Discovery and Early Clinical Development of an Inhibitor of 5-Lipoxygenase Activating Protein (AZD5718) for Treatment of Coronary Artery Disease

Identification of selective 5-LOX and FLAP inhibitors as novel anti-inflammatory agents by ligand-based virtual screening

Inflammation is a multifaceted biological process in which the conversion of arachidonic acid to eicosanoids, including prostaglandins and leukotrienes (LTs), plays a crucial role. 5-Lipoxygenase (5-LOX) is a key enzyme in cellular LT biosynthesis, and it is supported by the accessory protein 5-lipoxygenase-activating protein (FLAP). Pharmacological interventions to modulate LTs aim at either decreasing their biosynthesis or at mitigating their biological effects. Therefore, inhibiting 5-LOX or FLAP represents a useful strategy to reduce inflammation. Herein we present the identification and pharmacological evaluation of novel inhibitors targeting 5-LOX or FLAP. By means of a ligand-based virtual screening approach, we selected 38 compounds for in vitro assays. Among them, ALR-38 exhibits direct 5-LOX inhibition, while ALR-6 and ALR-27 showed potential as FLAP inhibitors. These latter not only reduced LT production but also promoted the generation of specialized pro-resolving mediators in specific human macrophage phenotypes. Interestingly, the identified compounds turned out to be selective for their respective targets, as none of them displayed activity towards microsomal prostaglandin E2 synthase-1 and soluble epoxide hydrolase, which are other proteins involved in eicosanoid biosynthesis. Thus, these compounds are endowed with potential therapeutic utility in mitigating inflammatory responses and might offer a venue for tackling inflammation-based disorders.

Substituted 1,2,4-Triazoles as Novel and Selective Inhibitors of Leukotriene Biosynthesis Targeting 5-Lipoxygenase-Activating Protein

5-Lipoxygenase-activating protein (FLAP) is a regulator of cellular leukotriene biosynthesis, which governs the transfer of arachidonic acid (AA) to 5-lipoxygenase for efficient metabolism. Here, the synthesis and FLAP-antagonistic potential of fast synthetically accessible 1,2,4-triazole derivatives based on a previously discovered virtual screening hit compound is described. Our findings reveal that simple structural variations on 4,5-diaryl moieties and the 3-thioether side chain of the 1,2,4-triazole scaffold markedly influence the inhibitory potential, highlighting the significant chemical features necessary for FLAP antagonism. Comprehensive metabololipidomics analysis in activated FLAP-expressing human innate immune cells and human whole blood showed that the most potent analogue 6x selectively suppressed leukotriene B4 formation evoked by bacterial exotoxins without affecting other branches of the AA pathway. Taken together, the 1,2,4-triazole scaffold is a novel chemical platform for the development of more potent FLAP antagonists, which warrants further exploration for their potential as a new class of anti-inflammatory agents.

Differential impact of 5-lipoxygenase-activating protein antagonists on the biosynthesis of leukotrienes and of specialized pro-resolving mediators

Lipoxygenases (LOX) transform arachidonic acid (AA, C20:4) and docosahexaenoic acid (DHA, C22:6) into bioactive lipid mediators (LMs) that comprise not only pro-inflammatory leukotrienes (LTs) but also the specialized pro-resolving mediators (SPMs) that promote inflammation resolution and tissue regeneration. The 5-LOX-activating protein (FLAP) is known to provide AA as a substrate to 5-LOX for generating LTs, such as LTB4, a potent chemoattractant and activator of phagocytes. Notably, 5-LOX is also involved in the biosynthesis of certain SPMs, namely, lipoxins and D-resolvins, implying a role of FLAP in SPM formation. FLAP antagonists have been intensively developed as LT biosynthesis inhibitors, but how they impact SPM formation is a matter of debate. Here, we show that FLAP antagonism suppresses the conversion of AA by 5-LOX to LT and lipoxins, while the conversion of DHA to SPM is unaffected. Screening of multiple prominent FLAP antagonists for their effects on LM formation in human M1- and M2-monocyte-derived macrophages by comprehensive LM profiling showed that all nine compounds reduced the production of 5-LOX-derived LTs but increased the formation of SPMs from DHA, e.g., resolvin D5. Some FLAP antagonists, especially those that contain an indole or benzimidazole moiety, even elicited SPM formation in resting M2-monocyte-derived macrophages. Intriguingly, in coincubations of human neutrophils and platelets that produce substantial AA-derived lipoxin and DHA-derived RvD5, FLAP antagonism abolished lipoxin formation, but resolvin D5 levels remained unaffected. Conclusively, antagonism of FLAP suppresses the conversion of AA by 5-LOX to LTs and lipoxins but not the conversion of DHA by 5-LOX to SPM, which should be taken into account for the development of such compounds as anti-inflammatory drugs.

