Human Pharmacokinetics of LYS006, an Oral Leukotriene A4 Hydrolase Inhibitor Displaying Target-Mediated Drug Disposition

Computational Approaches for Predicting Drug Interactions with Human Organic Anion Transporter 4 (OAT4)

Human Organic Anion Transporter 4 (OAT4) is predominantly expressed in the kidneys, particularly in the apical membrane of the proximal tubule cells. This transporter is involved in the renal handling of endogenous and exogenous organic anions (OAs), making it an important transporter for drug-drug interactions (DDIs). To better understand OAT4-compound interactions, we generated single concentration (25 μM) in vitro inhibition data for over 1400 small molecules against the uptake of the fluorescent OA 6-carboxyfluorescein (6-CF) in Chinese hamster ovary (CHO) cells. Several drugs exhibiting higher than 50% inhibition in this initial screen were selected to determine IC50 values against three structurally distinct OAT4 substrates: estrone sulfate (ES), ochratoxin A (OTA), and 6-CF. These IC50 values were then compared to the drug plasma concentration as per the 2020 FDA drug-drug interaction (DDI) guidance. Several screened compounds, including some not previously reported, emerged as novel inhibitors of OAT4. These data were also used to build machine learning classification models to predict the activity of potential OAT4 inhibitors. We compared multiple machine learning algorithms and data cleaning techniques to model these screening data and investigated the utility of conformal predictors to predict OAT4 inhibition of a leave-out set. These experimental and computational approaches allowed us to model diverse and unbalanced data to enable predictions for DDIs mediated by this transporter.

Structure-Guided Elaboration of a Fragment-Like Hit into an Orally Efficacious Leukotriene A4 Hydrolase Inhibitor

Leukotriene A4 hydrolase (LTA4H) is the final and rate-limiting enzyme in the biosynthesis of pro-inflammatory leukotriene B4 (LTB4). Preclinical studies have provided strong evidence that LTA4H is an attractive drug target for the treatment of chronic inflammatory diseases. Here, we describe the transformation of compound 2, a fragment-like hit, into the potent inhibitor of LTA4H 3. Our strategy involved two key steps. First, we aimed to increase the polarity of fragment 2 to improve its drug-likeness, particularly its solubility, while preserving both its promising potency and low molecular weight. Second, we utilized structural information and incorporated a basic amino function, which allowed for the formation of an essential hydrogen bond with Q136 of LTA4H and consequently enhanced the potency. Compound 3 exhibited exceptional selectivity and showed oral efficacy in a KRN passive serum-induced arthritis model in mice. The anticipated human dose to achieve 90% target engagement at the trough concentration was determined to be 40 mg administered once daily.

LTA4H inhibitor LYS006: Clinical PK/PD and safety in a randomized phase I clinical trial

LYS006 is a novel, highly potent and selective, new-generation leukotriene A4 hydrolase (LTA4H) inhibitor in clinical development for the treatment of neutrophil-driven inflammatory diseases. We describe the complex pharmacokinetic to pharmacodynamic (PD) relationship in blood, plasma, and skin of LYS006-treated nonclinical species and healthy human participants. In a randomized first in human study, participants were exposed to single ascending doses up to 100 mg and multiple ascending doses up to 80 mg b.i.d.. LYS006 showed rapid absorption, overall dose proportional plasma exposure and nonlinear blood to plasma distribution caused by saturable target binding. The compound efficiently inhibited LTB4 production in human blood and skin blister cells, leading to greater than 90% predose target inhibition from day 1 after treatment initiation at doses of 20 mg b.i.d. and above. Slow re-distribution from target expressing cells resulted in a long terminal half-life and a long-lasting PD effect in ex vivo stimulated blood and skin cells despite low plasma exposures. LYS006 was well-tolerated and demonstrated a favorable safety profile up to highest doses tested, without any dose-limiting toxicity. This supported further clinical development in phase II studies in predominantly neutrophil-driven inflammatory conditions, such as hidradenitis suppurativa, inflammatory acne, and ulcerative colitis.

Discovery of Amino Alcohols as Highly Potent, Selective, and Orally Efficacious Inhibitors of Leukotriene A4 Hydrolase

The discovery of chiral amino alcohols derived from our previously disclosed clinical LTA4H inhibitor LYS006 is described. In a biochemical assay, their optical antipodes showed similar potencies, which could be rationalized by the cocrystal structures of these compounds bound to LTA4H. Despite comparable stabilities in liver microsomes, they showed distinct in vivo PK properties. Selective O-phosphorylation of the (R)-enantiomers in blood led to clearance values above the hepatic blood flow, whereas the (S)-enantiomers were unaffected and exhibited satisfactory metabolic stabilities in vivo. Introduction of two pyrazole rings led to compound (S)-2 with a more balanced distribution of polarity across the molecule, exhibiting high selectivity and excellent potency in vitro and in vivo. Furthermore, compound (S)-2 showed favorable profiles in 16-week IND-enabling toxicology studies in dogs and rats. Based on allometric scaling and potency in whole blood, compound (S)-2 has the potential for a low oral efficacious dose administered once daily.