FDA Approves Fasenra for Hypereosinophilic Syndrome Based on Phase III NATRON Trial Results
核心洞察
The FDA has approved Fasenra (benralizumab) for treating hypereosinophilic syndrome (搜索) (HES (搜索)) in adults and pediatric patients aged 12 and older, marking the drug's third approved eosinophil-driven disease indication.
The approval is based on the Phase III NATRON trial, which demonstrated that benralizumab reduced the risk of first HES (搜索) flare by 65% compared to placebo over 24 weeks.
The study enrolled 133 patients and showed significant improvements in flare rates, time to hematologic relapse, and fatigue scores, with safety profiles consistent with benralizumab's known profile.
The FDA has approved Fasenra (benralizumab) for the treatment of hypereosinophilic syndrome (搜索) (HES (搜索)) in adults and pediatric patients aged 12 and older, expanding AstraZeneca's eosinophil-targeting therapy into a third rare disease indication. The approval provides a new treatment option for patients with a condition that has limited therapeutic alternatives and can cause progressive organ damage if left untreated.
NATRON Trial Demonstrates Significant Clinical Benefits
The approval is based on results from the Phase III NATRON trial, a multicenter, randomized, double-blind, placebo-controlled study that enrolled 133 patients with HES (搜索). Participants were randomized 1:1 to receive either benralizumab 30 mg or placebo subcutaneously every four weeks for 24 weeks while continuing their stable HES therapy.
The trial met its primary endpoint, demonstrating that benralizumab significantly delayed time to first HES (搜索) flare compared to placebo. HES flare was observed in 13 patients (19.4%) receiving benralizumab versus 28 patients (42.4%) receiving placebo, representing a statistically significant 65% reduction in risk (hazard ratio 0.35, 95% CI 0.18 to 0.69, P = 0.0024).
"Fasenra has been shown to reduce flares in hypereosinophilic syndrome (搜索), addressing an important need in a population with significant disease burden and few targeted therapies," said James Teague, vice president of U.S. respiratory and immunology at AstraZeneca.
Comprehensive Secondary Endpoint Success
All key secondary endpoints achieved statistical significance at the 1% level. The proportion of patients who experienced a HES (搜索) flare or withdrew from the study was significantly lower in the benralizumab group compared to placebo: 22.4% versus 45.5%, respectively (odds ratio 0.31, 95% CI 0.14 to 0.69, P = 0.0033). This represented a 52% relative reduction in the proportion of patients experiencing a flare.
Benralizumab treatment resulted in significantly fewer HES (搜索) flares compared to placebo (0.41 versus 1.23 flares per year, respectively), with a 66% reduction in the annualized rate of flares (rate ratio 0.34, 95% CI 0.18 to 0.63, P = 0.0008). A higher proportion of patients on benralizumab experienced no HES flare events during the 24-week period compared to placebo (80.6% versus 57.6%, respectively).
The trial also demonstrated a significant delay in time to first hematologic relapse, with benralizumab patients being 92% less likely to relapse at any given point during the double-blind period versus placebo (hazard ratio 0.08, 95% CI 0.03 to 0.20, P < 0.0001).
Addressing Debilitating Fatigue
Fatigue, a key symptom that significantly impacts quality of life in HES (搜索) patients, showed significant improvement with benralizumab treatment. The least squares mean difference in PROMIS Fatigue scores between groups was −4.72 (95% CI −7.64 to −1.80, P = 0.0017) at week 24, with improvements evident as early as week 4.
"The approval of benralizumab for the treatment of HES (搜索) 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," said 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.
Patient Population and Disease Burden
The NATRON trial enrolled a representative patient population with HES (搜索), with 62% female patients and a median age of 51.0 years. Most patients (75.2%) had idiopathic HES, and 12.0% had lymphocytic HES. The median time since diagnosis was 1.9 years, and patients had experienced a median of 2 HES flares in the 12 months before enrollment. Around three-quarters of patients (76.7%) were receiving background systemic oral corticosteroids at enrollment.
HES (搜索) is characterized by persistently elevated eosinophils (搜索) in the blood, accompanied by evidence of eosinophil-mediated damage to organs or tissues. The condition can cause progressive organ damage over time and may be fatal if left untreated. Patients commonly experience debilitating fatigue, skin manifestations, and other symptoms that significantly impair daily functioning, including the ability to work.
"People living with hypereosinophilic syndrome (搜索) 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," said Mary Jo Strobel, executive director of The American Partnership for Eosinophilic Disorders.
Safety Profile and Mechanism of Action
The safety profile of benralizumab in the NATRON trial was consistent with its known safety profile. The proportion of patients experiencing any adverse event during the double-blind period was similar between treatment groups (benralizumab 64.2%, placebo 66.7%). The most common adverse events were headache (16.4% benralizumab vs 7.6% placebo), upper respiratory tract infection (7.5% vs 7.6%), and coronavirus disease 2019 (6.0% vs 6.1%).
Consistent with benralizumab's known mechanism of action, durable near-complete depletion of blood eosinophils (搜索) was observed in patients treated with benralizumab. Most patients on benralizumab (91.0%) sustained absolute eosinophil count <500 cells μl⁻¹ for 24 weeks compared to 12.1% in the placebo group.
Expanding Treatment Options
Fasenra is now indicated for HES (搜索) without an identifiable non-hematologic secondary cause, administered as a 30 mg subcutaneous injection once every four weeks. The drug is already approved in more than 80 countries for severe eosinophilic asthma (搜索) and in more than 70 countries for eosinophilic granulomatosis with polyangiitis (搜索).
The HES (搜索) approval reinforces AstraZeneca's strategy of extending Fasenra's reach across the spectrum of eosinophil-driven inflammatory diseases, where the drug's mechanism of targeting the IL-5 receptor (搜索) to deplete eosinophils (搜索) has demonstrated consistent clinical utility across distinct but biologically related conditions.