Clinical question: Is baloxavir marboxil, a selective inhibitor of influenza cap-dependent endonuclease, a safe and effective treatment for acute uncomplicated influenza?
Background: The emergence of oseltamivir-resistant influenza A(H1NI) infection in 2007 highlights the risk of future neuraminidase-resistant global pandemics. Baloxavir represents a new class of antiviral agent that may help treat such outbreaks.
Study design: Phase 3 randomized, double-blind, placebo-controlled trial.
Setting: Outpatients in the United States and Japan.
Synopsis: The trial recruited 1,436 otherwise healthy patients aged 12-64 years of age (median age, 33 years) with a clinical diagnosis of acute uncomplicated influenza pneumonia. The patients were randomly assigned to receive either a single dose of oral baloxavir, oseltamivir 75 mg twice daily for 5 days, or matching placebo within 48 hours of symptom onset. The primary outcome was patient self-assessment of symptomatology.
Among the 1,064 adult patients (age 20-64) with influenza diagnosis confirmed by reverse transcription polymerase chain reaction (RT-PCR), the median time to alleviation of symptoms was lower in the baloxavir group than it was in the placebo group (53.7 hours vs. 80.2 hours; P less than .001). There was no significant difference in time to alleviation of symptoms in the baloxavir group when compared with the oseltamivir group. Adverse events were reported in 21% of baloxavir patients, 25% of placebo patients, and 25% of oseltamivir patients.
The enrolled patients were predominantly young, healthy, and treated as an outpatient. Patients hospitalized with influenza pneumonia are often older, have significant comorbidities, and are at higher risk of poor outcomes. This trial does not directly support the safety or efficacy of baloxavir in this population.
Bottom line: A single dose of baloxavir provides similar clinical benefit as 5 days of oseltamivir therapy in the early treatment of healthy patients with acute influenza.
Citation: Hayden FG et al. Baloxavir marboxil for uncomplicated influenza in adults and adolescents. N Eng J Med. 2018:379(10):914-23.
Dr. Holzer is an assistant professor of medicine in the division of hospital medicine at Mount Sinai Hospital, New York.