Efficacy of the oral chemoattractant receptor homologous molecule on T H 2 cells antagonist BI 671800 in patients with seasonal allergic rhinitis

Background: The inflammatory response in patients with seasonal allergic rhinitis (SAR) is partly mediated by the prostaglandin D2 receptor chemoattractant receptor homologous molecule on TH2 cells (CRTH2). Objective: We sought to investigate the efficacy and safety of the oral CRTH2 antagonist BI 671800 (50, 200, and 400 mg twice daily), fluticasone propionate nasal spray (200 mg once daily), or oral montelukast (10 mg once daily) administered for 2 weeks in patients with SAR. Methods: In this randomized, double-blind, placebo-controlled, partial-crossover study, participants aged 18 to 65 years with a positive skin prick test to Dactylis glomerata pollen were exposed to out-of-season allergen in the environmental challenge chamber for 6 hours. The primary efficacy variable was the total nasal symptom score assessed as the area under the curve (AUC)0-6h. Results: In total, 146 patients (63.7% male; mean age, 36.1 years) were randomized. The adjusted mean total nasal symptom score AUC0-6h was significantly reduced versus placebo with 200 mg of BI 671800 (absolute difference, 20.85; percentage difference,217%; P5 .0026), montelukast (absolute