Prime Minister Yoshihide Suga’s administration is planning to use the nation’s first approved drug for mild to moderate COVID-19 cases to treat nonhospitalized patients, in addition to the inpatients currently receiving it.

At the moment, the monoclonal antibody cocktail, which needs to be administered within seven days of the patient developing symptoms, has only been authorized for hospitalized patients.

But with COVID-19 cases rising quickly nationwide and amid increasing calls for its use from medical professions, Suga said last week that the government would work to make what he described as a “revolutionary” drug available to patients quarantined at home.

The hope is that the antibody treatment drug, which is effective in preventing patients from developing severe symptoms, will help stop the already heavily strained health system from becoming overwhelmed.

Despite the urgent need, the drug’s expanded use could take some time to be put into practice, as the health ministry has to revise its guidelines, which currently limit usage to hospitalized patients due to a lack of stable supply.

On July 19, the health ministry gave emergency use authorization to Ronapreve, which is composed of the artificially produced antibodies casirivimab and imdevimab, for inpatients age 12 and over who do not require oxygen and are at a higher risk of their condition becoming severe.

The antibody cocktail Ronapreve is administered intravenously as a single dose, with the process taking at least 20 minutes | CHUGAI PHARMACEUTICAL CO. / VIA KYODO 
The antibody cocktail Ronapreve is administered intravenously as a single dose, with the process taking at least 20 minutes | CHUGAI PHARMACEUTICAL CO. / VIA KYODO 

A final phase clinical trial overseas involving COVID-19 patients with a high risk of developing serious symptoms, such as those with obesity, diabetes or high blood pressure, showed that the drug reduced the risk of hospitalization or death by 70.4% and shortened the duration of symptoms by four days.

The U.S. Food and Drug Administration recommended using it for nonhospitalized patients when it gave emergency use authorization last November to the treatment, which is developed by U.S. firm Regeneron Pharmaceuticals Inc.

Hospitals in Japan welcomed the health ministry’s approval, as it gave them their first drug for mildly to moderately ill patients. But administering Ronapreve to inpatients within a week of the onset of symptoms has proved difficult in practice.

“To use the cocktail effectively, it needs to be administered within two to three days of the onset of symptoms, and after that the efficacy starts to fade,” said Dr. Joe Chiba, a professor emeritus at the Tokyo University of Science. “In reality, it takes about five days on average for patients to be hospitalized, with little efficacy to be then expected. So they must make it available to outpatients.”

In addition, some hospitals have reported that deliveries of the drug have not arrived until four days after they made the order, denting its usefulness.

So far more than 2,000 hospitals have been registered to receive the drug. Because of limited supplies, the government plans to prioritize its use in quarantined patients age 50 or above and those with existing conditions.

Patients can receive the drug for free. The cost of the treatment has not been released publicly, but it is said to cost around ¥250,000 per dose overseas, Chiba said.

Health minister Norihisa Tamura at the Diet on Thursday. | KYODO
Health minister Norihisa Tamura at the Diet on Thursday. | KYODO

The antibodies used in the drug target the receptor binding domain of the spike protein of the coronavirus. The cocktail, which is composed of laboratory-made recombinant antibodies, is administered intravenously as a single dose, with the process taking at least 20 minutes.

In-vitro examination has indicated that the cocktail retains its efficacy against the main variants of the coronavirus, including the delta variant that’s driving a record number of cases in Japan and across the world. The then-experimental treatment was used to treat then-U.S. President Donald Trump when he contracted the disease last October and is said to have helped him recover faster.

But some hospitals have given up administering the drug to some inpatients due to the lack of timely access to it. Some others have also reported that it did not lead to a dramatic improvement in patients’ conditions, as it was not administered within the first few days of symptoms emerging.

The health ministry is aware of the problem, but it is reportedly hesitant to administer Ronapreve to outpatients. So far, the ministry’s response has been to try to shorten the delivery time to hospitals rather than allowing it to be given to outpatients.

Last week, health minister Norihisa Tamura said that the ministry was aiming to deliver the drug the day after it is ordered, adding that the government would promptly work on measures to rectify the situation, including allowing stockpiles at some hospitals that treat many patients with the drug.

The government has reportedly procured 200,000 doses of Ronapreve. Given the limited supply from Chugai Co., which is licensed to produce the drug in Japan, the health ministry has decided to stockpile them and supply registered hospitals with doses free of charge as they are requested, with the treatment reserved for inpatients only.

In order for nonhospitalized patients to get the dose, as per Suga’s request, the registered hospitals should be allowed to keep a stockpile of the drug that they can dispense to inpatients and outpatients, Chiba said.

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