A Study of LY4005130 in Adult Participants With Severe Alopecia Areata (Hair Loss)

The purpose of this study is to evaluate how well LY4005130 works in participants with severe alopecia areata (hair loss) when compared with placebo, and how well it's tolerated and what side effects may occur. Blood tests will be performed to investigate how the body processes the study drug and how the study drug affects the body. The study drug will be administered intravenously (IV) (into a vein in the arm). The study will last approximately 48 weeks, including screening.