Arena's portfolio includes diverse and promising development-stage therapeutic candidates in gastroenterology, dermatology, and cardiology, including etrasimod, an oral, selective sphingosine 1-phosphate (S1P) receptor modulator currently in development for a range of immuno-inflammatory diseases, including gastrointestinal and dermatological diseases.

Arena has built a robust development program for etrasimod, including two phase III studies in ulcerative colitis (UC), a phase II/III program in Crohn's disease, a planned phase III program in atopic dermatitis, and ongoing phase II studies in eosinophilic esophagitis and alopecia areata. The data for the phase II OASIS trial for UC are expected to be reported in 2022.

Pfizer's financial advisors for the acquisition were Bank of America Securities and Centerview Partners while Ropes and Gray and Arnold and Porter Kaye Scholer acted as legal advisors. Guggenheim Securities and Evercore Group served as Arena's financial advisors, and Cooley served as its legal advisor.