The US Food and Drug Administration (FDA) has authorized the first COVID-19 drug designed to prevent infection in vulnerable and immunocompromised populations. The monoclonal antibody treatment is delivered by intramuscular injection and offers robust protection from infection for up to six months.
The drug, now formally named Evushield, is a combination of two monoclonal antibodies – tixagevimab and cilgavimab. The antibodies were initially isolated by researchers at Vanderbilt University Medical Center from recovered COVID-19 patients early in 2020.
AstraZeneca licensed the findings in mid-2020 and then optimized the antibodies to increase their durability and extend their half-life. This led to a single injectable treatment that could hypothetically remain effective up to a year after administration.
Evushield was trialed as a preventive prophylactic in those at high risk of severe COVID-19, and as a post-exposure treatment in hospitalized COVID-19 patients or those exposed to the virus but yet to test positive. The treatment was found to be most effective as a preventative tool in high-risk subjects, and this is the population the FDA has approved its use for.
At six-month follow-up a Phase 3 trial found those treated with Evushield were 83 percent less likely to have developed symptomatic COVID-19 compared to those in the placebo group. The trial enrolled unvaccinated individuals but the FDA authorization is primarily aimed at vaccinated people who are unable to mount effective immune responses to the vaccine.
“Millions of people in the US and around the world remain at serious risk for COVID-19 because their immune systems do not generate a sufficient immune response, even after receiving all recommended doses of vaccine,” says Myron Levin, a researcher who worked on the Evushield clinical trial, from the University of Colorado School of Medicine. “I am excited to offer my patients Evusheld as an easily-administered new option that provides long-lasting protection that could help them return to their everyday lives.”
The FDA’s emergency use authorization of Evushield is clear to state this treatment is not an alternative to vaccination, or a treatment for COVID-19 in those already testing positive. Instead, this treatment is authorized as additional protection for those vulnerable populations who cannot mount effective immune responses from vaccines alone.
AstraZeneca indicates there are around seven million people in the United States who could benefit from Evushield, including those undergoing chemotherapy and those on immunosuppressive drugs for conditions such as rheumatoid arthritis. The US government has announced a purchase agreement with AstraZeneca for up to 700,000 doses of Evushield, and they should be accessible to those across the country within the next few weeks.
AstraZeneca also notes investigations are underway to test the effectiveness of Evushield against the newly emerged Omicron variant. A recent statement from the company suggests it is confident the monoclonal antibody treatment will hold up against this variant.
“Of the Omicron binding site substitutions relevant to Evusheld that have been tested to date in preclinical assays, none have been associated with escape from Evusheld neutralization,” the company states. “In vitro findings demonstrate Evusheld neutralizes other recent emergent SARS-CoV-2 viral variants, including the Delta and Mu variants.”
Long-term follow-up studies are ongoing to evaluate exactly how long protection from a single treatment of Evushield may last.
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