Due to the 'Spike Protein Binding' Property
Binding Becomes Difficult When Spike Mutations Occur
"Antiviral Drugs Are Effective Regardless of Mutations"
[Asia Economy Reporter Kim Young-won] COVID-19 antibody treatments are proving ineffective against detailed Omicron subvariants such as BQ.1.1 and BF.7, which have emerged worldwide.
According to recent research by Assistant Professor Yun Long of the Biomedical Innovation Center at Peking University in China on the 21st, Eli Lilly's 'Bebtelovimab,' the only monoclonal antibody treatment effective against all variants so far, has been found to evade immunity in BQ.1.1, a subvariant of BA.5.
Bebtelovimab has been the only COVID-19 antibody treatment effective against various subvariants including BA.4, BA.5, and BA.4.6. Another monoclonal antibody drug, AstraZeneca's 'Evusheld,' maintained neutralizing activity against BA.4 and BA.5 but showed reduced effectiveness against BA.4.6, according to research findings. Earlier this month, the U.S. Food and Drug Administration (FDA) also stated that Evusheld may be ineffective against some variants.
Overseas experts are also closely monitoring Bebtelovimab's effectiveness against the BA.2.75.2 variant. BA.2.75.2 is a subvariant of BA.2.75, known as 'Kentauros,' which has three additional mutations in the spike protein compared to BA.2.75. It is detected at about 1.0% domestically as well. Raj Rajnarayanam, Dean and Associate Professor of Research at the New York Institute of Technology, said in a foreign media interview regarding variants and antibody treatments, "We used to say we had the tools, but those tools are gradually disappearing."
The reason antibody treatments are less effective against rapidly emerging variants lies in their characteristics. Antibody treatments work by binding to the virus's spike protein to neutralize it. However, when the spike protein mutates as in variant viruses, antibodies cannot bind, rendering the treatment ineffective.
Many pharmaceutical companies developed antibody treatments after the onset of COVID-19, but many cases saw usage discontinued after variants emerged. Celltrion's antibody treatment 'RekkiNona' had unclear effectiveness against Omicron variants and stopped new domestic supply from February 18. For the same reason, the U.S. halted supply of Eli Lilly's 'Bamlanivimab and Etesevimab' and Regeneron's 'REGEN-COV' in December last year. In April, when the stealth Omicron BA.2 was prevalent, the FDA suspended approval for GSK's 'Sotrovimab.'
On the other hand, experts explain that antiviral drugs, unlike antibody treatments, can maintain efficacy even when variants emerge. Paxlovid, Lagevrio, and Remdesivir, used domestically as COVID-19 treatments, are antiviral drugs. Professor Emeritus Baek Soon-young of the Catholic University Medical School said, "Paxlovid is a protease inhibitor that inhibits a specific enzyme the virus has," adding, "Even if variants arise, the enzyme does not change, so it can still function as an inhibitor."
In terms of formulation, administering COVID-19 antiviral drugs is also simpler than antibody treatments. Professor Baek explained, "Antiviral drugs like Paxlovid and Lagevrio can be made as oral treatments, but antibody treatments are difficult to develop for oral use," adding, "Because a certain blood concentration must be maintained to suppress the virus, they can only be used as injections."
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