ABSTRACT
LOXL2 catalyzes the oxidative deamination of ε-amines of lysine and hydroxylysine residues within collagen and elastin, generating reactive aldehydes (allysine). Condensation with other allysines or lysines drives the formation of inter- and intramolecular cross-linkages, a process critical for the remodeling of the ECM. Dysregulation of this process can lead to fibrosis, and LOXL2 is known to be upregulated in fibrotic tissue. Small-molecules that directly inhibit LOXL2 catalytic activity represent a useful option for the treatment of fibrosis. Herein, we describe optimization of an initial hit 2, resulting in identification of racemic-trans-(3-((4-(aminomethyl)-6-(trifluoromethyl)pyridin-2-yl)oxy)phenyl)(3-fluoro-4-hydroxypyrrolidin-1-yl)methanone 28, a potent irreversible inhibitor of LOXL2 that is highly selective over LOX and other amine oxidases. Oral administration of 28 significantly reduced fibrosis in a 14-day mouse lung bleomycin model. The (R,R)-enantiomer 43 (PAT-1251) was selected as the clinical compound which has progressed into healthy volunteer Phase 1 trials, making it the "first-in-class" small-molecule LOXL2 inhibitor to enter clinical development.
Subject(s)
Amino Acid Oxidoreductases/antagonists & inhibitors , Enzyme Inhibitors/chemistry , Enzyme Inhibitors/pharmacology , Pyridines/chemistry , Pyridines/pharmacology , Administration, Oral , Amino Acid Oxidoreductases/metabolism , Animals , Disease Models, Animal , Enzyme Inhibitors/administration & dosage , Enzyme Inhibitors/therapeutic use , Fibrosis , Halogenation , Humans , Lung/drug effects , Lung/enzymology , Lung/pathology , Lung Diseases/drug therapy , Lung Diseases/enzymology , Lung Diseases/pathology , Male , Methylation , Mice, Inbred C57BL , Models, Molecular , Pyridines/administration & dosage , Pyridines/therapeutic use , Structure-Activity RelationshipABSTRACT
Autotaxin (ATX) is a secreted glycoprotein that converts lysophosphatidylcholine (LPC) to the bioactive phospholipid lysophosphatidic acid (LPA) and is the major enzyme generating circulating LPA. Inhibition of LPA signaling has profound antifibrotic effects in multiple organ systems, including lung, kidney, skin, and peritoneum. However, other LPA-generating pathways exist, and the role of ATX in localized tissue LPA production and fibrosis remains unclear and controversial. In this study, we describe the preclinical pharmacologic, pharmacokinetic, and pharmacodynamic properties of a novel small-molecule ATX inhibitor, PAT-505 [3-((6-chloro-2-cyclopropyl-1-(1-ethyl-1H-pyrazol-4-yl)-7-fluoro-1H-indol-3-yl) thio)-2-fluorobenzoic acid sodium salt]. PAT-505 is a potent, selective, noncompetitive inhibitor that displays significant inhibition of ATX activity in plasma and liver tissue after oral administration. When dosed therapeutically in a Stelic Mouse Animal Model of nonalcoholic steatohepatitis (NASH), PAT-505 treatment resulted in a small but significant improvement in fibrosis with only minor improvements in hepatocellular ballooning and hepatic inflammation. In a choline-deficient, high-fat diet model of NASH, therapeutic treatment with PAT-505 robustly reduced liver fibrosis with no significant effect on steatosis, hepatocellular ballooning, or inflammation. These data demonstrate that inhibiting autotaxin is antifibrotic and may represent a novel therapeutic approach for the treatment of multiple fibrotic liver diseases, including NASH.
