A Study of GDC-0853 in Participants With Refractory Chronic Spontaneous Urticaria (CSU).

Exclusion Criteria

• •Treatment with omalizumab or other monoclonal antibody therapies used to treat CSU within 4 months prior to screening or primary nonresponse to omalizumab
• •Use of a non-biologic investigational drug or participation in an investigational study with a non-biologic drug within 30 days prior to study drug administration on Day 1 (or within 5 half-lives of the investigational product, whichever is greater)
• •Use of a biologic investigational therapy or participation in an investigational study involving biologic therapy within 90 days or 5 half-lives, whichever is greater, prior to study drug administration on Day 1
• •Previous treatment with GDC-0853 or other Bruton's tyrosine kinase (BTK) inhibitors
• •Participants whose urticaria is solely due to physical urticaria
• •Other diseases with symptoms of urticaria or angioedema, including urticarial vasculitis, urticaria pigmentosa, erythema multiforme, mastocytosis, hereditary or acquired angioedema, lymphoma, or leukemia
• •Atopic dermatitis, bullous pemphigoid, dermatitis herpetiformis, or other skin disease associated with itch such as psoriasis
• •Routine doses of the following medications within 30 days prior to screening: systemic or cutaneous (topical) corticosteroids (prescription or over the counter), hydroxychloroquine, methotrexate, cyclosporine, or cyclophosphamide
• •Prior utilization of intravenous (IV) steroids for treatment of laryngeal angioedema
• •Intravenous immunoglobulin G (IV IG) or plasmapheresis within 30 days prior to screening
• •History of anaphylactic shock without clearly identifiable avoidable antigen
• •Hypersensitivity to GDC-0853 or any component of the formulation
• •Major surgery within 8 weeks prior to screening or surgery planned prior to end of study (12 weeks after randomization)
• •Require any prohibited concomitant medications
• •History of live attenuated vaccine within 6 weeks prior to randomization or requirement to receive these vaccinations at any time during study drug treatment
• •Evidence of clinically significant cardiac, neurologic, psychiatric, pulmonary, renal, hepatic, endocrine, metabolic, or gastrointestinal (GI) disease that, in the investigator's opinion, would compromise the safety of the participant, interfere with the interpretation of the study results or otherwise preclude participant participation
• •Current treatment with astemizole, terfenadine, and/or ebastine
• •Uncontrolled disease states, such as asthma, psoriasis, or inflammatory bowel disease, where flares are commonly treated with oral or parenteral corticosteroids