Regeneron extends $270M Ebola drug deal

Regeneron Pharmaceuticals (REGN) has extended its procurement agreement with the U.S. Biomedical Advanced Research and Development Authority (BARDA) to supply additional doses of its Ebola treatment Inmazeb. The updated arrangement adds approximately $270 million in value and continues a supply relationship that began in 2020. Under the new terms, Regeneron expects to deliver additional treatment doses of Inmazeb to the U.S. government through 2031, supporting long‑term national preparedness for Ebola disease.

Inmazeb is a three‑antibody cocktail containing atoltivimab, maftivimab and odesivimab‑ebgn, developed using Regeneron’s VelociImmune platform and associated VelociSuite technologies. It is approved by the U.S. Food and Drug Administration for the treatment of infection caused by Orthoebolavirus zairense in adult and pediatric patients, including neonates born to infected mothers. The therapy has been administered to hundreds of patients since 2019, reflecting growing clinical use since its introduction.

In clinical testing, Inmazeb demonstrated a significant effect on survival in patients with Ebola disease caused by Orthoebolavirus zairense. Inmazeb reduced mortality by approximately 55% compared with an active control regimen in patients with low viral load.

The safety information for Inmazeb highlights several common adverse reactions. The most frequent events, occurring in at least 20% of treated subjects, included pyrexia or elevated fever, chills, tachycardia, tachypnea and vomiting. Assessment of these events can be complicated because many overlap with symptoms of the underlying Ebola infection, which can itself cause systemic illness. These safety findings inform monitoring and management strategies when the drug is used in clinical settings.

Inmazeb also has implications for vaccination planning. The treatment may reduce the efficacy of live vaccines, leading to guidance to avoid concurrent administration of live vaccines during therapy. The interval between starting Inmazeb and giving a subsequent live vaccine is recommended to follow current vaccination guidelines, reflecting the need to coordinate antiviral treatment with immunization programs in outbreak environments.

Beyond the extended Inmazeb supply deal, Regeneron is advancing research on maftivimab, one of the three antibodies in the Inmazeb cocktail. Maftivimab has shown strong efficacy against Bundibugyo virus in in vitro and non‑human primate studies. Maftivimab is being added to the PARTNERS clinical trial, a platform study evaluating potential treatments for Bundibugyo virus disease, for further assessment as a monotherapy or in combination regimens.

At present, there are no approved treatment options for Bundibugyo virus, underscoring the potential importance of maftivimab’s development. The work on Bundibugyo virus complements Inmazeb’s established indication against Orthoebolavirus zairense, broadening Regeneron’s engagement across filovirus threats. Together, these efforts point to a strategy that combines commercial supply agreements with ongoing clinical research to address current and emerging viral risks.

Regeneron’s activities with Inmazeb extend beyond U.S. government procurement. Since 2018, the therapy has been provided at no cost under a compassionate use protocol to infected individuals in countries experiencing Ebola virus disease outbreaks caused by Orthoebolavirus zairense, including the Democratic Republic of Congo and Guinea. This channel has supported access during acute public health emergencies outside higher‑income markets.

In September 2025, Regeneron committed to donate up to 500 doses of Inmazeb to the World Health Organization for exclusive use by governments of low‑ and lower‑middle income countries most at risk for Ebola disease outbreaks. In parallel, the company has worked with governments in higher‑ and middle‑income countries to establish Inmazeb stockpiles. When combined with the newly extended BARDA agreement valued at about $270 million through 2031, these measures position Inmazeb as a central element of both U.S. and international Ebola preparedness frameworks.