Japan's review of Avigan as COVID-19 treatment draws blank

Japanese health authorities have been unable to reach a conclusion on the effectiveness of antiviral drug Avigan in treating COVID-19 patients based on the results of clinical testing by its developer, government sources said Wednesday.

The latest assessment by the Pharmaceuticals and Medical Devices Agency will serve as key material for a health ministry review panel that will likely decide on Monday whether to approve the use of Avigan to treat COVID-19 in Japan.

Drugmaker Fujifilm Toyama Chemical Co., a unit of Fujifilm Holdings Corp., filed an application for use of the drug to fight COVID-19 in October. Avigan has already received approval for use with cases of influenza.

Some medical experts have opposed the use of Avigan, also known as favipiravir, for treating patients with COVID-19.

Possible side effects include the worsening of liver function, but Fujifilm said no new safety concerns were identified. Pregnant women cannot use the drug as some animal studies have pointed to the possibility of fetal abnormalities.

Expectations have grown that Avigan would become the third treatment drug for COVID-19 in Japan, after the anti-viral medication remdesivir developed by U.S. firm Gilead Sciences Inc. and the steroid dexamethasone.

The assessment acknowledged that approving the use of Avigan as a COVID-19 drug would be “meaningful” at a time when there are limited treatment options available.

Japan has been battling a resurgence of coronavirus cases in recent weeks, forcing Prime Minister Yoshihide Suga to suspend a subsidy program to promote domestic travel, in a reversal of his earlier stance.

According to data gathered during clinical testing on 156 patients without severe COVID-19 symptoms, Fujifilm found those administered with Avigan showed improvement after 11.9 days, shorter than the 14.7 days for those in a placebo group.

One of the issues raised in the assessment report was the way the tests were performed. The doctors knew which patients received Avigan or a placebo, which the report argues prevented them from properly assessing symptoms, the sources said.

The government sources also said the criteria for determining whether symptoms had improved, based on body temperature and other data, lacked clarity.

Fujifilm took longer than initially planned to complete its clinical study that began in March after facing difficulty in securing enough patients as the number of coronavirus cases was low in Japan.

While he was in office, Prime Minister Shinzo Abe had expressed hope that the drug would be approved in May and the government decided to stockpile enough of the drug to treat 2 million people.

Fujifilm is aiming to market Avigan for COVID-19 treatment overseas, including in China.