September 03, 2019
2 min read

Xofluza reduces risk for flu by 86% in household contacts

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Xofluza significantly reduced the risk for influenza infection among children aged younger than 12 years and adults living with infected individuals by 86%, according to phase 3 trial findings released by Genentech.

Researchers presented the results of the BLOCKSTONE study at the OPTIONS X 2019 congress in Singapore.

“Antivirals provide the next line of defense against influenza after vaccination,” Barry Clinch, PhD, group clinical science director and global head of influenza and infectious disease product development at Genentech/Roche, told Infectious Diseases in Children. “Unfortunately, vaccination efficacy and uptake rates are variable. Therefore, preventing healthy people who have been exposed to someone with influenza from developing the disease is an important way to prevent its rapid spread, reducing the disruption to people’s lives and, in some cases, serious illness or death.”

In the phase 3, randomized, post-exposure prophylaxis study, researchers compared the efficacy of one dose of Xofluza (baloxavir marboxil, Genentech) with placebo for preventing influenza infection in adults in children. All participants lived with a person with confirmed infection during the 2018-2019 influenza season in Japan.

According to the manufacturer, 1.9% of participants receiving baloxavir marboxil were infected with influenza compared with 13.6% of those receiving placebo (P < .0001). Investigators noted the statistically significant effects of baloxavir marboxil, even with influenza A infection (H1N1: 1.1% vs. 10.6%; P = .0023; H3: 2.8% vs. 17.5%; P < .0001).

Further, the post-exposure prophylaxis demonstrated superiority for household contacts at high risk for influenza-related complications (2.2% vs. 15.4%; P = .0435) and children aged younger than 12 years (4.2% vs. 15.5%; P = .0339) compared with placebo.

The researchers reported no serious adverse events related to treatment with baloxavir marboxil during the trial. The drug’s safety profile was comparable with placebo, with adverse events reported for 22.2% of participants receiving baloxavir marboxil and 20.5% of those receiving placebo.

Results of a previous phase 3 trial demonstrated that baloxavir marboxil was a safe and effective treatment option for children with influenza aged 1 to 12 years.

Clinch said that the company plans to submit the results of the BLOCKSTONE study to the FDA.

“If approved by the FDA, we believe that Xofluza in the preventive setting will be viewed favorably by payers as there are significant health care system and economic cost implications associated with flu,” he said. by Katherine Bortz


Ikematsu H, et al. Abstract 11718. Presented at: Options X for the control of influenza; Aug. 28-Sept. 1, 2019; Singapore.

Disclosure: Clinch is an employee of Genentech.