FDA Approves Postexposure Anthrax Vaccine

The FDA has approved Cyfendus (formerly known as AV7909), an anthrax vaccine developed by Emergent BioSolutions. It is approved as a postexposure prophylaxis for people 18 through 65 years of age when given with antibacterial drugs.

Emergent has been providing the Cyfendus vaccine to the U.S. Department of Health and Human Services since 2019, under a pre-emergency use authorization status, and will continue to work with the U.S. government to transition to postapproval procurement.

Paul Williams

“Cyfendus vaccine is a component of the U.S. government’s preparedness efforts against anthrax, which remains a high-priority national security threat due to its ability to be easily disseminated, lethality, and potential for major public health impact,” Paul Williams, Emergent’s senior vice president, products business, said in a press release.

Anthrax is a rare but serious infectious disease caused by gram-positive, rod-shaped bacteria known as Bacillus anthracis. It occurs naturally in soil and commonly affects domestic and wild animals around the world. Infection can cause inhalation, cutaneous, or gastrointestinal anthrax. Inhalation anthrax results from breathing in spores and has a high rate of mortality, according to the CDC.

Anthrax spores can be used as a biologic weapon. In 2001, anthrax was intentionally distributed through the mail, with 22 people being infected; five people died.

Cyfendus is comprised of anthrax vaccine adsorbed (AVA) and an additional adjuvant. It has been demonstrated that by using an additional adjuvant, two doses administered over 14 days provides protective levels of immune response.

The FDA approval is based on data from a series of studies supported by the U.S. government and conducted by Emergent. The company’s rolling BLA submission, completed in April 2022, was based on data from a pivotal phase 3 clinical study that evaluated the lot consistency, immunogenicity, and safety of the vaccine candidate following a two-dose schedule. It also included data from the phase 2 study that evaluated non-interference between antibacterial drugs approved for post-exposure prophylaxis of anthrax disease.

The efficacy of Cyfendus vaccine for post-exposure prophylaxis is based on studies in animal models of inhalational anthrax.