An Analysis of Successful Hit-to-Clinical Candidate Pairs

An analysis of 156 published clinical candidates from the Journal of Medicinal Chemistry between 2018 and 2021 was conducted to identify lead generation strategies most frequently employed leading to drug candidates. As in a previous publication, the most frequent lead generation strategies resulting in clinical candidates were from known compounds (59%) followed by random screening approaches (21%). The remainder of the approaches included directed screening, fragment screening, DNA-encoded library screening (DEL), and virtual screening. An analysis of similarity was also conducted based on Tanimoto-MCS and revealed most clinical candidates were distant from their original hits; however, most shared a key pharmacophore that translated from hit-to-clinical candidate. An examination of frequency of oxygen, nitrogen, fluorine, chlorine, and sulfur incorporation in clinical candidates was also conducted. The three most similar and least similar hit-to-clinical pairs from random screening were examined to provide perspective on changes that occur that lead to successful clinical candidates.

Structures of Leukotriene Biosynthetic Enzymes and Development of New Therapeutics

Leukotrienes are potent immune-regulating lipid mediators with patho-genic roles in inflammatory and allergic diseases, particularly asthma. These autacoids also contribute to low-grade inflammation, a hallmark of cardiovascular, neurodegenerative, metabolic, and tumor diseases. Biosynthesis of leukotrienes involves release and oxidative metabolism of arachidonic acid and proceeds via a set of cytosolic and integral membrane enzymes that are typically expressed by cells of the innate immune system. In activated cells, these enzymes traffic and assemble at the endoplasmic and perinuclear membrane, together comprising a biosynthetic complex. Here we describe recent advances in our molecular understanding of the protein components of the leukotriene-synthesizing enzyme machinery and also briefly touch upon the leukotriene receptors. Moreover, we discuss emerging opportunities for pharmacological intervention and development of new therapeutics.

Molecular Pharmacology of Inflammation Resolution in Atherosclerosis

Atherosclerosis is one of the most important problems of modern medicine as it is the leading cause of hospitalizations, disability, and mortality. The key role in the development and progression of atherosclerosis is the imbalance between the activation of inflammation in the vascular wall and the mechanisms of its control. The resolution of inflammation is the most important physiological mechanism that is impaired in atherosclerosis. The resolution of inflammation has complex, not fully known mechanisms, in which lipid mediators derived from polyunsaturated fatty acids (PUFAs) play an important role. Specialized pro-resolving mediators (SPMs) represent a group of substances that carry out inflammation resolution and may play an important role in the pathogenesis of atherosclerosis. SPMs include lipoxins, resolvins, maresins, and protectins, which are formed from PUFAs and regulate many processes related to the active resolution of inflammation. Given the physiological importance of these substances, studies examining the possibility of pharmacological effects on inflammation resolution are of interest.

Regioselective Synthesis of C3-Hydroxyarylated Pyrazoles

Pyrazoles are ubiquitous structures in medicinal chemistry. We report the first regioselective route to C3-hydroxyarylated pyrazoles obtained through reaction of pyrazole N-oxides with arynes using mild conditions. Importantly, this method does not require the C4 and C5 positions of the pyrazole to be functionalized to observe regioselectivity. Using this method, we completed the synthesis of a recently reported JAK 1/2 inhibitor. Our synthesis produces the desired product in 4 steps from commercially available starting materials.

