Shares of Axsome Therapeutics Inc. rocketed 164% in very active premarket trade Monday, after the biopharmaceutical company developing therapies to treat central nervous system disorders said a phase 2 trial of its AXS-05 met its primary endpoint, and "significantly improved symptoms of depression." Trading volume ballooned to about 1.5 million shares, already about 5-times the full-day average of about 306,000 shares, and enough to make the stock the most actively traded ahead of the open. The company said AXS-05 met the primary endpoint by demonstrating a "highly statistically significant reduction" in the Montgomery-Asberg Depression Rating Scale total score. The company said ASX-05 was also safe and well tolerated, with no serious adverse events. The stock had tumbled 28% over the past three months through Friday, while the iShares Nasdaq Biotechnology ETF had lost 12.0% and the S&P 500 had declined 12.3%.