A Study to Evaluate the Safety, Tolerability, Pharmacokinetics, and Pharmacodynamics of Multiple-Ascending Doses of BGB-16673 in Adults With Chronic Spontaneous Urticaria

Inclusion Criteria:

• Participants must be diagnosed with chronic spontaneous urticaria (CSU) for ≥ 6months before randomization.

• The presence of itch and hives for ≥6 consecutive weeks at any time prior torandomization despite the use of second-generation H1-antihistamines

• UAS7≥16 and HSS7≥8 during the 7 days before randomization

• Participants must not have had any missing UAS7 entry (ISS7 and HSS7) during the 7days before randomization

• Presence of hives must have been documented within 3 months before randomization

Exclusion Criteria:

• Participants who have a clearly defined, predominating or sole trigger for theirchronic urticaria (chronic inducible urticaria), including urticaria factitia (symptomatic dermographism) or cold, heat, solar, pressure, delayed pressure,aquagenic, cholinergic, or contact urticaria.

• Other diseases with symptoms of urticaria or angioedema

• Any other skin disease associated with chronic itching that might influence in theinvestigators opinion the study evaluations and results, eg, atopic dermatitis,bullous pemphigoid, dermatitis herpetiformis, senile pruritus, or psoriasis.

• Any uncontrolled disease state, including asthma or inflammatory bowel disease whereflares are commonly treated with oral or parenteral corticosteroids.

• Significant bleeding risk or coagulopathy.

• Prior exposure to any BTK inhibitors or protein degraders.

NOTE: Other protocol defined Inclusion/Exclusion criteria may apply.