FDA Accepts Supplemental New Drug Application for Baloxavir Marboxil for Treating Flu in People at High Risk of Complications

MARCH 06, 2019
Officials with the US Food and Drug Administration (FDA) have accepted a supplemental new drug application for baloxavir marboxil (Xofluza, Genentech) as a single-dose, oral treatment for people at high risk of complications from the flu, according to a statement from the manufacturer. 

The sNDA is based on results from the phase 3 CAPSTONE-2 study of a single dose of Xofluza compared with placebo or oseltamivir 75 mg, twice daily for 5 days, in people 12 years of age or older who are at high risk of complications from the flu. The study compared Xofluza with placebo and oseltamivir in 2184 people and measured the time to improvement of influenza symptoms. Study researchers noted that Xofluza significantly reduced the time to improvement of influenza symptoms versus placebo in people at high risk of complications from influenza (median time 73.2 hours versus 102.3 hours; P<.0001) and demonstrated superior efficacy (reduced time to improvement of influenza symptoms) versus placebo and oseltamivir in influenza type B (median time of 74.6 hours versus 100.6 hours and 101.6 hours, respectively (P=.0138, P=.0251).

Xofluza also demonstrated efficacy for secondary endpoints compared to placebo in that it significantly reduced the time to resolution of fever (median time of 30.8 hours versus 50.7 hours; P<.0001), the incidence of influenza-related complications (2.8% versus 10.4%; P<0.05), the use of systemic antibiotics (3.4% versus 7.5%; P=0.01) and the length of time the virus continued to be released from the body (viral shedding; median time of 48 hours versus 96 hours; p<0.0001).

Similar efficacy results were seen between Xofluza and oseltamivir for several secondary endpoints, but a significant difference was observed in the time to cessation of viral shedding favoring Xofluza.

The CDC defines people at high risk for serious flu complications to include adults 65 years of age or older, or those who have conditions such as asthma, chronic lung disease, morbid obesity or heart disease. The FDA is expected to make a decision on approval by November 4, 2019.