WASHINGTON -- Baloxavir marboxil, a first-in-class drug for shortening duration of influenza infection, won Wednesday and will be sold under the brand name Xofluza.
The drug inhibits the flu virus's cap-dependent endonuclease, thus distinguishing it from previously approved flu drugs including oseltamivir (Tamiflu), which target the viral neuraminidase protein.
"This is the first new antiviral flu treatment with a novel mechanism of action approved by the FDA in nearly 20 years. 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," said FDA Commissioner Scott Gottlieb, MD, in a statement announcing the approval.
The agency relied primarily on two randomized trials involving a total of 1,832 patients in approving baloxavir. Both tested the drug against placebo and against oseltamivir. Relative to placebo, baloxavir shortened the duration of flu symptoms by about 24 hours (e.g., median duration 53.7 hours vs 80.2 hours in one of the studies). The novel agent proved equivalent to oseltamivir in efficacy within the bounds of the studies' power. But the trial data also suggested baloxavir may have an advantage in patients with influenza B viral infection.
In announcing the approval, the FDA noted that the most common side effects with baloxavir included diarrhea and bronchitis.
Baloxavir is made by the Japanese firm Shionogi & Co.