CBRN Antivirals & Antitoxins MEDICAL COUNTERMEASURES Program

Enhancing preparedness and protecting the American people from anthrax, smallpox,
botulinum toxin, and filoviruses by supporting the advanced development of medical
countermeasures through regulatory approval and procurement.

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The Development of Antiviral and Antitoxin Therapeutics

The Antivirals and Antitoxins program partners with industry to develop safe and effective therapeutics for disease caused by anthrax, botulinum toxin, smallpox, and filoviruses. These high consequence pathogens would cause significant mortality if released into the US population, and the products we develop are designed to mitigate the consequences of deliberate or naturally occurring outbreaks of these biological threats.

Since the establishment of BARDA in 2006, a portfolio of FDA-approved therapeutics for these four threats has been developed and procured for national security preparedness. We continue to build on these successes by developing products that are sustainable, improve operational logistics, and diversify the current countermeasures portfolio.

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Antivirals and Antitoxins Program

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Anthrax Antitoxins

Anthrax Antitoxins

Bacillus anthracis, the etiological agent that causes anthrax, is a serious bioterrorism agent due to the ease of production and delivery of aerosolized spores that result in a high mortality systemic disease. The threat of anthrax is exemplified by the Amerithrax attacks in 2001, where anthrax spores were distributed through the U.S. postal system, causing 22 infections, 11 serious illnesses, and five fatalities despite the treatment of affected individuals with antibiotics.

BARDA is pursuing a comprehensive strategy to address the threat of inhalational anthrax, including the procurement of antimicrobial drugs, vaccines, and antitoxins. The Antivirals & Antitoxins program has supported the development and approval of Raxibacumab, Anthrasil, and Anthim® as three antibody-based therapeutics that bind to the B. anthracis protective antigen (PA), a central component of the B. anthracis toxin. Following the Amerithrax attacks, there was increased discussion of the limitations of antibiotics (which treat only bacteremia) alone in fulminant disease associated with inhalational anthrax. This ultimately was the impetus for development of therapeutics that could complement antibiotics by treating the toxemia associated with anthrax. BARDA will continue to enhance our preparedness against inhalational anthrax through efforts to improve treatment efficacy, reduce life-cycle cost by extending product usability, and pursue the next generation of products with improved deployment characteristics that include alternative targets and non-intravenous routes of administration.

Botulism Antitoxins

Botulism Antitoxins

The bacterium Clostridium botulinum can produce neurotoxins that cause botulinum intoxication, a neurological condition that is manifested by ptosis, spreading muscle paralysis, difficulty breathing, and death, if untreated. These toxins are among the most toxic compounds in nature, even at low concentrations. The Centers for Disease Control and Prevention has classified the seven serotypes of botulinum neurotoxins as Category A bioterrorism agents due to their potential for easy preparation and dissemination, high mortality, and the potential for an attack to have a major public health impact.

BATTM is a de-speciated equine polyclonal antibody-based treatment and remains the only licensed antitoxin against all seven botulism neurotoxin serotypes A-G. To improve the United States Government’s preparedness against this priority threat, BARDA is supporting the development of next-generation botulinum antitoxins with improved potency and deployment properties.

Smallpox Antivirals

Smallpox Antivirals

Smallpox is the most consequential infectious disease in human history with over 300 million fatalities in the 20th century alone. It was eliminated as an endemic disease by 1980 through a focused international vaccination campaign. However, the demonstration that poxviruses can be synthesized de novo provides additional evidence that smallpox remains a significant health security threat and that its re-emergence in the unvaccinated population, whether via natural or clandestine sources, would be calamitous.

The accidental or intentional introduction of smallpox into the population would likely result in highly contagious infected individuals who are refractory to vaccine treatment. BARDA’s advanced development efforts to prepare the US to treat this population has resulted in two FDA Approved smallpox therapeutics (TPOXX® and TEMBEXA®) and advancement of several other candidates. - BARDA continues to support the advanced development of multiple antivirals with distinct mechanisms of action to enhance our ability to respond to a smallpox emergency, obviate the danger posed by pathogen resistance to the approved antivirals, and provide healthcare professionals with multiple options for therapeutic intervention.

Therapeutics for Filoviruses: Ebolavirus & Marburgvirus

Therapeutics for Filoviruses: Ebolavirus & Marburgvirus

The three most consequential filoviruses for humans are Zaire ebolavirus, Sudan ebolavirus, and Marburg marburgvirus virus. The infections caused by these filoviruses result in highly lethal hemorrhagic fevers with mortality as high as 90 percent. The disease manifests with flu-like symptoms but progresses rapidly with diarrhea, dehydration, and disorientation. Severe cases also involve extensive hemorrhaging due to coagulation abnormalities and multi-organ dysfunction.

The 2014-2016 Zaire ebolavirus epidemic in West Africa highlighted the impact of unmitigated Ebola virus disease on public health, with greater than 28,000 confirmed cases and more than 11,300 deaths. In recognition of the threat to public health posed by filovirus infections, BARDA responded to this outbreak by pursuing the advanced development of prophylactic and therapeutic countermeasures, with the Antivirals and Antitoxins program supporting identification and development of multiple antibody-based therapeutics for Zaire ebolavirus. Two of the products, Inmazeb™ and Ebanga™, have since been deployed in subsequent Zaire ebolavirus outbreaks and were approved by the FDA in 2020, becoming the first approved therapeutics against a filovirus.

Recognizing the continued threat posed by Sudan ebolavirus and Marburg marburgvirus virus and the paucity of products to treat disease caused by these viruses, the Antivirals and Antitoxins program is focusing significant effort on the development of therapeutics against these two threats.

BARDA Programs

CBRN has a proven track record of developing life-saving medical countermeasures. We will continue to work with partners old and new to treat or prevent the medical consequences that result from CBRN threats.

ADDITIONAL REFERENCES

Website Refresh - www.medicalcountermeasures.gov is pleased to announce a phased launch of our newly redesigned public website. We are making website improvements to provide a more modern and customer-centric web experience. Over the next several months you will see differences throughout the site while we continue implementing updates. Thank you for your understanding and please let us know if you have any questions: techwatchinbox@hhs.gov