 This interventional, open study will evaluate clinical data in relation to biomarkers in patients 12 to 75 years of age with severe oral corticosteroid OCS - dependent asthma. Patients with uncontrolled asthma will be offered an additional escalation of OCS at a dose of 0.5 mgkg for 7 days. Patients enrolled in this study would be eligible to be enrolled in a future placebo-controlled intervention study designed to measure the steroid-sparing effect of lebrikizumab. 