 Shares of Protagonist Therapeutics Inc. PTGX, -0.58 tumbled 30.8 in premarket trading on Tuesday the day after the company said a Phase 2 clinical trial that gave patients a higher dose of its experimental ulcerative colitis treatment did not meet the primary endpoint. However, using a lower dose demonstrated clinical remission among some patients, and Protagonist said it plans to move forward with a Phase 3 clinical trial using this dosing. 