Phase 3 Study for Baloxavir Shows Efficacy in High-Risk Influenza Patients

Baloxavir marboxil showed superiority over placebo and similar efficacy to oseltamir in reducing influenza symptoms.

Baloxavir marboxil showed efficacy in reducing the time to improvement of influenza symptoms (TTIIS) in patients identified in having at least 1 high-risk factor, according to findings from a phase 3 assessment.

Baloxavir, a selective inhibitor of influenza cap-dependent endonuclease, was approved in the US and Japan in 2018 for the treatment of influenza (flu) in patients 12 years and older.

Investigators performed a double-blind, placebo-controlled and oseltamivir-controlled trial in patients aged 12 years and older. Enrollment included a total of 2184 outpatients.

The study was led by Michael Ison, MD, professor, Division of Infectious Disease and Organ Transplantation, Northwestern University, and an international group of investigators from 551 sites in 17 countries and territories.

Their findings were published in The Lancet.

“This study supports early therapy for patients at high risk of complications of influenza to speed clinical recovery and reduce complications,” investigators wrote.

For inclusion, patients had to be diagnosed with an influenza-like illness, had symptoms for less than 48 hours, and had at least 1 risk factor for associated complications.

The primary endpoint was TTIIS in the modified intention-to-treat population. All the patients had to receive at least 1 dose of a study drug and had RT-PCR-confirmed influenza virus. In addition, patient safety was reviewed in all that received at least 1 dose of a study drug.

Overall, 730 participants received baloxavir, 729 received placebo, and 725 received oseltamivir.

TTIIS performance in baloxair (73.2 hours [95% CI, 67.2-85.1]) was better than placebo (102.3 hours [95% CI, 92.7-113.1]), indicating a difference of 29.1 hours (95% CI, 14.6-42.8]; P< .0001). TTIIS in the oseltamivir-treated patients was 81.0 hours (95% CI, 69.4-91.5), with a difference from the baloxavir group of 7.7 hours (95% CI, −7.9 to 22.7).

In terms of safety, adverse events were seen in 5 patients for the baloxavir group, 9 patients in the placebo group, and 8 patients in the oseltamivir group. There was 1 case each of hypertension and nausea in the placebo group and 2 cases of transaminase elevation in the oseltamivir group. These cases were considered to be treatment-related.

Overall, the investigators concluded that baloxavir is a viable influenza therapy for clinicians to include in their treatment armamentarium.

“Single-dose baloxavir has superior efficacy to placebo and similar efficacy to oseltamivir for ameliorating influenza symptoms in high-risk outpatients,” investigators wrote. “The safety of baloxavir was comparable to placebo.”