A Phase 3 Study of Barzolvolimab in Participants With Chronic Spontaneous Urticaria

Open to people ages 18 years and up

1. Males and females, >/= 18 years of age.
2. Chronic spontaneous urticaria (CSU) >/= 6 months prior to Screening (Visit 1).

3. CSU despite the use of a stable regimen of second generation non-sedating

   H1-antihistamine as defined by:

   1. The presence of hives for >/= 6 weeks at any time prior to Visit 1 despite the use of non-sedating H1-antihistamines.
   2. Must be on a stable regimen of second generation non-sedating H1-antihistamine for >/= 4 weeks prior to study treatment.
   3. UAS7 of >/= 16 and ISS7 of >/= 8 during the 7 days prior to study treatment.
4. Normal blood counts and liver function tests.
5. Both males and females of child-bearing potential must agree to use highly effective contraceptives during the study and for 150 days after treatment.
6. Willing and able to complete a daily symptom electronic diary and comply with study visits.
7. Participants with and without prior biologic experience are eligible.

1. Women who are pregnant or nursing.
2. Chronic urticaria whose predominant manifestation is due to CIndU.
3. Other diseases associated with urticaria.
4. Active pruritic skin condition in addition to CSU.
5. Medical condition that would cause additional risk or interfere with study procedures.
6. Known HIV, hepatitis B or hepatitis C infection.
7. Vaccination of a live vaccine within 30 days prior to Screening (Visit 1) (subjects must agree to avoid live vaccinations during the study). Inactivated vaccines are allowed such as seasonal influenza injection or authorized COVID-19 vaccine.
8. History of anaphylaxis.
9. Prior treatment with barzolvolimab.

There are additional criteria that your study doctor will review with you to confirm you are eligible for the study.