Evaluating the Effect of Benralizumab in Severe, Poorly-controlled Eosinophilic Asthma Using Inhaled Hyperpolarized 129-Xenon MRI

The purpose of this study is to evaluate the effect of a drug called benralizumab in individuals with severe, poorly controlled asthma with eosinophilic airway inflammation. Eosinophils are a type of white blood cell that help fight off infections. Some people with asthma have too many eosinophils in their airways and blood, which can cause airway inflammation. Benralizumab is a new drug that is Health Canada approved and has been shown to rapidly eliminate eosinophils. It has been used in patients with severe asthma to improve lung function and reduce flair-ups, also known as exacerbations. Magnetic Resonance Imaging (MRI) is an imaging tool that can look at the structure of the lungs when a subject inhales a xenon gas mixture. In healthy individuals, the gas fills the lungs evenly, but in individuals with lung disease, some of the areas of the lungs are not filled by the gas and the image looks patchy. These patchy areas are called ventilation defects and they contribute to reduced lung function. The goal of the study is to see if treatment with benralizumab will improve these ventilation defects, overall lung function and blood and sputum eosinophil levels. Subjects will receive treatment with benralizumab a total of 3 times, 4 weeks apart. Before and after treatment, subjects will undergo a series of MRI tests, breathing tests, blood and sputum analysis and a series of questionnaires to evaluate daily quality of life. The hypothesis is that ventilation defects will significantly improve after benralizumab treatment, and that this improvement will be different based on how long the patient has had asthma.