Amid the ongoing coronavirus outbreak, Gilead Sciences’ experimental remdesivir has emerged as the most promising candidate against the deadly pathogen. But its patent in China has also drawn some unexpected confusion.

The Chinese pharma BrightGene has successfully copied remdesivir, the company said in a disclosure (PDF, Chinese) to China’s Nasdaq-style Star market on Wednesday.

What's more, the Suzhou-based firm said it has already mass-produced remdesivir's active ingredient and is in the process of turning it into finished doses. The company’s stock jumped 20% at the news, hitting the daily price move cap allowed on the exchange.

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BrightGene doesn’t seem to plan to bypass Gilead entirely, though. The company made clear the generic version is still in an R&D phase, and that its final marketing requires permission from the patent holder, Gilead.

In an interview with China’s business news publication Jiemian, BrightGene's board secretary explained that there isn’t any patent infringement issue at this point because it’s not selling the product. But manufacturing a copycat to a patent-protected med at scale without any license is an unusual move that could revive concerns about the protection of intellectual property in the country.

IP protection in China has long been criticized by the Western world and was cited as a reason behind the latest trade war President Donald Trump waged against the country. As part of the first phase of a broader trade deal (PDF), the White House recently signed with Beijing to resolve the dispute, China has promised to implement some American-style enforcement of drug patent rights. These include allowing for a preliminary injunction against a generic maker amid a patent fight.

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The BrightGene incident represents the latest twist to the patent controversy around remdesivir in China. A few days ago, researchers at the Chinese Academy of Sciences’ Wuhan Institute of Virology—based at the center of the outbreak—said they had applied for a patent on the use of remdesivir to treat the novel coronavirus disease, now officially named by the World Health Organization as COVID-19.

The research institute said it filed the application “from the perspective of protecting national interests,” but the move drew criticism.

At a recent internal company conference, Gilead CEO Daniel O’Day said the company owns all patents around remdesivir, including for coronaviruses. But he also stressed that the priority for the company is to examine the drug’s use in clinical trials and to ramp up production if its efficacy is confirmed. Gilead “will not get into a patent dispute,” he said.

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Last week, two phase 3 trials kicked off in Wuhan to test remdesivir in adult patients with mild-to-moderate or severe respiratory disease caused by the novel coronavirus. Together, investigators aim to enroll 760 patients, with readouts expected as early as April.

Gilead is providing the drug for free for the studies. BrightGene also said it will provide its version “mainly through donations” during the epidemic if it’s granted the marketing go-ahead.

On top of all those controversies, Chinese IP law does provide for compulsory licenses for eligible companies to produce generic versions of patented drugs during a state of emergency or other unusual circumstances, or in the interests of the public. However, authorities will not likely apply it to remdesivir, especially now that Gilead’s offering it free of charge and as drug IP remains a sensitive topic on the international community’s radar.