Its pipeline includes four investigational medicines in eight indications and eleven ongoing or planned clinical trials.

Arena’s lead investigational compound in dermatology, etrasimod, is a highly selective, once-daily, oral sphingosine 1-phosphate (S1P) receptor modulator intended to provide systemic and local effects on specific immune cell types with the potential to treat multiple immune-mediated inflammatory diseases, including ulcerative colitis, Crohn's disease, eosinophilic esophagitis, atopic dermatitis, and alopecia areata.