Japan Developing Antibody Drugs to Treat COVID-19 and Its Variants

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The development of drugs to treat COVID-19 is accelerating. Of particular interest are drugs that use “neutralizing antibodies” to prevent the virus from multiplying. 

These antibodies are artificially produced using gene recombination technology, and, when administered to patients, can defend against severe cases of the disease. 

While this type of drug is already being used in other countries, Japan’s Ministry of Health, Labor and Welfare (MHLW) is expected to approve an “antibody cocktail therapy” developed by United States- and Europe-based pharmaceutical companies and marketed by Chugai Pharmaceutical Co. before the end of July. 

With seemingly no end to the pandemic in sight, many hope this “wonder drug” will prove to be a game-changer. 

Artificially Produced Neutralizing Antibodies

Antibodies are neutralized in this treatment by preventing the virus from invading human cells. When administered to patients with mild or moderate symptoms, the antibodies can stop the virus from multiplying and prevent severe symptoms from developing.

The antibody drugs now being developed to treat COVID-19 mainly use artificially produced neutralizing antibodies. Here’s how it works:

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Immune cells that produce neutralizing antibodies are taken from the blood of a person who has recovered from COVID-19, and the antibody’s genes are extracted.

From there, several different development methods exist, including producing antibodies from the extracted genes themselves. Although many steps must be taken, once the “blueprint” of a high-performing artificial antibody is obtained, mass production becomes possible.

The Trump Cocktail

This treatment method has already been put into practical use overseas. Significantly, the U.S. Food and Drug Administration (FDA) has approved the emergency use of several antibody drugs. 

The cocktail therapy — developed by Roche, the Swiss pharmaceutical giant, and Regeneron, a U.S.-based pharmaceutical company — is an intravenous drug that combines two types of antibodies. It became well-known after it was given to former U.S. President Donald Trump as a special exception during clinical trials.

In Japan, Chugai Pharmaceutical Co. contracted with Roche for permission to market the drug in Japan, then submitted an application to the MHLW in late June for special approval of the cocktail therapy, and then scheduled for consideration by the committee on July 19. According to Chugai, overseas clinical trials have confirmed the efficacy of the drug in reducing the risk of hospitalization or death of patients by about 70%.

Promising Domestic Drugs

While delays have been evident in the development of a domestic vaccine, domestic development of antibody drugs is proceeding at a rapid pace.

A team from Keio University is working on joint research with the Mitsubishi Tanabe Pharma Corporation to commercialize artificial antibodies. 

Elsewhere, a group of universities — including Shimane University, Nagasaki University, and Hiroshima University — has developed artificial antibodies with promising attributes. The Sapporo-based drug discovery venture capital firm, Evec Inc., is aiming to commercialize a drug using them within 2021.

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Effectiveness Against COVID Mutations

There is concern that viral mutations may diminish the effectiveness of the treatment, but this decline in efficacy could be limited if multiple antibodies are mixed together in a cocktail therapy. 

Since mutations can be predicted to some extent, pathological biochemistry professor Takeshi Urano of Shimane University points out, “It is possible to prepare for mutations by producing multiple antibodies ahead of time that will react to mutant strains.”

The University of Toyama has also developed a “super neutralizing antibody” that is effective against most of the currently reported mutant strains, including the British variant and the Delta variant that originated in India. The research team says, “We believe that it will also be fully effective against variants that appear in the future.”

When Antibody Drugs are Used

Antibody drugs are useful for treating people for whom vaccines are not effective, or those who are not eligible for vaccination, such as children. 

Putting the medical approach to COVID-19 in perspective, antibody engineering professor Kouhei Tsumoto of the University of Tokyo noted: “We can only be safe from infectious diseases when both prevention and treatment options are available. A realistic approach to treatment is to skillfully combine existing drugs with highly-effective antibody drugs.”

Scientists express considerable hope in this field. “Japan’s technologies in antibody drug research are all at an extremely high level,” Tsumoto added. “We need to create a system that allows the government to take the lead in quickly commercializing good drugs.”

(Read The Sankei Shimbun report in Japanese at this link.)

Author: Yukiko Une

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