After rejection, Dynavax to shoot for limited hep B vaccine approval

GlaxoSmithKline ($GSK) and Merck ($MRK) can thank the FDA for staving off more hepatitis B vaccine competition--at least for the time being. After rejecting Dynavax's ($DVAX) hepatitis B vaccine Heplisav for safety issues, the FDA said it will meet with the company in 6 weeks' time to discuss a more restricted use of the vaccine.

The FDA said safety data provided by Dynavax were insufficient to support approval of Heplisav. But the company may not need to conduct more safety tests--a factor that could reduce potential approval from years to months. And Cowen & Co analyst Phil Nadeau told Reuters the vaccine could gain approval for a more limited population late this year or in the first half of 2014.

"It isn't going to be an instantaneous turnaround," Tyler Martin, Dynavax's president and chief medical officer, told analysts, as quoted by Reuters. "We are going to have to do some work to assemble all [the data] and make sure that it fits the FDA's requirement."

The limited age range Dynavax has in mind is those ages 40 to 70; the company initially sought approval for ages 18 to 70. Older adults tend to have more compromised immune systems and therefore benefit more from Heplisav, William Blair & Co analyst Katherine Xu told the news service.

An FDA panel was divided over the safety data Dynavax provided about the vaccine last November. The group voted 8-5 with one abstention, deeming the data inadequate.

GSK and Merck both sell hepatitis B vaccines, Engerix-B and Recombivax HB, respectively. And because these two companies have hepatitis B vaccines on the market already, the FDA wasn't swayed by Dynavax's argument that Heplisav should be used in a broad population.

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