But a study conducted in the country the virus emerged in last year showed use of remdesivir wasn't associated with a difference in time to clinical improvement or "any clinical or virological benefit," according to a document posted on the website of the World Health Organization (WHO).
The study involved 237 patients with confirmed cases of COVID-19 but was "terminated prematurely," researchers wrote.
The WHO described posting the information as "a mistake" that was quickly taken down.
Gilead's Chief Medical Officer, Dr. Merdad Parsey, said investigators running the study didn't give permission to publish the results.
"Furthermore, we believe the post included inappropriate characterizations of the study. The study was terminated early due to low enrollment and, as a result, it was underpowered to enable statistically meaningful conclusions. As such, the study results are inconclusive, though trends in the data suggest a potential benefit for remdesivir, particularly among patients treated early in disease," he said in a statement.
Gilead experts saw the results from its open-label study of remdesivir in patients with severe cases of COVID-19 at the end of April and the company expects data from a study looking at the drug in patients with moderate COVID-19 cases at the end of May. The trials saw 3,000 additional patients enroll earlier this month. Gilead has also distributed doses for use in hospitals to patients who can't take part in trials.
Additionally, the company expects data from the National Institute of Allergy and Infectious Diseases' study of remdesivir.
"There are multiple ongoing Phase 3 studies that are designed to provide the additional data needed to determine the potential for remdesivir as a treatment for COVID-19," the statement read. "These studies will help inform whom to treat, when to treat and how long to treat with remdesivir."
Gilead stocks dropped after the draft document was posted.
"This is pretty close to a worst case scenario as not only did the clinical effect not manifest, but there wasn't even an antiviral effect to explore," Baird's Brian Skorney wrote in a note.
Others urged caution.
“The bottom line is that stating the trial flopped appears overly aggressive and premature, particularly in light of Gilead’s comments,” Piper Sandler analyst Tyler Van Buren said in a note.
Other drugs being tested against COVID-19 include Kevzara, baricitinib, and Avigan.