Dynavax says FDA rejects its hepatitis B vaccine

(Reuters) - The U.S. Food and Drug Administration rejected Dynavax Technologies Corp's marketing application for its hepatitis B vaccine, Heplisav-B, for the second time in three years, sending the company's shares tumbling 71 percent in premarket trade. The drug developer said on Monday it received a "complete response letter" from the FDA, seeking information about certain "adverse events" during clinical trials, among other clarifications. There was no request from the FDA for additional clinical trials and there were no apparent concerns about rare serious events, Dynavax said.