Sébastien Guiral

MF63 [2-(6-Chloro-1H-phenanthro[9,10-d]imidazol-2-yl)-isophthalonitrile], a Selective Microsomal Prostaglandin E Synthase-1 Inhibitor, Relieves Pyresis and Pain in Preclinical Models of Inflammation

Microsomal prostaglandin E synthase-1 (mPGES-1) is a terminal prostaglandin E2 (PGE2) synthase in the cyclooxygenase pathway. Inhibitors of mPGES-1 may block PGE2 production and relieve inflammatory symptoms. To test the hypothesis, we evaluated the antipyretic and analgesic properties of a novel and selective mPGES-1 inhibitor, MF63 [2-(6-chloro-1H-phenanthro-[9,10-d]imidazol-2-yl)isophthalonitrile], in animal models of inflammation. MF63 potently inhibited the human mPGES-1 enzyme (IC50 = 1.3 nM), with a high degree (>1000-fold) of selectivity over other prostanoid synthases. In rodent species, MF63 strongly inhibited guinea pig mPGES-1 (IC50 = 0.9 nM) but not the mouse or rat enzyme. When tested in the guinea pig and a knock-in (KI) mouse expressing human mPGES-1, the compound selectively suppressed the synthesis of PGE2, but not other prostaglandins inhibitable by nonsteroidal anti-inflammatory drugs (NSAIDs), yet retained NSAID-like efficacy at inhibiting lipopolysaccharide-induced pyresis, hyperalgesia, and iodoacetate-induced osteoarthritic pain. In addition, MF63 did not cause NSAID-like gastrointestinal toxic effects, such as mucosal erosions or leakage in the KI mice or nonhuman primates, although it markedly inhibited PGE2 synthesis in the KI mouse stomach. Our data demonstrate that mPGES-1 inhibition leads to effective relief of both pyresis and inflammatory pain in preclinical models of inflammation and may be a useful approach for treating inflammatory diseases.

Development of a Liver-Targeted Stearoyl-CoA Desaturase (SCD) Inhibitor (MK-8245) to Establish a Therapeutic Window for the Treatment of Diabetes and Dyslipidemia

The potential use of SCD inhibitors for the chronic treatment of diabetes and dyslipidemia has been limited by preclinical adverse events associated with inhibition of SCD in skin and eye tissues. To establish a therapeutic window, we embarked on designing liver-targeted SCD inhibitors by utilizing molecular recognition by liver-specific organic anion transporting polypeptides (OATPs). In doing so, we set out to target the SCD inhibitor to the organ believed to be responsible for the therapeutic efficacy (liver) while minimizing its exposure in the tissues associated with mechanism-based SCD depletion of essential lubricating lipids (skin and eye). These efforts led to the discovery of MK-8245 (7), a potent, liver-targeted SCD inhibitor with preclinical antidiabetic and antidyslipidemic efficacy with a significantly improved therapeutic window.

Synthesis and biological activity of a potent and orally bioavailable SCD inhibitor (MF-438)

A series of stearoyl-CoA desaturase 1 (SCD1) inhibitors were developed. Investigations of enzyme potency and metabolism led to the identification of the thiadiazole-pyridazine derivative MF-438 as a potent SCD1 inhibitor. MF-438 exhibits good pharmacokinetics and metabolic stability, thereby serving as a valuable tool for further understanding the role of SCD inhibition in biological and pharmacological models of diseases related to metabolic disorders.

Discovery of disubstituted phenanthrene imidazoles as potent, selective and orally active mPGES-1 inhibitors

Phenanthrene imidazoles 26 and 44 have been identified as novel potent, selective and orally active mPGES-1 inhibitors. These inhibitors are significantly more potent than the previously reported chlorophenanthrene imidazole 1 (MF63) with a human whole blood IC50 of 0.20 and 0.14 microM, respectively. It exhibited a significant analgesic effect in a guinea pig hyperalgesia model at oral doses as low as 14 mg/kg. Both active and selective mPGES-1 inhibitors (26 and 44) have a relatively distinct pharmacokinetic profile and are suitable for clinical development.

SAR and optimization of thiazole analogs as potent stearoyl-CoA desaturase inhibitors.

