FDA: Dynavax's Heplisav effective against hepatitis B

California's Dynavax Technologies ($DVAX) scored a win when FDA staff said the company's Heplisav vaccine works against the contagious liver disease hepatitis B.

The FDA said in a report that Heplisav worked as well after two doses as three doses of GlaxoSmithKline's ($GSK) Engerix-B vaccine. The vaccine also had a similar safety profile to Engerix-B.

Company stock rose 13% upon the news, closing Tuesday at $4.74. This marks the largest single-day jump since September 2011.

Dynavax does not yet have a product on the market, so Heplisav will be first should the FDA approve the vaccine Feb. 24, when the organization is scheduled to make a decision. The product could rake in an estimated $775 million in worldwide sales come 2020, Katherine Xu, an analyst with William Blair & Co., told Bloomberg.

In a study of about 2,400 patients ages 18 to 55, 95% of those who took two doses of Heplisav were protected from hepatitis B. By comparison, 81% of those who took three doses of Glaxo's Engerix-B were protected.

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