Xofluza Approved to Treat, Prevent Influenza in Pediatric Patients

The expanded approval was based on data from two phase 3 studies, miniSTONE-2 and BLOCKSTONE.

The Food and Drug Administration (FDA) has expanded the approval of Xofluza® (baloxavir marboxil) to include treatment of acute uncomplicated influenza in otherwise healthy children 5 years of age and older who have been symptomatic for no more than 48 hours, as well as for postexposure prophylaxis of influenza in children 5 years of age and older following contact with an individual who has influenza. Previously, the antiviral agent had not been indicated for patients younger than 12 years old.

The expanded approval was based on data from two phase 3 studies, miniSTONE-2 (ClinicalTrials.gov Identifier: NCT03629184) and BLOCKSTONE (ClinicalTrials.gov Identifier: NCT03969212). The miniSTONE-2 study compared the efficacy and safety of Xofluza with oseltamivir in 118 otherwise healthy children 5 to less than 12 years of age with a confirmed influenza infection. Patients were randomly assigned to receive a single oral dose of Xofluza or oseltamivir for 5 days based on body weight.

Results from miniSTONE-2 showed that the median time to alleviation of signs and symptoms of influenza was 138 hours (95% CI, 117-163) in the Xofluza arm and 126 hours (95% CI, 96-166) in the oseltamivir arm. The most common adverse reactions in the Xofluza arm were vomiting (5%) and diarrhea (5%), while vomiting was reported in 18% of patients in the oseltamivir arm.

BLOCKSTONE evaluated the efficacy of a single oral dose of Xofluza compared with placebo in the prevention of influenza in participants 5 years of age and older who were living with someone with an influenza infection. Results showed a statistically significant reduction in the proportion of household contacts (participants) with laboratory-confirmed clinical influenza from 13% (95% CI, 10-17) in the placebo group to 2% (95% CI, 1-4) in the Xofluza group (P <.0001).

“Despite the ongoing COVID-19 pandemic, influenza continues to be a threat to public health, and effective influenza antivirals remain critical to alleviating the burden on healthcare systems,” said Levi Garraway, MD, PhD, chief medical officer and head of Global Product Development. “Xofluza has proven to be an important tool in fighting and preventing influenza in adults as well as adolescents, and we are pleased to now offer households and younger children our single-dose oral treatment.”

Xofluza is supplied as 40mg and 80mg tablets.


  1. Genentech announces FDA approval of Xofluza to treat influenza in children aged five and older. News release. Genentech. Accessed August 11, 2022. https://www.gene.com/media/press-releases/14964/2022-08-11/genentech-announces-fda-approval-of-xofl
  2. Xofluza. Package insert. Genentech; 2022. Accessed August 11, 2022. https://www.gene.com/download/pdf/xofluza_prescribing.pdf