Tocilizumab (Actemra), an interleukin-6 (IL-6) inhibitor, was authorized to treat certain hospitalized COVID-19 patients, the FDA announced late on Thursday.

The drug received emergency use authorization (EUA) for hospitalized patients ages 2 and up who are receiving systemic corticosteroids and require supplemental oxygen, non-invasive or invasive mechanical ventilation, or extracorporeal membrane oxygenation (ECMO). It is not authorized for outpatients, the agency said.

“Providing additional therapies for those who do become hospitalized is an important step in combating this pandemic,” said Patrizia Cavazzoni, MD, director of the FDA’s Center for Drug Evaluation and Research, in a statement.

Tocilizumab is an IL-6 inhibitor given by intravenous infusion, which is approved to treat inflammatory diseases such as rheumatoid arthritis, and is used in certain hematologic cancers to quell cytokine release syndrome following CAR T-cell therapy.

Results of early trials in COVID-19 patients were mixed, but the FDA pointed to the results of four randomized trials, two of which showed either a mortality benefit or an improvement in composite clinical outcomes.

Chief among them was the U.K.’s pragmatic RECOVERY trial, which found a significantly lower risk of death by day 28 compared to usual care (31% vs 35%, respectively) among patients with COVID-19 pneumonia treated with tocilizumab. The tocilizumab group also had a shorter hospital stay (19 vs 28 days).

The agency also noted results of the EMPACTA trial, where a significantly lower proportion of COVID-19 patients treated with tocilizumab progressed to mechanical ventilation or died by day 28 versus those receiving only usual care (12% vs 19%).

Tocilizumab showed no statistically significant difference in clinical status on an ordinal scale or significant difference in time to hospital discharge in two other trials, COVACTA and REMDACTA, but the agency excused those results by saying both trials “contributed to the assessment of the safety for Actemra when used for the treatment of COVID-19.”

Common adverse events reported in the COVID-19 trials of tocilizumab included constipation, anxiety, diarrhea, insomnia, hypertension, and nausea.

The FDA noted that tocilizumab does not directly target the SARS-CoV-2 virus, and clarified that the drug is “not approved as a treatment for COVID-19,” and should only be used under the terms of the EUA.