Elevated stearoyl-CoA desaturase (SCD) activity has been linked to a number of metabolic disorders including obesity and type II diabetes. Compound 3j, a potent SCD inhibitor (human HepG2 IC(50)=1nM) was identified from the optimization of a lead thiazole compound MF-152 with over 100-fold improvement in potency. In a 4-week chronic oral dosing at 0.2mg/kg, 3j gave a robust 24% prevention of body weight gain in mice fed on a high fat diet accompanied with an improved metabolic profile on insulin and glucose levels.

Biarylimidazoles as inhibitors of microsomal prostaglandin E2 synthase-1

Microsomal prostaglandin E(2) synthase (mPGES-1) represents a potential target for novel analgesic and anti-inflammatory agents. High-throughput screening identified several leads of mPGES-1 inhibitors which were further optimized for potency and selectivity. A series of inhibitors bearing a biaryl imidazole scaffold exhibits excellent inhibition of PGE(2) production in enzymatic and cell-based assays. The synthesis of these molecules and their activities will be discussed.

Discovery of MK-1439, an orally bioavailable non-nucleoside reverse transcriptase inhibitor potent against a wide range of resistant mutant HIV viruses.

The optimization of a novel series of non-nucleoside reverse transcriptase inhibitors (NNRTI) led to the identification of pyridone 36. In cell cultures, this new NNRTI shows a superior potency profile against a range of wild type and clinically relevant, resistant mutant HIV viruses. The overall favorable preclinical pharmacokinetic profile of 36 led to the prediction of a once daily low dose regimen in human. NNRTI 36, now known as MK-1439, is currently in clinical development for the treatment of HIV infection.

Biological activity and preclinical efficacy of azetidinyl pyridazines as potent systemically-distributed stearoyl-CoA desaturase inhibitors

Potent and orally bioavailable SCD inhibitors built on an azetidinyl pyridazine scaffold were identified. In a one-month gDIO mouse model of obesity, we demonstrated that there was no therapeutic index even at low doses; efficacy in preventing weight gain tracked closely with skin and eye adverse events. This was attributed to the local SCD inhibition in these tissues as a consequence of the broad tissue distribution observed in mice for this class of compounds. The search for new structural scaffolds which may display a different tissue distribution was initiated. In preparation for an HTS campaign, a radiolabeled azetidinyl pyridazine displaying low non-specific binding in the scintillation proximity assay was prepared.

An Automated Multistep High-Throughput Screening Assay for the Identification of Lead Inhibitors of the Inducible Enzyme mPGES-1

Prostaglandin E2 synthase (mPGES-1), the enzyme which catalyzes the synthesis of PGE2, is induced during the inflammatory response. For this reason, mPGES-1 could be a potential therapeutic target. A high-throughput screening assay was developed to identify potential inhibitors of mPGES-1. The assay consisted of a 30-s mPGES-1 enzymatic reaction followed by the detection of PGE2 by enzyme immunoassay (EIA). The enzymatic reaction was performed in a batch mode because the instability of the substrate (10 min) limited the number of plates assayed within a working day. The detection of the product by EIA was performed on 3 instruments requiring 14 different steps for complete automation. The authors describe here the optimization and implementation of a 2-part assay on a Thermo CRS robotic system. More than 315,000 compounds were tested, and a hit rate of 0.84% was obtained for this assay. Although the entire assay required multiple steps, the assay was successfully miniaturized and automated for a high-throughput screening campaign.

Discovery of potent and liver-targeted stearoyl-CoA desaturase (SCD) inhibitors in a bispyrrolidine series

Inhibition of stearoyl-CoA desaturase (SCD) activity represents a potential novel mechanism for the treatment of metabolic disorders including obesity and type II diabetes. To circumvent skin and eye adverse events observed in rodents with systemically-distributed SCD inhibitors, our research efforts have been focused on the search for new and structurally diverse liver-targeted SCD inhibitors. This work has led to the discovery of novel, potent and structurally diverse liver-targeted bispyrrolidine SCD inhibitors. These compounds possess suitable cellular activity and pharmacokinetic properties to inhibit liver SCD activity in a mouse pharmacodynamic model.