TPOXX (tecovirimat), the first drug with an indication for treatment of smallpox, was just approved by the U.S. Food and Drug Administration to SIGA Technologies Inc. The development of TPOXX was in conjunction with the U.S. Department of Health and Human Services’ Biomedical Advanced Research and Development Authority (BARDA).
Even though eradicated in 1980, the World Health Organization (WHO) announced that smallpox as a contagious and sometimes fatal infectious disease that can be used as a bioweapon.
“To address the risk of bioterrorism, Congress has taken steps to enable the development and approval of countermeasures to thwart pathogens that could be employed as weapons. Today’s approval provides an important milestone in these efforts. This new treatment affords us an additional option should smallpox ever be used as a bioweapon,” said FDA Commissioner Scott Gottlieb, M.D. "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.”
Before its 1980 eradication, variola virus, the virus that leads to smallpox, it was mainly spread by direct contact between people. The symptoms typically began 10 to 14 days after infection and include fever, exhaustion, headache, and backache followed by a rash initially with small, pink bumps progressed to pus-filled sores before finally crusting over and scarring. Smallpox complications include encephalitis (inflammation of the brain), corneal ulcerations (an open sore on the clear, front surface of the eye) and blindness.
The efficacy of TPOXX against smallpox was concluded by studies on animals infected with viruses that are closely related to the virus that results in smallpox and was based on measuring survival at the end of the studies. The studies showed that the animals treated with TPOXX have survived compared to the animals treated with a placebo.
Using the FDA’s Animal Rule, which ensures efficacy are adequate from well-controlled animal research findings, TPOXX was approved.
TPOXX safety was evaluated using clinical trials on 359 healthy human volunteers without a smallpox infection and the most frequently reported side effects included a headache, nausea, and abdominal pain. Additionally, TPOXX received the Orphan Drug designation, which allows incentives to assist and inspire the development of drugs for rare diseases and a Material Threat Medical Countermeasure Priority Review Voucher, which provides additional incentives for specific medical products intended to treat or prevent harm from specific chemical, biological, radiological and nuclear threats.