This study is testing a new medication called **povorcitinib** to see how well it works and how safe it is for people with moderate to severe asthma. Asthma is a condition that makes it hard to breathe because the airways in the lungs are swollen. Doctors want to see if povorcitinib can help improve lung function, which is how well your lungs work. People who can join this study must have been diagnosed with asthma by a doctor and need to have been on certain asthma medications for at least a year. They also need to have had serious asthma attacks that required treatment in the past year. However, people who smoke or have other serious health problems cannot participate.

• Participants will receive one of three doses of povorcitinib.
• The study will involve several visits to the doctor over a period of time.
• Participants will be monitored closely for any side effects.