Kevzara was not expected to directly block the coronavirus, SARS-CoV-2, that is causing a global pandemic. But it was hoped that the drug would help ease the immune system’s overreaction to the virus — a “cytokine storm” that causes inflammation and fluid buildup in the lungs of many of the sickest patients — potentially helping to keep patients off of ventilators or saving their lives. Early data from a 21-patient study in China using Actemra had appeared promising.

But there was no benefit in the group of patients most like those in that Chinese study: those termed “severe,” meaning they needed oxygen, but not with air pressure that is faster than normal breathing and certainly not those on ventilators. A 276-patient study in this group was stopped because there was no chance it would succeed.

There is still a glimmer of a positive result in sicker patients, whom the companies call “critical.”