Discovery and Characterization of the Topical Soft JAK Inhibitor CEE321 for Atopic Dermatitis

The JAK kinases JAK1, JAK2, JAK3, and TYK2 play key roles in cytokine signaling. Activation of the JAK/STAT pathways is linked to many diseases involving the immune system, including atopic dermatitis. As systemic JAK inhibitor pharmacology is associated with side effects, topical administration to the skin has been considered to locally restrict the site of action. Several orally bioavailable JAK inhibitors repurposed for topical use have been recently approved or are in clinical development. Here, we disclose our clinical candidate CEE321, which is a potent pan JAK inhibitor in enzyme and cellular assays. In contrast to repurposed oral drugs, CEE321 does not display high potency in blood and has a high clearance in vivo. Therefore, we consider CEE321 to be a "soft drug". When applied topically to human skin that was stimulated with the cytokines IL4 and IL13 ex vivo, CEE321 potently inhibited biomarkers relevant to atopic dermatitis.

ADAM17 is the main sheddase for the generation of human triggering receptor expressed in myeloid cells (hTREM2) ectodomain and cleaves TREM2 after Histidine 157

Triggering receptor expressed in myeloid cells (TREM2) is a member of the immunoglobulin superfamily and is expressed in macrophages, dendritic cells, microglia, and osteoclasts. TREM2 plays a role in phagocytosis, regulates release of cytokine, contributes to microglia maintenance, and its ectodomain is shed from the cell surface. Here, the question was addressed at which position sheddases cleave TREM2 and what are the proteases involved in this process. Using both pharmacological and genetic approaches we report that the main protease contributing to the release of TREM2 ectodomain is ADAM17, (a disintegrin and metalloproteinase domain containing protein, also called TACE, TNFα converting enzyme) while ADAM10 plays a minor role. Complementary biochemical experiments reveal that cleavage occurs between histidine 157 and serine 158. Shedding is not altered for the R47H-mutated TREM2 protein that confers an increased risk for the development of Alzheimers disease. These findings reveal a link between shedding of TREM2 and its regulation during inflammatory conditions or chronic neurodegenerative disease like AD in which activity or expression of sheddases might be altered.

Evaluation of relative MS response factors of drug metabolites for semi-quantitative assessment of chemical liabilities in drug discovery

Drug metabolism studies are performed in drug discovery to identify metabolic soft spots, detect potentially toxic or reactive metabolites and provide an early insight into potential species differences. The relative peak area approach is often used to semi-quantitatively estimate the abundance of metabolites. Differences in the liquid chromatography-mass spectrometry responses result in an underestimation or overestimation of the metabolite and misinterpretation of results. The relative MS response factors (RF) of 132 structurally diverse drug candidates and their 233 corresponding metabolites were evaluated using a capillary-liquid chromatography/high-resolution mass spectrometry system. All of the synthesized metabolites discussed here were previously identified as key biotransformation products in discovery investigations or predicted to be formed. The most commonly occurring biotransformation mechanisms such as oxygenation, dealkylation and amide cleavage are represented within this dataset. However, relatively few phase II metabolites were evaluated because of the limited availability of authentic standards. Approximately 85% of these metabolites had a relative RF in the range between 0.2 (fivefold under-prediction) and 2.0 (twofold over-prediction), and the median MS RF was 0.6. Exceptions to this included very small metabolites that were hardly detectable. Additional experiments performed to understand the impact of the MS platform, flow rate and concentration suggested that these parameters do not have a significant impact on the RF of the compounds tested. This indicates that the use of relative peak areas to semi-quantitatively estimate the abundance of metabolites is justified in the drug discovery setting in order to guide medicinal chemistry efforts. Copyright © 2017 John Wiley & Sons, Ltd.

Increasing metabolic stability via the deuterium kinetic isotope effect: An example from a proline-amide-urea aminothiazole series of phosphatidylinositol-3 kinase alpha inhibitors

In vitro metabolic identification studies with a PI3K-α inhibitor lead molecule 1 identified a single predominant site of oxidative metabolism to be occurring within a tert.butyl moiety. Modification of the tert.butyl group within the lead molecule 1, to the corresponding d9-tert.butyl analogue 2, led to an increase in both the in vitro and in vivo metabolic stability. This increase in metabolic stability resulted in a 2-fold increase in the oral bioavailability measured in the rat, and a 3-fold increase in potency in a chronic in vivo study in the mouse, for 2 when compared to 1.

