SIGA Technologies announced that the Food and Drug Administration (FDA) has approved TPOXX (tecovirimat) for the treatment of human smallpox disease in adults and pediatric patients weighing at least 13kg. 

TPOXX is the first small-molecule oral antiviral agent to be specifically approved for this indication. It targets and inhibits the activity of the orthopoxvirus VP37 protein and blocks its interaction with cellular Rab9 GTPase and TIP47, which prevents the formation of egress-competent enveloped virions necessary for cell-to-cell and long-range dissemination of virus. 

The approval was supported by findings from 12 clinical trials of TPOXX with more than 700 healthy human volunteers that showed no drug-related serious adverse events. 

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The most commonly reported adverse effects were headache, nausea, and abdominal pain. In addition, significant reductions in mortality and viral load were seen in non-human primates infected with monkeypox virus and in rabbits infected with rabbitpox virus in 4 trials. Overall, treatment with TPOXX for 14 days led to a statistically significant improvement in survival vs placebo, except when given to cynomolgus macaques on day 6 post-challenge. 

“The FDA approval of TPOXX achieves an important objective for both SIGA and our lead partner in the U.S. Government, the Biomedical Advanced Research and Development Authority (BARDA). The approval validates this novel smallpox therapy as an important medical countermeasure in response to a potential smallpox outbreak,” stated Dr. Phil Gomez, CEO of SIGA Technologies, Inc. 

For now, TPOXX will be available only through the US government’s Strategic National Response Stockpile (SNS) and is supplied as 200mg strength capsules. The Company plans to evaluate the potential expansion of the TPOXX indication to include prophylactic use in those exposed to smallpox and other orthopoxviruses (eg, monkeypox). 

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This article originally appeared on MPR