Baloxavir Marboxil Wins FDA Label Expansion for Post-exposure Flu Prevention

The US Food and Drug Administration (FDA) has expanded the labeled indication for baloxavir marboxil (Xofluza, Genentech) to include post-exposure prophylaxis in persons aged ≥12 years following contact with someone known to be infected with the influenza virus, according to a press release from the FDA.

Baloxavir marboxil was originally approved in 2018 for treating uncomplicated influenza in otherwise healthy patients aged ≥12 years who had been symptomatic for no more than 48 hours or who were at high risk of developing flu-related complications.

The current approval was supported by data from the randomized, double-blind, placebo-controlled phase 3 BLOCKSTONE trial in which 607 subjects, aged ≥12 years were exposed to a person with influenza in their household. Participants were randomized 1:1 to receive either a single dose of baloxavir marboxil (n=303) or placebo (n=304). The primary endpoint was laboratory- confirmed influenza over a period of 10 days.

The study found a statistically significant reduction in the proportion of household contacts with laboratory-confirmed clinical influenza from 13% in the placebo group to 1% in the baloxavir marboxil group. No new safety signals were identified and the drug was well tolerated. The most common adverse events reported with baloxavir marboxil included diarrhea (3%), bronchitis (3%), nausea (2%), sinusitis (2%) and headache (1%).

“This expanded indication for Xofluza will provide an important option to help prevent influenza just in time for a flu season that is anticipated to be unlike any other because it will coincide with the coronavirus pandemic,” said Debra Birnkrant, MD, director of the Division of Antiviral Products in the FDA’s Center for Drug Evaluation and Research.

A new granule formulation for oral suspension (2mg/mL) has also been approved for patients who are unable to swallow or have difficulty swallowing tablets, or for those who require enteral administration.

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