The FDA ( US Food and Drug Administration ) has approved a supplemental New Drug Application ( sNDA) for Xofluza ( Baloxavir marboxil ) for the treatment of acute, uncomplicated influenza, or flu, in people 12 years of age and older who have been symptomatic for no more than 48 hours and who are at high risk of developing flu-related complications.
Xofluza is a first-in-class, one-dose oral medicine with a novel proposed mechanism of action that inhibits polymerase acidic endonuclease, an enzyme essential for viral replication.
Flu has the potential to cause a variety of complications, ranging from sinus or ear infections to more serious complications such as pneumonia.
This expanded indication for Xofluza was approved based on results from the phase III CAPSTONE-2 study of a single dose of 40mg or 80mg of Xofluza compared to Oseltamivir ( 75mg twice daily for five days ), or placebo in people 12 years of age or older who met CDC criteria for being at high risk of complications from flu.
Xofluza has significantly reduced the time to improvement of flu symptoms compared to placebo, including in people infected with the flu type B virus.
Adverse events reported in at least 1% of adult and adolescent subjects treated with Xofluza included diarrhoea ( 3% ), bronchitis ( 3% ), nausea ( 2% ), sinusitis ( 2% ) and headache ( 1% ).
Xofluza is currently approved in several countries for the treatment of influenza types A and B.
In October 2018, Xofluza was first approved by the FDA for the treatment of acute, uncomplicated flu in otherwise healthy people 12 years of age and older who have been symptomatic for no more than 48 hours, representing the first new antiviral to treat influenza in the United States in 20 years.
CAPSTONE-2 is a phase III, multicentre, randomised, double-blind study that has evaluated a single dose of Xofluza compared with placebo and Oseltamivir in people 12 years of age or older who are at a high risk of complications from flu.
The Centers for Disease Control and Prevention ( CDC ) defines people at high risk of serious flu complications as those who have conditions such as asthma, chronic lung disease, diabetes, heart disease or morbid obesity, or adults 65 years of age or older.
Participants enrolled in the study were randomly assigned to receive a single dose of 40mg or 80mg of Xofluza, placebo or 75mg of Oseltamivir twice a day for five days.
The primary objective of the study was to evaluate the efficacy of a single dose of Xofluza compared with placebo by measuring the time to improvement of influenza symptoms.
Xofluza has significantly reduced the time to improvement of influenza symptoms versus placebo in people at high risk of complications from influenza ( median time 73 hours versus 102 hours; p less than 0.001 ).
Similar efficacy results were seen between Xofluza and Oseltamivir in relation to duration of symptoms ( median time 73 hours versus 81 hours ).
In subjects infected with type B virus, the median time to improvement of influenza symptoms was shorter in the Xofluza group compared to the placebo group ( 75 hours versus 101 hours respectively ).
Xofluza is a first-in-class, one-dose oral medicine with a novel proposed mechanism of action that has demonstrated efficacy in a wide range of influenza viruses, including in vitro activity against Oseltamivir-resistant strains and avian strains ( H7N9, H5N1 ) in non-clinical studies.
Unlike other currently available antiviral treatments, Xofluza is the first in a new class of antivirals designed to inhibit the cap-dependent endonuclease protein, which is essential for viral replication. ( Xagena )
Source: Roche, 2019