This study aims to demonstrate a clinically significant improvement in Forced Expiratory Volume in one second (FEV1) in moderate to severe allergic asthmatics inadequately controlled by Inhaled Corticosteroid (ICS) therapy. Patients will be treated with QAW039, an active comparator, or placebo. This will be a randomized, placebo-controlled, dose-ranging, multi-centre trial.

Inclusion Criteria:

• Physician diagnosis of asthma, as per the Global Initiative for Asthma (GINA) (2009) guidelines, and currently prescribed Inhaled Corticosteroids (ICS) therapy.
• Patients with a pre-bronchodilator Forced Expiratory Volume in 1 second (FEV1) value of 40% to 80% of individual predicted value.
• Patients should be allergic or atopic, as diagnosed historically or prior to entry into the study.
• Patients who are demonstrated to have reversible airway obstruction or airways hyper-reactivity or have shown either of such responses in previous test(s) within the last year.
• An Asthma Control Questionnaire (ACQ) score ≥ 1.5 at randomization.

Exclusion Criteria:

• Pregnant or nursing (lactating) women, where pregnancy is defined as the state of a female after conception and until the termination of gestation, confirmed by a positive human chorionic gonadotropin (hCG) laboratory test (> 5 mIU/mL).
• Patients with serious co-morbidities including uncontrolled diabetes (HbA1c≥8%), heart failure, cancer, neurodegenerative diseases, rheumatoid arthritis and other autoimmune diseases, other lung diseases including chronic bronchitis, chronic obstructive pulmonary diseases or emphysema or other conditions characterized by eosinophilia and pulmonary symptoms (i.e. Churg-Strauss syndrome, allergic bronchopulmonary aspergillosis, eosinophilic pneumonia, etc.).
• Acute illness other than asthma at the start of the study
• History of life-threatening asthma, including a history of significant hypercarbia (pCO2>45mmHg), prior intubation, respiratory arrest, or seizures as a result of asthma.
• Patients who have had a respiratory tract infection within 4 weeks of the screening visit. Patients who develop a respiratory tract infection between screening and the randomization visit must be screen failed, and may be permitted to re-enroll at a later date.
• Current smokers or ex-smokers who stopped smoking within 6 months prior to screening or have a smoking history of ≥ 10 pack years.