Regeneron halts placebo enrollment in Covid-19 cocktail trial after IDMC finds 'clear' efficacy — but there are no data yet
Despite having already received an emergency use authorization for its Covid-19 antibody in non-hospitalized patients last November, Regeneron continued to conduct trials to evaluate the cocktail’s effectiveness. Now, the big biotech has received some good news from their IDMC.
On the IDMC’s recommendation, Regeneron will be shutting down enrollment in the placebo group of a Phase III outpatient trial for their REGN-COV program — a mix of casirivimab with imdevimab — after investigators found “clear clinical efficacy” in both doses compared to the control, the company announced Thursday. CSO George Yancopoulos also said in a statement that the cocktail can neutralize emerging strains of the novel coronavirus.
“Our cocktail approach using two functionally-independent antibodies safeguards against variants that may impact potency to a single antibody,” Yancopoulos said.
Regeneron still does not have access to the unblinded data, including the relative treatment benefit of the 1,200mg and 2,400mg doses, and said they will release results next month. Researchers will continue enrolling patients at both dosage levels.
This is not the only trial Regeneron is conducting for its experimental therapy. Last month, the company released interim data from a separate trial looking at whether it could prevent symptomatic infections from occurring in people exposed through a family connection.
Those data showed that zero infections manifested among 186 people treated in the treatment arm, compared to eight of 223 infections occurring in the placebo group. Additionally, when adding asymptomatic infections, there were 23 cases among the placebo patients compared to 10 in the cocktail arm.
In that study, researchers also noted significantly lower peak viral loads and shorter periods of viral loading for the drug arm. Full data are expected early in the second quarter.
Following an EUA for the cocktail last November, the US has been rapidly buying up supply of the therapy. Last month, Regeneron scored a $2.625 billion supply deal with the government. The biotech’s best-case scenario for supply is to deliver 1.25 million doses by the end of June, but that may depend on the FDA’s stance on the lower dose — currently, only the 2,400mg cocktail dose is authorized.
If regulators don’t soon expand the EUA to cover the lower-dose regimen, which is still being tested for the same population of non-hospitalized, mild to moderate Covid-19 patients at high risk of progression, Regeneron will only be able to supply around 750,000 finished doses by that time.
In the company’s pivotal outpatient trial, only the higher dose helped newly diagnosed patients achieve statistically significant reductions in virus levels and require fewer medical visits. The cocktail is not authorized for hospitalized patients or patients requiring supplemental oxygen, either due to Covid-19 or those with a high-risk comorbidity.
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