ONO-7300243 is a potent and selective antagonist of the chemoattractant receptor-homologous molecule expressed on Th2 cells (CRTH2, also known as DP2 receptor), which is involved in allergic and inflammatory responses mediated by prostaglandin D2. It is primarily used in pharmaceutical research to investigate the role of the DP2 receptor in conditions such as asthma, allergic rhinitis, and other Th2-driven inflammatory diseases. By blocking DP2 receptor activity, ONO-7300243 helps researchers study eosinophil recruitment, Th2 cytokine production, and immune cell migration, aiding in the development of novel anti-inflammatory therapies. It is a valuable tool in preclinical studies for evaluating drug candidates targeting allergic and inflammatory pathways, though its use is limited to research and not approved for clinical use in humans.