Dynavax falls by more than 30% after FDA cancels Adcomm

During the Labor Day weekend, small cap Dynavax ($DVAX) found it hard to relax after the FDA cancelled an advisory committee meeting for its experimental hep B vaccine, sending its shares plummeting before Friday’s close.

The Californian biotech, which now has a market cap of less than $500 million, was told by the U.S. regulator on Friday that it was abandoning its planned 16 Nov. Adcomm meeting over its BLA for Heplisav-B.

The FDA’s final date for a decision for the drug, currently set at 15. Dec, remains unchanged according to the biotech, with remaining questions set to “be addressed between Dynavax and the review team via the normal process,” it said in a statement released two days after the FDA’s notice.

“The FDA informed Dynavax that it plans to provide information requests related to remaining questions in the upcoming weeks. Dynavax is prepared to address these questions expeditiously in order to enable the FDA to complete its review as soon as possible.”

But there has been a blow as the FDA will now not look at immunogenicity data related to certain subpopulations in its original BLA, including results in patients with diabetes.

This is because these data were not a “direct response” to the FDA’s concerns and requirements set out in its Complete Response Letter to the biotech, sent back in Feb. 2013.  

These data “therefore fell outside of the review time allocated to a Class 2 resubmission,” Dynavax said--and will therefore need to be submitted as a supplemental BLA following any approval, delaying the vax getting to this subpopulation.

The FDA will however review the overall immunogenicity data from HBV-23, the company's most recent pivotal Phase III trial, Dynavax said.

"Our dialogue with the FDA has been very open and productive, and we look forward to providing the review team with any additional information they may need to complete their review," said Eddie Gray, CEO of Dynavax. "We are committed to bringing HEPLISAV-B to market as we believe it offers a better level of protection than the currently available hepatitis B vaccines."

At the start of the year, the company released its third Phase III study for the vax, comparing it with Glaxo’s ($GSK) Engerix-B in order to provide a “sufficiently-sized safety database for the FDA” to complete its review of Dynavax’s BLA.

The new trial met both of its co-primary endpoints with the rates of clinically significant adverse events consistent with randomization. The vax also provided a statistically significant higher rate of seroprotection than Engerix-B in diabetic participants and in all participants as a group.

As well as GSK, Merck ($MRK) also already sells its own hepatitis B vaccines, with Gilead ($GILD), Merck, Bristol-Myers Squibb ($BMY) and Biogen ($BIIB) among other companies also now developing new drugs to treat the disease.

Dynavax hopes to have an edge over the marketed treatments, however, as its vaccine is injected in two doses over one month, whereas its rivals are administered in three doses over a 6-month schedule.

William Blair analyst Katherine Xu said at the release of its new study earlier this year that the vaccine's efficacy was “good and adverse events well balanced to merit an approval.” Xu estimated peak annual sales of $600 million for the vaccine.

The biotech rebounded in premarket trading, however, and was up 16% before normal Tuesday trading began and was up by just under 30% by midday.