In a preliminary phase 2 study carried out in patients with chronic eosinophilic asthma, the CRTH2 antagonist fevipiprant reduced sputum eosinophil numbers, and improved lung function and asthma-related quality of life [185]; however, in the subsequent LUSTER-1 and LUSTER-2 phase 3 trials fevipiprant was not able to guarantee in patients with severe asthma a significant reduction of disease exacerbations, which represented the primary study endpoint [186]. The gene discussed is PTGDR2; the disease is asthma.