This study investigates the effect of an investigational medication on preventing or slowing the decline of lung function in adults with uncontrolled moderate to severe asthma. Asthma is a condition where the airways narrow and swell, producing extra mucus, which can make breathing difficult. This study involves comparing the investigational medication with the standard of care therapy to see which is more effective in managing asthma symptoms.

Participants in this study will be randomly assigned to one of two study arms. They will receive either the investigational medication or a placebo, which is an inactive substance that looks like the investigational medicine but does not contain any medicine. The study is double-blinded, meaning neither the participants nor the researchers will know who receives the investigational medication or the placebo.

• Who can participate: Adults aged 18 years and older with a diagnosis of asthma for at least 12 months may participate. Key eligibility includes treatment with medium to high dose inhaled corticosteroids and a second controller, and a history of severe exacerbation in the past year.
• Study details: Participants will be randomly assigned to receive either the investigational medication or a placebo. They will undergo regular assessments to monitor lung function and asthma symptoms.
• Study timelines: The study will last 3 years.