Roche has announced that in the Phase III BLOCKSTONE study, preventive treatment with Xofluza (baloxavir marboxil) after exposure to an infected household member significantly reduced the risk of people developing flu by 86% versus placebo.

The results showed just 1.9% of Xofluza-treated household members had flu compared with 13.6% in the placebo-treated group, a benefit which remained statistically significant versus placebo regardless of the influenza A subtype.

It was also observed in household contacts who are at high risk of flu-associated complications (2.2% vs 15.4%), and children under 12 years of age who are more vulnerable to developing flu (4.2% vs 15.5%).

The company also announced that the drug had a comparable safety profile to placebo, with an overall incidence of adverse events being 22.2% for Xofluza and 20.5% for placebo.

Further to the results, the study also demonstrated that even when fewer criteria for flu were applied, there was still a significant 76% reduction in the risk of household members developing flu with Xofluza versus placebo (5.3% vs 22.4%).

“As the influenza virus can rapidly infect those around us, limiting the spread of infection within households potentially avoids a significant impact on the wider community – a critical step in the global fight against flu,” said Sandra Horning, Roche’s chief medical officer and head of Global Product Development.

“We are encouraged by the BLOCKSTONE study, the first to show that Xofluza is an effective preventive treatment following exposure to flu and we look forward to sharing these data with health authorities.”

Xofluza is the first and only one-dose oral medicine approved to treat flu in otherwise-healthy patients, and the first new flu medicine with a novel proposed mechanism of action approved by the FDA in nearly 20 years.