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FDA Turns Down Hep B Vaccine for Now

2/28/2013

FDA Turns Down Hep B Vaccine for Now

By David Pittman, Washington Correspondent, MedPage Today
Published: February 26, 2013



The FDA wants more safety data on an investigational adult hepatitis B vaccine before granting approval, the vaccine's manufacturer said Monday.

Berkeley, Calif.-based Dynavax Technologies said it had received a "complete response letter" from the FDA stating the need for "further safety evaluation" among patients ages 18 to 70, the target age group for its Heplisav vaccine.

"The FDA also continues to express concern that novel adjuvants may cause rare autoimmune events," Dynavax said in a statement. "However, the agency indicated its willingness to continue discussions regarding a more restricted use of Heplisav."

Dynavax gave no time frame for meeting the FDA's demands, which also included concerns about the product's manufacturing.

At a meeting in November 2012, the FDA's Vaccines and Related Biologics Advisory Committee voted 5-8, with one abstention, against the idea that Heplisav had been shown to be safe among adults ages 18 to 70. Some committee members questioned the lack of representation of specific populations, including Asians, blacks, and Hispanics.

"Some felt the company needed to go back and get more immunogenic data sets in other racial groups in order to make a responsible decision on safety and effectiveness of the vaccine in light of the fact that it contains an adjuvant," according to a summary of the meeting provided to MedPage Today by the FDA.

Some panelists also wanted longer studies and more data on adverse events, according to the FDA's report of the panel meeting.

A study of nearly 4,000 patients found that two doses of Heplisav were non-inferior to three doses of GlaxoSmithKline's hepatitis B vaccine Engerix-B, used as the active comparator drug in trials. Efficacy was measured by adequate hepatitis B antibody concentration. The FDA advisory committee voted 13-1 in support of the efficacy of the hepatitis B vaccine.

At least 90% of subjects maintained antibody levels against hepatitis B almost a year after two doses.

Safety was evaluated in more than 5,800 adults up to 28 weeks after injection and up to a year in one pivotal study.

Heplisav combines hepatitis B surface antigen produced in yeast cells with a novel agonist to enhance the immune response. Two doses are administered 1 month apart.

While there are two hepatitis B vaccines already on the market, as well as one that combines hepatitis B and A, all require three doses given up to a year between the first and last. Heplisav is only two doses given 1 month apart.

U.S. prevalence of hepatitis B remains high at around 800,000 to 1.4 million, the FDA said, causing between 2,000 and 4,000 deaths a year. Infection rates have dropped since 1992, when universal childhood vaccinations were first recommended.

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