FDA refuses adult approval for hepatitis B vaccine

Dynavax Technologies, Inc., may be forced to target its newly developed hepatitis B vaccine to a smaller market after U.S. health regulators denied the vaccine's approval for adults.

The U.S. Food and Drug Administration recently announced that Dynavax failed to provide sufficient safety data to support the approval of Heplisav, the company's most advanced clinical candidate. The global market for the drug is estimated at $700 million, according to Reuters.

Dynavax said that the FDA has indicated that it may be willing to discuss a restricted use of the vaccine. The company will meet with the regulatory agency within six weeks to discuss the ruling and Heplisav's potential future.

The news hit the company's stock price, causing it to fall 37 percent to $1.87. It was the stock's lowest price in more than a year.

Dynavax remains optimistic, saying it may not need to conduct further tests in order to asses Heplisav's safety, according to Reuters.

"It isn't going to be an instantaneous turnaround. We are going to have to do some work to assemble all (the data) and make sure that it fits the FDA's requirement. Let's just say we're talking in months and not years," Tyler Martin, Dynavax's president and chief medical officer, said, Reuters reports.