Celltrion's COVID-19 antibody gets a phase 3 win as virus variants snare existing therapies

Celltrion Chairman Jung Jin Seo (Celltrion)

Chalk one up for COVID-19 antibodies: Celltrion’s prospect, regdanvimab, beat placebo at preventing hospitalization and death in patients with mild to moderate symptoms and helped those patients recover more quickly in a phase 3 study.

The results arrive as the rise of SARS-CoV-2 variants raise concerns about existing antibody drugs, especially those given as single agents. 

The South Korean biotech reported the data in a press release with plans to present full data at a medical meeting in July. The results come from more than 1,300 patients who received either regdanvimab, also known as CT-P59, or placebo. After 28 days of treatment, the antibody reduced risk of hospitalization or death by 72% in patients at high risk of developing severe disease and by 70% in all patients. 

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Patients taking the antibody also recovered more quickly than those on placebo. Of patients at high risk of progressing to severe disease, those taking regdanvimab recovered within a median of 9.3 days, compared to a minimum of 14 days for those on placebo. As for the broader patient group, those taking the antibody recovered in a median of 8.4 days versus 13.3 days for placebo. 

Regdanvimab had a similar safety profile to placebo, “with no clinically meaningful differences,” the company said in the statement. Patients recovered from infusion-related reactions in one to three days, the company said. 

“As many hospitals across the globe now exceed their ability to accommodate patients due to COVID-19, it is critical that we use every resource to reduce the burden on the healthcare system,” said HoUng Kim, Ph.D., head of the Medical and Marketing Division at Celltrion, in the statement. 

If the antibody can do in the real world what it’s shown in the clinic, it could relieve pressure on healthcare systems by stopping patients from needing intensive care and getting them well enough to leave the hospital sooner. The antibody earned a conditional authorization from South Korean regulators in February. 

RELATED: Lilly takes variant-busting COVID-19 antibody into the clinic 

Eli Lilly and Regeneron were the first companies to snag emergency FDA nods for SARS-CoV-2 antibodies, but there remains room for similar treatments, thanks to the rise of viral variants and barriers that have limited the use of antibody treatments. 

Researchers have shown COVID-19 antibodies including Lilly’s bamlanivimab are less effective against some variants compared to the original SARS-CoV-2 virus when given as single agents.  

Eli Lilly stopped supplying bamlanivimab as a solo therapy to the U.S., and the FDA revoked its emergency use authorization in April this year. Lilly’s combination, as well as Regeneron’s tandem casirivimab and imdevimab, are authorized for the treatment of mild to moderate COVID-19 infection, but the FDA halted the distribution of Lilly’s combo to eight states where the P.1 variant, now designated as Gamma by the World Health Organization, was taking hold. Lilly is now working on an antibody treatment designed to work against all currently known circulating variants of concern.

In May, the FDA authorized GlaxoSmithKline and Vir Biotechnology’s sotrovimab for patients with mild to moderate COVID-19 who are not hospitalized but are at high risk of progressing to severe disease. Several other players, including Adagio Therapeutics and Bristol Myers Squibb, are developing antibody treatments as well.