Discovery of NVP-BYL719 a potent and selective phosphatidylinositol-3 kinase alpha inhibitor selected for clinical evaluation

Phosphatidylinositol-3-kinase α (PI3Kα) is a therapeutic target of high interest in anticancer drug research. On the basis of a binding model rationalizing the high selectivity and potency of a particular series of 2-aminothiazole compounds in inhibiting PI3Kα, a medicinal chemistry program has led to the discovery of the clinical candidate NVP-BYL719.

Orthoamide und Iminiumsalze, LXXIV [1]. Umsetzung von N,N,N´,N´-Tetramethyl-chlorformamidiniumchlorid mit Metallen

N,N,N’,N’-Tetramethyl-formamidinium chloride (2a) reacts with elemental sodium in various solvents to give N,N,N’,N’,N’’,N’’-hexamethyl-guanidinium chloride (4a). The reaction of 2a with potassium affords N,N,N’,N’,N’’,N’’,N’’’,N’’’-octamethyl-oxamidinium dichloride (3a). From the reaction of 2a with magnesium in different solvents in general result mixtures of the salts 4a, 3a and N,N,N’,N’-tetramethyl-formamidinium chloride (10a). The composition of these mixtures depends on the solvent and the reaction temperature. Similar results are obtained, when a zinc/copper couple is used instead of magnesium. Very likely from 2a and magnesium or zinc, respectively, organometallic intermediates 11, 12 are formed which could be trapped by aromatic aldehydes and phenylisocyanate. The salt 2a can be reductively coupled by a low-valent titanium reagent to give the oxamidinium salt 3a.

Biocatalytic synthesis and structure elucidation of cyclized metabolites of the deacetylase inhibitor panobinostat (LBH589)

Panobinostat (LBH589) is a novel pan-deacetylase inhibitor that is currently being evaluated in phase III clinical trials for treatment of Hodgkin's lymphoma and multiple myeloma. Under catalysis of recombinant human CYP3A4 and CYP2D6 coexpressed with human cytochrome P450 reductase in Escherichia coli JM109, five metabolites of panobinostat were produced via whole-cell biotransformation. The structures of the metabolites were elucidated with the spectroscopic methods mass spectrometry (MS) and NMR and revealed an oxidative cyclization of the ethyl-amino group to the methylindole moiety. The MS(2) spectrum of the cyclized metabolite showed a base peak, where the closed ring is reopened and that, taken as sole base for structure proposals, would have lead to wrong conclusions. The metabolites were substantially less potent deacetylase inhibitors than the parent compound.

Exploring subtype selectivity and metabolic stability of a novel series of ligands for the benzodiazepine binding site of the GABAA receptor

A novel series of agonists at the benzodiazepine binding site of the GABA(A) receptor was prepared by functionalizing a known template. Adding substituents to the pyrazolone-oxygen of CGS-9896 led to a number of compounds with selectivities for either α2- or α1-containing GABA(A) receptor subtypes offering an entry into indications such as anxiety and insomnia. In this communication, structure-activity relationship and efforts to increase in vitro stabilities are discussed.

In vivo and in vitro SAR of tetracyclic MAPKAP-K2 (MK2) inhibitors. Part I

Pyrrolo[2,3-f]isoquinoline based amino acids, tetracyclic lactams and cyclic ketone analogues are described as novel MK2 inhibitors with IC(50) as low as 5nM and good selectivity profiles against a number of related kinases including ERK, p38alpha and JNKs. TNFalpha release was suppressed from human peripheral blood mononuclear cells (hPBMCs), and a representative compound inhibited LPS induced TNFalpha release in mice illustrating the potential of this series to provide orally active MK2 inhibitors.

