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By Joseph Walker 

A pair of experimental Covid-19 treatments produced positive results in clinical trials, the companies developing the drugs said Monday.

Humanigen Inc. said hospitalized patients receiving its drug lenzilumab had a 54% greater likelihood of surviving without the need for mechanical ventilation with a breathing tube after one month than a comparison group that received placebos in a late-stage, or Phase 3, study.

Separately, a midstage study of healthier patients with mild to moderate symptoms showed encouraging results for a cocktail of monoclonal antibody drugs from Eli Lilly & Co. and partners Vir Biotechnology Inc. and GlaxoSmithKline PLC.

Humanigen, based in Burlingame, Calif., said it would use the data to seek the drug's authorization from the U.S. Food and Drug Administration as soon as possible.

Its drug is intended to reduce inflammation experienced by some Covid-19 patients that is thought to occur as a result of an overactive immune response to the new coronavirus.

The study didn't prove the drug reduces deaths, however. Among patients receiving lenzilumab, the death rate was 9.6%, compared with 13.9% in the placebo group. The difference wasn't statistically significant, though the company said the study wasn't designed primarily to demonstrate a reduction in deaths.

Shares of Humanigen rose more than 90% on Monday; the stock has quadrupled in the past 12 months.

The drug was studied in combination with other treatments including remdesivir, an antiviral, and dexamethasone, an anti-inflammatory steroid.

Humanigen is one of many companies and academic groups researching drugs targeting the immune system to help treat severe inflammation, sometimes called "cytokine storm," caused by Covid-19.

The steroid dexamethasone reduced deaths by a third in a study conducted by U.K. researchers last summer and is thought to work by broadly blunting the immune system. The drug is now a standard treatment for most hospitalized patients.

The same U.K. scientists recently reported that the rheumatoid arthritis drug tocilizumab reduced deaths by 20%. The drug blocks an immune-system protein called Interleukin-6. Tocilizumab is sold in the U.S. under the brand name Actemra by Genentech, a subsidiary of Roche Holding AG.

The cocktail under development by Glaxo, Lilly and Vir reduced virus levels by 70% compared with a placebo after one week in a study of about 200 younger, relatively healthy patients with mild to moderate Covid-19 symptoms who are at low-risk of developing severe disease. Virus levels were measured using nasal swabs.

The study evaluated Lilly's bamlanivimab, the first antibody drug authorized for Covid-19, and Vir and Glaxos's VIR-7831, which recently showed strong results in treating high-risk patients.

No patients in the Phase 2 study were hospitalized or died regardless of whether they received the drug cocktail or a placebo, which could raise questions of how much utility antibody drugs will have in lower-risk patients if most of them are likely to recover on their own.

One study patient who received the drug cocktail visited an emergency room for Covid-19 related symptoms, the companies said.

The companies didn't say whether they would advance the cocktail into a Phase 3 study to show it prevents hospitalizations. A Glaxo spokeswoman said the companies are in discussions about any future trials.

Monoclonal antibody drugs are designed to mimic the function of natural antibodies produced by the immune system to fight the coronavirus. So far, they are only authorized to treat patients who because of age or other illnesses are at high risk of developing severe cases of Covid-19 that could result in hospitalization or death.

Write to Joseph Walker at joseph.walker@wsj.com

(END) Dow Jones Newswires

March 29, 2021 12:35 ET (16:35 GMT)

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