Open-label Study to Assess Reduction of Background Asthma Medication While Sustaining Asthma Control and Clinical Remission With Tezepelumab in Patients 12-80yrs With Severe Asthma.

The objective of this study is to assess the potential for tezepelumab-treated patients (subcutaneous administration) to reduce maintenance therapy without loss of asthma control in adolescent and adults with severe asthma.. Study details include: 1. The study duration will be up to 72 weeks. 2. The treatment duration will be up to 68 weeks. 3. The visit frequency will be once every 4 weeks (Q4W).