2-Cyano-pyrimidines: A New Chemotype for Inhibitors of the Cysteine Protease Cathepsin K

Starting from the purine lead structure 1, a new series of cathepsin K inhibitors based on a pyrimidine scaffold have been explored. Investigations of P3 and P2 substituents based on molecular modeling suggestions resulted in potent cathepsin K inhibitors with an improved selectivity profile over other cathepsins.

Dipeptide nitrile inhibitors of cathepsin K

A series of dipeptidyl nitriles as inhibitors of cathepsin K have been explored starting from lead structure 1 (Cbz-Leu-NH-CH2-CN, IC50 = 39 nM). Attachment of non-natural amino acid side chains in P1 and modification of the P3 subunit led to inhibitors with higher potency and improved pharmacokinetic properties.

Identification of natural ligands of retinoic acid receptor-related orphan receptor α ligand-binding domain expressed in Sf9 cells––a mass spectrometry approach

The ligand-binding domain (LBD) of the human retinoic acid receptor-related orphan receptor (RORalpha-LBD), expressed in Sf9 cells, was purified and analyzed by electrospray ionization-mass spectrometry (ESI-MS). ESI-MS operated under native conditions showed the presence of a fortuitous ligand with molecular weight 386. Further analysis by gas chromatography-mass spectrometry (GC-MS) allowed the identification of the ligands bound to the LBD. Cholesterol (77%) and 7-dehydrocholesterol (provitamin D(3); 18%) were shown to be the major ligands. A monohydroxylated cholesterol derivative was identified as a minor ligand. In addition, ligand exchange experiments monitored by ESI-MS showed that cholesterol sulfate has a higher affinity for RORalpha-LBD than cholesterol and 25-hydroxycholesterol. Binding of coactivator (CoA) peptide GRIP1P was shown to occur in a stoichiometric manner. Therefore, monitoring of binding of CoAs by mass spectrometry could be used for classification of the ligands as agonist or antagonist molecules.

Complementary use of ion trap/time-of-flight mass spectrometry in combination with capillary high-pressure liquid chromatography: early characterization of in vivo metabolites of the cathepsin K inhibitor NVP-AAV490 in rat

Cathepsin K is a cysteine proteinase, primarily expressed in osteoclasts, which has a strong collagenolytic activity and plays an essential role involved in bone matrix degradation. Its inhibition could provide a novel approach to the treatment and prevention of osteoporosis. One structural class of lead compounds in our cathepsin K inhibitors program is based on an arylaminoethyl amide scaffold, which has potential metabolic weak points that might be stabilized by appropriate chemical modification(s). For the identification of potential metabolic "soft spots" and the rational design of improved derivatives, early biotransformation of a potent arylaminoethyl amide cathepsin K inhibitor (NVP-AAV490-NX) was investigated in plasma, urine and liver homogenates of rats after intravenous bolus administration of 10 mg/kg. The detection and identification of metabolites was achieved by high-resolution mass spectrometry (time-of-flight MS) and multi-dimensional mass spectrometry (ion trap MS). Both mass spectrometers were combined with reversed-phase capillary high-performance liquid chromatography columns. It was demonstrated that both mass analyzers complement each other and that, even in the sub-nanogram range, the resulting set of MS data can be successfully used to elucidate most of the metabolic changes unambiguously, solely by mass spectrometric techniques. The proposed metabolite structures were additionally corroborated by exact mass measurement of the protonated molecular ions to confirm the predicted elemental composition, by determination of the number of the exchangeable hydrogen atoms replacing water against deuterium oxide as mobile phase and, in one case, by an MS(3) product ion experiment in order to elucidate the site of conjugation.

