The Strategic Market Shaped by the National Stockpile

The FDA's biodefense strategy focuses on procuring strategic national stockpile (SNS) assets rather than addressing general prescription demand. With the eradication of naturally occurring smallpox, government contracts represent a more substantial market size than commercial patient numbers. Emergent BioSolutions Inc. (EBS) secured a contract from the U.S. BARDA for Tembexa, valued at approximately USD 680 million over a maximum of 10 years, including 1.7 million treatment courses and post-administration costs. Consequently, revenue is driven more by federal government option exercises, delivery schedules, and restocking cycles than by infection outbreaks.

Tembexa Acquisition and Competitive Landscape

In September 2022, Emergent BioSolutions Inc. (EBS) acquired global rights to Tembexa (brincidofovir) from Chimerix, Inc. This approved therapy is an orthopoxvirus nucleoside analog DNA polymerase inhibitor, which the FDA approved on June 4, 2021, for the treatment of smallpox in adults, children, and infants. Due to the impossibility of conducting human efficacy trials, it was approved based on animal rule data and without an FDA advisory committee (AdComm) vote. The primary competitor is tecovirimat (TPOXX), a VP37 inhibitor from SIGA Technologies, Inc. (SIGA), which received FDA approval on July 13, 2018, as the first treatment for smallpox.

The Value of Cyfendus Approval

Cyfendus (Anthrax Vaccine Adsorbed, Adjuvanted) is a two-dose vaccine combining anthrax protective antigen (PA) with the TLR9 agonist CpG 7909. The FDA approved it on July 20, 2023, based on safety, lot consistency, immunogenicity, and animal inhalation anthrax efficacy data from the Phase 3 EBS.AVA.212 trial. It is indicated for pre-exposure prophylaxis in individuals aged 18 to 65 who are suspected or confirmed to have been exposed, and it should be used in conjunction with recommended antibiotics. In November 2023, BARDA granted a USD 75 million purchase option, demonstrating how approval translates directly into procurement revenue.

Investment and Industry Implications

The standard of care for anthrax exposure involves the use of antibiotics, such as ciprofloxacin or doxycycline, in combination with vaccines, with BioThrax and CYFENDUS as the approved vaccine options. In the treatment area, there are protective antigen-targeting monoclonal antibodies, such as Anthim (obiltoxaximab) and raxibacumab, but their limited prophylactic indications prevent them from completely replacing pre-exposure prophylaxis. Emergent's strength lies in its possession of both approved products and government delivery infrastructure; however, the option is at the discretion of BARDA, so it is important to distinguish between the maximum contract value and confirmed revenue. Chimerix was acquired by Jazz Pharmaceuticals plc (JAZZ) in April 2025, but the contingent payment rights related to the Tembexa transaction remain important for analyzing the economics of the deal.