FDA approved Fasenra (benralizumab) for the treatment of adults and pediatric patients aged 12 and older with hypereosinophilic syndrome.

The approval expands the drug's previously approved indications into a third eosinophil-driven disease and provides a targeted therapy for a rare condition with limited treatment options.

James Teague, vice president of U.S. respiratory and immunology at AstraZeneca, said, "This approval builds on Fasenra's foundation in targeting eosinophilic-driven diseases. Fasenra has been shown to reduce flares in hypereosinophilic syndrome, addressing an important need in a population with significant disease burden and few targeted therapies."

What was approved?

Fasenra is now indicated for HES without an identifiable non-hematologic secondary cause, administered as a 30 mg subcutaneous injection once every four weeks.¹ The drug is already approved in more than 80 countries for severe eosinophilic asthma and in more than 70 countries for eosinophilic granulomatosis with polyangiitis.

What is HES and why is treatment important?

HES is a group of rare disorders characterized by persistently elevated eosinophils, a type of white blood cell, in the blood, accompanied by evidence of eosinophil-mediated damage to organs or tissues. The condition can cause progressive organ damage over time and, if left untreated, may be fatal. Patients commonly experience debilitating fatigue, skin manifestations, and other symptoms that significantly impair daily functioning including the ability to work.¹

What is the approval based on?

Fasenra’s approval is based on results from the Phase III Natron trial, a multicenter, randomized, double-blind, placebo-controlled study enrolling 133 patients with HES who were randomized 1:1 to Fasenra or placebo every four weeks for 24 weeks while continuing their stable HES therapy.²

Fasenra met the primary endpoint, delaying time to first HES flare and reducing the risk of a first flare by 65% compared to placebo.² Key secondary endpoints included proportion of patients experiencing flares, annualized flare rate, and change in fatigue scores. The most common adverse reactions were headache, hypersensitivity reactions, and influenza-like illness.

Princess U. Ogbogu, division chief of pediatric allergy, immunology, and rheumatology at University Hospitals Rainbow Babies and Children's Hospital and principal investigator of the Natron trial, said: "The approval of benralizumab for the treatment of HES is an important step forward for patients, providing an additional treatment option. The study demonstrated meaningful reduction in flares while addressing fatigue, a symptom that may impact patients."

Mary Jo Strobel, executive director of The American Partnership for Eosinophilic Disorders, said: "People living with hypereosinophilic syndrome struggle every single day. Debilitating fatigue, risk of organ damage, skin manifestations, and other symptoms adversely impact patients' lives, making it difficult to maintain normal daily activities, including work. Today's news brings hope to these people and their families."

The HES approval reinforces AstraZeneca's strategy of extending Fasenra 's reach across the spectrum of eosinophil-driven inflammatory diseases, where the drug's mechanism, targeting the IL-5 receptor to deplete eosinophils, has demonstrated consistent clinical utility across distinct but biologically related conditions.

Sources

1. ​​Fasnera approved in ​US​ for ​hypereosinophilic syndrome​ AstraZeneca May 14, 2026 https://www.astrazeneca-us.com/content/az-us/media/articles/2026/FASENRA-approved-in-US-for-hypereosinophilic-syndrome.html
2. A Phase III Study to Evaluate the Efficacy and Safety of Benralizumab in Patients With Hypereosinophilic Syndrome (HES) (NATRON) National Library of Medicine April 2, 2026 https://clinicaltrials.gov/study/NCT04191304