Mutation associated to remdesivir resistance discovered in Covid patient.

Researchers discovered resistance to Gilead Sciences Inc.’s antiviral remdesivir in coronavirus samples taken from an immunocompromised patient being treated with the medicine for a chronic Covid-19 infection.

Similar resistance-causing mutations have been created in lab trials, but have not previously been documented in patients treated with the injectable drug, according to Shiv Gandhi, Akiko Iwasaki, and colleagues at Yale University School of Medicine. The patient, a woman in her 70s who had been treated for non-Hodgkin’s lymphoma, caught Covid in May 2020. Remdesivir helped alleviate symptoms, but wasn’t able to completely clear the infection. It persisted for several months, affecting her sense of smell.

Genetic analysis of the virus showed that it acquired a mutation during treatment that appeared to reduce the effectiveness of the drug, the first cleared for Covid-19. The infection was successfully treated with monoclonal antibody therapy, which also led to a recovery of her sense of smell.

“While the finding is limited to a single case and requires confirmation of its generalizability in larger patient populations, it suggests that remdesivir can impart selective pressure” in patients to drive evolution of the virus, the researchers said in a study, which was released on medRxiv ahead of peer-review and publication.

The scientists found the mutation, called E802D, reduced the fitness of the SARS-CoV-2 virus that causes Covid-19. They said the case illustrates the importance of monitoring for remdesivir resistance and the potential benefit of using a combination of therapies in immunocompromised patients.