ZURICH (Reuters) – Influenza drug baloxavir marboxil significantly sped time to relief for patients highly vulnerable to serious complications, a late-stage clinical trial has shown, Swiss drugmaker Roche said on Thursday.

If approved, it would mark the first new way to treat influenza in nearly two decades, Roche added.

The CAPSTONE-2 phase III trial showed the median time to improvement of symptoms versus placebo dropped to 73.2 hours from 102.3 hours for at-risk patients including people aged 65 or older and those with asthma, chronic lung disease, morbid obesity or heart disease.

The single-dose oral medicine — discovered and developed by Shionogi & Co Ltd and sold in Japan as Xofluza — is the first to show such benefits, Roche said in a statement.

The drug was well tolerated and the trial threw up no new safety signals.

“This study adds to the growing body of evidence supporting baloxavir marboxil as a potential first-in-class antiviral flu treatment, and we plan to discuss these data with health authorities around the world,” Roche Chief Medical Officer Sandra Horning said.

The U.S. Food and Drug Administration has granted priority review for the drug in people aged 12 and older based on results from earlier studies, Roche said. It is set to decide by Dec. 24 whether to approve it.

(Reporting by Michael Shields; editing by Brenna Hughes Neghaiwi)