Virus World

A drug once hailed as Japan’s biggest contribution in the global fight against COVID-19 suffered another setback on Friday, as Fujifilm Holdings Corp. said it was halting enrollment in a clinical trial of the pill, Avigan. The emergence of the omicron variant of coronavirus, which usually causes milder infections, made it tough to determine the drug’s effectiveness in preventing severe symptoms, the company said in a statement. Clinical data from patients already enrolled in the trial will continue to be analyzed, it said. In the first few months of the pandemic, Japan ordered Fujifilm to triple national stockpiles of the drug, which had originally been approved as an emergency flu treatment. Then-Prime Minister Shinzo Abe said he hoped Avigan would be approved in May 2020 for COVID-19, and he pledged donate supplies to needy countries.

Known generically as favipiravir, the drug was eventually approved in India and Russia, based on early studies showing it eased the symptoms of COVID-19 and cut hospital stays. But studies in Japan have been inconclusive, leading domestic regulators to hold off approval for it, partly because animal study data showed it could lead to birth defects. As Avigan stumbled in clinical trials, other antiviral pills have come to the fore against COVID-19. Japan has bought millions of doses of oral treatments developed by Pfizer Inc. and Merck & Co. A third option, developed by domestic firm Shionogi & Co., was submitted for regulatory approval last month.

Randomized trials of the broad-spectrum antiviral favipiravir, marketed as an anti-influenza treatment by Fujifilm Holdings Corp., have shown "obvious efficacy" against COVID-19, according to Zhang Xinmin, head of the China National Center for Biotechnology Development. Zhang's comments were reported by Xinhua News Agency, China's official state-run press agency.

Remarks about the drug's apparent promise, made during a press conference hosted by Chinese government officials on March 17, drove Fujifilm shares (TYO:4901) up 15.4% to ¥5,230 (US$48.55) by the close of March 18 trading in Tokyo. It was the second time the stock rose in anticipation of the antiviral's potential application for treatment of COVID-19. In one trial, testing favipiravir with interferon in Shenzhen, results showed that patients treated with the combination had significantly reduced the duration of symptoms, as measured by viral load chest imaging, vs. a control group. In another study, clinical recovery rates were higher for COVID-19 patients treated with favipiravir vs. those in a control group. 

Fujifilm representative Christine Jackman told BioWorld "the company is not in a position to talk about the use of favipiravir for coronavirus patients in China or Japan," but that, as a viral RNA polymerase inhibitor with a mechanism of action that inhibits viral gene replication within infected cells, the medicine "is expected to have an antiviral effect on avian influenza A (H5N1 and H7N9) and other viruses."