Design of FLAIR: a Phase 2b Study of the 5-Lipoxygenase Activating Protein Inhibitor AZD5718 in Patients With Proteinuric CKD

Introduction

Patients with chronic kidney disease (CKD) remain at risk for kidney and cardiovascular events resulting from residual albuminuria, despite available treatments. Leukotrienes are proinflammatory and vasoconstrictive lipid mediators implicated in the etiology of chronic inflammatory diseases. AZD5718 is a potent, selective, and reversible 5-lipoxygenase activating protein (FLAP) inhibitor that suppresses leukotriene production.

Methods

FLAIR (FLAP Inhibition in Renal disease) is an ongoing phase 2b, randomized, double-blind, placebo-controlled, multicenter study to evaluate the efficacy and safety of AZD5718 in patients with proteinuric CKD with or without type 2 diabetes. Participants receive AZD5718 at 3 different doses or placebo once daily for 12 weeks, followed by an 8-week extension in which they also receive dapagliflozin (10 mg/d) as anticipated future standard of care. The planned sample size is 632 participants, providing 91% power to detect 30% reduction in urinary albumin-to-creatinine ratio (UACR) between the maximum dose of AZD5718 and placebo. The dose-response effect of AZD5718 on UACR after the dapagliflozin extension is the primary efficacy objective. Key secondary objectives are the dose-response effect of AZD5718 plus current standard of care on UACR and acute effects of treatment on the estimated glomerular filtration rate. Safety, tolerability, AZD5718 pharmacokinetics, and analyses of biomarkers that may predict or reflect response to AZD5718 are additional objectives.

Conclusion

FLAIR will provide data on the effects of 5-lipoxygenase pathway inhibition in patients with proteinuric CKD with or without type 2 diabetes, and will form the basis for future clinical trials (ClinicalTrials.gov: NCT04492722).

Mechanism-Based Insights into Removing the Mutagenicity of Aromatic Amines by Small Structural Alterations

Aromatic and heteroaromatic amines (ArNH₂) are activated by cytochrome P450 monooxygenases, primarily CYP1A2, into reactive N-arylhydroxylamines that can lead to covalent adducts with DNA nucleobases. Hereby, we give hands-on mechanism-based guidelines to design mutagenicity-free ArNH₂. The mechanism of N-hydroxylation of ArNH₂ by CYP1A2 is investigated by density functional theory (DFT) calculations. Two putative pathways are considered, the radicaloid route that goes via the classical ferryl-oxo oxidant and an alternative anionic pathway through Fenton-like oxidation by ferriheme-bound H₂O₂. Results suggest that bioactivation of ArNH₂ follows the anionic pathway. We demonstrate that H-bonding and/or geometric fit of ArNH₂ to CYP1A2 as well as feasibility of both proton abstraction by the ferriheme-peroxo base and heterolytic cleavage of arylhydroxylamines render molecules mutagenic. Mutagenicity of ArNH₂ can be removed by structural alterations that disrupt geometric and/or electrostatic fit to CYP1A2, decrease the acidity of the NH₂ group, destabilize arylnitrenium ions, or disrupt their pre-covalent transition states with guanine.

Intrinsic 5-lipoxygenase activity regulates migration and adherence of mantle cell lymphoma cells

