Siga seeks FDA approval for intravenous smallpox therapy

Siga Technologies has filed for FDA approval of an intravenous formulation of its smallpox treatment Tpoxx. The new formulation is designed to enable the treatment of patients who cannot swallow the already-approved capsules.

The FDA approved an oral formulation of Tpoxx in 2018 for the treatment of human smallpox disease in adults and children weighing 13 kg or more. Siga has contracts to supply oral Tpoxx to Canada and the U.S. but also acknowledges the limitations of the formulation in some populations, leading it to work on an intravenous version of the antiviral.

Siga recently took a step toward bringing the intravenous formulation to market by submitting a new drug application to the FDA. The filing, which is the first application for approval of the intravenous formulation, leveraged earlier work.

“Siga developed IV Tpoxx in partnership with the U.S. government, and the combined expertise has helped generate a robust set of data supporting the NDA for the IV product. As a result of the extensive effort that went into our initial filing with the FDA, we were not required to complete any additional preclinical or clinical work for our IV application,” Dennis Hruby, chief scientific officer at Siga, said in a statement. 

The symptoms of smallpox infection underpin the desire to have an intravenous option. Notably, the virus can damage the throat, making it hard or impossible for patients to swallow pills. That concern led the U.S. government to work with Siga on the intravenous formulation. Siga is now working to make 20,000 courses of intravenous Tpoxx for the U.S. at a time of supply chain pressures. 

Talking to investors on a first quarter results conference call, Siga CEO Phil Gomez said production of COVID-19 vaccines “has significantly impacted the availability of materials for sterile products” such as vials, filters and excipients. Gomez said Siga will work with BARDA “in terms of securing necessary supplies and manufacturing capacity” as needed.