Gilead Sciences shares popped by more than 8% on Friday after details leaked of a closely watched clinical trial of the company's antiviral drug remdesivir, showing what appears to be promising results in treating Covid-19.
The University of Chicago's phase 3 drug trial found that most of its patients had "rapid recoveries in fever and respiratory symptoms" and were discharged in less than a week, health-care publication STAT News reported Thursday.
"The best news is that most of our patients have already been discharged, which is great. We've only had two patients perish," University of Chicago infectious disease specialist Kathleen Mullane said, according to STAT News, which obtained a video of her remarks.
Gilead shares jumped as much as 16% in after-hours trading Thursday immediately after the report published.
Gilead didn't immediately respond to a request for comment.
In a statement to CNBC, a University of Chicago spokesperson said, "Partial data from an ongoing clinical trial is by definition incomplete and should never be used to draw conclusions about the safety or efficacy of a potential treatment that is under investigation."
The University of Chicago Medicine recruited 125 patients with the virus into Gilead's two late-stage clinical trials, 113 of whom were severely ill. Gilead intends to enroll 4,000 people in its trials.
There are no proven therapies to treat Covid-19, which has infected more than 2.1 million worldwide and killed at least 142,148 as of Thursday night, according to data compiled by Johns Hopkins University. U.S. health officials say producing a vaccine to prevent Covid-19 will take at least 12 to 18 months, making finding an effective drug treatment soon crucial.
President Donald Trump has touted remdesivir and malaria drug hydroxychloroquine as "very exciting." Both drugs are in clinical trials examining their effectiveness in treating the coronavirus, but neither are proven treatments.
Remdesivir has shown some promise in treating SARS and MERS, which are also caused by coronaviruses. Some health authorities in the U.S., China and other parts of the world have been using remdesivir, which was tested as a possible treatment for the Ebola outbreak, in hopes that the drug can reduce the duration of Covid-19 in patients.
Gilead's clinical trial results involving patients with severe cases of the virus are expected this month. Data on a trial testing patients with moderate symptoms is expected in May.