- Disease Severity: Subjects must be assessed as having life-threatening /serious debilitating asthma in order to enroll, as defined by the following: Subjects enrolled in MEA115588 must meet one of the following criteria: a) Subject has a history of at least one intubation during their lifetime; b) >=3 asthma exacerbations in the 12 months prior to screening for MEA115588; c) >=1 or more hospitalization for asthma exacerbation in the 12 months prior to screening for MEA115588. Subjects enrolled in MEA115575 must meet one of the following criteria: d) Subject has a history of at least one intubation during their lifetime; e) Their optimized dose at randomization in MEA115575 was >=10mg of prednisone; f) >=1 or more hospitalization for asthma exacerbation in the 12 months prior to screening for MEA115575.