Baloxavir Marboxil Safe and Effective for High-Risk Influenza Patients

senior man in hospital bed
senior man in hospital bed
When compared to placebo, baloxavir marboxil was associated with reduced risk of influenza complications and faster recovery.
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SAN FRANSISCO — When compared with a placebo, the oral selective, cap-dependent, endonuclease inhibitor baloxavir marboxil was associated with reduced risk for influenza complications and faster recovery in patients who run a higher risk of such complications. Further, baloxavir marboxil was shown to be superior to oseltamivir in shortening virus replication duration and resolving influenza B, according to research presented at IDWeek 2018, held October 3-7, 2018, in San Francisco, California.

Researchers in this double-blind, randomized, placebo- and oseltamivir-controlled international treatment study examined the safety and efficacy of baloxavir marboxil for patients with a higher risk of influenza complications. Eligible participants age >12 years old, had influenza symptoms and fever for less than 48 hours, and fulfilled at least 1 Centers for Disease Control criteria high risk factor. Participants (N=2184) were randomly assigned to either 1 oral dose of baloxavir marboxil (40/80 mg for body weight </≥80 kg), placebo, or twice daily oseltamivir 75 mg for 5 days. The primary study end point was time to influenza symptom improvement for participants with confirmed influenza infection via reverse transcription polymerase chain reaction (RT-PCR) and secondary end points included influenza-related complications and antibiotic prescriptions.

Fifty-three% (n=1163) of the participants had confirmed RT-PCR influenza (47.9% strain A/H3N2, 6.9% strain A/H1N1, 41.6% influenza B) and the most prevalent risk factors were being over 65 years of age (27.4%) and having chronic lung disease or asthma (39.2%). Time to symptom improvement was significantly shorter in baloxavir marboxil than in placebo (median 73.2 hr vs 102.3 hr, P<.0001), as well as when compared to oseltamivir (81.0 hr, P=.8347). Time to symptom improvement in baloxabir marboxil for participants with influenza A/H3N2 virus was significantly shorter than in placebo (median: 75.4 hr vs 100.4 hr; P=.0141), and significantly shorter for patients with influenza B than in either placebo or oseltamivir (74.6 hr vs 100.6 hr; P=.0138, and 101.6 hr; P=.0251, respectively). Influenza complications and systemic antibiotic use were both significantly fewer in baloxavir marboxil (2.8% and 3.4%, respectively) compared to placebo (10.4% and 7.5% respectively; P<.0001 and P=.0112). There was no significant difference across the 3 groups in the incidence of adverse events (25.1%-29.7%) or serious adverse events (.7%-1.2%).

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Study investigators concluded that oral baloxavir marboxil “is a promising treatment option for [patients] with risk factors for influenza complications.”

Disclosures: Research support was provided by GlaxoSmithKlein.

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Ison MG, Portsmouth S, Yoshida Y, Shishido T, Hayden F, Uehara T. Phase 3 trial of baloxavir marboxil in high risk influenza patients (CAPSTONE-2 Study). Presented at: IDWeek 2018; October 3-7, 2018; San Francisco, California.