FDA Approves Baloxavir Marboxil for Post-Exposure Prophylaxis of Influenza

The FDA has approved baloxavir marboxil (Xofluza; Genentech) to prevent influenza in individuals 12 years of age and older following contact with a person infected with the flu, making it the first single-dose influenza medicine approved for post-exposure prophylaxis.

Baloxavir marboxil is currently available in the United States and several other countries for the treatment of influenza types A and B; the drug was the first new antiviral to be approved by the FDA in 20 years. The medication is an antiviral designed to inhibit the cap-dependent endonuclease protein essential for viral replication.

Since 2010, the CDC has estimated that influenza causes between 9 to 45 million illnesses, 140,000 to 810,000 hospitalizations, and 12,000 to 61,000 deaths each year. Beyond vaccines, Genentech stressed the need for new medical options for the prophylaxis and treatment of influenza.

Approval was based on the phase 3, double-blind, multicenter, randomized, placebo controlled BLOCKSTONE study recently published in The New England Journal of Medicine. Investigators compared baloxavir marboxil with placebo in adult and children household members who had been living with someone with confirmed influenza.

Investigators ran the phase 3 clinical trial amid the 2018-2019 influenza season in Japan and reported a statistically significant prophylactic effect on influenza after administering 1 oral dose to the infected household member. One percept of the participants treated with baloxavir marboxil developed influenza compared with 13% of participants receiving placebo.

In addition, analysis of the study did not show any new safety signals. The most frequent adverse events (AEs) included diarrhea (3%), bronchitis (3%), nausea (2%), sinusitis (2%), and headache (1%).

With the coronavirus disease 2019 (COVID-19) pandemic coinciding with the 2020-2021 influenza season, this approval of baloxavir marboxil may play a key part in keeping viral infections down in the US.

“With today’s approval, Xofluza is now available as the first single-dose, post-exposure preventive treatment for influenza,” said Levi Garraway, MD, PhD, chief medical officer and head of Global Product Development. “We’re hopeful that reducing the burden of influenza may help to mitigate the strain on our healthcare system amid the COVID-19 pandemic.”

Reference:

1. Genentech Announces FDA Approval of Xofluza for the Prevention of Influenza Following Contact With an Infected Person. News Release. Genentech; November 23, 2020. Accessed November 23, 2020. https://www.gene.com/media/press-releases/14885/2020-11-23/genentech-announces-fda-approval-of-xofl.