Sanofi will stop studying its arthritis drug Kevzara as a potential COVID-19 treatment, announcing Tuesday that Kevzara did not shorten hospital stays for patients with coronavirus disease who needed intensive breathing support. The French drugmaker had earlier canceled research in hospitalized patients who had not yet progressed to mechanical ventilation after finding Kevzara did not benefit them.Kevzara was part of an early wave of approved drugs that researchers suggested might help reduce the coronavirus pandemic’s toll by easing an overactive immune response thought to lead to serious complications among severely sick COVID-19 patients.Research is still underway on some of those drugs. Roche is studying its similarly acting Actemra in combination with Gilead’s antiviral Veklury, although a Phase 3 study of its drug alone didn’t show any benefit. EUSA Pharma’s Sylvant, meanwhile, has been cleared for a late-stage clinical trial.

Kevzara, Actemra and Sylvant work in rheumatoid arthritis and other autoimmune disorders by blocking a protein called IL-6, which can cause tissue damage if levels are chronically elevated.

IL-6 is part of the body’s immune response to viral infections. However, an immune response in overdrive, sometimes termed a “cytokine storm,” is thought to intensify the respiratory distress that leads to death and complications in COVID-19.

The hypothesis that blocking IL-6 can help hasn’t been supported by clinical testing, however. Kevzara failed to show a benefit in a range of patients, and Sanofi appears to have judged that even its use in combination won’t help.

The drugmaker made its decision despite finding some tentative signs, albeit ones missing the threshold for statistical significance, that Kevzara may offer some help. Sanofi reported, for example, that patients given Kevzara early on were discharged two to three days earlier than those on placebo. Drawing conclusions from study sub-groups can often mislead, however, especially when the data aren’t clearly positive.

Roche, despite the failure of the COVACTA trial in July, has kept up study of Actemra through testing in combination with Gilead’s Veklury — a trial called REMDACTA.

The study aims to assess whether Actemra and Veklury together can improve patient status after four weeks any more than Veklury on its own.

EUSA Pharma, meanwhile, received Food and Drug Administration clearance to begin a Phase 3 clinical trial of Sylvant in July, but has made no further announcement on its progress. The only Phase 3 trial of Sylvant listed in is a Belgian university study that will test combinations of Actemra and Sylvant with an IL-1 blocking drug called Kineret.

Meanwhile, the small U.K.-based biotech Tiziana Life Sciences is planning on advancing its IL-6 blocking experimental agent TZLS-501 into clinical trials early in 2021.