** Shares of drugmaker Agios Pharmaceuticals AGIO.O fall 14.03% to $34.44 premarket

** Co says says it will stop developing its experimental drug, tebapivat, for sickle cell disease after a mid-stage trial failed to show a meaningful advantage over similar treatments

** Says the drug showed activity “consistent with this class of medicine,” but did not establish the differentiation needed to justify further development

** Sickle cell disease is an inherited blood disorder that causes red blood cells to become misshapen, restricting blood flow and leading to anemia, severe pain and organ damage

** Says hemoglobin response rates ranged from 29.4% to 47.1% across three tebapivat doses, versus 33.3% for placebo

** As of last close, AGIO up 47.2% YTD