The US Food and Drug Administration (FDA) has approved AstraZeneca’s Fasenra (benralizumab) for the treatment of adult and pediatric patients aged 12 years and older with hypereosinophilic syndrome (HES) without an identifiable non-hematologic secondary cause.

The approval was based on positive results from the NATRON phase 3 trial that evaluated the efficacy and safety of Fasenra in patients with HES. In the trial, treatment with Fasenra delayed the time to first HES flare and significantly reduced the risk of first HES flare compared to placebo by 65 percent (HR 0.35; 95 percent CI: 0.18-0.69; P=0.0024).

HES is a group of rare disorders characterised by persistently elevated levels of eosinophils (a type of white blood cell) in the blood and evidence of eosinophil-mediated organ or tissue damage. This may lead to progressive organ damage over time and if left untreated, may be fatal. The most common adverse reactions (≥5 percent and more common than placebo) with Fasenra in the NATRON study were headache, hypersensitivity reactions (including urticaria, urticaria papular, rash), and influenza like illness. For the treatment of HES, the recommended dosage of Fasenra is 30 mg (one injection) administered subcutaneously once every 4 weeks.

Princess U. Ogbogu, Division Chief of Pediatric Allergy, Immunology, and Rheumatology, University Hospitals Rainbow Babies and Children’s Hospital and Case Western Reserve University, Cleveland, OH, 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." 

Fasenra is currently approved as an add-on maintenance treatment for Severe Eosinophilic Asthma (SEA) in over 80 countries, including the US, Japan, EU and China. It is also approved for SEA in children and adolescents aged 6 years and older in the US and Japan.

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.”

Fasenra is also approved in over 70 countries for the treatment of adults with eosinophilic granulomatosis with polyangiitis (EGPA). It is currently approved in Chile for hypereosinophilic syndrome.

James Teague, Vice President, US Respiratory and Immunology, and Vaccine and Immune Therapies, 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.”