Regeneron puts kibosh on 4 antibody studies as Pfizer's Paxlovid dominates the COVID treatment scene

In a sign of the times, Regeneron Pharmaceuticals—whose antibody cocktail REGEN-COV once helped form the vanguard of COVID-19 therapeutics—has axed a clutch of trials weighing the med across a range of patients and clinical stages. The move comes about half a year after the FDA pulled the cocktail from the market after data suggested its efficacy had waned in the face of the surging omicron variant.

It’s a fate shared by a number of early-pandemic therapeutics, which have largely fallen by the wayside in the U.S. as the virus swiftly evolves.

Now, Regeneron has terminated four clinical trials of REGEN-COV, comprising the monoclonal antibodies casirivimab and imdevimab.

Those studies include REGEN-COV as a treatment in high-risk patients younger than 12 years old, plus a prevention study in immunocompromised teens and adults. Regeneron also put the kibosh on a study of REGEN-COV as a treatment for kids hospitalized with COVID-19 and as a treatment for non-hospitalized patients, according to the federal clinical trial database

The company terminated the trials, which ranged from early to late stage, because of “[e]merging SARS-CoV-2 variants impacting susceptibility to study drug,” recent updates on state.

Regeneron’s REGEN-COV shares the fate of several earlier COVID-19 drugs, including antibody peers sotrovimab from GSK and Vir Biotechnology, plus the combination of bamlanivimab and etesevimab developed by Eli Lilly.

In late January, the FDA said it was trimming the emergency use authorizations (EUAs) for Regeneron and Eli Lilly’s antibody cocktails, at the time limiting the therapies to patients who’d been infected with or exposed to a variant susceptible to the treatments.

On the FDA’s online roster of pandemic emergency use authorizations, the regulator states that both Regeneron’s REGEN-COV and Lilly’s bamlanivimab and etesevimab are “not currently authorized in any U.S. region,” and therefore, “may not be administered for the treatment or post-exposure prevention of COVID-19.”

In terms of COVID therapeutics still on the U.S. market, Pfizer’s antiviral Paxlovid is largely dominating the scene, trailed by Merck’s rival pill Lagevrio.

In February, the FDA also gave an emergency nod to Eli Lilly’s solo antibody bebtelovimab to treat mild-to-moderate COVID-19 in adults and kids ages 12 and older at high risk of progressing to severe disease. Lab tests found Lilly’s mAb retained activity against both the omicron variant and the BA.2 omicron subvariant, the FDA noted in its approval announcement earlier this year.

Currently, Pfizer’s antiviral, much like its BioNTech-partnered vaccine Comirnaty, reigns supreme on the therapeutic sales front. In the second quarter of 2022, Paxlovid pulled down revenues of $8.1 billion, Pfizer said in a recent earnings release. The company stuck by Paxlovid sales predictions of $22 billion for the full year.

Merck’s Ridgeback-partnered pill Lagevrio, also known as molnupiravir, generated just $1.2 billion in the second quarter, coming off a $3.2 billion high during the first three months of the year.