Regeneron's Inmazeb Becomes First Ebola Treatment Approved by FDA

Inmazeb is the world's first treatment for Ebola. 

Although Regeneron Pharmaceuticals has been in the news lately for its antibody cocktail against COVID-19 that was used to treat President Trump, it’s not the only arrow in the company’s quiver. Today it announced that the U.S. Food and Drug Administration (FDA) approved Inmazeb, a three-antibody cocktail to treat Ebola infections in adults and children. It has also been approved for newborns of mothers who have tested positive for Ebola.

Inmazeb is made up of three monoclonal antibodies: atoltivimab, maftivimab and odesivimab-ebgn. The cocktail was engineered using the company’s VelocImmune platform and associated VelociSuite technologies. The antibodies have similar structure, but bind to different, non-overlapping antigens on Zaire ebolavirus glycoprotein. They neutralize the virus by blocking its ability to invade patients’ bodies and by recruiting other immune cells to target infected cells.

Ebola is rare and deadly and typically causes outbreaks in sub-Saharan Africa, although there were 11 people treated in the U.S. during the 2014 to 2016 epidemic. There is currently an ongoing outbreak in the Democratic Republic of the Congo (DRC). The disease spreads through contact with blood, body fluids and tissues of animals, and through contact with infected people, as well as through sexual contact with someone sick with the disease, as well as after recovery from the disease. The early signs of the disease include fever, aches and pains, severe headache, and abdominal pain, weakness, diarrhea and vomiting, then moves onto hemorrhaging, bleeding or bruising. The average case fatality rate of Ebola virus disease (EVD) is about 50%.

In 2019, the FDA approved an Ebola vaccine, Merck’s Ervebo.

“We are incredibly proud that the FDA has approved Inmazeb, which is also known as REGN-EB3,” said George D. Yancopoulos, president and chief scientific officer of Regeneron. “This is the first time the FDA has approved a treatment specifically for Ebola, which has caused a number of deadly outbreaks. Decades of investment in our VelociSuite rapid response technologies, the dedication of world-class scientists, and the courageous contributions of healthcare providers and patients, together with remarkable cooperation between leading international health organizations and govenrments, have led to this important moment.”

As part of a deal announced in July, Regeneron will produce a specific number of Inmazeb doses over six years to the Biomedical Advanced Research and Development Authority (BARDA). In response to the 2018 outbreak in the DRC, Regeneron worked with the World Health Organization (WHO), FDA and other global health organizations to provide Inmazeb under a compassionate use protocol and include it in the four-arm PALM (Pamoja TuLinde Maisha) Trial. With BARDA, Regeneron plans to continue to offer the therapy for free in response to outbreaks in the DRC through the MNEURI protocol for compassionate use.

“Since 2015, BARDA has partnered with Regeneron to develop a life-saving treatment for Ebola Zaire,” said Gary Disbrow, acting director of BARDA. “The Food and Drug Administration’s approval of Inmazeb shows the power of public private partnerships to bring forward these critical treatments and improve global public health. BARDA is continuing our collaboration with Regeneron on other life-threatening diseases such as MERS and COVID-19, and we look forward to continued success.”

The therapy’s safety and efficacy were demonstrated in the 681-patient PALM Trial, which was initiated in 2018 in the DRC. The trial was jointly sponsored by the WHO, the National Institutes of Health (NIH) and the Institut National de Recherche Biomedical (INRB) in the DRC. The trial was halted early after a pre-specified interim analysis showed Inmazeb was superior to Gilead’s remdesivir, currently the only approved therapy for COVID-19, and Mapp Biopharmaceutical’s ZMAPP.