BI-671800 is a highly specific and potent antagonist of chemoattractant receptor-homologous molecule on Th2 cells (DP2/CRTH2), with IC50 values of 4.5 nM and 3.7 nM for PGD2 binding to CRTH2 in hCRTH2 and mCRTH2 transfected cells, respectively[1]. BI-671800 has potential for the treatment of poorly controlled asthma[2].

BI-671800 (compound A) exhibits low nM potency as an antagonist of human or mouse CRTH2 in transfected cells[1].

BI-671800 (compound A, 0.1-10 mg/kg, i.g.) shows significant inhibition of AHR in mice[1]. BI-671800 (compound A), effectively blocks edema formation and greatly reduces the inflammatory infiltrate and skin pathology observed in drug vehicle-treated animals[3].|| Animal Model:|6-8-week-old age- and sex-matched BALB/c mice (mice were sensitized for 14 days, challenged intranasally)[1].|Dosage:|10-0.1 mg/kg|Administration:|Oral gavage for 4 weeks|Result:|Shows significant inhibition of AHR in mice.

[1]. Boehme SA, et al. A small molecule CRTH2 antagonist inhibits FITC-induced allergic cutaneous inflammation. Int Immunol. 2009 Jan;21(1):81-93. [2]. Miller D, et al. A randomized study of BI 671800, a CRTH2 antagonist, as add-on therapy in poorly controlled asthma. Allergy Asthma Proc. 2017 Mar 1;38(2):157-164. [3]. Lukacs NW, et al. CRTH2 antagonism significantly ameliorates airway hyperreactivity and downregulates inflammation-induced genes in a mouse model of airway inflammation. Am J Physiol Lung Cell Mol Physiol. 2008 Nov;295(5):L767-79.