AstraZeneca reports statistical significance in NATRON trial

Full results from the NATRON Phase III trial showed AstraZeneca’s (AZN) Fasenra demonstrated a statistically significant delay in the time to first worsening or flare in hypereosinophilic syndrome, a rare disease driven by elevated eosinophils. These data will be presented at the American College of Allergy, Asthma and Immunology 2025 meeting in Orlando, Florida. NATRON was a Phase III trial evaluating the efficacy and safety of Fasenra in patients with HES. Patients were randomized to receive either a single 30 mg subcutaneous injection of Fasenra or a placebo once every four weeks. The trial successfully met the primary endpoint, as treatment with Fasenra delayed the time to first HES worsening/flare and significantly reduced the risk of HES worsening/flare compared to placebo by 65%. All key secondary endpoints in the trial were also met, as treatment with Fasenra resulted in fewer proportion of patients experiencing a flare or withdrawing and a 66% reduction in the annualized rate of HES flares compared to placebo: 0.41 vs 1.23 flares per year, respectively. Time to first hematologic relapse was delayed for patients on Fasenra compared to placebo. A greater improvement in PROMIS Fatigue scores was observed in patients treated with Fasenra compared to placebo by Week 4 and persisted to Week 24. Data from NATRON will also be shared at the upcoming American Society of Hematology annual meeting and exposition in December. The safety and tolerability profile for Fasenra in the NATRON trial was consistent with the known profile of the medicine.