Dynavax further delayed as FDA says wait until Christmas for hep B vax decision

Janet Woodcock

Three years after the FDA originally turned down Dynavax’s ($DVAX) hepatitis B vaccine Heplisav-B over safety concerns, the biotech faces more uncertainty as the regulator has pushed back its PDUFA date.

Berkeley, CA-based Dynavax Technologies said in a brief statement today that the FDA will now need until mid-December to assess whether to approve its experimental vaccine after the biotech submitted a new data aimed at allaying the regulator’s concerns.

In a notice received from the FDA, the Prescription Drug User Fee Act (PDUFA) action date for Heplisav-B has now been extended by three months to December 15, 2016.

On 8 April, in response to an FDA request, Dynavax said it submitted individual trial data sets that had been provided as integrated data in its March 2016 BLA resubmission. But the FDA then determined that the addition of these large data sets represented a “major amendment” to its new BLA--and therefore extended the PDUFA action date to allow for a “full review.”

“We appreciate the commitment of the FDA staff to conduct a complete review of all of the data supporting our BLA and we remain committed to working closely with them over the coming months in order to achieve Heplisav-B approval in 2016," said Eddie Gray, CEO of Dynavax.

The setback sent it shares down 3% this early this morning.

At the start of the year, the company said it 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 with over the marketed treatments as its vaccine however as it is injected in two doses over one-month--whereas its rivals are administered in three doses over a six-month schedule.

Dynavax has also turned to the results of a recent Vaccine Safety Datalink study that showed just 54% of adults completed the three-dose hepatitis B vaccine series in one year.

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 is also studying SD-101, an investigational cancer immunotherapeutic, which is currently in several Phase I/II studies.

-check out the release
-see its latest Phase III data