After the company unveiled phase 2 data results for its clinical-stage ulcerative colitis drug, etrasimod, shares in Arena Pharmaceuticals (NASDAQ: ARNA) are shooting 31.6% higher as of 1 p.m. EDT today.The ulcerative colitis market is worth billions of dollars in sales annually. Arena Pharmaceuticals hopes etrasimod can vie for a share of that market someday, if late-stage data confirm results from its midstage study.IMAGE SOURCE: GETTY IMAGES.Continue reading