PTGDR2 and asthma: To date, only one phase 3b study (NCT03681093) evaluated fevipiprant, as an add-on to nasal spray standard-of-care in reducing NP size in patients with nasal polyposis and concomitant asthma, but no prominent clinical benefits were observed, which may be explained by our study that NP with concomitant asthma did not present an over-expression of CRTH2 (47).