Human B-lymphocytes express 5-lipoxygenase (5-LOX) and 5-LOX activating protein (FLAP) and can convert arachidonic acid to leukotriene B₄. Mantle cell lymphoma (MCL) cells contain similar amounts of 5-LOX as human neutrophils but the function and mechanism of activation of 5-LOX in MCL cells, and in normal B-lymphocytes, are unclear. Here we show that the intrinsic 5-LOX pathway in the MCL cell line JeKo-1 has an essential role in migration and adherence of the cells, which are important pathophysiological characteristics of B-cell lymphoma. Incubation of JeKo-1 with the FLAP inhibitor GSK2190915 or the 5-LOX inhibitor zileuton, at a concentration below 1 μM, prior to stimulation with the chemotactic agent CXCL12, led to a significant reduction of migration. CRISPR/Cas9 mediated deletion of ALOX5 gene in JeKo-1 cells also led to a significantly decreased migration of the cells. Furthermore, 5-LOX and FLAP inhibitors markedly decreased the adherence of JeKo-1 cells to stromal cells. In comparison, these drugs had a similar effect on adherence of JeKo-1 cells as the Bruton tyrosine kinase inhibitor ibrutinib, which has a proven anti-tumour effect. These results indicate that inhibition of 5-LOX may be a novel treatment for MCL and certain other B-cell lymphomas.

Lipoxygenase Inhibitors as Cancer Chemopreventives: Discovery, Recent Developments and Future Perspectives

BACKGROUND

Leukotrienes (LTs) constitute a bioactive group of Polyunsaturated Fatty Acid (PUFA) metabolites molded by the enzymatic activity of lipoxygenase (LO) and have a pivotal role in inflammation and allergy. Evidence is accumulating both by in vitro cell culture experiments and animal tumor model studies in support of the direct involvement of aberrant metabolism of arachidonic acid (ACD) in the development of several types of human cancers such as lung, prostate, pancreatic and colorectal malignancies. Several independent experimental data suggest a correlation between tumoral cells viability and LO gene expression, especially, 5-lipoxygenase (5-LO). Overexpressed 5-LO cells live longer, proliferate faster, invade more effectively through extracellular matrix destruction and activate the anti-apoptotic signaling mechanisms more intensively compared to the normal counterparts. Thus, some groups of lipoxygenase inhibitors may be effective as promising chemopreventive agents.

METHODS

A structured search of bibliographic databases for peer-reviewed research literature regarding the role of LO in the pathogenesis of cancer was performed. The characteristics of screened papers were summarized and the latest advances focused on the discovery of new LO inhibitors as anticancer agents were discussed.

RESULTS

More than 180 papers were included and summarized in this review; the majority was about the newly designed and synthesized 5-LO inhibitors as anti-inflammatory and anticancer agents. The enzyme's structure, 5-LO pathway, 5-LO inhibitors structure-activity relationships as well as the correlation between these drugs and a number of most prevalent human cancers were described. In most cases, it has been emphasized that dual cyclooxygenase-2/5-lipoxygenase (COX-2/5-LO) or dual 5-lipoxygenase/microsomal prostaglandin E synthase-1 (5-LO/mPGES-1) inhibitors possess considerable inhibitory activities against their target enzymes as well as potent antiproliferative effects. Several papers disclosing 5-lipoxygenase activating protein (FLAP) antagonists as a new group of 5-LO activity regulators are also subject to this review. Also, the potential of 12-lipoxygenase (12- LO) and 15-lipoxygenase (15-LO) inhibitors as chemopreventive agents was outlined to expand the scope of new anticancer agents discovery. Some peptides and peptidomimetics with anti-LT activities were described as well. In addition, the cytotoxic effects of lipoxygenase inhibitors and their adverse effects were discussed and some novel series of natural-product-derived inhibitors of LO was also discussed in this review.

CONCLUSION

This review gives insights into the novel lipoxygenase inhibitors with anticancer activity as well as the different molecular pharmacological strategies to inhibit the enzyme effectively. The findings confirm that certain groups of LO inhibitors could act as promising chemopreventive agents.

