Guarding against a nightmare scenario, FDA approves new drug to counter smallpox outbreak

Whenever the FDA approves a drug, companies usually tout the patient population that it’s going to help. That’s not exactly the case for the most recent approval to come through at the FDA, though.

Phil Gomez

Tecovirimat, or Tpoxx, treats smallpox, an often fatal infectious disease that was declared eradicated in 1980 by the World Health Organization. But strains of the virus that causes the ailment still exist — there are two known samples stored in labs in Russia and the US, and at least one previous discovery of forgotten vials — which, when unleashed, could cause a lethal pandemic. Add that to the possibility that terrorists can rebuild the virus using gene-editing techniques, and disaster scenarios abound.

Regulators made it clear that the risk of bioterrorism is the chief concern here.

“This new treatment affords us an additional option should smallpox ever be used as a bioweapon,” said FDA Commissioner Scott Gottlieb in a statement. “This is the first product to be awarded a Material Threat Medical Countermeasure priority review voucher. Today’s action reflects the FDA’s commitment to ensuring that the U.S. is prepared for any public health emergency with timely, safe and effective medical products.”

To prove the pill’s efficacy in the absence of actual smallpox patients, researchers turned to animals deliberately infected with monkeypox and rabbitpox — both induced by viruses closely related to the smallpox-causing variola virus. Altogether, they conducted four trials in non-human primates and two in rabbits.

The FDA liked the survival data, as well as the safety profile as demonstrated by a trial involving 359 healthy human volunteers.

The approval goes to Siga Technologies, which had teamed up with the Biomedical Advanced Research and Development Authority (BARDA) on the project and is now eligible to receive $41 million.

“The approval validates this novel smallpox therapy as an important medical countermeasure in response to a potential smallpox outbreak,” said CEO Phil Gomez.

For now, Tpoxx will only be available through the US government’s Strategic National Stockpile, which already has 2 million courses of the oral therapy.

That might change as New York-based Siga explores additional indications for the drug, including monkeypox, which also infects humans.

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Research Scientist - Immunology
Recursion Pharmaceuticals Salt Lake City, UT
Director of Operations
Atlas Venture Cambridge, MA

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