Sanofi SA and partner Regeneron Pharmaceuticals Inc. have started a clinical trial of their rheumatoid arthritis drug sarilumab (Kevzara) as a treatment for the coronavirus, the companies said on Monday. Enrollment for the mid-to-late stage trial will begin immediately, and the companies anticipate the trial will test up to 400 patients. Sarilumab is an infection-fighting protein known as monoclonal antibody. Regeneron in February announced a partnership with the US Department of Health and Human Services to develop a coronavirus treatment, and had said it would focus on monoclonal antibodies. Source