This study looks at a medication called barzolvolimab for people with Chronic Spontaneous Urticaria (CSU), which is a condition causing persistent hives despite taking regular allergy medicines. It compares the effects of barzolvolimab to a placebo (a harmless pill) to see if it helps. The study has several parts: a 4-week screening period, a 24-week placebo-controlled period, a 28-week treatment period where everyone gets barzolvolimab, and a 16-week break period without treatment. To join, you must be at least 18 years old, have had CSU for at least 6 months, and be on a stable allergy medication. You shouldn’t join if you’re pregnant, nursing, or have other skin conditions or certain infections. You need to visit the study site regularly and keep a symptom diary. Your study doctor will discuss more criteria with you.

• Participation involves regular visits and keeping a symptom diary.
• The study lasts for over a year, with different treatment phases.
• You can't have certain other health conditions or be pregnant.