Simple heteroaryl modifications in the 4,5-diarylisoxazol-3-carboxylic acid scaffold favorably modulates the activity as dual mPGES-1/5-LO inhibitors with in vivo efficacy

Microsomal prostaglandin E₂ synthase-1 (mPGES-1), 5-lipoxygenase (5-LO) and 5- lipoxygenase-activating protein (FLAP) are key for biosynthesis of proinflammatory lipid mediators and pharmacologically relevant drug targets. In the present study, we made an attempt to explore the role of small heteroaromatic fragments on the 4,5-diarylisoxazol-3-carboxylic acid scaffold, which are selected to interact with focused regions in the active sites of mPGES-1, 5-LO and FLAP. We report that the simple structural variations on the benzyloxyaryl side-arm of the scaffold significantly influence the selectivity against mPGES-1, 5-LO and FLAP, enabling to produce multi-target inhibitors of these protein targets, exemplified by compound 18 (IC₅₀ mPGES-1 = 0.16 µM; IC₅₀ 5-LO = 0.39 µM) with in vivo efficacy in animal model of inflammation. The computationally modeled binding structures of these new inhibitors for three targets provide clues for rational design of modified structures as multi-target inhibitors. In conclusion, the simple synthetic procedure, and the possibility of enhancing the potency of this class of inhibitors through structural modifications pave the way for further development of new multi-target inhibitors against mPGES-1, 5-LO and FLAP, with potential application as anti-inflammatory agents.

Characterization and demonstration of drug compound ring-chain tautomer formation and its impacts on quality control

Unknown chromatographic peaks, potential impurities, were observed in a series of related compounds. This led to the identification and characterization of tautomeric equilibria. Structural elucidation was required to understand the potential impurity profile, thus impacting method development for quality control. In this work, characterization of the chemical structures, AZ13581258 and AZD5718, and equilibria of the tautomeric forms was performed using a range of advanced analytical techniques such as preparative chromatography, nuclear magnetic resonance (NMR), chromatographic detection by mass spectrometry (MS), MSMS, and ultraviolet spectroscopy (UV). Predictions using density functional theory (DFT) further explains and confirms the tautomer equilibria through predictions of reaction barrier energies, UV-spectra and NMR data. These investigations led to fully understand the impurity profile and to the development of a quality control method for AZD5718 drug substance and drug product. In conclusion, ring-chain tautomeric structures are predominately formed under acidic conditions, and the additional peaks observed in LC during organic impurity determination were found to originate from ring-chain closed tautomers in equilibria with the parent open form compound. Hence, the closed and open tautomer forms should all be considered as the same compound.

Discovery of LYS006, a Potent and Highly Selective Inhibitor of Leukotriene A4 Hydrolase

The cytosolic metalloenzyme leukotriene A4 hydrolase (LTA4H) is the final and rate-limiting enzyme in the biosynthesis of pro-inflammatory leukotriene B4 (LTB4). Preclinical studies have validated this enzyme as an attractive drug target in chronic inflammatory diseases. Despite several attempts, no LTA4H inhibitor has reached the market, yet. Herein, we disclose the discovery and preclinical profile of LYS006, a highly potent and selective LTA4H inhibitor. A focused fragment screen identified hits that could be cocrystallized with LTA4H and inspired a fragment merging. Further optimization led to chiral amino acids and ultimately to LYS006, a picomolar LTA4H inhibitor with exquisite whole blood potency and long-lasting pharmacodynamic effects. Due to its high selectivity and its ability to fully suppress LTB4 generation at low exposures in vivo, LYS006 has the potential for a best-in-class LTA4H inhibitor and is currently investigated in phase II clinical trials in inflammatory acne, hidradenitis suppurativa, ulcerative colitis, and NASH.

