By Joseph Walker 

The promise and limitations of remdesivir, the first drug to prove capable of helping fight Covid-19, have kicked off efforts to see if it can work better in combination with other treatments and to create new, easier methods of administering it.

Researchers are exploring whether the drug, made by Gilead Sciences Inc., can be combined with other antiviral treatments to make a more potent coronavirus-fighting cocktail.

Six Covid-19 drug trials currently under way specify testing remdesivir with another medicine, according to Informa Pharma Intelligence. Another five trials are of drugs that would be given in tandem with whatever a hospital uses as standard treatment -- which increasingly means remdesivir.

Gilead is also studying new formulations of remdesivir so patients can take it outside of a hospital.

Remdesivir, originally aimed at treating Ebola, has emerged as the go-to Covid-19 treatment. Federal health regulators quickly authorized its emergency use May 1, after it proved effective in a large, rigorously-designed study. Hospitals are lined up for doses.

But the drug isn't a silver bullet. So far at least, it has shown to be only modestly effective in treating a sliver of very sick patients.

Remdesivir's standard use in Covid-19 treatment "can be misleading because it suggests this is very, very good therapy, but it isn't," said Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases.

"It's standard because it's better than nothing," Dr. Fauci said.

Development of HIV drugs in the 1980s proceeded on a similar path, with researchers in the 1980s building upon the early but limited success of the first agent to develop progressively better treatment regimens.

In its key clinical trial, remdesivir shortened the recoveries of hospitalized patients by four days compared with a placebo. The seriously-ill patients still spent an average of 11 days in the hospital. NIAID supported the study.

Moreover, the drug's use is limited to the hospital because it has to be administered with an intravenous infusion.

A number of studies are under way exploring how to make remdesivir's impact stronger by pairing it with a separate drug that tamps down on the overactive immune response, known as a cytokine storm, triggered in some infected patients.

Drug researchers want to see whether an arthritis drug, for example, can beat back the cytokine storm, while remdesivir stops the virus from replicating itself inside the lungs. Certain arthritis drugs reduce inflammation.

"That's the ideal situation for me, where you have combinations of drugs that are doing multiple jobs to holistically attack the disease," said Timothy Sheahan, assistant professor of epidemiology at the University of North Carolina, who has helped conduct laboratory tests of remdesivir in coronaviruses.

Researchers conducting NIAID's trial of the drug are now testing it in combination with Eli Lilly & Co.'s arthritis therapy baricitinib, which is sold under the brand name Olumiant.

A study evaluating arthritis drug Actemra, from Roche Holding AG's Genentech unit, will include subjects taking remdesivir as part of their care, said Mark Eisner, a senior vice president at Genentech overseeing Actemra's clinical development.

Researchers are unsure whether there will be enough supply of remdesivir to include it in all trials going forward, Dr. Eisner said. "It's a question that all of the clinical trial investigators have now," he said.

Gilead, based in Foster City, Calif., is working on new ways to administer the drug outside of the hospital and whether it can be combined with other antivirals to make a more potent virus-killing cocktail.

The company is developing an inhalation device so patients can suck the drug into their respiratory tracts. The company is also trying to make a prefilled syringe that can be injected into the skin at home.

If the new formulations pan out, they could be used to test remdesivir in patients who aren't in the hospital, Gilead Chief Medical Officer Merdad Parsey said last month.

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

 

(END) Dow Jones Newswires

May 13, 2020 05:44 ET (09:44 GMT)

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