In vivo metabolism of epothilone B in tumor-bearing nude mice: identification of three new epothilone B metabolites by capillary high-pressure liquid chromatography/mass spectrometry/tandem mass spectrometry

Epothilone B is a 16-membered macrolide produced by the myxobacterium Sorangium cellulosum and is currently under clinical investigation. Experimentally, epothilone B demonstrates potent antiproliferative activity at the nanomolar level in vitro, and potent regression-producing antitumor activity in vivo, similar to paclitaxel (Taxol). In order to foster the design of improved derivatives, the potential biotransformation products of epothilone B formed in liver of tumor-bearing mice after intravenous administration of 10 mg/kg were characterized in an early stage of compound development. Solely on the basis of capillary high-performance liquid chromatography, combined either with electrospray tandem mass spectrometry (in precursor and product ion scan mode) and single analyzing time-of-flight mass spectrometry (H/D exchange and accurate mass measurement), three main metabolites could be detected. The three metabolites, formed by the liver, have in common that the epoxide ring was hydrolyzed and that the macrocyclic lactone ring was opened to the acid. In two cases it is assumed that open-chain intermediates re-cycled either to a lactone or, after conjugation with taurine, to the respective lactam. The proposed structures were additionally supported by the determination of the number of the exchangeable hydrogen atoms and by confirmation of the proposed elemental composition by exact mass measurement.

Determination of the GABA(B) receptor agonist CGP 44532 (3-amino-2-hydroxypropylmethylphosphinic acid) in rat plasma after pre-column derivatization by micro-high-performance liquid chromatography combined with negative electrospray tandem mass spectrometry

An assay, based on pre-column derivatization and micro-high-performance liquid chromatography-tandem mass spectrometry, was developed for the determination of the GABA(B) agonist CGP 44532 in rat plasma. CGP 44532, a highly polar 3-amino-2(S)-hydroxypropylmethylphosphinic acid, presented difficulties in developing a chromatographic method for the analysis of the compound in rat plasma. Instead of analyzing the target compound directly, it was derivatized prior to separation to a 4-nitrobenzylcarbamate isopropyliden derivative. In order to reach the required quantitation limit, on-line solid-phase extraction was utilized for sample clean-up and reversed-phase micro-column high-performance liquid chromatography, for separation of the plasma samples. The separated compounds were detected by negative electrospray tandem mass spectrometry in selected reaction monitoring mode. The derivatives show good chromatographic and mass spectrometric properties and both the target compound and the internal standard, could be eluted as symmetrical peaks with good signal/noise ratio. The MS-MS detection was selective and sensitive due to the straight fragmentation pattern. After injection of 200-microl sample aliquots, the limit of quantification was 10 ng ml(-1). The analytical assay is usable in the range of 10-500 ng ml(-1).

Investigation of combwax of honeybees with high-temperature gas chromatography and high-temperature gas chromatography-chemical ionization mass spectrometry. II: High-temperature gas chromatography-chemical ionization mass spectrometry

Crude combwax of six various honey bee species have been analyzed by high-temperature gas chromatography (HTGC)-chemical ionization mass spectrometry after a two-step silylation procedure. An optimized chromatographic procedure, described previously, enables the separation of high-molecular mass lipid compounds resulting in a characteristic fingerprint of the combwaxes of different honeybee species. The coupling of HTGC to mass spectrometry requires appropriate instrumentation in order to achieve sufficient sensitivity at high elution temperatures and avoid loss of chromatographic resolution. Chemical ionization was carried out using methane as reagent gas in order to determine the molecular mass of the individual compounds by means of abundant quasi molecular ions. To confirm the presence of unsaturated wax esters, ammonia was used as reagent gas. More than 80 lipid constituents were separated and characterized by their mass spectra. Representative chemical ionization mass spectra of individual compounds are presented. Both, HTGC-flame ionization detection data and the results of the HTGC-mass spectrometric investigations enabled a rapid profiling of the individual classes of compounds in crude combwaxes.

Investigation of combwax of honeybees with high-temperature gas chromatography and high-temperature gas chromatography-chemical ionization mass spectrometry. I. High-temperature gas chromatography

The combwaxes of the honeybee species Apis mellifera, Apis cerana, Apis dorsata, Apis laboriosa, Apis florea and Apis andreniformis have been examined by high-temperature gas chromatography. Combwax consists of a complex mixture of homologous neutral lipids. These compounds containing up to 64 carbons were chromatographed intact on a 10 m x 0.2 mm high-temperature stable SOP-50-PFD (50%-diphenyl/50%-1H,1H,2H,2H-perfluorodecylmethylpolysiloxane)-co ated Duran glass capillary column. The use of this stationary phase results in lower retention values and, at last, in lower thermal stress of the analytes. In order to minimize the discrimination effect due to adsorption and/or degradation, a two-step derivatization was performed resulting in the formation of tert.-butyldimethylsilyl esters of the long chain fatty acids and trimethylsilyl ethers of complex hydroxyesters, respectively. The derivatization procedure was optimized using a modification of the extended Donike test. In addition this test allows the quantification of the thermal stability of the derivatives performed. The derivatization procedure was applied for combwax analysis. More than 80 compounds were separated and their peak areas semiquantitatively exploited.

