 RADNOR, Pa., June 1, 2021 PRNewswire -- The law firm of Kessler Topaz Meltzer Check, LLP reminds investors that a securities fraud class action lawsuit has been filed against FibroGen, Inc. NASDAQ: FGEN FibroGen on behalf of those who purchased or acquired FibroGen securities andor sold put options from October 18, 2017 through April 6, 2021 , inclusive the Class Period. 