Montelukast Use Decreases Cardiovascular Events in Asthmatics

Cysteinyl leukotrienes are proinflammatory mediators with a clinically established role in asthma and a human genetic and preclinical role in cardiovascular pathology. Given that cardiovascular disease has a critical inflammatory component, the aim of this work was to conduct an observational study to verify whether the use of a cysteinyl leukotriene antagonist, namely, montelukast, may protect asthmatic patients from a major cardiovascular event and, therefore, represent an innovative adjunct therapy to target an inflammatory component in cardiovascular disease. We performed an observational retrospective 3-year study on eight hundred adult asthmatic patients 18 years or older in Albania, equally distributed into two cohorts, exposed or nonexposed to montelukast usage, matched by age and gender according to information reported in the data collection. Patients with a previous history of myocardial infarction or ischemic stroke were excluded. In summary, 37 (4.6%) of the asthmatic patients, 32 nonexposed, and five exposed to montelukast suffered a major cardiovascular event during the 3-year observation period. All the cardiovascular events, in either group, occurred among patients with an increased cardiovascular risk. Our analyses demonstrate that, independent from gender, exposure to montelukast remained a significant protective factor for incident ischemic events (78% or 76% risk reduction depending on type of analysis). The event-free Kaplan–Meier survival curves confirmed the lower cardiovascular event incidence in patients exposed to montelukast. Our data suggest that there is a potential preventative role of montelukast for incident cardiac ischemic events in the older asthmatic population, indicating a comorbidity benefit of montelukast usage in asthmatics by targeting cysteinyl leukotriene-driven cardiac disease inflammation.

Structure-based, multi-targeted drug discovery approach to eicosanoid inhibition: Dual inhibitors of mPGES-1 and 5-lipoxygenase activating protein (FLAP)

BACKGROUND

Due to the importance of both prostaglandins (PGs) and leukotrienes (LTs) as pro-inflammatory mediators, and the potential for eicosanoid shunting in the presence of pathway target inhibitors, we have investigated an approach to inhibiting the formation of both PGs and LTs as part of a multi-targeted drug discovery effort.

METHODS

We generated ligand-protein X-ray crystal structures of known inhibitors of microsomal prostaglandin E2 synthase-1 (mPGES-1) and the 5-Lipoxygenase Activating Protein (FLAP), with their respective proteins, to understand the overlapping pharmacophores. We subsequently used molecular modeling and structure-based drug design (SBDD) to identify hybrid structures intended to inhibit both targets.

RESULTS

This work enabled the preparation of compounds 4 and 5, which showed potent in vitro inhibition of both targets.

SIGNIFICANCE

Our findings enhance the structural understanding of mPGES-1 and FLAP's unique ligand binding pockets and should accelerate the discovery of additional dual inhibitors for these two important integral membrane protein drug targets.

Integral Membrane Enzymes in Eicosanoid Metabolism: Structures, Mechanisms and Inhibitor Design

Eicosanoids are potent lipid mediators involved in central physiological processes such as hemostasis, renal function and parturition. When formed in excess, eicosanoids become critical players in a range of pathological conditions, in particular pain, fever, arthritis, asthma, cardiovascular disease and cancer. Eicosanoids are generated via oxidative metabolism of arachidonic acid along the cyclooxygenase (COX) and lipoxygenase (LOX) pathways. Specific lipid species are formed downstream of COX and LOX by specialized synthases, some of which reside on the nuclear and endoplasmic reticulum, including mPGES-1, FLAP, LTC4 synthase, and MGST2. These integral membrane proteins are members of the family "membrane-associated proteins in eicosanoid and glutathione metabolism" (MAPEG). Here we focus on this enzyme family, which encompasses six human members typically catalyzing glutathione dependent transformations of lipophilic substrates. Enzymes of this family have evolved to combat the topographical challenge and unfavorable energetics of bringing together two chemically different substrates, from cytosol and lipid bilayer, for catalysis within a membrane environment. Thus, structural understanding of these enzymes are of utmost importance to unravel their molecular mechanisms, mode of substrate entry and product release, in order to facilitate novel drug design against severe human diseases.

