 A double-blind, placebo-controlled study to evaluate the efficacy and safety of two doses Dose 1 and Dose 2 of QAW039 compared with placebo over a 52-week treatment period in in each of the groups patients with severe asthma and high eosinophil counts and all patients with severe asthma. Efficacy will be measured by the rate of asthma exacerbations. In addition, asthma quality of life score, asthma control score and lung function will be assessed. Safety will be assessed by adverse event monitoring. 