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A vial of remdesivir is visually inspected at a Gilead manufacturing site in the US in March. Photo: Gilead Sciences via AP

Coronavirus: Gilead shares tumble after report that Chinese remdesivir trial flopped

  • Test results showing drug did not make significant difference in likelihood of death or time patients took to improve were posted then quickly removed by WHO
  • Gilead and scientist involved in trial dispute how results were interpreted

Gilead Sciences shares plunged after reports that its experimental drug being tested in Covid-19 patients failed to show a positive result in a Chinese trial.

The drug company and a scientist involved in the trial disputed that characterisation, however.

According to reports from the Financial Times and Stat, the drug, called remdesivir, did not make a significant difference in the amount of time it took patients to improve, or their likelihood of death. A summary of the trial results was posted and quickly removed by the World Health Organisation, according to the publications.

Gilead shares fell as low as US$75.37 before ending the day 4.34 per cent down at US$77.78.

An exterior view of the Gilead Sciences campus in Foster City, California, on April 17. Photo: EPA-EFE

The summary posted by Stat shows results from 237 patients in the trial. Use of the drug was not associated with patients getting better, faster. And 13.9 per cent of patients getting the drug died, versus 12.8 per cent getting standard care, according to the summary.

Frederick Hayden, an infectious disease expert at the University of Virginia School of Medicine who helped the Chinese doctors conduct the study, disputed the characterisation that the study had failed.

“That is not correct,” Hayden said in an interview, when asked whether the results showed remdesivir had flopped. “My interpretation of them is not consistent with that headline.”

Gilead, in a statement, said that the summary mischaracterises the results of the study, which was stopped early after not enough patients could be found. A study with low enrolment can lead to results that are less conclusive.

Hayden said there was a mistake in the original manuscript and that it had since been revised. He said that the study was under review at a journal, which he would not identify. and that the authors were still waiting for page proofs. He declined further comment or elaborate until the study was published.

Gilead’s stock has been whipsawed by incremental reports on the drug, as investors grasp for any sign of data that the company’s compound could be an effective therapy for Covid-19 patients.

Last week, the shares surged 9.7 per cent on April 17 after a report that the drug appeared to have helped a group of Chicago that were part of a separate, wider trial.

Existing drugs ‘may prove effective on coronavirus before vaccine comes’

Gilead, in its statement, said that “trends in the data suggest a potential benefit for remdesivir, particularly among patients treated early in disease”. The company said that the full data are being submitted for review and publication.

The study in question was one of two main trials in China of remdesivir, and looked at patients with severe cases of Covid-19. This group was considered one of the hardest to treat with antiviral drugs, as by the time the disease becomes advanced there may already be significant lung damage.

In addition, the immune system may spin out of control in some patients with advanced disease, a process that antivirals like the Gilead drug will not help with.

Rubber stoppers are placed onto filled vials of remdesivir at a Gilead manufacturing site in the US in March. Photo”: Gilead Sciences via AP

The study ran into enrolment difficulties as the epidemic in China slowed down and was not able to get anywhere near the number of patients it had aimed for. This meant the study was likely to show an inconclusive result, unless the drug was massively beneficial or massively harmful.

The authors of the study provided a draft document to the WHO, which had asked for information to be shared early, and it was inadvertently posted on a research-sharing platform, according to Tarik Jasarevic, a WHO spokesman.

The study is undergoing peer review and the WHO is awaiting a final version before making any comments. The document was removed from the site as soon as the mistake was noticed, the spokesman said.