Small-molecule CRTH2 antagonists for the treatment of allergic inflammation: an overview

The discovery of a second receptor for prostaglandin D2, chemoattractant receptor-homologous molecule expressed on T helper type 2 (CRTH2), has revived significant efforts into the development of small-molecule antagonists for allergic diseases as the receptor is predominantly expressed on cells such as eosinophils, TH2 cells and basophils, which are major pro-inflammatory cells in diseases such as asthma and allergic rhinitis. This brief review serves to illustrate current patent literature focusing on the similarities and differences of an ever-growing number of CRTH2 antagonists emerging from corporate laboratories.