Trending Clinical Topic: COVID Antibody Cocktail

Ryan Syrek


April 23, 2021

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In early March, Regeneron presented data regarding protection against COVID-19 conferred after a one-time injection of the monoclonal antibody cocktail casirivimab with imdevimab (REGEN-COV) at a virtual Conference on Retroviruses and Opportunistic Infections 2021 Annual Meeting. The company has now unveiled phase 3 results of a prevention trial (see Infographic below), which resulted in this week's top trending clinical topic.

The newly available data found that REGEN-COV provided 72% protection against symptomatic infections in the first week and 93% protection in following weeks. The antibody cocktail also helped those who did become sick clear the infection faster. Among patients treated with REGEN-COV who had symptomatic COVID-19 recovered in 1 week, compared with 3 weeks among those in the placebo arm. Those receiving the antibody cocktail also cleared the virus faster, and none were hospitalized owing to COVID-19 over the course of 29 days. Adverse events were reported in 29% of those receiving placebo and 20% of those receiving REGEN-COV.

Regeneron's cocktail was given to President Donald Trump after he got sick with COVID-19 last fall. It received emergency authorization from the US Food and Drug Administration (FDA) last November. In February, the FDA also cleared use of an antibody cocktail from Eli Lilly that consists of bamlanivimab and etesevimab administered together. Recently released guidelines from the Infectious Diseases Society of America (IDSA) recommended use of that cocktail to treat outpatients with mild to moderate COVID-19 at risk of progressing to severe disease. The IDSA guidelines also recommend the use of tocilizumab in certain patients and recommended against use of ivermectin outside of clinical trials.

Antibodies are making news related to infections beyond COVID-19 as well. A recent phase 2b trial of more than 4500 individuals across three continents found that an experimental monoclonal antibody drug, VRC01, effectively prevented 75% of infections from HIV-1 isolates sensitive to that antibody. The study, published March 18 in The New England Journal of Medicine, found that although VRC01 reduced incidence of HIV-1 cases from VRC01-sensitive isolates, it did not significantly reduce overall HIV-1 infection. However, the hope is that researchers may be able to develop an effective prophylaxis using a cocktail that contains a combination of broadly neutralizing antibodies that act on most circulating HIV-1 isolates.

Investigations into the use of antibody cocktails for HIV and COVID-19 prevention and treatment are ongoing. Even as COVID vaccination efforts continue to ramp up worldwide, interest remains high in any drugs that may provide immediate protection to unvaccinated individuals, as well as help those who are infected combat the disease.

Read more about investigational drugs and other therapies for COVID-19.


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