Determination of 2-hydroxypropyl-gamma-cyclodextrin in plasma of cynomolgus monkeys after oral administration by gas chromatography-mass spectrometry

This report describes a specific and highly sensitive gas chromatography-mass spectrometry (GC-MS) assay for the analysis of industrially produced 2-hydroxypropyl-gamma-cyclodextrin, a heterogeneous mixture of homologues and isomers, in plasma of cynomolgus monkeys. Instead of analyzing the polysaccharide mixture as a whole, in a first step the HP-gamma-cyclodextrin mixture, together with the internal standard (2,6-di-O-methyl-beta-cyclodextrin), was deuteromethylated, and in a second step hydrolyzed with hydrochloric acid to the respective monosaccharides. The resulting reaction mixture was trimethylsilylated to 1,4-bis(O-trimethylsilyl)-2,3-bis-O-deuteromethyl-6-O-2'-deuter omethoxypropylglucose (representative for HP-gamma-CD) and 1,4-bis-(O-trimethylsilyl)-bis-2,6-O-methyl-3-O-deuteromethylglucose+ ++ (representative for the internal standard), respectively, and analyzed by GC-MS. The limit of quantification of this assay was 20 nmol/l.

Analysis of the seed oil of Heisteria silvanii (Olacaceae)--a rich source of a novel C18 acetylenic fatty acid

Besides some usual fatty acids (FA), two conjugated ene-yne acetylenic FA [trans-10-heptadecen-8-ynoic acid (pyrulic acid) (7.4%), and trans-11-octadecen-9-ynoic acid (ximenynic acid) (3.5%)], a novel ene-yne-ene acetylenic FA [cis-7, trans-11-octadecadiene-9-ynoic acid (heisteric acid) (22.6%)], and 9,10-epoxystearic acid (0.6%) could be identified in the seed oil of Heisteria silvanii (Olacaceae). Two further conjugated acetylenic FA [9,11-octadecadiynoic acid (0.1%) and 13-octadecene-9,11-diynoic acid (0.4%)] were identified tentatively by their mass spectra. The FA mixture has been analyzed by gas chromatography/mass spectrometry (GC/MS) of their methyl ester and 4,4-dimethyloxazoline derivatives. The structure of heisteric acid was elucidated after isolation via preparative silver ion thin-layer chromatography and by various spectroscopic methods [ultraviolet; infrared; 1H, 13C nuclear magnetic resonance (NMR); 1H-1H and 1H-13C correlation spectroscopy]. To determine the position of the conjugated ene-yne-ene system, the NMR spectra were also measured after addition of the lanthanide shift reagent Resolve-Al EuFOD. Furthermore, the triyglyceride mixture was analyzed by high-temperature GC and high-temperature GC coupled with negative chemical ionization MS. A glass capillary column coated with a methoxy-terminated 50%-diphenyl-50%-dimethylpolysiloxane was used for the separation of the triacylglycerol (TAG) species. No evidence of decomposition of the TAG species containing conjugated ene-yne-ene FA was observed. Twenty-six species of the separated TAG were identified by means of their abundant quasi molecular ion [M - H]- and their corresponding carboxylate anions [RCOO]- of the fatty acids, respectively. The major molecular species of the TAG were found to be 16:0/18:1/18:1, 16:0/18:1/18:3 (heisteric acid), 17:2 (pyrulic acid)/18:1/18:1, 18:1/18:1/18:3 (heisteric acid). The TAG containing acetylenic FA showed an unexpected increase of the retention time in comparison to the TAG containing usual FA, thus making the prediction of the elution order of lipid samples containing acetylenic FA difficult.