Development of a highly sensitive liquid chromatography-mass spectrometry method to quantify plasma leukotriene E4 and demonstrate pharmacological suppression of endogenous 5-LO pathway activity in man

Low basal endogenous concentrations (<20 pg/mL) of the 5-lipoxygenase (5-LO) pathway biomarker leukotriene E₄ (LTE₄) in human plasma present a significant analytical challenge. Analytical methods including liquid chromatography-mass spectrometry and enzyme linked immunosorbent assays have been used to quantify plasma LTE₄ in the past but have not provided consistent data in the lower pg/mL-range. With our new method, a detection limit (<1 pg/mL plasma) significantly below basal levels of LTE₄ was achieved by combining large volume sample purification and enrichment by anion-exchange mixed mode solid phase extraction (SPE) with large volume injection followed by chromatographic separation by ultra performance liquid chromatography (UPLC) and quantification by highly sensitive negative-ion electrospray tandem mass spectrometry (MS/MS). The method was reproducible, accurate and linear between 1 and 120 pg/mL plasma LTE₄. The method was used to perform an analysis of plasma samples collected from healthy volunteers in a Phase 1 study with the FLAP (5-lipoxygenase activating protein) inhibitor AZD5718. Basal endogenous LTE₄ levels of 5.1 ± 2.7 pg/mL were observed in healthy volunteers (n = 34). In subjects that had been administered a single oral dose of AZD5718, significant suppression (>80%) of plasma LTE₄ level was observed, providing pharmacological evidence that endogenous 5-LO pathway activity could be assessed.

Phase 1 Pharmacokinetic Study of AZD5718 in Healthy Volunteers: Effects of Coadministration With Rosuvastatin, Formulation and Food on Oral Bioavailability

AZD5718 is a first‐in‐class small‐molecule anti‐inflammatory drug with the potential to reduce the residual risk of cardiovascular events after myocardial infarction in patients receiving lipid‐lowering statin therapy. Leukotrienes are potent proinflammatory and vasoactive mediators synthesized in leukocytes via 5‐lipoxygenase and 5‐lipoxygenase‐activating protein (FLAP). AZD5718 is a FLAP inhibitor that dose‐dependently reduced leukotriene biosynthesis in a first‐in‐human study. We enrolled 12 healthy men in a randomized, open‐label, crossover, single‐dose phase 1 pharmacokinetic study of AZD5718 to investigate a potential drug‐drug interaction with rosuvastatin, and the effects of formulation and food intake (ClinicalTrials.gov identifier: NCT02963116). Rosuvastatin (10 mg) were absorbed more rapidly when coadministered with AZD5718 (200 mg), probably owing to weak inhibition of hepatic statin uptake, but relative bioavailability was unaffected (geometric least‐squares mean ratio [GMR], 100%; 90% confidence interval [CI], 86%‐116%). AZD5718 pharmacokinetics were unaffected by coadministration of rosuvastatin. AZD5718 (200 mg) was absorbed less rapidly when formulated as tablets than oral suspension, with reduced relative bioavailability (GMR, 72%; 90%CI, 64%‐80%). AZD5718 absorption was slower when 200‐mg tablets were taken after a high‐fat breakfast than after fasting, but relative bioavailability was unaffected (GMR, 96%; 90%CI, 87%‐106%). In post hoc pharmacodynamic simulations, plasma leukotriene B₄ levels were inhibited by >90% throughout the day following once‐daily AZD5718, regardless of formulation or administration with food. AZD5718 was well tolerated, with no severe or serious adverse events. These data supported the design of a phase 2a efficacy study of AZD5718 in patients with coronary artery disease.

Highly sensitive and specific LC–MS/MS method to determine endogenous leukotriene B4 levels in human plasma

Aim: To develop a high sensitivity and specific analytical method to measure endogenous levels of leukotriene B4 (LTB4) in human plasma. Methodology: LC–MS/MS and ELISA. Results: An LC–MS/MS method was developed with a sensitivity of 1.0 pg/ml, and within and between batch precision of <16% and <13% RSD, respectively. Conclusion: We have developed a sensitive LC–MS/MS method that can detect endogenous LTB4 in human plasma. The LC–MS/MS method displayed correlation with a commercial LTB4 ELISA when analyzing in ex vivo ionophore-stimulated blood samples. For untreated plasma this correlation was lost. Endogenous LTB4 was shown to be unstable in plasma during storage at -20°C and subject to stereoisomer formation. Neither of the assays could quantify endogenous plasma LTB4 in samples stored for long term.