FDA expands Fasenra label to hypereosinophilic syndrome

AstraZeneca’s Fasenra won US FDA approval on May 13, 2026, for adults and pediatric patients age 12 and older with hypereosinophilic syndrome, or HES, without an identifiable non-hematologic secondary cause. The label update adds a new indication for benralizumab, an anti-IL-5 receptor monoclonal antibody first approved for severe eosinophilic asthma in 2017 and later for eosinophilic granulomatosis with polyangiitis. In the updated prescribing information, the recommended HES dose is 30 mg by subcutaneous injection every four weeks. The approval was supported by the phase 3 NATRON trial, which showed benralizumab delayed time to first HES flare and cut the risk of a first flare by 65% versus placebo during the 24-week double-blind period. (accessdata.fda.gov)

Why it matters: For veterinary professionals tracking the broader biologics and regulatory landscape, this is another sign that eosinophil-targeting therapies are continuing to expand beyond their original respiratory indications into rare immune-mediated diseases. HES is a rare, potentially life-threatening disorder marked by persistent eosinophilia and organ damage, and treatment responses to existing options can vary. In NATRON, 19.4% of benralizumab-treated patients had an HES flare versus 42.4% on placebo, and the annualized flare rate fell from 1.23 to 0.41 flares per year. That kind of label expansion matters because it reinforces the commercial and clinical momentum behind cytokine- and cell-targeted biologics, a trend veterinary medicine continues to watch closely for translational relevance, specialty practice expectations, and pet parent awareness of advanced immunology therapies. (nature.com)

What to watch: Watch for payer coverage decisions, uptake in specialty hematology and allergy clinics, and whether additional global regulators follow the FDA after the EMA’s positive opinion in May 2026. (ema.europa.eu)