Another day, another delay: NIH halts phase 3 study of Lilly's COVID-19 antibody

The National Institutes of Health (NIH) is hitting pause on a phase 3 study testing Eli Lilly and AbCellera’s COVID-19 antibody treatment in hospitalized patients. The reason? “An abundance of caution,” the company says.

The trial's independent data safety monitoring board recommended the company pause enrollment, a Lilly spokesperson told CNBC in an email Tuesday, adding, “Lilly is supportive of the decision by the independent DSMB to cautiously ensure the safety of the patients participating in this study.

As of Tuesday evening, only the DSMB had seen data from the study, Eli Lilly said in a statement. Neither NIH leadership nor Lilly have seen any results.

The stalled NIH trial doesn't affect other studies of the antibody, including an NIH-led phase 2 study in patients recently diagnosed with mild to moderate COVID-19 and a pair of Lilly-run studies testing it in ambulatory patients and as a preventive treatment.

The news comes one day after Johnson & Johnson paused the phase 3 study for its COVID-19 vaccine because a patient had an “unexplained illness” and about a month after AstraZeneca suspended a trial for its COVID-19 jab because a patient developed transverse myelitis, a type of spinal cord inflammation that can be triggered by infections.

RELATED: NIH to test COVID-19 antibodies in hospitalized patients—starting with Eli Lilly's

The NIH designed the ACTIV-3 trial, unveiled in early August, to test experimental antibody treatments for COVID-19 in about 300 patients. Although the trial started with Lilly and AbCellera’s prospect, known as LY-CoV555 or bamlanivimab, the plan includes adding more candidates as the trial goes on.

The study is pitting LY-CoV555 against placebo in patients who have been hospitalized with mild or moderate COVID-19 and who have had symptoms for fewer than 13 days. After five days of treatment, investigators assess the patients’ symptoms and whether they need supportive care, like supplemental oxygen or mechanical ventilation. Once investigators get to this point for all of the patients, they’ll decide whether to test the drug in more patients.

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If Lilly’s treatment gets the green light, the study will enroll another 700 patients, including sicker ones who may need supportive care for organ failure. If it’s deemed unsafe or not likely to be effective, it will be dropped.

The trial design allows additional antibodies to be tested in the first or second stage of the study and for more patients to be recruited along the way, the NIH said in August. Patients at “select hospitals” may volunteer to participate in the study; these include sites that are already part of clinical trial networks around the world.

Eli Lilly reported early phase 2 data for the treatment in September, noting it reduced hospitalizations in patients recently diagnosed with mild to moderate COVID-19, but that two of the three doses tested did not beat placebo at cutting viral load. The company did not share statistical analyses for the trial’s primary endpoint, but it thinks it has enough to go on—it submitted a request for emergency authorization a few weeks later.

Editor's note: This story has been updated with additional comments from Eli Lilly.