After months of conflicting results from smaller trials, the eagerly anticipated RECOVERY trial has found that the IL-6 inhibitor tocilizumab does in fact improve outcomes in patients hospitalised with COVID-19.

“Previous trials of tocilizumab had shown mixed results, and it was unclear which patients might benefit from the treatment,” said Prof Peter Horby, of the University of Oxford and the RECOVERY trial’s joint chief investigator. “We now know that the benefits of tocilizumab extend to all COVID patients with low oxygen levels and significant inflammation.”

Previously, the REMAP-CAP trial had shown some benefit with tocilizumab, but other trials conducted in the US and Brazil found the drug did little to improve survival or other outcomes in severe cases.

The new results, which were posted to medRxiv but have not yet been peer reviewed, was the largest study of tocilizumab so far. It included a total of 4,116 patients hospitalised with COVID-19, subsets of whom were receiving invasive mechanical ventilation (14%), non-invasive respiratory support (41%), and no respiratory support other than oxygen (45%).

Of the patients randomised to receive tocilizumab, 29% died within 28 days, compared with 33% of those who received usual care, for a rate ratio of 0.86 (p = .007). A “clear mortality benefit” was seen specifically in patients who also received systemic corticosteroids.

Patients receiving tocilizumab were also more likely to be discharged from the hospital alive within 28 days, and among those who were not receiving invasive mechanical ventilation tocilizumab resulted in a lower risk of a composite endpoint including invasive mechanical ventilation or death.

The government has updated its guidance to NHS trusts and clinicians, recommending tocilizumab’s use.

The treatment landscape for severe COVID-19 has taken time to smooth out, with a series of conflicting or uncertain results seen for several types of treatment. Prof Fiona Watt, executive chair of the Medical Research Council, which co-funded the RECOVERY trial, said: “It’s incredibly encouraging that doctors now have an additional COVID-19 treatment that can save lives and reduce the length of hospital stays.”