Cats point the way to potential COVID-19 remedies

Last week, Gilead Sciences said it would test its COVID-19 drug remdesivir against a related compound in its library called GS-441524 in animal trials, after facing scrutiny over the latter drug, which has been used for years to treat feline infectious peritonitis (FIP) despite not being licensed for that use.

Now, another California biotech, Anivive Lifesciences, is working on a COVID-19 antiviral drug that’s inspired by cats, and it has new preclinical research findings to back up the project.

Scientists led by the University of Alberta reported that a drug developed to treat a coronavirus that can cause FIP inhibited the main protease of both SARS-CoV and SARS-CoV-2. That prevented the human coronaviruses from replicating in cell cultures, they reported in the journal Nature Communications.

Anivive originally licensed the drug, called GC376, from Kansas State University in 2018 and has been working since then to develop it as an antiviral to treat FIP, a progressive disease in cats that’s often caused by a coronavirus and is fatal if left untreated. Last month, Anivive said it had started two preclinical studies to determine whether GC376 could also treat COVID-19.

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GC376 was designed to inhibit a protease called 3C, which promotes the replication of several coronaviruses that infect animals and people. They include feline coronavirus (FCoV), which usually causes mild symptoms in cats but can lead to FIP.

Two pilot studies of GC376 in pet cats infected with FIP showed that the drug was effective against the disease within two weeks and was well tolerated. Anivive is currently scaling up production of the drug for larger studies in cats.

For the new study, the University of Alberta team tested both GC376 and its parent drug, GC373, for their ability to inhibit the 3C protease. Both drugs blocked viral replication, they reported.

The authors acknowledged that vaccines against COVID-19 are advancing rapidly, but they suggested antiviral drugs are still necessary in the short term. SARS-CoV-2 “is a virus with a significant mutation rate. Also, in some patients the virus has persisted longer than 2 months with some possibility of re-infection,” they wrote in the study.

M. Joanne Lemieux, Ph.D., professor of structural biology at the University of Alberta, pointed out in an interview with Genetic Engineering & Biotechnology News that GC376 could be advanced rapidly into human trials, given its track record in veterinary medicine.

“Because this drug has already been used to treat cats with coronavirus, and it’s effective with little to no toxicity, it’s already passed [preclinical] stages, and this allows us to move forward,” Lemieux said.