After rejecting it twice in the last 4 years on safety grounds, the US Food and Drug Administration (FDA) has approved a hepatitis B vaccine called Heplisav-B (Dynavax) that is the first and only two-dose vaccine for this infection, the manufacturer announced yesterday.
However, the question of safety still dogs the new vaccine. FDA approval hinges on a large post-marketing study that will compare the risk of acute myocardial infarctions (AMIs) and immune-mediated diseases with that for a currently licensed hepatitis B vaccine called Engerix-B (GlaxoSmithKline).
The new vaccine’s approval follows a mostly positive evaluation in July by the FDA’s Vaccines and Related Biological Products Advisory Committee. It voted 12 to 1 with three abstentions in favor of administering Heplisav-B to adults 18 years of age and older. Committee members said the vaccine’s shorter schedule — two doses over 1 month compared with three doses over 6 months for rival products such as Engerix-B — would improve patient adherence.
However, some committee members expressed concern about one clinical trial that showed more deaths and serious heart problems like AMI among patients taking Heplisav-B than among those taking Engerix-B. Dynavax had proposed a post-marketing study to investigate this issue further.
In a conference call with investment analysts yesterday, Dynavax CEO Eddie Gray outlined the design of the post-marketing study. It will enroll 50,000 patients in the Kaiser Permanente system over 10 months, with 25,000 to receive Heplisav-B and the other 25,000 Engerix-B, and then follow them for 1 year for AMIs. The study also will compare the rate of immune-mediated diseases in these same patients, plus an additional 10,000 who will receive the two vaccines in equal number. Gray said the final results should be available in 2 and a half years.
The FDA approval of Heplisav-B, in baseball terms, is a homerun after two strike-outs. The FDA rejected the hepatitis B vaccine in early 2013 over safety worries, including the possibility that the vaccine’s proprietary adjuvant, which boosts immune response, might cause rare autoimmune problems. The decision reflected a vote by the agency’s vaccine advisory committee several months earlier that evidence for the vaccine’s safety was wanting.
In November 2016, Dynavax announced that the FDA had turned down another marketing application for Heplisav-B and requested more information on, among other things, “a numerical imbalance in a small number of cardiac events in a single study.”
Heplisav-B is indicated to protect against infection by all known subtypes of the hepatitis B virus, according to a Dynavax news release. It should not be given to anyone who has had a severe allergic reaction after receiving any hepatitis B vaccine or any component of Heplisav-B, including yeast. Injection site pain, fatigue, and headache were the most common adverse events reported within 7 days of vaccination in the clinical trials, the company said.
More information about Heplisav-B is available on the Dynavax website.
Follow Robert Lowes on Twitter @LowesRobert
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