BEIJING – Beijing-based Sihuan Pharmaceutical Holdings Group Ltd. said it has initiated clinical trials of broad-spectrum antiviral favipiravir to treat COVID-19. China now has six clinical trials investigating the drug, originally developed for influenza and also tested against Ebola virus disease.

“We began the clinical trial in late February,” Winnie Yam, investor relations director at Sihuan, told BioWorld. “A total of 60 cases of regular COVID-19 patients are planned to be recruited for a treatment period of 10 days.

“We will initiate efficacy and safety verification trials on a larger scale once expected results are obtained from the clinical trials,” she added, without giving a specific timeline for the clinical trials.

According to the Chinese Clinical Trial Registry, it is a randomized, open-label, controlled trial to investigate the efficacy and safety of favipiravir. The low-, middle- and high-dosage groups will each see 20 patients, who will receive favipiravir twice a day at 1,600 mg, 1,800 mg and 2,400 mg, respectively, for 10 days. The clinical trial was registered on Feb 20.

Given the public health emergency, it took Sihuan only one day to obtain a human genetic resources administrative license from the regulators, which Yam said was a necessary part for initiating the clinical trials of favipiravir.

The trial is led by Beijing Chaoyang Hospital and joined by Union Hospital and Jinyintan Hospital in Wuhan, which are designated for COVID-19 patients.

Favipiravir is designed to act as an inhibitor of the viral enzyme RNA polymerase that is essential for viral replication. After oral absorption, it is converted into a bioactive nucleoside triphosphate compound that shares a similar structure with purine and competes with purine to inhibit RNA polymerase. The nucleoside triphosphate compound of favipiravir can also be inserted into the virus RNA chain to induce fatal mutations of the virus.

Previous studies have shown that favipiravir has efficacy against a range of RNA viruses, such as Ebola, influenza, yellow fever, the arena virus and the bunyaviridae virus.

Sihuan co-developed favipiravir with the Institute of Microbiology and Epidemiology of the Academy of Military Medical Sciences. In 2014, Sihuan paid the Chinese military scientific unit ¥10 million (US$1.435 million) for the ownership and franchise of the drug. Favipiravir was approved for emergency military use to treat Ebola in the same year.

It remains to be seen if the military-linked pharma company can clear the regulatory hurdles required as rapidly for the drug to be used in the treatment of COVID-19.

Sihuan said in a statement that it is fully stocked with the raw materials needed for favipiravir’s preparation and production. Once the drug is approved, Sihuan will provide it for free as a treatment for COVID-19 in response to the public health emergency.

Last month, Chinese authorities named favipiravir, along with chloroquine phosphate and Gilead Sciences Inc.’s remdesivir, as potential treatments for the coronavirus after Chinese researchers scanned more than 70,000 drugs or compounds through computer simulations and in vitro enzyme activity tests in hopes of identifying available drugs that could be repurposed for the novel virus.

Chinese pharma companies quickly responded to the call. A few days later, Zhejiang Hisun Pharmaceutical Co. Ltd. was granted approval to start clinical trials of favipiravir as an investigational therapy for COVID-19. Hisun bought the exclusive rights to favipiravir from Japan’s Toyama Chemical Co. Ltd., which is under Fujifilm Holdings Corp., in June 2016.

Currently, China is holding six clinical trials that involve investigating favipiravir’s safety and efficacy for COVID-19, with some comparing favipiravir to lopinavir/ritonavir or baloxavir marboxil.

Favipiravir is also seen as a promising treatment for COVID-19 in Japan. Katsunobu Kato, Japan’s Minister of Health, Labor and Welfare, said on Feb. 22 that the country is planning to test Fujifilm’s favipiravir, also known as Avigan, against the coronavirus.

Kana Matsumoto, of Fujifilm’s corporate communications division, told BioWorld in a previous interview that The National Center for Global Health and Medicine has formed a project team for research purposes and is preparing responses for the treatment of patients with novel coronavirus at two medical centers. One of the centers had started administration of Avigan.

Meanwhile, South Korea’s Ministry of Food and Drug Safety also said on Feb. 25 that it is considering fast-track approval to import Avigan for the treatment of COVID-19.

Avigan was approved in Japan in March 2014 to treat influenza in patients who do not respond to other therapies, and last month China approved it, with conditions, to treat new and recurring influenza in adults. The drug has not yet been approved as a COVID-19 treatment anywhere.

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