Dynavax tumbles after FDA blocks shortcut on hepatitis B vax salvage operation

Shares of Dynavax Technologies ($DVAX) took a fresh dive this morning after the biotech announced the FDA had provided some fresh insights into the safety data it wants to see before it can approve the hepatitis B vaccine Heplisav, likely adding to the delay before the biotech can try again in seeking an approval.

"The safety database does indeed need additional subjects," noted Dynavax in a statement. And while the agency acknowledged the review panel's endorsement of the vaccine's efficacy, trying to divvy up the patient population into more restrictive groups which might pass muster with the regulators isn't going to work, as hoped, in spurring a near-term reversal on last February's rejection letter. "It was concluded that to do so would unnecessarily restrict the patient population that could benefit from Heplisav's approval," says the biotech, adding that the "additional safety data collected would facilitate review for an indication in adults 18 to 70 years of age."

The company's shares plunged 25% this morning. The biotech had spurred hopes that it could gain a quick approval for chronic kidney disease patients, a group that was already being studied, or for older patients. That may leave just one option: Mounting a new safety study for the full patient group.

A panel of outside experts voted 8 to 5 last fall that the company had failed to clearly demonstrate the safety of the hepatitis B vaccine. In one troubling case a woman taking the vaccine had developed Guillain-Barre syndrome while another had to battle Wegener's granulomatosis. With other hepatitis B vaccines to choose from, regulators clearly were not won over by Dynavax's case for using Heplisav in a broad population. Now it has to do better the next time around.

"We are encouraged by the supportive feedback received from the FDA and appreciate the informative interactions and clarity provided regarding Heplisav's path toward approval in the broader indication," said Dynavax CEO Eddie Gray. "We understand the rationale for the agency's recommendations and will give full consideration to their feasibility and timing as we advance Heplisav's development."

- here's the press release