Antiviral Remdesivir – Efficacy in an Animal Model
As reported by Brandi Williamson et al. in bioRxiv, remdesivir is the first antiviral treatment with proven efficacy against SARS-CoV-2 in an animal model of COVID-19.
This study involving four laboratories from the National Institute of Allergy and Infectious Diseases (NIAID), National Institutes of Health (NIH) and the Gilead Sciences, Foster City, CA, USA, indicates that remdesivir treatment in rhesus macaques infected with SARS-CoV-2 was highly effective in reducing clinical disease and damage to the lungs.
As per a recent NIH’s News release the study followed dosing and treatment procedures used for hospitalized COVID-19 patients being administered remdesivir in a large, multi-center clinical trial led by NIH’s NIAID.
Remdesivir is considered one of the most promising antiviral medications against Covid-19 and is already undergoing numerous trials. This antiviral drug developed by the American biopharmaceutical company Gilead Sciences is a nucleotide analog, which inserts into viral RNA chains, causing their premature termination.
The study reported in bioRxiv and led by Emmie de Wit, Ph.D, from the Laboratory of Virology, NIAID, NIH, used the recently established rhesus macaque model of SARS-CoV-2 infection that results in transient lower respiratory tract disease. In this model, infected rhesus macaques developed mild to moderate transient respiratory disease with pulmonary infiltrates that were visible on radiographs.
The efficacy of therapeutic remdesivir treatment was tested in two groups (remdesevir and control) of six adult rhesus macaques (3 males and 3 females each).
The authors report that in rhesus macaques, the drug administered shortly before the peak of virus replication resulted in a significant clinical improvement, reduction in pulmonary infiltrates, and a reduction in pulmonary pathology. There was, however, no reduction in virus shedding.
The authors discuss that “the efficacy of direct-acting antivirals against acute viral respiratory tract infections typically decreases with delays in treatment initiation”. Furthermore, “as data from clinical trials in humans are pending” the authors also believe that their data in rhesus macaques indicate that “remdesivir treatment should be considered as early as clinically possible to prevent progression to severe pneumonia in COVID-19 patients”.
Of note, the study of Williamson et al. is in good agreement with some preliminary results in humans. Recently, STAT News reported encouraging results from an ongoing clinical trial in a Chicago hospital treating severe Covid-19 patients with remdesivir, where rapid recoveries in fever and respiratory symptoms were monitored.
These human data were also discussed by CNN. Yet, CNN stated that “the trial does not include what’s known as a control group, so it will be difficult to say whether the drug is truly helping patients recover better”. They also report a statement by the University of Chicago saying that “Partial data from an ongoing clinical trial is by definition incomplete and should never be used to draw conclusions about the safety or efficacy of a potential treatment that is under investigation”.