FDA Integrates TPOXX, Tembexa, and Jynneos into National Emergency Response System
Standing Medical Countermeasure System
The U.S. Food and Drug Administration (FDA), through its Center for Drug Evaluation and Research (CDER), supports the development, review, and stockpiling of medical countermeasures (MCMs) to address bioterrorism, chemical, radiological events, and emerging infectious diseases. This document focuses on the standing regulatory infrastructure that connects individual new drug approvals with Emergency Use Authorizations (EUAs), the Animal Rule, shelf-life extensions, and the Strategic National Stockpile (SNS), rather than individual new drug approvals. A key aspect is the ability to approve products by combining animal efficacy and human safety data, even when patient-based efficacy trials are impossible or unethical for certain threats.
Approved Therapies and Molecular Targets
SIGA Technologies' (SIGA) TPOXX (tecovirimat) is an approved therapy that inhibits the VP37 protein of orthopoxviruses, preventing the release of mature virions. The FDA Advisory Committee supported the benefit-risk profile by a vote of 17-0. The oral formulation was approved on July 13, 2018, and the intravenous formulation and expansion to children weighing 3 kg or more were approved on May 18, 2022. Emergent BioSolutions' (EBS) Tembexa (brincidofovir) is a lipid conjugate of cidofovir that inhibits viral DNA polymerase and was approved on June 4, 2021, for the treatment of smallpox in adults and children, including neonates. Both products are approved and marketed assets that utilized the Animal Rule instead of a Phase 3 efficacy trial.
Vaccine Competitive Landscape and Regulatory History
Bavarian Nordic's (BAVA) Jynneos (MVA-BN) is a non-replicating modified vaccinia Ankara virus vaccine that received approval on September 24, 2019, for the prevention of smallpox and mpox in high-risk adults. In a Phase 3 clinical program with two doses, the immunogenicity, measured by neutralizing antibody titers, was non-inferior to the replicating live vaccine ACAM2000. The lyophilized formulation also received FDA approval on March 31, 2025. Emergent's ACAM2000, a competitive standard, was licensed in 2007 for smallpox prevention, and the mpox indication was added on August 29, 2024; however, its characteristic as a replicating vaccine influences product selection due to safety considerations. Jynneos and ACAM2000 are co-stocked for prevention, and TPOXX and Tembexa are co-stocked for treatment, to reduce the risk of supply disruptions and reliance on a single mechanism.
Procurement Market and Investment Implications
This market is driven more by federal government contracts, stockpile replenishment, and shelf-life extensions than by typical prescription volumes. The U.S. BARDA budget request for fiscal year 2025 was USD 970 million, and SIGA reported USD 88 million in TPOXX product revenue for 2025, demonstrating the reality of procurement demand. Bavarian Nordic's Jynneos/Imvanex/Imvamune public response revenue expanded to DKK 5.027 billion in 2024, with U.S. private market revenue reaching DKK 178 million. Regulatory, manufacturing, and government contracting capabilities represent high barriers to entry, but revenue is more sensitive to order timing and budget execution than in the commercial infectious disease market.
In the short term, the FDA's MCM system strengthens the government procurement and SNS replenishment base for TPOXX, Tembexa, Jynneos, and ACAM2000, which are already approved and marketed. SIGA's USD 88 million in TPOXX product revenue for 2025 and Bavarian Nordic's DKK 5.027 billion in public response revenue for 2024 demonstrate that governments can create independent markets even in areas with limited patient populations. From an R&D perspective, the parallel stockpiling of VP37 inhibitors and DNA polymerase inhibitors, and the competition between Phase 3 Jynneos and replicating ACAM2000, will drive subsequent pipelines focused on resistance, safety, and supply capabilities. In the medium to long term, corporate value is sensitive to the execution of the USD 970 million BARDA budget request for fiscal year 2025, contract options, manufacturing facility qualifications, and shelf-life extension performance.
Source: FDA Drug Approvals (rss)