A Safety Extension Study With Benralizumab for Asthmatic Adults on Inhaled Corticosteroid Plus Long-acting β2 Agonist

Inclusion Criteria: * Informed consent for study participation must be obtained prior to any study related procedures being performed and according to international guidelines and/or applicable European Union guidelines. * Female and male patients who have completed at least 16 and not more than 40 weeks in Study D3250C00021. * Women of childbearing potential (WOCBP) must agree to use an effective form of birth control throughout the study duration and for 16 weeks after the last dose of Investigational Product (IP) * For WOCBP only: Have a negative urine pregnancy test prior to administration of IP at Visit 1. * All male patients who are sexually active must agree to use a double barrier method of contraception (condom with spermicide) from the first dose of IP until 16 weeks after their last dose. Exclusion Criteria: * Any disorder including but not limited to cardiovascular, gastrointestinal, hepatic, renal, neurological, musculoskeletal, infectious, endocrine, metabolic, hematological, psychiatric or major physical impairment that is not stable in the opinion of the Investigator and could: * Affect the safety of the patient throughout the study * Influence the findings of the study or their interpretations * Impede the patient's ability to complete the entire duration of study * A helminth parasitic infection diagnosed during a predecessor study that has either required hospitalization, has not been treated, has been incompletely treated or has failed to respond to standard of care therapy * Any clinically significant change in physical examination, vital signs, ECG, hematology, clinical chemistry, or urinalysis during the predecessor study which in the opinion of the investigator may put the patient at risk because of his/her participation in the study, or may influence the results of the study, or interfere with the patient's ability to complete the entire duration of the study * Current malignancy or malignancy that developed during the predecessor study (subjects that had basal cell carcinoma, localized squamous cell carcinoma of the skin which was resected for cure, or in situ carcinoma of the cervix that has been treated/cured will not be excluded). * Receipt of live attenuated vaccines within 30 days prior to initiation of treatment in this study, during the treatment period, and for 16 weeks (5 half-lives) after the last dose of the IP * Receipt of immunoglobulin or blood products within 30 days prior to Visit 1 * Planned major surgical procedures during the conduct of the study * Previous participation in the present study * Concurrent enrolment in another drug-related interventional clinical trial * AstraZeneca staff involved in the planning and/or conduct of the study * Employees of the study center or any other individuals involved with the conduct of the study or immediate family members of such individuals * Patients with important protocol deviations in the predecessor study at the discretion of the Sponsor * Patients with ongoing serious adverse events (SAEs) from the prior study should not be enrolled into the this extension study until the SAE has resolved