BMS-309403

BMS-309403 is a **potent, selective, small molecule inhibitor of fatty acid binding protein 4 (FABP4, also called adipocyte FABP or A-FABP)**, with a reported inhibition constant (Ki) of less than 2 nM for FABP4, and significantly weaker affinity for other FABPs (Ki ≈ 250 nM for FABP3 and ≈ 350 nM for FABP5)[1][3][11]. It is a biphenyl azole compound that competes with endogenous fatty acids for the binding pocket of FABP4, inhibiting its lipid-binding activity[3][1]. Mechanistically, BMS-309403 reduces lipid accumulation, cholesterol efflux, and inflammatory responses in macrophages, and suppresses fatty acid uptake in adipocytes in a FABP4-dependent manner[1][8]. In preclinical studies, it has shown efficacy in models of **atherosclerosis, type 2 diabetes, obesity, and kidney fibrosis**, improving glucose uptake, insulin sensitivity, and endothelial function[1][3][5][8]. BMS-309403 also demonstrates off-target effects: it stimulates glucose uptake in myotubes via activation of the AMP-activated protein kinase (AMPK) signaling pathway independent of FABP inhibition, and attenuates endoplasmic reticulum (ER) stress in various tissues[1][5][7]. BMS-309403 is considered a pharmacological tool compound for metabolic and inflammatory disease research but is not approved for human therapy[6][3][11].