Benralizumab is a medicine given as a small injection under the skin. It works by targeting a specific type of white blood cell that can cause inflammation in the lungs. By reducing these cells, the drug helps people with certain types of asthma breathe more easily and have fewer asthma attacks. In this study, participants who already felt better after using the medicine continue to receive it so researchers can watch how safe it is over a longer time and see how well it continues to work.

Hypereosinophilic syndrome (HES) – A condition in which the blood contains an abnormally high number of eosinophils for a prolonged period. The excess eosinophils can infiltrate various organs such as the heart, lungs, skin, and gastrointestinal tract. Over time, this infiltration may lead to tissue damage and functional impairment. Symptoms often develop gradually and can include fatigue, rash, and shortness of breath. The disease course varies, but without control the organ involvement can become more extensive.
Eosinophilic granulomatosis with polyangiitis (EGPA) – An inflammatory disorder that affects small blood vessels and is associated with high eosinophil counts. It usually begins with asthma-like symptoms and allergic rhinitis, then progresses to a vasculitic phase that can involve nerves, skin, and other organs. The vasculitic phase may cause numbness, skin purpura, and abdominal pain. Organ involvement tends to increase as the disease advances, and relapses can occur after periods of stability.
Asthma – A chronic disease marked by inflammation and narrowing of the airways, leading to wheezing, coughing, and difficulty breathing. Triggers such as allergens, cold air, or exercise can worsen symptoms. Repeated episodes may cause the airway walls to thicken, reducing lung function over time. Symptoms can fluctuate daily and may become more persistent if the underlying inflammation is not managed.