Arena Pharmaceuticals, Inc. is a biopharmaceutical company. The Company is focused on developing small molecule drugs across a range of therapeutic areas. The Company has three primary investigational clinical programs: etrasimod (APD334) in Phase II evaluation for ulcerative colitis, APD371 entering Phase II evaluation for the treatment of pain associated with Crohn's disease, and ralinepag (APD811) in Phase II evaluation for pulmonary arterial hypertension (PAH). The Company's drug, Lorcaserin, is approved for marketing in the United States and South Korea for the indication of weight management. The Company's drug candidates in clinical development include APD334 for autoimmune diseases, ralinepag for vascular diseases and APD371 for pain. The Company's programs under collaboration include nelotanserin for dementia-associated psychosis, temanogrel for thrombotic diseases, and an undisclosed orphan GPCR for central nervous system (CNS) indication(s).