A clinical trial of anti-flu drug Avigan, which the government wanted approved by mid-May to treat the new coronavirus, is foundering.
The main reason is difficulty rounding up subjects due to the decline in infections. It is not easy to demonstrate a drug's effectiveness and it appears approval will take more time.
"We are giving up on getting approval in May. The clinical trial will continue and approval will be granted as soon as the drug's efficacy is confirmed," Health, Labor and Welfare Minister Katsunobu Kato said at a press conference at the end of May to announce a change to the government's original plan.
Pharmaceutical companies must conduct clinical trials to obtain approval for drugs.
Tokyo-based Fujifilm Toyama Chemical Co. planned to register 96 patients for the Avigan trial, which began at the end of March. Pneumonia patients with relatively mild symptoms would be given Avigan or a placebo for up to 14 days to look for differences in the therapeutic effects.
However, the number of new patients has declined since mid-April. It has become more difficult to attract participants to the trial, and so far the target number has not been reached.
A Fujifilm representative said, "We want to find new medical institutions to participate and finish as soon as possible."
However, the trial may drag on into July. It is also unclear when the application for approval will be submitted. A clinical trial is also underway in the United States, but it will take some time to obtain the results.
Due to the variations in patient numbers in infectious diseases, attracting patients is key to the success or failure of clinical trials.
Remdesivir (trade name Veklury), the only drug approved to treat the new coronavirus, was part of a joint international trial in which the U.S. manufacturer recruited patients from around the world.
The drug was approved for emergency use in the United States, and in Japan approval was granted in just three days. This is a much different framework for the preliminary clinical trial than for Japan-made Avigan.
Nagasaki University President Shigeru Kono, a respiratory physician and expert on clinical trials, said, "If a joint international trial had been conducted for Avigan, they could have obtained high-quality data, even with few patients from Japan. Japan needs to consider having public institutions like the U.S. National Institutes of Health to guide clinical trials during an emergency."
Apart from the clinical trial aimed at drug approval, Avigan can still be administered at the discretion of doctors after being screened by the medical institution. As of mid-May, it had been used by at least 2,000 patients at least 400 hospitals.
Fujita Health University in Aichi Prefecture released an interim analysis of this data in May. About 90 percent of patients with mild symptoms saw improvement by day 14 of administration.
However, this is only an "observational study" tracking the courses of patients who are taking an unapproved drug. Even if it is administered to a large number of patients, because the effects cannot be closely compared to patients who did not take the drug, such findings provide little scientific evidence on its effectiveness.
"The vast majority of patients improve naturally in a few weeks. We didn't perform comparisons with patients who didn't take it, so we can't assess the effects," Yohei Doi, a professor at the university and the study's chief investigator, said at a press conference.
Some are hesitant about the rapid approval of Avigan. Hiroyuki Shimizu is a physician of the clinical examinations department at Fujisawa City Hospital in Kanagawa Prefecture who used Avigan for treatment.
He said, "I think if the government approves it, it will be used more widely than it is now, but I'm worried about side effects such as higher uric acid levels. It should only be administered to people who are prone to severe disease, such as the elderly."
In a statement, an expert panel of the Japan Medical Association said, "Hasty special approval should not be carried out for drugs with insufficient scientific basis," and warned about political influence.
--Avigan
Developed by Fujifilm Toyama Chemical Co. to treat new forms of influenza. It acts by suppressing the proliferation of a virus inside cells, and is hoped to have similar effects on the new coronavirus. However, animal experiments have indicated that if administered to pregnant women it could result in birth defects. Elevated uric acid levels have also been reported as a side effect.
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