Shares of Akari Therapeutics PLC rocketed 61% to pace all premarket gainers in very active trading Wednesday, after the biopharmaceutical company said its treatment (nomacopan) of stem-cell transplant associated thrombotic microangiopathy (HSCT-TMA) in pediatric patients was granted "Fast Track" designation by the U.S. Food and Drug Administration. Trading volume swelled to 1.7 million shares, compared with the full-day average of about 96,000 shares. A Fast Track designation helps facilitate the development and expedite the review of new drugs for the treatment of serious or life-threatening conditions that address unmet medical needs. ""Fast Track designation provides our HSCT-TMA clinical program a pathway for an expedited approval for nomacopan, and we plan to commence a pivotal trial in the fourth quarter of 2019," said Chief Executive Clive Richardson. The stock has tumbled 42% over the past three months, while the iShares Nasdaq Biotechnology ETF has gained 2.9% and the S&P 500 has tacked on 3.2%.