A Phase 2a Study of TAS5315 in Patients With Chronic Spontaneous Urticaria

Key Inclusion Criteria: * Aged 18 to 75 years * Diagnosis of chronic spontaneous urticaria (CSU) * Presence of itch and hives for at least 6 consecutive weeks prior to screening in spite of use of non-sedating H1-antihistamines for CSU * UAS7 score ≥ 16 and HSS7 score ≥ 8 during 7 days prior to study entry * In-clinic UAS ≥ 4 on study entry * Willing and able to complete and Participate Daily for the duration of the study Key Exclusion Criteria * Diseases other than CSU with symptoms of urticaria or angioedema, including urticarial vasculitis, erythema multiforme, mastocytosis, or hereditary or acquired angioedema * Atopic dermatitis, psoriasis, ichthyosis, or other skin disease associated with chronic itching * Bleeding diathesis * Uncontrolled hypertension disease states * Treatment with omalizumab or other humanized anti-human IgE monoclonal antibody therapies used to treat CSU within 4 months prior to screening * Nonresponse to omalizumab or other humanized anti-human IgE monoclonal antibody therapies * Have been treated with other Bruton's Tyrosine Kinase inhibitors * Pregnant or lactating women