From the Journals

Drug cocktail significantly reduced severe COVID, death in outpatients


A monoclonal antibody combination of casirivimab and imdevimab (REGEN-COV) significantly reduced the risk of COVID-19–related hospitalizations and death from any cause in the phase 3 portion of an adaptive trial of outpatients.

Researchers, led by David Weinreich, MD, MBA, executive vice president of the drug cocktail’s manufacturer Regeneron, found in the randomized trial that the combination also resolved symptoms and reduced the SARS-CoV-2 viral load more quickly, compared with placebo.

Findings were published in the New England Journal of Medicine.

COVID-related hospitalization or death from any cause occurred in 18 of 1,355 patients (1.3%) in the group getting 2,400 mg infusions of the study drug, compared with 62 (4.6%) of 1,341 in the matching placebo group, indicating a relative risk reduction of 71.3%; P < .001.

Sunil Joshi, MD, president of the Duval County Medical Society Foundation and an immunologist in Jacksonville, Fla., said in an interview that these findings confirm benefits of REGEN-COV and are very good news for a patient group that includes those age 65 and older with high blood pressure, diabetes, or obesity; and for people not vaccinated, who are all at high risk of hospitalization or death if they get COVID-19.

“Vaccines are critically important,” he said, “but if you were to be infected and know that there’s a way to keep yourself out of the hospital, this is very good news.”

Researchers seek lowest doses

This trial found that the effect was similar when researchers cut the doses in half. These outcomes occurred in 7 of 736 (1%) of patients given 1,200 mg of REGEN-COV and in 24 (3.2%) of 748 in the matching placebo group (relative risk reduction, 70.4%; P = .002).

Symptoms were resolved on average 4 days earlier with each REGEN-COV dose than with placebo (10 days vs. 14 days; P < .001 for both comparisons).

Dr. Weinreich said in an interview that trials will continue to find the lowest effective doses that can stand up to all evolving variants.

“This is one of those settings where you don’t want to underdose. You’ve got one shot at this,” he said. “We’d love to do lower doses. It would be more convenient and we could treat more patients, but if it generates more clinical failures or doesn’t work with certain variants, then you’ve done a huge disservice to the world.”

Also new in this study is that researchers tested not only seronegative patients, but patients at high risk regardless of blood antibody status, he said.

“It’s the first suggestion of data that if you’re breaking through a vaccine and you’re at high risk, the use of the cocktail is something to strongly consider because treatment early is better than treatment later,” Dr. Weinreich said.

In addition to efficacy, the phase 3 trial demonstrated the cocktail had a good safety profile. Serious adverse events occurred more often in the placebo group (4%) than in the 1,200-mg group (1.1%) and the 2,400-mg group (1.3%). Infusion reactions (grade 2 or higher) occurred in less than 0.3% of patients in all groups.

William Fales, MD, state medical director for the Michigan Department of Health and Human Services, said the results confirm the promise of REGEN-COV for reducing hospitalizations and death in a peer-reviewed publication.


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