TPOXX is claimed to be the first drug with an indication for treatment of smallpox, which is a contagious and fatal infectious disease.
The approval of small-molecule antiviral treatment was based on data from 12 clinical trials, which show no drug-related serious adverse events in more than 700 healthy human volunteers.
According to the company, four pivotal trials in non-human primates (NHPs) and two pivotal trials in rabbits showed that TPOXX significantly reduced both mortality and viral load in NHP infected with monkeypox virus (MPXV) and in rabbits infected with rabbitpox virus.
SIGA Technologies CEO Dr Phil said: “TPOXX is proof that public-private partnerships work when the partners are committed to a focused mission.
“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).”
SIGA also secured priority review voucher (PRV) from the regulator, which can be used to secure an accelerated FDA review of a future product or sold to a third party.
The FDA also approved a seven-year expiry for TPOXX. Under existing contract with the Biomedical Advanced Research and Development Authority (BARDA), the firm intends to request BARDA to exercise an option for a $50m payment to the company based on this extended shelf-life determination.
Initially, SIGA will supply TPOXX through the US government’s Strategic National Stockpile (SNS).
As part of $472m procurement and development contract with BARDA, the company already delivered two million courses of oral TPOXX to the SNS.
FDA commissioner Dr Scott Gottlieb said: “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.”