Paris, Apr 29 (IANS): With different approaches to treating Covid-19 patients being tried, varying results of two different arthritis drug trials on patients have further complicated the search for a cure.

While makers of the drug Kevzara (sarilumab) found that it proved to be less effective in treating "severe" respiratory illness caused by Covid-19 as compared to the "critical patients in trials conducted in the US", another drug Actemra (tocilizumab) showed benefit in treating seriously ill patients in a trial in France.

Announcing the preliminary results from the Phase 2 portion of an ongoing Phase 2/3 trial evaluating Kevzara, Sanofi and Regeneron Pharmaceuticals Inc. on Monday said that Kevzara had no notable benefit on clinical outcomes when combining the "severe" and "critical" groups, versus placebo.

However, there were negative trends for most outcomes in the "severe" group, while there were positive trends for all outcomes in the "critical" group, the results showed.

Following a review by the Independent Data Monitoring Committee (IDMC) of all available Phase 2 and Phase 3 data, the trial will be immediately amended so that only "critical" patients continue to be enrolled to receive Kevzara 400 mg or placebo, Sanofi and Regeneron Pharmaceuticals said.

The randomised Phase 2 portion of the trial compared intravenously-administered Kevzara higher dose (400 mg), Kevzara lower dose (200 mg) and placebo.

It assessed 457 hospitalised patients, who were categorised at baseline as having either "severe" illness, "critical" illness or "multi-system organ dysfunction".

"Emerging evidence with Kevzara and other repurposed drugs in the Covid-19 crisis highlight the challenges of making decisions about existing medicines for new viral threats using small, uncontrolled studies," George D. Yancopoulos, Regeneron Co-Founder, President and Chief Scientific Officer, said in a statement.

"We await results of the ongoing Phase 3 trial to learn more about Covid-19, and better understand whether some patients may benefit from Kevzara treatment," Yancopoulos said.

The trail of Roche Holding AG's Actemra by the Assistance Publique -- Hopitaux de Paris (AP-HP) -- showed that seriously ill patients due to complications from Covid-19 might benefit from the drug.

While the hospital revealed the results of the small study, the findings are yet to be published.

Further studies will be required to know if the drug can prove to be effective against the disease, according to researchers.

Interestingly, the Kevzara trial was designed after a small, single-arm study in China among mostly severe, febrile hospitalised Covid-19 patients, which found elevated IL-6 levels, and suggested that inhibiting this pathway with the IL-6 inhibitor tocilizumab rapidly reduced fever and improved oxygenation in severe patients, allowing for successful hospital discharge.