Laboratory (illustrative)
Laboratory (illustrative) iStock

Drugmaker Eli Lilly has said it is pausing its trial of a combination antibody treatment for coronavirus due to safety reasons. Shares of Eli Lilly dropped as much as 3.3% in afternoon trading following the news.

According to Bloomberg News, the independent data safety monitoring board recommended pausing enrollment in the U.S. government-sponsored trial. Eli Lilly has not divulged the reasons for the monitoring board's recommendation, merely stating that:

"Out of an abundance of caution, the ACTIV-3 independent data safety monitoring board (DSMB) has recommended a pause in enrollment. Lilly is supportive of the decision by the independent DSMB to cautiously ensure the safety of the patients participating in this study."

Eli Lilly is one of several companies investigating treatments for Covid-19 that use monoclonal antibodies — mass-produced mimics of immune molecules the human body produces in reaction to the coronavirus. The treatment is similar to the Regeneron protocol received by President Donald Trump several weeks ago.

The National Institutes of Health opened the trial to volunteers in August. Around 300 volunteers were recruited initially, who had been hospitalized with mild to moderate coronavirus with less than 13 days of symptoms. Participants were randomly assigned to either IV infusion of the test substance or a saline placebo. They also received "standard care" for coronavirus including treatment with remdesivir, and were to be followed for 90 days.