Baloxavir Effective in High-Risk Flu Patients

Michael Ison, MD

The article, “Phase 3 Study for Baloxavir Shows Efficacy in High-Risk Influenza Patients,” was originally published on ContagionLive.

Findings of a recent study suggest baloxavir marboxil reduces the time to improvement of influenza (flu) symptoms (TTIIS) in patients having at least 1 high-risk factor.

Baloxavir, a selective inhibitor of influenza cap-dependent endonuclease, was approved in the US and Japan in 2018 for the treatment of 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 to study the efficacy of baloxavir in outpatients at high risk of developing flu-associated complications. 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.

“This study supports early therapy for patients at high risk of complications of influenza to speed clinical recovery and reduce complications,” Ison and the team of 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,” Ison and the team concluded. “The safety of baloxavir was comparable to placebo.”

The study, “Early treatment with baloxavir marboxil in high-risk adolescent and adult outpatients with uncomplicated influenza (CAPSTONE-2): a randomized, placebo-controlled, phase 3 trial,” was published online in The Lancet Infectious Diseases.