FDA Approves Baloxavir Marboxil to Treat Uncomplicated Influenza

Updated: 1/3/2018 at 10:55 AM EST

The US Food and Drug Administration (USDA) has announced the approval of baloxavir marboxil (Xofluza) for the treatment of acute uncomplicated influenza. The approval is indicated for patients 12 years of age and older who have been experiencing flu symptoms for less than 48 hours. This approval marks the first new antiviral flu treatment with a novel mechanism of action in nearly 20 years.

Baloxavir marboxil is a single-dose oral medication that targets the influenza virus by inhibiting the cap-dependent endonuclease protein which is essential for the replication of the virus.

At ID Week 2018, Mike Ison, MD, MS, professor at Northwestern University Feinberg School of Medicine and an investigator on the CAPSTONE-2 study which evaluated baloxavir marboxil in comparison to oseltamivir, sat down with Contagion® to discuss the unique nature of the medication (see video).

"[P]atients will be able to take a pill and will be done taking the medication for the treatment for influenza," Dr. Ison explained, "And after taking it, they will be at reduced risk for complications, including those requiring antibiotics or other complications of influenza."

The safety and efficacy of baloxavir marboxil, was demonstrated in the Phase 3 CAPSTONE 1 trial which evaluated 1,832 patients who participants were assigned to receive either the candidate, a placebo, or oseltamivir.

With a primary endpoint of time to alleviation of symptoms, the investigators indicate that baloxavir marboxil met the primary endpoints compared to placebo. Use of baloxavir reduced the duration of flu symptoms by more than 1 day (54 hours vs 80 hours; p<0.001). When compared to oseltamavir, the duration of symptoms were both estimated to be a median time of 54 hours.

The most common adverse reactions in patients taking baloxavir marboxil included diarrhea (3%) and bronchitis (2.6%).

"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." FDA Commissioner Scott Gottlieb, MD, said when making the announcement.

The drug has been developed in Japan by Shionogi, but will be sold in the United States and in other countries by Genentech.

On January 3, 2019, Genentech announced that baloxavir marboxil is now available in pharmacies across the United States.