This study looks at how safe and effective a drug called dexpramipexole is for people aged 12 and up with severe eosinophilic asthma. Asthma is a condition where breathing can be difficult due to the swelling of airways. Eosinophilic asthma is a type where there are too many eosinophils, which are a type of white blood cell that can cause inflammation. Key Points: - **Duration**: The study involves several visits; check with the study team for specific time commitments. - **Eligibility**: Participants need a confirmed asthma diagnosis and meet specific health criteria. - **Risks/Benefits**: The study aims to help those with asthma not controlled by regular medicines, but there may be risks involved. Participants will have regular check-ups and tests to see how they respond to the medication. It’s important to follow the study rules and attend all appointments. Always talk to your doctor before deciding to join a study to understand the potential benefits and risks.

Note: Pregnant women, smokers, or those with certain medical conditions may not be able to participate.