The US Food and Drug Administration has approved Roche/Shionogi & Co’s Xofluza for the treatment of acute uncomplicated flu, opening the door to the first new antiviral with a novel mechanism of action in nearly 20 years.

The decision allows doctors to prescribe Roche’s Xofluza (baloxavir marboxil) for patients 12 years of age and older who have been symptomatic for no more than 48 hours.

Xofluza is a first-in-class, single-dose investigational oral medicine with a novel proposed mechanism of action designed to target the flu virus, including oseltamivir-resistant strains and avian strains (H7N9, H5N1).

The drug is designed to inhibit the cap-dependent endonuclease protein within the flu virus, which is essential for viral replication, setting it aside from other currently available antiviral therapies.

Recently released data from the Phase III CAPSTONE-2 study showed treatment with Xofluza significantly cut the time to improvement of flu symptoms versus placebo (73.2 hours versus 102.3 hours, respectively) in people at high risk of serious complications from the virus.

Results for the overall patient population showed numerically shorter time to improvement of influenza symptoms in the group taking the drug versus those taking oseltamivir, with a median time to improvement of symptoms of 73.2 hours versus 81.0 hours, respectively.

“With thousands of people getting the flu every year, and many people becoming seriously ill, having safe and effective treatment alternatives is critical. This novel drug provides an important, additional treatment option,” noted FDA commissioner Scott Gottlieb.

Flu is one of the most common infectious diseases and represents “a significant threat to public health,” said Roche. Globally, annual epidemics result in 3 to 5 million cases of severe disease, millions of hospitalisations and up to 650,000 deaths worldwide.

Baloxavir marboxil was discovered by Shionogi and is being co-developed globally by the Roche Group.