BERKLEY, Calif. (AP) — Dynavax Technologies Corp. said Thursday that a government advisory panel returned a mix opinion on its hepatitis B vaccine Heplisav, concluding that the drug works but that its safety hasn't been proved.
The company's shares plunged nearly 60 percent in aftermarket trading.
Dynavax said the Food and Drug Administration panel voted 13 to 1 that Heplisav was able to provoke an immune response in patients. However the biologic drug panel voted 8 to 5, with one abstention, that there was not enough data to demonstrate the product is safe.
The company said it is working with the FDA as it completes its review of Heplisav, which is Dynavax's most advanced experimental drug. The FDA is scheduled to make a decision by Feb. 24.
Shares of Dynavax closed at $4.63 and then fell $2.73, or 59 percent, to $1.90 in after-hours trading. Dynavax shares have traded between $2.67 and $5.34 in the last year.