Etrasimod is a new generation of oral S1P receptor modulator, which can specifically bind to S1P receptors 1, 4, and 5. It is being studied for a range of immune inflammatory diseases, including ulcerative colitis, Crohn's disease, atopic dermatitis, eosinophilic esophagitis and alopecia areata. At present, the highest stage of research and development of the drug is to apply for marketing, which is used to treat ulcerative colitis and is expected to be approved by FDA in this month.