NEW YORK (AP) -- Dynavax Technologies Corp. said Monday that the Food and Drug Administration wants it to run a new safety study on its hepatitis B vaccine Heplisav, and the company's shares fell almost 30 percent in morning trading.
Dynavax said the FDA wants it to get safety data from more patients. The agency added that analyzing the drug for smaller groups of patients did not fully address its concerns. Those analyses could lead to a more limited approval of Heplisav, but according to Dynavax, the FDA said that might prevent patients who might benefit from the drug from getting treatment. The company said the FDA could approve the drug in patients ages 18 to 70 if it provides more safety data.
The Berkeley, Calif., company plans to have another meeting with the FDA to discuss collection of the new safety data. Dynavax is also working to address questions about the manufacturing and testing of Heplisav.
Shares of Dynavax lost 67 cents, or 27.3 percent, to $1.79 in morning trading. Earlier the stock hit a two-year low of $1.72.
Dynavax has no approved drugs. In November an FDA advisory panel questioned the safety of Heplisav and said there was no enough data to show the drug is safe. Some panelists said Dynavax should study the drug on more diverse groups of patients to better reflect the population of the U.S. In February Dynavax said the FDA had refused to approve the drug because it wanted more safety data as well as more information about the manufacturing and quality of Heplisav.
Hepatitis B is a chronic liver infection that is spread through the blood or bodily fluids of infected people. It can cause liver inflammation and jaundice. A vaccine is available and treatment can manage the virus. Heplisav is designed is given in two doses instead of three for traditional vaccines, and Dynavax says it provides protection faster than other drugs.
Shares of Dynavax have lost more than 45 percent of their value since Nov. 15.