Dynavax (DVAX) - Get Report plunged in premarket trading Monday after U.S. regulators rejected the company's marketing application for Heplisav-B, a preventative hepatitis B vaccine.

The company now says it will need assistance from another drug company or financial partner to resubmit Heplisav-B for another shot at approval.

Shares of Dynavax are down 68% to $3.70 in Monday premarket trading. The stock closed Friday at $11.60 per share.

In October, the U.S. Food and Drug Administration cancelled an advisory panel scheduled for November that was supposed to review the Heplisav-B efficacy and safety data. The meeting cancellation spooked Dynavax investors at that time because it suggested the FDA was leaning towards rejection.

Those fears were correct. Dynavax said Monday that the FDA could not approve Heplisav-B because of unresolved safety issues, among other problems. The agency wants the company to submit additional information regarding "adverse events of special interest" -- a reference to data from previous clinical trials suggesting Heplisav-B can cause rare autoimmune side effects.

The FDA did not ask for additional clinical trials to be conducted, Dynavax said.

"The CRL is consistent with our opinion that Heplisav-B is approvable and we are seeking to meet with the FDA as soon as possible," said Dynavax CEO Eddie Gray, in a statement. "However, the time and resources that will be required to gain approval leads us to consider that we may not be able to advance this program on our own and we are moving swiftly to identify a potential pharmaceutical or financial partner."

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