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While bronchodilators and inhaled corticosteroids are the mainstay of asthma treatment, up to 50% of asthmatics remain uncontrolled. Many studies show that the cysteinyl leukotriene cascade remains highly activated in some asthmatics, even those on high-dose inhaled or oral corticosteroids. Hence, inhibition of the leukotriene C4 synthase (LTC4S) enzyme could provide a new and differentiated core treatment for patients with a highly activated cysteinyl leukotriene cascade. Starting from a screening hit ( 3 ), a program to discover oral inhibitors of LTC4S led to (1 S ,2 S )-2-({5-[(5-chloro-2,4-difluorophenyl)(2-fluoro-2-methylpropyl)amino]-3-methoxypyrazin-2-yl}carbonyl)cyclopropanecarboxylic acid (AZD9898) ( 36 ), a picomolar LTC4S inhibitor (IC 50 = 0.28 nM) with high lipophilic ligand efficiency (LLE = 8.5), which displays nanomolar potency in cells (peripheral blood mononuclear cell, IC 50,free = 6.2 nM) and good in vivo pharmacodynamics in a calcium ionophore-stimulated rat model after oral dosing (in vivo, IC 50,free = 34 nM). Compound 36 mitigates the GABA binding, hepatic toxicity signal, and in vivo toxicology findings of an early lead compound 7 with a human dose predicted to be 30 mg once daily.

In order to assess the potential of sPLA 2 -X as a therapeutic target for atherosclerosis, novel sPLA 2 inhibitors with improved type X selectivity are required. To achieve the objective of identifying such compounds, we embarked on a lead generation effort that resulted in the identification of a novel series of indole-2-carboxamides as selective sPLA2-X inhibitors with excellent potential for further optimization., Competing Interests: The authors declare no competing financial interest.

A lead generation campaign identified indole-based sPLA 2 -X inhibitors with a promising selectivity profile against other sPLA 2 isoforms. Further optimization of sPLA 2 selectivity and metabolic stability resulted in the design of (-)- 17 , a novel, potent, and selective sPLA 2 -X inhibitor with an exquisite pharmacokinetic profile characterized by high absorption and low clearance, and low toxicological risk. Compound (-)- 17 was tested in an ApoE -/- murine model of atherosclerosis to evaluate the effect of reversible, pharmacological sPLA 2 -X inhibition on atherosclerosis development. Despite being well tolerated and achieving adequate systemic exposure of mechanistic relevance, (-)- 17 did not significantly affect circulating lipid and lipoprotein biomarkers and had no effect on coronary function or histological markers of atherosclerosis., Competing Interests: The authors declare no competing financial interest.

In order to detect a biochemical analyte with a mass spectrometer (MS) it is necessary to ionize the analyte of interest. The analyte can be ionized by a number of different mechanisms, however, one common method is electrospray ionization (ESI). Droplets of analyte are sprayed through a highly charged field, the droplets pick up charge, and this is transferred to the analyte. High levels of salt in the assay buffer will potentially steal charge from the analyte and suppress the MS signal. In order to avoid this suppression of signal, salt is often removed from the sample prior to injection into the MS. Traditional ESI MS relies on liquid chromatography (LC) to remove the salt and reduce matrix effects, however, this is a lengthy process. Here we describe the use of RapidFire™ coupled to a triple-quadrupole MS for high-throughput screening. This system uses solid-phase extraction to de-salt samples prior to injection, reducing processing time such that a sample is injected into the MS ~every 10 s.