SIGA Technologies, Inc. (SIGA), a commercial-stage pharmaceutical company focused on the health security market, today announced that the U.S. Food and Drug Administration (FDA) has approved oral TPOXX® (tecovirimat) for the treatment of smallpox to mitigate the impact of a potential outbreak. TPOXX, a small-molecule antiviral treatment for smallpox, is the first therapy specifically approved for this indication.

Image/CDC/ John Noble, Jr., M.D.
Image/CDC/ John Noble, Jr., M.D.

On May 1, 2018, the FDA’s Antimicrobial Drugs Advisory Committee voted unanimously, 17 to 0, that the benefits of TPOXX outweigh its risks.

FDA approval is based on data from 12 clinical trials of oral TPOXX in over 700 healthy human volunteers, which showed no drug-related serious adverse events. Four pivotal trials in non-human primates (NHPs) and two pivotal trials in rabbits demonstrated that TPOXX significantly reduced both mortality and viral load in NHP infected with monkeypox virus (MPXV) and in rabbits infected with rabbitpox virus. The results of these studies were published in the July 5, 2018 issue of the New England Journal of Medicine.

TPOXX, also known as tecovirimat and ST-246®, is an orally administered and IV formulation antiviral drug for the treatment of human smallpox disease caused by variola virus. TPOXX is a novel small-molecule drug of which 2 million courses have been delivered to the Strategic National Stockpile under Project BioShield.


Smallpox is a contagious, disfiguring and often deadly disease that has affected humans for thousands of years. Naturally-occurring smallpox was eradicated worldwide by 1980, the result of an unprecedented global immunization campaign.

Thoughts on the eradicator of smallpox: ‘You can argue that he’s may of saved more lives than any other single human being in human history’

Samples of smallpox virus have been kept for research purposes. This has led to concerns that smallpox could someday be used as a biological warfare agent.  No cure or treatment for smallpox exists. A vaccine can prevent smallpox, but the risk of the vaccine’s side effects is too high to justify routine vaccination for people at low risk of exposure to the smallpox virus.