inhibition of mPGES1 may be an effective treatment for chronic pain associated with OA.

Impact of Cross-Coupling Reactions in Drug Discovery and Development

Cross-coupling reactions have played a critical role enabling the rapid expansion of structure-activity relationships (SAR) during the drug discovery phase to identify a clinical candidate and facilitate subsequent drug development processes. The reliability and flexibility of this methodology have attracted great interest in the pharmaceutical industry, becoming one of the most used approaches from Lead Generation to Lead Optimization. In this mini-review, we present an overview of cross-coupling reaction applications to medicinal chemistry efforts, in particular the Suzuki-Miyaura and Buchwald-Hartwig cross-coupling reactions as a remarkable resource for the generation of carbon-carbon and carbon-heteroatom bonds. To further appreciate the impact of this methodology, the authors discuss some recent examples of clinical candidates that utilize key cross-coupling reactions in their large-scale synthetic process. Looking into future opportunities, the authors highlight the versatility of the cross-coupling reactions towards new chemical modalities like DNA-encoded libraries (DELs), new generation of peptides and cyclopeptides, allosteric modulators, and proteolysis targeting chimera (PROTAC) approaches.

Druggable Prostanoid Pathway

Prostanoids (prostaglandins, prostacyclin and thromboxane) belong to the oxylipin family of biologically active lipids generated from arachidonic acid (AA). Protanoids control numerous physiological and pathological processes. Cyclooxygenase (COX) is a rate-limiting enzyme involved in the conversion of AA into prostanoids. There are two COX isozymes: the constitutive COX-1 and the inducible COX-2. COX-1 and COX-2 have similar structures, catalytic activities, and subcellular localizations but differ in patterns of expression and biological functions. Non-selective COX-1/2 or traditional, non-steroidal anti-inflammatory drugs (tNSAIDs) target both COX isoforms and are widely used to relieve pain, fever and inflammation. However, the use of NSAIDs is associated with various side effects, particularly in the gastrointestinal tract. NSAIDs selective for COX-2 inhibition (coxibs) were purposefully designed to spare gastrointestinal toxicity, but predisposed patients to increased cardiovascular risks. These health complications from NSAIDs prompted interest in the downstream effectors of the COX enzymes as novel drug targets. This chapter describes various safety issues with tNSAIDs and coxibs, and discusses the current development of novel classes of drugs targeting the prostanoid pathway, including nitrogen oxide- and hydrogen sulfide-releasing NSAIDs, inhibitors of prostanoid synthases, dual inhibitors, and prostanoid receptor agonists and antagonists.

A selective antagonist of prostaglandin E receptor subtype 4 attenuates abdominal aortic aneurysm

Abdominal aortic aneurysm (AAA) is a progressive disease that has an increasing prevalence with aging, but no effective pharmacological therapy to attenuate AAA progression is currently available. We reported that the prostaglandin E receptor EP4 plays roles in AAA progression. Here, we show the effect of CJ-42794, a selective EP4 antagonist, on AAA using two mouse models (angiotensin II- and CaCl2 -induced AAAs) and human aortic smooth muscle cells isolated from AAA tissue. Oral administration of CJ-42794 (0.2 mg/kg per day) for 4 weeks significantly decreased AAA formation in ApoE-/- mice infused with angiotensin II (1 μg/kg per min), in which elastic fiber degradation and activations of matrix metalloproteinase (MMP)-2 and MMP-9 were attenuated. Interleukin-6 (IL-6) proteins were highly expressed in the medial layer of angiotensin II-induced mouse AAA tissues, whereas this expression was significantly decreased in mice treated with CJ-42794. AAA formation induced by periaortic CaCl2 application in wild-type mice was also reduced by oral administration of CJ-42794 for 4 weeks. After oral administration of CJ-42794 beginning 2 weeks after periaortic CaCl2 application and continuing for an additional 4 weeks, the aortic diameter and elastic fiber degradation grade were significantly smaller in CJ-42794-treated mice than in untreated mice. Additionally, in smooth muscle cells isolated from human AAA tissues, stimulation of CJ-42794 inhibited PGE2 -induced IL-6 secretion in a dose-dependent manner and decreased PGE2 -induced MMP-2 activity. These data suggest that inhibition of EP4 has the potential to be a pharmacological strategy for attenuation of AAA progression.

LY3127760, a Selective Prostaglandin E4 (EP4) Receptor Antagonist, and Celecoxib: A Comparison of Pharmacological Profiles

Safety, tolerability, and pharmacology profiles of LY3127760, an EP4 antagonist, were explored in healthy subjects in a subject/investigator‐blind, parallel‐group, multiple‐ascending dose study. Cohorts consisted of 13 patients randomized to LY3127760, celecoxib (400 mg), or placebo (9:2:2 ratio) for 28 days. LY3127760 was well tolerated; the most commonly observed adverse events were gastrointestinal, similar to celecoxib. LY3127760 increased release of ex vivo tumor necrosis factor alpha after lipopolysaccharide/prostaglandin E2 stimulation when compared with placebo, suggesting a dose‐dependent blockade of the EP4 receptor. Compared with placebo, 24‐h urinary excretion of prostaglandin E metabolite was modestly increased; prostacyclin metabolite was inhibited; and thromboxane A2 metabolite was unchanged. Effects on sodium and potassium excretion were similar to those of celecoxib. We conclude that LY3127760 demonstrated similar effects on prostacyclin synthesis and renal sodium retention as celecoxib. These data support exploration of LY3127760 at daily doses of 60 mg to 600 mg in phase II trials. This trial's registration number: NCT01968070.

Analgesic and anti-inflammatory properties of novel, selective, and potent EP4 receptor antagonists

Prostaglandin (PG) E2 is the key driver of inflammation associated with arthritic conditions. Inhibitors of PGE 2 production (NSAIDs and Coxibs) are used to treat these conditions, but carry significant side effect risks due to the inhibition of all prostanoids that play important physiological function. The activities of PGE 2 are transduced through various receptor sub-types. Prostaglandin E2 type 4 receptor (EP4) is associated with the development of inflammation and autoimmunity. We therefore are interested in identifying novel EP4 antagonists to treat the signs and symptoms of arthritis without the potential side effects of PGE 2 modulators such as NSAIDs and Coxibs. Novel EP4 antagonists representing distinct chemical scaffolds were identified using a variety of in vitro functional assays and were shown to be selective and potent. The compounds were shown to be efficacious in animal models of analgesia, inflammation, and arthritis.