Shares of Gemphire Therapeutics Inc. more than doubled (up 142%) in active premarket trade Friday, after the biopharmaceutical company said a phase 2b trial for gemcabene, a treatment for severe hypertriglyceridemia (SHTG), achieved the primary endpoint. Volume topped 218,000 shares about 100 minutes before the open, which is already more than the full-day regular-session average of about 215,000 shares. The trial results set gemcabene to advance into phase 3 trials. The trial also met several secondary endpoints. SHTG is a condition in which patients have high triglycerides, which increases of the risk of cardiovascular disease and acute pancreatitis. The stock had tumbled 19.5% over the past three months through Thursday, whjle the iShares Nasdaq Biotechnology ETF has gained 1.1% and the S&P 500 has tacked on 2.9%.