Pfizer has agreed to acquire Arena Pharmaceuticals, a clinical stage company focused on the development of therapies for immuno-inflammatory diseases. The latter’s lead candidate, etrasimod, is a potential treatment for a variety of inflammatory diseases including Crohn’s disease and ulcerative colitis. The deal, which values Arena at US$6.7 B, marks Pfizer’s third acquisition this year, following its buyout of Amplyx Pharmaceuticals in April and Trillium Therapeutics in August.