University of Chicago Medicine researchers said they saw “rapid recoveries” in 125 COVID-19 patients taking Gilead Sciences Inc.’s experimental drug remdesivir as part of a clinical trial, according to a Thursday afternoon report.

Shares of Gilead Sciences Inc. GILD, +0.01% jumped 8% Friday, following the publication of the Stat News report.

There are no proven treatments or vaccines for the novel coronavirus which has sickened more than two million people world-wide and killed nearly 150,000 people, but remdesivir is considered a front-runner in the race to develop a treatment for COVID-19 infections that works. Though the findings reported by Stat are promising, they are not based on full clinical trial data from the company.

In a statement, Gilead said the “totality of the data [needs] to be analyzed in order to draw any conclusions from the trial. Anecdotal reports, while encouraging, do not provide the statistical power necessary to determine the safety and efficacy profile of remdesivir as a treatment for COVID-19.”

For more: These 21 companies are working on coronavirus treatments or vaccines — here’s where things stand

According to Stat, 125 people with COVID-19 receiving care at the University of Chicago are participating in two Phase 3 clinical trials conducted by Gilead; 113 of them have severe forms of the disease. Two of the 113 patients died. Stat said it obtained a recorded video discussion about the trial among University of Chicago faculty members in which a physician said when some people start taking the drug, fevers come down and some come off ventilators.

“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,” a University of Chicago spokesperson said in an email on Friday morning. “In this case, information from an internal forum for research colleagues concerning work in progress was released without authorization. Drawing any conclusions at this point is premature and scientifically unsound.”

One trial is evaluating remdesivir in 2,400 people with severe forms of the disease, the other is testing the drug in 1,600 patients who are moderately ill. Both trials are being conducted at multiple sites around the world. According to ClinicalTrials.gov, both trials began in March and are expected to conclude in May.

It has been a dramatic week for Gilead’s stock, starting with the release last Friday of a small clinical data set published in The New England Journal of Medicine showcasing that 68% of 53 hospitalized patients who had received remdesivir on a compassionate-use basis showed clinical improvement. At that time, a J.P. Morgan analyst called the data “a promising first look” but warned the results “need to be kept in context.”

On Wednesday, shares tumbled after a clinical-trial listing was updated to say Chinese authorities had stopped recruiting for a remdesivir clinical trial in severely ill COVID-19 patients there. Shares rose again on a Bloomberg News report that Gilead is considering taking a stake in Arcus Biosciences Inc. RCUS, -1.12% .

”This disclosure, like last Friday’s NEJM article, offers encouraging evidence that the most severe manifestations of the disease can be reduced by Gilead’s medicine,” SVB Leerink’s Geoffrey Porges wrote in a note on Thursday evening.