On Aug. 11, 2022, Roche announced that the U.S. Food and Drug Administration (FDA) had approved a supplemental New Drug Application (sNDA) for Xofluza (baloxavir marboxil) for the treatment of acute uncomplicated influenza in otherwise healthy children aged five to less than 12 years of age who have been symptomatic for no more than 48 hours. This marked the first single-dose oral influenza medicine approved in the US for children in this age group. Additionally, the FDA approved Xofluza for the prevention (post-exposure prophylaxis) of influenza in children aged five to less than 12 years of age following contact with someone with influenza.

According to the U.S. Centers for Disease Control and Prevention, influenza can be a serious illness for young children.1 During the ongoing COVID-19 pandemic there have been significantly fewer influenza cases, likely due in large part to social distancing and mask wearing.2 However, in the US 2018-2019 influenza season, there were more than 6 million illnesses, thousands of hospitalisations and over 100 deaths among children aged five to 17 caused by influenza.

The FDA approval is based on results from two phase III studies: miniSTONE-2, which evaluated the use of Xofluza in children, and BLOCKSTONE, which evaluated Xofluza as a preventive treatment for household members, in both adults and children. The results from these studies were published in The Pediatric Infectious Disease Journal and The New England Journal of Medicine respectively.

Xofluza is already FDA-approved to treat influenza in people 12 years of age and older who have had influenza symptoms for no more than 48 hours and who are otherwise healthy or at high risk of developing influenza-related complications. Xofluza is also approved to prevent influenza in people 12 years of age and older following contact with someone with influenza (known as post-exposure prophylaxis). Xofluza is available as a one-dose, single-tablet.

BLOCKSTONE was a phase III, double-blind, multicentre, randomised, placebo-controlled, post-exposure prophylaxis study that evaluated single-dose Xofluza® (baloxavir marboxil) compared with placebo in household members (adults and children) who were living with someone with influenza confirmed by a rapid influenza diagnostic test (the ‘index patient’).

Participants enrolled in the study were household members of someone who had been diagnosed with influenza. The participants were randomised to receive a single-dose of Xofluza (dose according to body weight) or placebo as a preventive measure against developing influenza.

Xofluza showed a statistically significant prophylactic effect on influenza after a single oral dose, by reducing the risk of individuals aged 12 years and above from developing influenza after exposure to an infected household member by 90% versus placebo. The proportion of household members aged 12 years and above who developed laboratory-confirmed clinical influenza was 1.3% in participants treated with Xofluza and 13.2% in the placebo-treated group. Xofluza was well tolerated in this study and no new safety signals were identified. The study was conducted in Japan by Shionogi & Co.