ABSTRACT
5-Lipoxygenase (5-LO)-activating protein (FLAP) inhibitors have proven to attenuate 5-LO pathway activity and leukotriene production in human clinical trials. However, previous clinical candidates have been discontinued and the link between FLAP inhibition and outcome in inflammatory diseases remains to be established. We here describe a novel series of FLAP inhibitors identified from a screen of 10k compounds and the medicinal chemistry strategies undertaken to progress this series. Compound 4i showed good overall properties and a pIC50 hWBfree of 8.1 and an lipophilic ligand efficiency of 5.2. Target engagement for 4i was established in dogs using ex vivo measurement of leukotriene B4 (LTB4) levels in blood with good correlation to in vitro potency. A predicted human dose of 280 mg b.i.d. suggests a wide margin to any identified in vitro off-target effects and sufficient exposure to achieve an 80% reduction of LTB4 levels in humans. Compound 4i is progressed to preclinical in vivo safety studies.
Subject(s)
5-Lipoxygenase-Activating Protein Inhibitors/pharmacology , Cyclohexanes/pharmacology , Pyrazoles/pharmacology , 5-Lipoxygenase-Activating Protein Inhibitors/chemical synthesis , 5-Lipoxygenase-Activating Protein Inhibitors/toxicity , Animals , Caco-2 Cells , Coronary Artery Disease/drug therapy , Cyclohexanes/chemical synthesis , Cyclohexanes/toxicity , Dogs , Female , Humans , Leukotriene B4/antagonists & inhibitors , Male , Molecular Structure , Pyrazoles/chemical synthesis , Pyrazoles/toxicity , Rats, Sprague-Dawley , Structure-Activity RelationshipABSTRACT
In order to assess the potential of sPLA2-X as a therapeutic target for atherosclerosis, novel sPLA2 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.
ABSTRACT
A lead generation campaign identified indole-based sPLA2-X inhibitors with a promising selectivity profile against other sPLA2 isoforms. Further optimization of sPLA2 selectivity and metabolic stability resulted in the design of (-)-17, a novel, potent, and selective sPLA2-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 sPLA2-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.
