Study finds virus can form resistance to key treatment
The Covid-19 virus can develop partial resistance to the antiviral medication remdesivir, a laboratory study has shown.
Researchers in the United States and Canada found that Sars-CoV-2, the official name of the coronavirus, developed mutations that enabled it to partially evade remdesivir’s antiviral effect upon repeated exposure to the parent molecule used to make the drug in cell culture.
The researchers said that despite very few reports of patient resistance to remdesivir, it was vital to understanding factors that promoted or prevented resistance to the drug so that it could continue to be used to treat Covid19 and other coronaviruses.
Remdesivir is a treatment given by injection that stops the coronavirus by preventing its RNA genome from being copied.
The World Health Organization updated its guidelines in April to suggest remdesivir for treating mild or moderate Covid-19 patients at high risk of hospitalisation, reversing a 2020 recommendation against its use.
The update is based on phase 3 trial data that showed a threeday course of the drug vastly reduced the risk of hospitalisation for patients at high risk of disease progression, according to its developer Gilead Sciences.
In 2020 the drug was approved by the US Food and Drug Administration as the first Covid19 treatment for people aged over 12. In April, the FDA also approved its use in high-risk children older than 28 days.
Meanwhile in Hong Kong, the drug has been approved for use among patients with moderate symptoms or those that require oxygen therapy.
In the new study, researchers found the coronavirus developed mutations in the polymerase – a type of enzyme that copies the RNA genome – which emerged after prolonged exposure of the virus to the drug.
“Our studies present potential pathways to resistance for SarsCoV-2 to remdesivir and provide multiple mechanisms of resistance that the virus uses to overcome sensitivity to remdesivir,” the team from North America wrote in the journal Science
Translational Medicine last week. “Our results create a reference for surveillance for remdesivir resistance, and support the need to pursue combination therapies targeting the RdRp [the polymerase enzyme that replicates the genome of the virus] through different mechanisms.”
Mark Denison, the lead author and head of a US coronavirus lab at Vanderbilt University Medical Centre that led the development of remdesivir, said the drug remained a key treatment that limited illnesses, hospitalisations and deaths from the virus.
“To date, there have been very few reports of resistance to remdesivir in clinical practice. We must be sure that we can continue to use this antiviral against Covid19, future human coronaviruses and potentially even against our known human coronaviruses.
“So, it is critical to understand how coronaviruses might try to escape from the drug, and to use that data to monitor for any potential emergence of resistance in Covid-19 patients,” he said.
We must be sure that we can continue to use this antiviral against Covid-19
MARK DENISON, LEAD AUTHOR