Biochemical and functional characterization of lysyl oxidase like 2 (LOXL2) inhibitors

Introduction: A lysyl oxidase like 2 (LOXL2) directed monoclonal antibody (simtuzumab) is being clinically evaluated for the treatment of various fibrotic diseases including idiopathic pulmonary fibrosis (IPF). Objective: To characterize small molecule LOXL2 inhibitors biochemically and in functional assays to assess anti-fibrotic activity. Methods: High throughput screening was used to identify small molecule LOXL2 inhibitors. Screening hits were profiled for biochemical inhibition of LOXL2 and closely related amine oxidases (AOs). Binding to LOXL2 was confirmed by surface plasmon resonance (SPR) methods. Mechanistic experiments were used to judge substrate activity, reversibility, and allosteric and/or non-competitive LOXL2 inhibition. A novel collagen cross-linking assay was developed to evaluate the inhibitors. Results: Both reversible and irreversible LOXL2 inhibitors from various chemotypes were identified with biochemical IC50s of 100-fold over monoamine oxidase A and B was achieved. Lead molecules demonstrated low micromolar inhibition of collagen cross-linking. Conclusions: We have identified novel LOXL2 selective small molecule inhibitors, which demonstrate activity in functional assays relevant to fibrosis.