New research sheds light on why the experimental drug remdesivir might become the most powerful weapon in the fight against Covid-19: It is highly effective against an enzyme that plays a crucial role in the spread of the new coronavirus.

Remdesivir is one of several drugs being fast-tracked in various coronavirus treatment trials around the world. Just last week, a small, “compassionate use” trial published in the New England Journal of Medicine found the drug improved outcomes for people with Covid-19.

More than two-thirds of 53 severely ill patients showed improvement in oxygen support, the Cedars-Sinai Medical Center researchers said. Seventeen of 30 patients who were on ventilators were able to be taken off the life-support machines, the study showed.

The latest research, published in the Journal of Biological Chemistry, explains how remdesivir, developed in 2014 to fight the Ebola epidemic, works against the new coronavirus.

‘Direct-acting antiviral’

Remdesivir “is a very potent inhibitor for coronavirus polymerases”, and if “you target the polymerase, the virus cannot spread, so it’s a very logical target for treatment”, explained study author Matthias Götte, chair of medical microbiology and immunology at the University of Alberta, in Canada.

Remdesivir tricks the coronavirus by mimicking its building blocks, the investigators found.

“These coronavirus polymerases are sloppy, and they get fooled, so the inhibitor gets incorporated many times and the virus can no longer replicate,” Götte explained.

Evidence from this study and previous research in animals and cell cultures showed that remdesivir can be classified as a “direct-acting antiviral” against the new coronavirus, Götte noted.

This reinforces the promise of clinical trials being conducted worldwide of remdesivir in people with Covid-19.

Almost identical results

While the evidence provided by lab studies justify clinical trials, those results can’t predict how remdesivir will work in human patients, Götte noted.

“We’ve got to be patient and wait for the results of the randomised clinical trials,” he said in a university news release.

In February, Götte’s lab published a study showing how remdesivir worked against the Middle East respiratory syndrome (MERS) virus, which is related to the new coronavirus that causes Covid-19, officially called SARS-CoV-2.

“We were optimistic that we would see the same results against the SARS-CoV-2 virus,” Götte said. “We obtained almost identical results as we reported previously with MERS, so we see that remdesivir is a very potent inhibitor for coronavirus polymerases.”

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