Patient description: A 39-year-old man came to the clinic with cough and shortness of breath that was not relieved by his inhaler. He had these symptoms for 5 days during the past 2 weeks. He doubled his oral corticosteroids in the past week. He is a chef with a history of asthma for 3 years, suffering from frequent cough, wheezing, and shortness of breath and chest tightness. The symptoms become more bothersome within 1-2 hours of starting work every day and worsen throughout the work week. His symptoms improve within 1-2 hours outside the workplace. Spirometry was performed revealing a forced expiratory volume in the first second (FEV1) of 63% of the predicted. His past medical history is significant for seasonal allergic rhinitis in the summer. He doesn't smoke or use illicit drugs. His family history is significant for asthma in his father and sister. He currently uses inhaled corticosteroid (ICS) and fluticasone 500 mcg/salmeterol 50 mcg, one puff twice daily.

Clinical trial eligibility criteria: eligible ages (years): 12.0-75.0,  Asthma with the diagnosis of allergic asthma >1 year duration who, in addition to the standards of the American Thoracic Society (ATS) meet the following with a positive prick skin test (diameter of wheal > 3 mm) to at least one perennial allergen (e.g. dust mite, animal dander, cockroaches), within the past 5 years or at Visit 1, to which the patient will be exposed on a regular basis (most days) for the duration of the study. A RAST test may be performed for patients with a borderline skin prick test result with total serum IgE level 30 to 700 IU/ml demonstrating 12% increase in FEV1 over baseline value within 30 minutes of taking up to 4 puffs salbutamol (albuterol) or nebulized salbutamol up to 5mg (or equivalent of alternative B-2 agonist) documented within the past year, at screening, during the run-in period or at baseline prior to randomization with FEV1 40-80% of predicted normal value for the patient (demonstrable at least 6 hours after short acting B-2 agonist use or 12 hours after long acting B-2 agonist use) at baseline who have either experienced at least two independent asthma exacerbations requiring unscheduled clinical intervention with a systemic corticosteroid in the past year. or been admitted to hospital (including intensive care unit) or received emergency room (including urgent care centers) treatment in the past 12 months for an asthma exacerbation, which in accordance with the GINA guidelines met all of the following for a severe exacerbation: 1. PEF or FEV1< 60% of predicted/personal best, or patient is too breathless to provide PEF. 2. No improvement after initial treatment and therefore requiring repeated treatment with inhaled B-2 agonist (high dose, spacer or nebulized). 3. Requiring treatment with systemic corticosteroids receiving high dose inhaled corticosteroid (at least 1000ug beclomethasone dipropionate or equivalent) and a regular inhaled long acting B-2 agonist for at least 3 months prior to screening and prior to at least two independent asthma exacerbations requiring unscheduled clinical intervention with a systemic corticosteroid in the past year or the severe asthma exacerbation requiring the hospitalization/ER visit who are receiving an ICS dosage > 1000ug beclomethasone dipropionate or equivalent and a regular inhaled long acting B-2 agonist for the last 4 weeks of the run-in period and at randomization (to be maintained throughout the study) whose asthma medication remains unchanged in the final 4 weeks of the run-in period (to be maintained throughout the study)