Swiss drugmaker Novartis is halting its trial of malaria drug hydroxychloroquine (HCQ) against Covid-19 after struggling to find participants, it said on Friday, as data emerged from other studies raising doubts about its efficacy.
Novartis' trial began in April and sought to test the drug in 440 hospitalised patients. But the project only managed to recruit a handful.
Novartis' move follows this week's US Food and Drug Administration's (FDA) decision to revoke emergency use authorisation for hydroxychloroquine against Covid-19 on grounds it and a related drug, chloroquine, are unlikely to help patients.
Hydroxychloroquine, also used to treat inflammatory disorders including rheumatoid arthritis and lupus, has been caught in a political debate as US President Donald Trump promoted it, even though there was no scientific evidence that it helps against the new coronavirus.
Several studies of the decades-old malaria drug including in Britain were recently halted after scientists concluded it was "useless" against Covid-19.
This week the World Health Organisation halted the hydroxychloroquine arm of one of its trials.
"The recruitment challenge facing our hydroxychloroquine trial has made it unlikely that the clinical team will be able to collect meaningful data in a reasonable time frame to determine the efficacy of hydroxychloroquine in treating patients with Covid-19," Novartis said.
Trump, who said he used HCQ as a Covid-19 prophylactic, criticised the FDA decision to revoke its emergency authorization.
The Basel-based company said its study, so far, raised no safety issues and drew no conclusions about HCQ's efficacy.
Novartis' trial coincided with increasing use of Gilead Science's drug remdesivir, which has been shown in trials to speed recovery from Covid-19.
The FDA has also warned against mixing remdesivir with HCQ.
French drugmaker Sanofi, which previously suspended recruitment of patients for two HCQ trials, told Reuters it would make a decision in "coming days" over whether it would resume its own studies.
Novartis had donated up to 130 million doses of hydroxychloroquine, including millions in the United States, and Chief Executive Vas Narasimhan two months ago pegged it as the company's biggest hope against the new coronavirus.