Inhibition of eosinophilia in vivo by a small molecule inhibitor of very late antigen (VLA)-4

The α4β1 integrin (very late antigen-4, VLA-4) plays an important role in the migration of lymphocytes, monocytes, and eosinophils, but not neutrophils, to sites of inflammation. Pharmacological antagonism of VLA-4 is an attractive prospect for the treatment of predominantly eosinophil mediated diseases such as asthma and allergic rhinitis. We report here on a potent and selective, small molecule VLA-4 inhibitor, (2S)-3-(2′, 5'-dichlorobiphenyl-4-yl)-2-({[1-(2-methoxybenzoyl)piperidin-3-yl]carbonyl}amino) propanoic acid, compound 1, and characterize the antagonist activities of this molecule in various cell-based assays and in an animal model of eosinophil migration. Compound 1 inhibited VLA-4/ vascular cell adhesion molecule-1(VCAM-1) interactions with in vitro potencies (IC50 value of 210 nM) in VLA-4-expressing Ramos cells, although the compound did not inhibit cell adhesion to fibronectin via α5β1 integrin (very late antigen-5, VLA-5). Blockade of phorbol-12-myristate-13-acetate (PMA)- or Mn2+-stimulated VLA-4 interactions with compound 1 was observed in human T lymphocytes (IC50 value of 230 nM), human eosinophils (IC50 value of 4.0 μM) and mouse eosinophils (IC50 value of 1.6 μM). Furthermore, compound 1 administered by intraperitoneal injection inhibited eosinophil infiltration in a dose-dependent manner by up to 80% in an air pouch model. These data support the use of small molecule VLA-4 antagonists in the treatment of relevant diseases, such as asthma, atopic dermatitis, or allergic rhinitis.