Gilead Sciences on Wednesday announced that the company “is aware of positive data” from a federal trial of its experimental coronavirus drug, remdesivir, even as a new study reported that the drug offered no benefit to severely ill patients in China.
Neither Gilead nor officials at the National Institute of Allergy and Infectious Diseases, sponsor of the federal research, provided further details about the trial sponsored by N.I.A.I.D., part of the National Institutes of Health.
President Trump is expected to discuss the findings at a White House briefing later today. In the past, Mr. Trump has hailed remdesivir as a potential “game changer,” despite spotty evidence.
The other study, conducted in China and published in the Lancet, questioned the value of the drug for treatment of severely ill patients but left open the possibility that it might be useful for others. The research was incomplete, however, because not enough participants could be enrolled.
Regarding the federal trial, the brief announcement by Gilead read: “We understand that the trial has met its primary endpoint and that N.I.A.I.D. will provide detailed information at an upcoming briefing.”
Trading in the company’s stock was halted before the market opened. The news drove stocks higher, and the S&P 500 rose about 2 percent in early trading.
The Food and Drug Administration acknowledged that officials were discussing approval of remdesivir for treatment of Covid-19 patients, presumably under emergency use provisions.
The N.I.A.I.D. study includes 400 patients who were hospitalized with Covid-19, the illness caused by the coronavirus, and randomly assigned to take remdesivir or a placebo. Outcomes were scored on a scale ranging from recovery to death.
Remdesivir has never been approved as a treatment for any disease. It was developed to fight Ebola, but results from a clinical trial in Africa were disappointing.
But as the coronavirus pandemic took hold, the drug emerged as one of the more promising potential treatments. It interrupts the production of the virus in lab studies and seems safe in animals.
Expectations were fueled by anecdotal reports of Covid-19 patients who took remdesivir and recovered.
Without trials comparing the drug to a placebo, it has been impossible to know whether the drug made a difference or patients got better on their own with normal supportive care.
The study of remdesivir published in the Lancet found no benefit to the drug, compared to placebo.
“Unfortunately, our trial found that while safe and adequately tolerated, remdesivir did not provide significant benefits over placebo,” said the lead investigator of the new study, Dr. Bin Cao of the China-Japan Friendship Hospital and Capital Medical University in Beijing.
“This is not the outcome we hoped for,” he added.
The results are hard to interpret, because the study was far smaller than planned — enrolling 236 patients instead of the 453 that had been expected, because there were too few severely ill patients now in China.
Dr. Eric Peterson, a clinical trials expert at Duke University, said that with too few patients, “all you can say is it doesn’t seem to work in this population.” If there had been a big effect of the drug, he added, that would have been seen.
He added that the trial should not be repeated with this population but instead in those who are less severely ill.
Dr. Michele Barry, an infectious disease expert at Stanford, echoed his observations. “Remdesivir appears not to be a magic bullet,” she said.
Still, she added, “this is a flawed study,” and it remains possible that the drug might help if given at a higher dose or earlier in the course of the disease.
Acceding to demands, Gilead has distributed the drug to hundreds of patients under so-called compassionate use, a regulatory exemption by which patients may receive a drug apart from a clinical trial.
Gilead itself published reports of uncontrolled studies. On Wednesday, in another news release, the company announced that a study comparing a five- to 10-day course of treatment with the drug showed that those getting the shorter course of treatment did just as well.
That study had no control group and was “noninformative,” said Dr. Peterson.
Sheila Kaplan contributed reporting.