Regeneron halts trial of COVID-19 antibody drug in sickest hospitalized patients

Regeneron Pharmaceuticals said Friday it has paused a clinical study of its antibody drug to treat some of the sickest COVID-19 patients because of a potential safety concern.

The recommendation from an independent monitoring board marks the second time a clinical trial of an experimental coronavirus antibody drug has been paused because of safety issues.

Regeneron said it is pausing enrollment of hospitalized COVID-19 patients receiving mechanical ventilation or intense oxygen after the independent monitoring committee observed “a potential safety signal and an unfavorable risk/benefit profile at this time.”

The monitoring board recommended collecting additional data on the patients already enrolled.

The pause does not impact other studies of Regeneron’s antibody drug, which is under consideration for emergency use authorization in mild-to-moderate outpatients at high risk for poor outcomes.

Earlier this week, the company said a separate study definitively showed a significant reduction in viral load and the need for further medical visits.

The data monitoring board also recommended continuing trial enrollment of hospitalized patients who require little or no oxygen.

Earlier this month, a different monitoring board recommended pausing enrollment in a study testing an Eli Lilly antibody drug to investigate a possible safety issue in hospitalized patients. 

On Monday, the National Institute of Allergy and Infectious Diseases (NIAID), which is funding the study, announced there was no longer a safety issue, but the study had been stopped because the board found little clinical benefit in the treatment.

Monoclonal antibodies are lab-generated versions of one of the human body’s main defenses against pathogens.

No antibody drugs have been authorized for use yet, but they made headlines recently after President Trump said he received Regeneron’s antibody cocktail and touted it as a “miracle” and a “cure.” 

While treatments are improving, there is no cure, and the available treatments depend on how sick someone is.

NIAID Director Anthony Fauci this week said treatment is all about timing; dexamethasone and other steroids can help with severely ill patients on ventilation, as can the antiviral drug remdesivir. Studies with experimental antibody treatments, on the other hand, suggest they are most effective when given on an outpatient basis to someone with mild symptoms.