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 ≥ 6 months before randomization. * The presence of itch and hives for ≥6 consecutive weeks at any time prior to randomization 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 7 days 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 their chronic 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 the investigators 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 where flares 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.