Regeneron Pharmaceuticals said on Monday it began late-stage clinical trials to assess the effectiveness of its antibody cocktail in preventing and treating Covid-19, sending its shares up nearly 4%.
The trial, run jointly with the National Institute of Allergy and Infectious Diseases, would test the therapy's ability to prevent infection in those who have had close exposure to a Covid-19 patient.
The cocktail has also entered into the mid-to-late-stage phase of two trials testing its effectiveness in hospitalized and non-hospitalized Covid-19 patients, Regeneron said.
Regeneron is among the few front-runners who have begun human trials testing their experimental therapies to fight Covid-19, including Gilead Sciences, Eli Lilly and AbbVie.
Regeneron in June began human trial of the antibody cocktail as a treatment for Covid-19, with an "adaptive" design to quickly move to include thousands of patients.
The late-stage trial will be conducted across 100 sites and expected to enroll 2,000 patients in the U.S. It follows a safety assessment of the cocktail in an early-stage trial by an independent committee.
Antibodies are proteins made by the body's immune system that recognize, bind and neutralize an invading virus. Regeneron's cocktail, a combination of an antibody made by the company and a second antibody isolated from recovered Covid-19 patients, is designed to bind the antibodies to the coronavirus' spike protein.
The drugmaker was also testing its rheumatoid arthritis drug, Kevzara, with Sanofi to treat COVID-19, which on Thursday failed to meet the main goal of a U.S. study testing it in the most critically ill Covid-19 patients.
Shares of the drugmaker were up 3.6% at $645 in trading before the bell.