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

Inclusion Criteria: * Patient understands study procedures and is willing to participate in the study as indicated by the patient's signature * Provision of written, informed consent prior to any study specific procedures * Males and females with a clinical diagnosis of asthma aged 18 to 70 years, inclusively, at the time of Visit 1 (enrolment), under the care of a respirologist * Patient is a current non-smoker, having not smoked tobacco or cannabis for at least 12 months prior to the study with a tobacco smoking history of no more than 1 pack-year (i.e., 1 pack per day for 1 year) * Women of childbearing potential (after menarche) must use a highly effective form of birth control (confirmed by the investigator or designee). A highly effective form of birth control includes true sexual abstinence, a vasectomized sexual partner, Implanon®, female sterilization by tubal occlusion, any effective intrauterine device (IUD)/levonorgestrel intrauterine system (IUS), Depo-Provera (trademark) injections, oral contraceptive and Erva Patch (trademark) or Nuvaring (trademark) * Women of childbearing potential (after menarche) must agree to use a highly effective form of birth control, as defined above, from enrolment, throughout the study duration, and within 16 weeks after last dose of study drug, and have negative serum pregnancy test result on enrolment * Male patients who are sexually active must agree to use a double barrier method of contraception (condom with spermicide) from the first dose of the study drug until 16 weeks after last dose * Patient has documented treatment with medium- to high-dosage inhaled corticosteroids (ICS) (\>250μg fluticasone dry powder formulation equivalents total daily dosage) and a long-acting β2-agonist (LABA) for at least 12 months prior to enrolment. * Patient has been treated with high dose ICS (at least 500μg/day fluticasone propionate dry powder formulation or equivalent daily) and LABA for at least 3 months prior to Visit 2 with or without oral corticosteroids (OCS) and additional asthma controllers * Patient demonstrates pre-bronchodilator (Pre-BD) forced expiratory volume in one second ˂ 80% predicted * Patient demonstrated significant bronchodilator reversibility (≥ 12% AND ≥ 200 mL improvement) or positive methacholine challenge test (PC20 \< 4.0 mg/ml) in past 24 months * Patient has blood eosinophils ≥ 300 cells/μl * Patient has ACQ-6 ≥ 1.5 at visit 1 * Patient has a history of poorly controlled asthma Exclusion Criteria: * Patient is, in the opinion of the investigator, mentally or legally incapacitated, preventing informed consent from being obtained, or cannot read or understand written material * Patient has clinically important pulmonary disease other than asthma (e.g. active lung infection, chronic obstructive pulmonary disease, bronchiectasis, pulmonary fibrosis, cystic fibrosis, hypoventilation syndrome associated with obesity, lung cancer, alpha-1 antitrypsin deficiency and primary ciliary dyskinesia) or been diagnosed with pulmonary or systemic disease other than asthma that is associated with elevated peripheral eosinophil counts (e.g. allergic bronchopulmonary aspergillosis/mycosis, Churg-Strauss syndrome, hypereosinophilic syndrome), except for those atopic conditions that can be associated with asthma (e.g. allergic rhinitis, sinusitis with or without polyposis, eczema, and eosinophilic esophagitis) * Any disorder, including, but not limited to, cardiovascular, gastrointestinal, hepatic, renal, neurological, musculoskeletal, infectious, endocrine, metabolic, haematological, psychiatric, or major physical impairment that is not stable in the opinion of the Qualified Investigator and/or could affect the safety of the patient throughout the study, influence the findings of the study or their interpretations, or impede the patient's ability to complete the entire duration of the study, as assessed by the Qualified Investigator. * Known history of allergy or reaction to the study drug formulation * History of anaphylaxis to any biologic therapy * A helminthic parasitic infection diagnosed within 24 weeks prior to the date of informed consent that has not been treated with or failed to respond to standard-of-care therapy * Acute upper or lower respiratory infections requiring antibiotics or antiviral medication within 30 days prior to the date of informed consent * Use of immunosuppressive medication (including but not limited to methotrexate, troleandomycin, cyclosporine, azathioprine, intramuscular long-acting depot corticosteroid or any experimental anti-inflammatory therapy) within 3 months prior to the date of informed consent * Chronic maintenance prednisone for the treatment of asthma is allowed * Clinically significant asthma exacerbation, in the opinion of the investigator, including those requiring the use of OCS, or an increase in maintenance dosage of OCS 14 days prior to the date of informed consent * Receipt of immunoglobulin or blood products within 30 days prior to the date of informed consent * Receipt of live attenuated vaccines 30 days prior to the date of enrolment * Receipt of any marketed (e.g., omalizumab) or investigational biologic within 4 months or 5 half-lives prior to the date of informed consent, whichever is longer AND blood eosinophils ≥ 300 cells/µl. * Receipt of any investigational nonbiologic within 30 days or 5 half-lives prior to enrolment, whichever is longer * Previously randomized in any benralizumab (MEDI-563) study * Initiation of new allergen immunotherapy within 30 days prior to the date of informed consent * Current use of any oral of opthalmic nonselective β-adrenergic antagonist (e.g., propranolol) * Planned surgical procedure during the conduct of the study * Concurrent enrolment in another clinical trial * Patient has donated a unit of blood within 4 weeks prior to Visit 1 or anticipates donating blood at any time during the study * Patient has history of alcohol or drug abuse within 12 months prior to the date of informed consent * Patient is a female who is ≤8 weeks post-partum or breast feeding an infant * Patient is pregnant, or intends to become pregnant during the time course of the study * Patient is unable to perform MRI breath-hold maneuver * Patient is unable to perform spirometry maneuver * Patient is hospitalized or has had a major surgical procedure, major trauma requiring medical attention, or significant illness requiring medical attention within 4 weeks of Visit 1 * Patient has a blood pressure of \>150 mmHg systolic or \>95 mmHg diastolic on \>2 measurements done \>5 minutes apart at Visit 1 or Visit 2 * Patient has ECG abnormalities consistent with previous myocardial infarction, hypertrophic cardiomyopathy, ischemic heart disease or conduction system disease * In the opinion of the investigator, patient suffers from any physical, psychological or other condition(s) that might prevent performance of the MRI, such as severe claustrophobia * Patient has implanted mechanically, electrically or magnetically activated device or any metal in their body, which cannot be removed, including but not limited to pacemakers, neurostimulators, biostimulators, implanted insulin pumps, aneurysm clips, bioprosthesis, artificial limb, metallic fragment or foreign body, shunt, surgical staples (including clips or metallic sutures and/or ear implants) - at the discretion of the MRI Technologist.