TOKYO -- The approval of Avigan, a candidate drug for treating coronavirus infections, has been postponed by Japan's Ministry of Health, Labor and Welfare until June or later.
The delay has dashed the hopes of many, including Prime Minister Shinzo Abe, who previously said that he "will aim for approval by the end of May." It comes as the anti-flu drug's effectiveness as a coronavirus treatment has yet to be proven.
In the meantime, Avigan will continue clinical trials and research.
Health minister Katsunobu Kato said at a news conference on Tuesday that the ministry had "assumed" Avigan would be approved "if its extremely high efficacy is shown in the interim analysis of clinical studies."
Clinical research has been conducted by Fujita Health University and other organizations since March, which tested Avigan's effectiveness on patients with mild or no symptoms.
An interim analysis covering 40 patients by a third-party organization stated, "It is too soon to evaluate [Avigan's effectiveness]." The organization is unlikely to finish research until June or later.
One source familiar with the matter said, "We have known from the studies conducted so far that drastic efficacy is not expected."
About 80% of new coronavirus patients seem to recover on their own. And it is difficult to ascertain the drug's effectiveness when comparing mildly symptomatic patients given the drug with those who were not.
Fujifilm Toyama Chemical, which developed Avigan, is also proceeding with clinical trials to check the drug's efficacy.
In response to the health ministry's decision not to approve Avigan by the end of May, parent Fujifilm Holdings, said it "will continue talks with authorities and seek to apply for [the drug's] approval at the earliest possible date."
Some within Fujifilm have been cautious about early approval based on clinical research. If trials are conducted with placebos, sources say, positive results will boost the company's bid to win approval in foreign countries.
But Fujifilm is having difficulty finding participants for trials. In April, few patients could be located with mild or moderate symptoms -- the trial's targets -- as hospitals were mostly accepting only the seriously ill.
The number of patients itself declined in May. Fujifilm has set the end of June as the target date for completing its trials, but this is likely to be extended.
There are a growing number of observational studies in which Avigan can be administered if doctors and hospitals accept the need for medication and patients agree to taking it.
According to the health ministry, Avigan has so far been administered to more than 3,000 patients at over 600 medical institutions. But due to a lack of comparison with a control group not taking the drug, it is difficult to prove efficacy.
The ministry has no choice but to await for data showing Avigan's worth as an effective drug.