This is a randomized, double-blind, parallel group, placebo-controlled study designed to evaluate the effect of a fixed 30 mg dose of benralizumab administered subcutaneously every 4 weeks on allergen-induced inflammation in subjects with mild atopic asthma challenged with an inhaled allergen.

This randomized, double-blind, parallel group, placebo-controlled study will evaluate the effect of a fixed 30 mg dose of benralizumab administered subcutaneously every 4 weeks for 3 doses on allergen-induced inflammation in subjects with mild atopic asthma challenged with an inhaled allergen.

Approximately 38 non-smoking men and women (18 - 65 years of age) corticosteroid-free (oral and inhaled) mild, atopic asthmatics who have demonstrated a dual (early and late) asthmatic response to inhaled allergen challenge at screening will be recruited to complete the study.

Inclusion Criteria:

1. Provision of informed consent prior to any study specific procedures
2. Female or male aged 18 to 65 years, inclusively, at the time of enrolment.
3. General good health
4. Mild, stable, allergic asthma and asthma therapy limited to inhaled, short-acting beta 2 agonists (not more than twice weekly)
5. Positive skin-prick test to at least one common aeroallergen

Exclusion Criteria:

1. Current lung disease other than mild allergic asthma
2. Any history or symptoms of disease, including, but not limited to, cardiovascular, neurologic, autoimmune or haematologic
3. Any clinically significant abnormal findings in laboratory test results in complete blood count, coagulation, chemistry panel and urinalysis at enrolment and during screening period
4. History of anaphylaxis to any biologic therapy or vaccine

From Visit 1a to Visit 17

This allergen challenge study was conducted in a mild, atopic asthma patient population, distinct from the current approved severe eosinophilic asthma indication.